Next Article in Journal
A Critical Review of Overheating Risk Assessment Criteria in International and National Regulations—Gaps and Suggestions for Improvements
Previous Article in Journal
Assessment of Possibilities of Using Local Renewable Resources in Road Infrastructure Facilities—A Case Study from Poland
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Energies
Volume 17
Issue 24
10.3390/en17246353
energies-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Review

Aspects of Relevance of Hybrid Power Plants in Control and Stability of Weak Grids

by
Fatemeh Shahnazian
1,*,
Kaushik Das
1,
Ruifeng Yan
2 and
Poul Sørensen
1
1
Department of Wind and Energy Systems, Technical University of Denmark (DTU), 4000 Roskilde, Denmark
2
School of Information Technology and Electrical Engineering, University of Queensland, Brisbane 4072, Australia
*
Author to whom correspondence should be addressed.
Energies 2024, 17(24), 6353; https://doi.org/10.3390/en17246353
Submission received: 7 November 2024 / Revised: 27 November 2024 / Accepted: 4 December 2024 / Published: 17 December 2024
(This article belongs to the Section F1: Electrical Power System)
Browse Figures
Versions Notes

Abstract

:
This paper reviews the possible contributions of Hybrid Power Plants (HPPs) to support weak grids while maintaining the desired system stability. Moving towards a converter-dominant power system with less inherent inertia and distant connections to the nearest synchronous generator, frequency and voltage controls are becoming more critical to ensure the stability of the weak grid. In this regard, state-of-the-art literature is reviewed for frequency and voltage controllers in single-technology power plants, like wind and solar power plants. The contribution of this paper lies in providing a clear overview of available literature in terms of frequency and voltage control stages, regardless of the utilized control method. On the other hand, focus has been put on the increased utilization of HPPs to provide more flexibility, increased availability, and reduced variability through the combination of various sources, i.e., wind, solar, and storage. Furthermore, investigating the specific capabilities and challenges of HPPs, this review shows that very little literature has been conducted on voltage control using HPPs. Finally, the aspect of relevance of HPPs is discussed in the control and stability of modern power systems.

1. Introduction

Prospects for clean energy production have profoundly changed the structure of modern power systems during the last decades [1]. With that in mind, renewable energy resources are clearly maintaining an increasing share of electricity generation due to environmental concerns and the maturity of the technological features as well as the improved economic aspects [2]. The EU climate and energy targets for 2030 are set to increase the share of renewables to at least 39% of EU energy use, while Denmark aims for at least a 55% share of renewables in the gross final consumption of energy use by 2030 [3].
This increased share of renewables will eventually lead to a more converter-dominant power system since the converter-connected generation is replacing conventional fossil fuel generators [4]. Therefore, since fewer conventional synchronous power plants are connected, the modern power system will be prone to frequency instabilities due to the lower inertia [5]. On the other hand, most of the potential installation sites to exploit clean energy are usually dominated by far locations with long and low-capacity connections to the nearest synchronous generator. This long and low-capacity connection to the nearest synchronous generator represents a high equivalent impedance which inevitably decreases the grid short-circuit current levels [6]. As a result, voltage stability assessments of such weak grids also become important since they face higher voltage sensitivity regarding reactive power compared to conventional strong grids [7].
Various solutions have been proposed in the literature to overcome the challenges regarding the lack of appropriate inertial response in the system [8,9,10]. The most recent research trends are focused on different methods of grid forming controls to improve the power system stability, e.g., droop-based controllers [11,12], the concept of the virtual synchronous generator (VSG) [13,14], synchronous power controller (SPC) [15], etc. The abovementioned methods have also been applied to different configurations of renewable energy resources (e.g., wind, solar, etc.) to demonstrate the different potentials and the provided capabilities [16]. Besides fast frequency control, the power system’s need to maintain a steady frequency after an imbalance between generation and load asks for further frequency support through primary and secondary frequency controls, which will be discussed in detail in the following sections. Additionally, several solutions have been proposed considering reactive power and voltage control in the presence of wind and solar integrations; however, most of the present literature is focused on renewable single-technology power plants [17,18,19,20]. Voltage stability demonstrates the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition. This can be further classified into small and large disturbance voltage stability [21]. Similar to frequency stability, voltage stability is categorized as short-term and long-term stability, depending on the time span of the controller action, and will be discussed in detail later on. It is also good to mention that several review papers have been published on frequency and voltage control in renewable single-technology power plants. To mention a few recent studies, papers [22,23] mainly focus on the definition and explanation of available frequency control strategies in wind and solar power plants while studying their impact on the stability of power systems. With a more generalized view concerning the massive integration of renewables, grid frequency stability challenges have been reviewed in [24], while [25] provides significant information about the models and parameters used in frequency control studies. Unlike frequency control, voltage stability issues in renewable-based networks have been less studied. Paper [26] classifies the implemented reactive power control techniques in solar power plants into fixed power factor, constant active power control, and constant reactive power control. Explaining the basics of each method, the paper shows that the simultaneous implementation of two control methods can improve the stability of the system. Also, the robustness of centralized, decentralized, and distributed voltage control strategies to variations in grid characteristics have been evaluated in [27]. Considering the abovementioned reviews, a clear overview of the available literature in terms of frequency and voltage control stages, regardless of the utilized control method, has been neglected and will be covered in this paper.
Despite the above-mentioned challenges due to the increasing share of renewables, converter-based renewable generation will also provide new opportunities. In this regard, the converters can provide a faster control response compared to synchronous generators. However, due to the variable wind speed and solar irradiation, renewable energy resources usually demonstrate less availability than conventional thermal power plants [28,29]. Thus, renewable energy resources usually represent inherent volatility and uncertainty with a high dependency on environmental conditions [30,31]. As a consequence, the focus has been put on the increased utilization of Hybrid Power Plant (HPP) configurations in order to provide more flexibility through the combination of various sources, i.e., wind, solar, storage, etc. [32]. This way, more capabilities can be provided through HPPs which can demonstrate reduced variability and increased availability as well.
Based on the document published by WindEurope [33], HPP can be defined as a power-generating facility that produces electrical energy through more than one power-generating module, which all share one connection point to the network. It is good to mention that this definition covers a wide range of primary energy resources; however, this paper only considers the combination of renewable-based generation (wind and solar) with or without storage while referring to the term HPP. Based on this, several configurations of wind, solar, and storage have been discussed for co-located hybrid power plants in [34] which also briefly introduces pilot HPP projects running by Vestas as the first utility-scale HPP in the world. It is also good to mention that there are different types of HPPs, considering how the various generating modules are integrated. In this regard, as shown in Figure 1a, we can have WPP and SPP layouts that share the same grid connection point, or otherwise, Photovoltaic (PV) panels can be individually integrated with the Wind Turbines (WTs) (Figure 1b) [33]. Generally, both configurations can increase the capacity factor of installation, and thus, maximize the grid connection capacity usage. In addition to that, sharing the grid connection point and substation in both topologies can lead to reduced CAPEX and permitting time. Joint project development and O&M services as well as the adaptability of HPP based on different site conditions and the easier optimization of the substation sizing are also among the common advantages of these two topologies. The first topology shown in Figure 1a is developed more than the other one since the configuration is simpler and more flexible to develop and size with storage integrated. The other topology is an alternative where solar inverters can be eliminated in certain cases, and therefore, the evacuation capacity of WTs can be used for solar power in this configuration. On the other hand, the connection and metering processes of these topologies are new to the authorities and standardization is yet needed. Furthermore, the second topology faces additional challenges, e.g., potential shading of PV panels from WT blades, limited PV capacity due to WT’s power export capacity and space, and the limitation of the provision of ancillary services since the solar inverters are not interfaced with the grid [33].
The concept of HPPs has gained global attention lately due to the numerous advantages that come from combining renewable sources plus energy storage [35]. In this regard, a few advantages and benefits of HPPs can be mentioned as follows:
  • A combination of wind and solar power enhances the system efficiency and power reliability since the variability and power fluctuations will be less here than in an individual RES due to the complementary nature of wind and solar energy. It is good to mention that as the negative correlation becomes stronger, the utilization of the grid connection will be better while the energy output will be more balanced [36].
  • In addition to that, power curtailment in future power systems with a large integration of renewables will become more viable in the presence of the storage unit. While generating hydrogen for future use in a fuel cell can offer long-term storage solutions, battery stacks and supercapacitors are considered short-term storage options [37]. The literature shows an expanded interest in hydrogen energy storage systems during the past years which can improve operational efficiency as well as the environmental sustainability of this technology. By ensuring a reliable power supply, reducing costs, and increasing flexibility, the hydrogen energy storage industry has essential effects on HPPs [38]. Also, the flexibility of battery energy storage in providing both ramps up and down in active power output within short time responses can improve the HPP capability of frequency support [39]. In this regard, fast frequency support from HPPs has been proposed by [35] which considers integrating supercapacitors into the HPP configuration.
  • Another important aspect of HPPs is the optimal utilization of the electrical infrastructure and its enhanced controllability. Since wind and solar plants have low-capacity factors, the electrical infrastructure remains unutilized most of the time in single-technology power plants. Therefore, combining these technologies together can increase the annual energy production and capacity factor while reducing the LCOE as well [36].
On the other hand, the hybridization of single-technology power plants can face some challenges. Coupling renewable energy with a battery behind the point of interconnection can reduce the operational flexibility of the battery since the charging and discharging cannot be conducted independently anymore [40]. In addition to that, there are only a few hybrid-specific policy schemes currently available since HPP is a new development. In this regard, if specific challenges of HPP are neglected, costs and uncertainty will arise. Also, it is good to mention that another aspect that needs to be standardized for HPPs is metering. Finally, in order to benefit from the complementarity of wind and solar generation, the total capacity of the installed HPP must be higher than the existing grid connection capacity. At the same time, developers need to be flexible in sizing requirements based on the optimized generation output of the HPP [33]. Overall, a summary of the pros and cons of hybrid power plant projects has been provided in Table 1.
Considering the current literature, frequency and voltage control have been individually studied in a few papers concerning HPP-like configurations. However, there is an obvious gap in reviewing these methods and categorizing them for comparison purposes; this will be covered in this paper.
This paper studies the possible contributions of hybrid power plants in weak grid control architectures in order to maintain the desired stability criteria. Therefore, the contributions of this review paper can be listed as follows:
  • State-of-the-art literature is reviewed for both frequency and voltage stability challenges in single-technology power plants in Section 2. The novelty of this paper compared to previous studies lies in providing an overview of available literature in terms of frequency and voltage control stages, regardless of the utilized control method.
  • In Section 3, the current literature has been studied for frequency and voltage controls of hybrid power plants and the shortcomings have been mentioned. The novelty of this review shows that very little research has been conducted on voltage support and reactive power control using HPPs which highlights the need to contribute more studies to this field.
  • Finally, in Section 4, the aspects of the relevance of HPPs will be discussed in the control and stability of modern power systems since this technology has been gaining more and more attention recently.

2. Control Approaches in Single-Technology Power Plants

In this section, various frequency and voltage control approaches are reviewed for single-technology power plants based on the existing literature.

2.1. Frequency Control

Following a major power imbalance, three main stages can be distinguished within the typical frequency response of the power system, as demonstrated in Figure 2: Fast Frequency Response (FFR), Frequency Containment Reserve (FCR), and Frequency Restoration Reserve (FRR) [41,42].
FFR is the fast reaction of the generators (or the converter-based generation units) to the active power and frequency dynamics of the power system. This stage has been traditionally named inertial response (IR) since it was associated with the natural uncontrollable inertial response of the synchronous generators in the power system [43,44]. It is good to mention that the most recent definitions distinguish between the two. As mentioned by [45], the synthetic inertia of a unit is its controlled contribution of electrical torque which is proportional to the Rate of Change of Frequency (ROCOF); FFR is defined as its controlled contribution of electrical torque, which is quickly responding to frequency changes to counteract the effect of a reduced inertial response. To clarify, the synthetic inertial response can be considered as a subset of FFR. The detection time for FFR including the frequency measurement is typically less than one second while the recovery time during this stage should be less than 10 s [41]. Following FFR, FCR refers to an automatically activated corrective measure for power balancing and bringing the frequency to a steady state in a generation unit while FRR adjusts the active power set points to recover the nominal frequency value of the generation units. It is good to mention that the last two stages are also called Primary Frequency Response (PFR) and Secondary Frequency Response (SFR) in the literature [46,47]. It is also good to mention that the full activation time for FCR lies over some seconds (typically less than 30 s) while FFR is expected to restore the system frequency to the nominal value within 15 min after the event occurrence [41].
Various control strategies have been proposed in the literature in order to support the active power and frequency dynamics of the power system, considering single-technology power plants. The importance of frequency control as a critical component of power system stability arises as the share of conventional synchronous generation decreases while integrating renewables into the power system. In this regard, wind and solar power plants are required to provide frequency support with or without auxiliary devices. These control strategies can vary in complexity and performance and reduce the frequency oscillations, i.e., droop and de-loading, load frequency control, inertia emulation, etc. [48,49,50].
Without auxiliary devices, frequency control can be classified into three categories in wind power plants [51]:
  • Wind turbine level control such as inertial control [52], droop control [53], and de-loading control [54,55]
  • Wind farm level control including central or local control methods [51,56,57]
  • Power system level control such as wind-thermal coordination control.
Other than this, auxiliary devices including batteries [58,59], supercapacitors [60], flexible AC transmission systems (FACTS) devices [61], and superconducting magnetic energy storage (SMES) [62] can also be used to improve the frequency stability of wind power plants.
Similar to the above, for solar power plants, there are several frequency control methods that do not use any auxiliary devices, including the inertial response technique [63], de-loading technique [64], grid forming control techniques [65], artificial neural network [66,67,68], and other soft computing approaches [69]. This is while battery storage systems [70], flywheel energy storage [71,72], and superconducting storage devices [73,74] can also be used as auxiliary devices for frequency control in solar power plants.
Table 2 represents an overview of the proposed frequency control methods, considering Wind Power Plants (WPPs), Solar Power Plants (SPPs), and storage units. The abovementioned approaches are further classified into fast frequency control (FFC), primary frequency control(PFC), and secondary frequency control (SFC) for each case. In addition to that, plant level controllers (P) and asset level controllers (A) have been distinguished for wind and solar power plants while the utilized storage technology has also been modified for each relevant case. The classification of the available literature in Table 2 shows that for frequency control in wind power plants, the controllers are applied at both the plant level and asset level (turbine level). This is while the majority of proposed frequency controllers using solar plants are employed at the plant level. It is also good to mention that based on the reviewed literature, storage technologies are mostly used for PFC and solar plants seem to be rarely used for SFC. This table demonstrates the contribution of each technology in various frequency control stages and the neglected potential in each case.
Among various frequency control methods applied at different frequency dynamic stages, the concept of grid-forming control has attracted a lot of attention in recent years. The increased implementation of renewable energy sources in the grid results in weaker networks which highlights the importance of frequency control as early as the synchronization stage of the renewable with the connected grid. This is why grid-forming controllers are becoming more and more popular, and the current frequency control literature is mostly focused on these controllers. Considering the important and increasing role of grid-forming controllers in the frequency stability of weak grids, SubSection 2.1.1 is dedicated to analyzing current trends in grid-forming controllers.

2.1.1. Analysis of Recent Trends in Grid-Forming Controllers

As previously mentioned, Grid-Forming (GFM) controllers can provide inertia support for grids to improve system stability. Considering their crucial role in ensuring reliable grid performance, it is important to discuss various GFM control methods. Explaining the changing dynamics of the grid, ref. [106] classifies grid-connected inverter control to Grid-Following (GFL) and grid-forming methods. Explaining the fundamentals of each approach, it is mentioned that GFM can maintain a stiff voltage operation under step phase changes in voltage phasors, while GFL might face voltage violations before resynchronization with the grid. Various studies explain different GFM control approaches in detail which can be categorized as follows: droop control, Power Synchronization Control (PSC), synchronous machine emulation controllers (e.g., Virtual Synchronous Generator (VSG) Control and synchronverter), Virtual Oscillator Control (VOC), etc. Describing each method thoroughly, ref. [107] investigates different characteristics of each method while introducing their typical application scenarios in the power system. Considering the most recent commissioned projects in Australia, the UK and the US, the current challenges of adding the GFM trend into the existing power systems have been discussed in [108], i.e., small signal and transient stability, stand-alone and grid-connected mode transition, over-current protection, and Fault Ride-through (FRT). Research shows that most of the GFM control methodologies are communication-less, dispatchable, and employ overcurrent protection. Also, besides the droop-based controllers, other approaches have tunable and adaptive virtual inertia and damping parameters [108]. It is also good to mention that some of the most recent publications in 2024 focus on the leading role of GFMs in future power systems. In this regard, ref. [109] assesses GFM performance and robustness across various operational scenarios using frequency and time domain simulations. This evaluation of controllers can reveal their strengths and weaknesses to properly select the most appropriate controller for each desired practical application. In addition to that, ref. [110] explores the basic and advanced GFM control methods to interpret their ability to enhance the overall system stability. Thus, detailed analysis and performance comparisons have been provided for advanced control methods such as predictive control, model predictive control, and adaptive control which utilize innovative algorithms and real-time data to improve the overall system efficiency.

2.2. Voltage Control

Most renewable energy sites are located far from the synchronous generation centers, and therefore, connected to the weak end of the grid [111]. The increasing share of renewable energy sources can lead to a number of major challenges in the grid, e.g., voltage rise, voltage fluctuations, interactions with voltage regulating devices, and reverse power flow [112]. In order to overcome these issues, various devices have been utilized by wind farms to provide continuous and discrete voltage control support as follows:
  • Wind turbine converters: the rotor-side converters in Double-Fed Induction Generator (DFIG) [113] and full-scale turbines [114] are used to support reactive power and maintain appropriate voltage. Traditionally, voltage control, reactive power control, and power factor control can be applied to the converter. It should be noted that voltage control faces limitations based on the reactive power capacity of the converter [115]. Paper [116] proposes a variable droop gain control method that can use the full capability of each wind turbine converter to mitigate voltage fluctuations.
  • On load tap changing transformer (OLTC): Reference [117] performs a reactive power-based voltage support assessment for wind turbines under stressed voltage conditions. In this regard, the wind power plant’s voltage support capability is increased by controlling the tap-changing transformer.
  • Capacitors/inductors: These elements can be used to provide suitable reactive power and voltage interactions with the grid [111].
  • Other shunt devices such as static var compensators (SVC) and static synchronous compensators (STATCOM): there are several papers studying various capabilities of SVC [118] and STATCOM [119,120,121] to improve the voltage stability of the power system.
However, combining several of these technologies requires coordination to avoid unintended or even destabilizing operations. Thus, coordinated controls have been proposed and studied in the literature. These control methods can be further categorized as centralized, decentralized, and distributed control [27]. It is also good to mention that considering the computational burden in the central control methods or the complexity of the communication network in the decentralized control strategies, a hybrid control method is proposed in [122] which uses the distributed consensus control and the central model predictive control together.
In addition to that, optimization-based voltage controllers have also been studied in recent years [123]. In this regard, paper [124] proposes a reactive power and voltage control scheme considering the stochastic deviation from baseline wind power, while [125] proposes an autonomous wind farm voltage control strategy considering the impact of voltage support ability from the integrated grid.
The converters in solar power plants can also be utilized to regulate grid voltage (mostly during nighttime) [112,126]. Similar coordinated controls and optimization methods are utilized here as well. It should be noted that the voltage control problem is becoming more challenging in bulk power systems. The coordination process becomes more detailed and sensitive due to the increasing complexity and dimensionality, together with the growing stochastic and dynamic behaviors of these systems [127]. To overcome these limitations, artificial intelligence and machine learning-based approaches have been introduced recently. In this regard, several studies address the novel contributions of these methods in solar or wind power plants [128,129,130,131,132,133].
Table 3 presents an overview of the proposed voltage control methods considering wind and solar power plants and energy storage. The abovementioned controllers are further classified into fault ride-through (FRT), primary voltage control (PrVC), and secondary voltage control (SeVC) for each studied case. In this regard, FRT is the capability of a generation unit to remain connected to the grid during faults while injecting reactive power to support transient voltage [134]. In addition to that, PrVC has a short response time (several seconds) and is responsible for the regulation of voltage at the inner loop of control [135]. As an example, droop control is mostly used at the primary control level. On the other hand, the operation time of the secondary control is longer than the primary control (several minutes) [136]. At this control level, reactive power sharing, coordinated control, voltage quality, etc., are considered as the main objectives [137]. Following this, as in Table 2, plant level controllers (P) and asset level controllers (A) have been distinguished for wind and solar power plants in Table 3 while the utilized storage technology has also been modified for each relevant case. It can be seen that voltage control is mostly embedded through plant-level controllers in wind and solar power plants. Table 3 also shows that wind power plants are capable of providing voltage support in all three stages of FRT, PrVC, and SeVC. This is while solar plants have less potential in voltage support and mostly provide short-term services like FRT. In addition to that, it can be seen that storage technologies are only utilized for primary and secondary voltage control stages since battery performance is not suitable for fast dynamics.

3. Control Approaches in Hybrid Power Plants

Similar to what has been discussed in the previous sections, HPPs can be used for voltage and frequency control. The first thing to mention here is the superiority of HPPs compared to single-technology power plants in reassuring power generation stability through having a higher number of converters. Due to their stochastic nature, the usage of one of these renewable sources can lead to the potential reduction or loss of power supply; using a combination of them, especially in the presence of an energy storage device provides an energy capacity that is less dependent on changes in climate conditions [151]. Another point to mention here is the problems that arise as the grid becomes weak. This will be more deeply discussed in the next section; however, it should be mentioned that very few studies have addressed voltage control in the currently available literature on hybrid power plants. For example, ref. [152] demonstrates the role of battery energy storage in the mitigation of rapid voltage fluctuations due to variations in solar and wind generation. In addition to that, ref. [151] uses statistical indices of solar irradiations and wind speed data to model the power flow and study voltage fluctuations in microgrids with an HPP configuration. A droop-based frequency and voltage control method is also proposed in [153] which uses energy storage to balance the renewable generation and the load to maintain stability.
There are relatively more studies on the frequency control of hybrid configurations. Most studies do not mention the specific HPP definition but have more or less the same layout. The combination of wind, solar, and one or more types of storage has been used in [154,155] while others combine one renewable source with storage [156,157,158]. It is also good to mention that some studies focus on more simple approaches like PID controllers and droop control [155,159,160,161], while others propose more advanced methods like virtual inertia [46], model predictive control [55,162], and hierarchical control [163]. Table 4 presents an overview of the proposed control objectives in hybrid configurations. To the best knowledge of the authors, there is very little literature on voltage support and reactive power control using HPPs. This highlights the need to contribute more studies to this field, which will be further discussed in the next section.

4. Relevance of Hybrid Power Plants in Control and Stability of Weak Grids

Frequency and voltage stability (as the two main stability factors) have been studied in this paper for renewable single technology and also hybrid power plants. Following that, this section will address the relevance of HPPs in the control and stability of weak grids. The term weak grid corresponds to the small short-circuit ratio of the grid which can happen in the presence of long low-capacity lines of renewable connection to the grid. There are several challenges associated with weak grids such as fragile voltage and frequency support, weak fault ride-through capabilities, etc. [167]. Therefore, some control approaches are superior to others in weak grid operation which can easily happen while integrating large amounts of renewables to the grid. In this regard, the grid-following control should generally be used in strong power systems since it uses a phase-locked loop (PLL) to follow the operating phase angle of the grid and cannot provide any frequency or voltage support [168]. Several methods are proposed to improve the performance of PLLs and grid-following controllers in case of weak grid operation [169]. On the contrary, grid-forming controllers are more suitable under weak grid conditions since they are able to support grid frequency and voltage during disturbances [170].
It is important to mention that considering a weak grid scenario, the utilization of hybrid power plants can improve schedulable power dispatch and provide a more reliable power supply [33]. However, there are various challenges which need to be addressed as follows:
  • Various control layers: There are several controllers at different control levels in an HPP (one more control level in HPP than in single-technology power plants) which highlights the necessity of coordination. The hierarchical control of HPPs has been proposed in [171] to address this issue. As shown in Figure 3, there are three main control layers: the HPP control level, the technology plant control level, and the asset control level from top to bottom. Each of these control layers provides appropriate command and parameter references for the lower control level. This is while system states and measurements are sent backward to the higher control levels as feedback signals. It is important to mention that these control layers have different time scales. In this regard, the higher-level controller should respond slower than the lower-level controller and vice versa. The appropriate and efficient collaboration of these control layers is of high importance in HPPs.
  • Oscillations: It is well known that a large gain in voltage control can lead to instability, especially when the grid is weak and the grid impedance is high [172]. Research shows that there are three main factors that can lead to the oscillations: communication delay between plant and asset level control, high volt/var sensitivity at a high power exporting level, and the volt/var feedback system consisting of plant and asset level controllers as well as the grid impact [173]. In this regard, we can see that lower grid strength and higher power exporting level can make the voltage more sensitive to reactive power, and the stability margin is reduced this way (because the grid is weak). Time delays regarding the various control levels and the interaction between them can be another source of oscillations and instability (because of the presence of HPP configuration). Other reasons for instability like insufficient damping in the PLL can be studied as well [174].
  • Simulation study platforms: While some early studies show very few discrepancies (especially in the long-term stability of the system) between Electro-Magnetic Transient (EMT) and Root Mean Square (RMS) simulations [175], most recent studies emphasize the differences between the two. This is due to the shift in generation modules from synchronous generators to converter-based resources. In this regard, modeling challenges arise, including the need for EMT models and simulations since positive sequence simulators and phasor-based models are not adequate anymore to assess the transient stability issues [176]. The advantage of RMS over EMT simulation is that the simulation time will significantly reduce, and therefore, longer events and more complex systems can be simulated. However, this comes at the cost of losing fast electromagnetic transients. Therefore, it is important to consider the fact that numerous stability issues arise while integrating dominating amounts of converter-based generation that can only be accurately captured with EMT models [177].
In addition to the above, it should be mentioned that the large-scale integration of HPPs usually faces specific challenges and limitations. In this regard, several cases of large renewable integration around the world have shown stability challenges based on literature review and publicly available information. In Australia and Hawaii, a reduction in system strength due to the increased share of renewables has greatly limited the grid integration capacity of renewables. Also, in China and Texas, voltage oscillations at different frequencies have been reported. In these cases, the main reasons are believed to be the interactions between converter-based power plants in a weak grid, time delays in switching devices, and digital control. Various cases in Texas, Chile, and Nigeria show that as the sensitivity of dV/dQ grows in a weak grid, additional reactive power support is required to maintain voltage stability. Therefore, the connection of a reactive power supply has been proposed to improve the voltage control and reactive power support in such cases [178]. Considering the abovementioned challenges in this section together with the provided review of the available literature on HPP controllers in Section 3, the relevance of HPPs in the control and stability of weak grids remains almost untouched and requires further investigation in future studies.

5. Conclusions

This paper presents the aspects of the relevance of hybrid power plants in the control and stability of weak grids. In this regard, first, an overview of frequency and voltage control methods has been provided, considering renewable single-technology power plants (i.e., solar and wind power plants). These two main stability aspects have been discussed in detail since they are greatly affected by this reconfiguration of modern power systems due to the integration of renewables. To clarify, an increased share of renewables leads to a decrease in the inherent frequency support from synchronous generators, and therefore, various proposed approaches have been discussed and categorized to maintain appropriate frequency stability. At the same time, voltage stability sensitivity also increases since the renewable connection lines to the grid are long and low capacity, and thus, the grid becomes weaker. This issue makes voltage control strategies very important, and therefore, it has been discussed and categorized in detail for renewable-based power plants. The contribution of this review paper compared to the literature lies in providing a clear overview of the available literature in terms of frequency and voltage control stages, regardless of the utilized control method. Following that, the advantages and challenges of hybrid power plants have been discussed in detail since the technology has been gaining more and more attention recently. The current literature has been studied for frequency and voltage controls of hybrid power plants and the shortcomings have been mentioned. The novelty of this review shows that very little research has been conducted on voltage support and reactive power control using HPPs which highlights the need to contribute more studies to this field as mentioned in the last section. Finally, the current research questions and challenges of HPPs have been discussed, considering their relevance to the weak grid configuration.

Funding

This paper is an output from a joint alliance research project “Electrical Control of Hybrid Power Plants Connected to Weak Grids” funded by the Technical University of Denmark and the University of Queensland.

Acknowledgments

Kaushik Das would like to acknowledge EUDP IEA Wind Task 50 project for supporting his contribution.

Conflicts of Interest

The authors declare no conflicts of interest.

Abbreviations

CAPEXCapital Expenditure
DFIGDouble-Fed Induction Generator
EMTElectro-Magnetic Transient
EUEuropean Union
FACTSFlexible AC Transmission Systems
FCRFrequency Containment Reserve
FFCFast Frequency Control
FFRFast Frequency Response
FRRFrequency Restoration Reserve
FRTFault Ride-Through
GFLGrid-Following
GFMGrid-Forming
HPPHybrid Power Plant
IRInertial Response
LCOELevelized Cost of Energy
OLTCOn Load Tap Changing transformers
O&MOperation and Maintenance
PFCPrimary Frequency Control
PFRPrimary Frequency Response
PIDProportional – Integral – Derivative
PLLPhase-Locked Loop
PrVCPrimary Voltage Control
PSCPower Synchronization Control
PVPhotovoltaic
RESRenewable Energy Source
RMSRoot Mean Square
ROCOFRate of Change of Frequency
SeVCSecondary Voltage Control
SFCSecondary Frequency Control
SFRSecondary Frequency Response
SPCSynchronous Power Controller
SMESSuperconducting Magnetic Energy Storage
SPPSolar Power Plant
SSSCStatic Synchronous Series Compensator
STATCOMStatic Synchronous Compensator
SVCStatic Var Compensators
VOCVirtual Oscillator Control
VSGVirtual Synchronous Generator
WPPWind Power Plant
WTWind Turbine

References

  1. Saleem, M.; Saha, S.; Izhar, U.; Ang, L. Integration Challenges of Inverter Based Renewable Energy Sources in Weak Grids. In Proceedings of the 2022 IEEE Industry Applications Society Annual Meeting (IAS), Detroit, MI, USA, 9–14 October 2022; pp. 1–18. [Google Scholar]
  2. Sinsel, S.R.; Riemke, R.L.; Hoffmann, V.H. Challenges and solution technologies for the integration of variable renewable energy sources—A review. Renew. Energy 2020, 145, 2271–2285. [Google Scholar] [CrossRef]
  3. Commission, E.; Climate Action, D. Denmark and the European Green Deal: Climate and Energy Targets in Denmark; Publications Office of the European Union: Luxembourg, Luxembourg, 2022. [Google Scholar]
  4. Li, Y.; Chi, Y.; Tian, X.; Liu, C.; Hu, J.; Fan, Y. Research on Capacity Planning of Renewable Energy Grid Integration Based on Effective Short Circuit Ratio. In Proceedings of the 2020 IEEE Sustainable Power and Energy Conference (iSPEC), Chengdu, China, 23–25 November 2020; pp. 622–627. [Google Scholar]
  5. Sepehr, A.; Pouresmaeil, E.; Saeedian, M.; Routimo, M.; Godina, R.; Yousefi-Talouki, A. Control of Grid-Tied Converters for Integration of Renewable Energy Sources into the Weak Grids. In Proceedings of the 2019 International Conference on Smart Energy Systems and Technologies (SEST), Porto, Portugal, 9–11 September 2019; pp. 1–6. [Google Scholar]
  6. Song, Y.; Wang, X.; Blaabjerg, F. High-Frequency Resonance Damping of DFIG-Based Wind Power System Under Weak Network. IEEE Trans. Power Electron. 2017, 32, 1927–1940. [Google Scholar] [CrossRef]
  7. Givaki, K.; Chen, D.; Xu, L.; Xu, Y. An Alternative Current-Error Based Control for VSC Integration to Weak Grid. In Proceedings of the 2018 IEEE Power & Energy Society General Meeting (PESGM), Portland, OR, USA, 5–10 August 2018; pp. 1–5. [Google Scholar]
  8. Shahnazian, F.; Adabi, J.; Pouresmaeil, E. Enhanced control of voltage source converters considering virtual inertia theory. Int. Trans. Electr. Energy Syst. 2021, 31, e13245. [Google Scholar] [CrossRef]
  9. Tinajero, M.Z.; Ornelas-Tellez, F.; Garcia-Barriga, N. Optimal Control of an Inverter-based Virtual Synchronous Generator with Inertial Response. IEEE Lat. Am. Trans. 2022, 20, 780–786. [Google Scholar] [CrossRef]
  10. Fu, R.; Wang, X.; Zhang, Y.; Li, L. Inertial and Primary Frequency Response of PLL Synchronized VSC Interfaced Energy Resources. IEEE Trans. Power Syst. 2022, 37, 2998–3013. [Google Scholar] [CrossRef]
  11. Wang, Z.; Shi, L.; Wu, F.; Peng, Y.; Lou, B.; Lee, K. Coordinated Droop and Virtual Inertia Control of Wind Farm for Frequency Regulation. In Proceedings of the 2020 IEEE Power & Energy Society General Meeting (PESGM), Montreal, QC, Canada, 2–6 August 2020; pp. 1–5. [Google Scholar]
  12. Kang, J.; Hur, K. Shaping the Transient Performance of Droop-Controlled Grid Forming Converters for Frequency Regulation. In Proceedings of the 2021 IEEE 12th Energy Conversion Congress & Exposition—Asia, Singapore, Singapore, 24–27 May 2021. [Google Scholar]
  13. Badreldien, M.; Johnson, B. Virtual Synchronous Generator Controller for Solar Photovoltaic System. In Proceedings of the 2021 IEEE Electrical Power and Energy Conference (EPEC), Virtual, 22–31 October 2021; pp. 480–485. [Google Scholar]
  14. Jiang, K.; Su, H.; Lin, H.; He, K.; Zeng, H.; Che, Y. A Practical Secondary Frequency Control Strategy for Virtual Synchronous Generator. IEEE Trans. Smart Grid. 2020, 11, 2734–2736. [Google Scholar] [CrossRef]
  15. Shahnazian, F.; Adabi, J.; Pouresmaeil, E. Frequency stability improvements based on automatic adjustment of synchronous power controller parameters. Electr. Eng. 2022, 104, 3453–3463. [Google Scholar] [CrossRef]
  16. Zhang, H.; Xiang, W.; Lin, W.; Wen, J. Grid Forming Converters in Renewable Energy Sources Dominated Power Grid: Control Strategy, Stability, Application, and Challenges. J. Mod. Power Syst. Clean Energy 2021, 9, 1239–1256. [Google Scholar]
  17. Wang, Z.; Miao, Z.; Fan, L.; Yazdani, A. Weak Grid Operation of A Grid-Following Current-Sourced PV Solar System. In Proceedings of the 2021 North American Power Symposium (NAPS), College Station, TX, USA, 14–16 November 2021; pp. 1–6. [Google Scholar]
  18. Liu, J.; Yao, W.; Wen, J.; Fang, J.; Jiang, L.; He, H. Impact of Power Grid Strength and PLL Parameters on Stability of Grid-Connected DFIG Wind Farm. IEEE Trans. Sustain. Energy 2020, 11, 545–557. [Google Scholar]
  19. Li, Y.; Fan, L.; Miao, Z. Stability Control for Wind in Weak Grids. IEEE Trans. Sustain. Energy 2019, 10, 2094–2103. [Google Scholar] [CrossRef]
  20. Bao, L.; Fan, L.; Miao, Z. Wind farms in weak grids stability enhancement: SynCon or STATCOM? Electr. Power Syst. Res. 2022, 202, 107623. [Google Scholar] [CrossRef]
  21. Hatziargyriou, N.; Milanovic, J.; Rahmann, C.; Ajjarapu, V.; Canizares, C.; Erlich, I. Definition and Classification of Power System Stability—Revisited & Extended. IEEE Trans. Power Syst. 2021, 36, 3271–3281. [Google Scholar]
  22. Wen, Z.; Yao, L.; Cheng, F.; Xu, J.; Mao, B.; Chen, R. A comprehensive review of wind power based power system frequency regulation. Front. Energy 2023, 17, 611–634. [Google Scholar] [CrossRef]
  23. Nazemi, M.; Liang, X. Frequency Control Techniques for Solar PV Systems: A Review. In Proceedings of the 2023 IEEE Canadian Conference on Electrical and Computer Engineering (CCECE), Regina, Saskatchewan, 24–27 September 2023; pp. 43–48. [Google Scholar]
  24. Al Kez, D.; Foley, A.M.; Ahmed, F.; Morrow, D.J. Overview of frequency control techniques in power systems with high inverter-based resources: Challenges and mitigation measures. IET Smart Grid 2023, 16, 447–469. [Google Scholar] [CrossRef]
  25. Fernández-Guillamón, A.; Muljadi, E.; Molina-García, A. Frequency control studies: A review of power system, conventional and renewable generation unit modeling. Electr. Power Syst. Res. 2022, 211, 108191. [Google Scholar] [CrossRef]
  26. Sufyan, M.; Rahim, N.; Eid, B.; Raihan, S. A comprehensive review of reactive power control strategies for three phase grid connected photovoltaic systems with low voltage ride through capability. J. Renew. Sustain. Energy 2019, 25, 042701. [Google Scholar] [CrossRef]
  27. Asadollah, S.; Zhu, R.; Liserre, M. Analysis of Voltage Control Strategies for Wind Farms. IEEE Trans. Sustain. Energy 2020, 11, 1002–1012. [Google Scholar] [CrossRef]
  28. Sulawa, T.; Jami, I.; Pound, R. Balancing availability, reliability and future regulatory impact against overall project capex for offshore wind farms. In Proceedings of the 2009 CIGRE/IEEE PES Joint Symposium Integration of Wide-Scale Renewable Resources into the Power Delivery System, Calgary, AB, Canada, 29–31 July 2009; pp. 1–7. [Google Scholar]
  29. Nallainathan, S.; Arefi, A.; Lund, C.; Mehrizi-Sani, A.; Stephens, D. Reliability Evaluation of Renewable-Rich Microgrids Using Monte Carlo Simulation Considering Resource and Equipment Availability. In Proceedings of the 2020 IEEE International Conference on Power Systems Technology (POWERCON), Bangalore, India, 14–16 September 2020; pp. 1–6. [Google Scholar]
  30. Habte, A.; Sengupta, M.; Yuan, H.; Buster, G.; Tan, J. Simulation of PV Variability as a Function of PV Generation and Plant Size. In Proceedings of the 2021 IEEE 48th Photovoltaic Specialists Conference (PVSC), Fort Lauderdale, FL, USA, 20–25 June 2021; pp. 2136–2140. [Google Scholar]
  31. Chattopadhyay, D.; Loon, V. Modeling Long-term Variability of Renewable Energy in Generation Planning. In Proceedings of the 2020 IEEE Power & Energy Society General Meeting (PESGM), Montreal, QC, Canada, 2–6 August 2020; pp. 1–5. [Google Scholar]
  32. A, L. Integration of a Microgrid Consisting of Hybrid Energy Sources to a Weak AC Grid. In Proceedings of the 2021 International Conference on Industrial Electronics Research and Applications (ICIERA), New Delhi, India, 22–24 December 2021; pp. 1–6. [Google Scholar]
  33. Wind Europe. Renewable Hybrid Power Plants: Exploring the Benefits and Market Opportunities; Wind Europe: Brussels, Belgium, 2019. [Google Scholar]
  34. Petersen, L.; Hesselbæk, B.; Martinez, A.; Borsotti-Andruszkiewicz, R.; Tarnowski, G.; Steggel, N. Vestas Power Plant Solutions Integrating Wind, Solar PV and Energy Storage. In Proceedings of the 3rd International Hybrid Power Systems Workshop, Crete, Greece, 14–15 May 2024; Ackermann, T., Betancourt, U., Eds.; Energynautics: Darmstadt, Germany, 2024. [Google Scholar]
  35. Long, Q.; Celna, A.; Das, K.; Sørensen, P. Fast Frequency Support from Hybrid Wind Power Plants Using Supercapacitors. Energies 2021, 14, 3495. [Google Scholar] [CrossRef]
  36. Das, K.; Hansen, A.; Vangari, D.; Koivisto, M.; Sørensen, P.; Altin, M. Enhanced Features of Wind based Hybrid Power Plants, 2019. In Proceedings of the 4th International Hybrid Power Systems Workshop, Crete, Greece, 14–15 May 2024; Available online: https://api.semanticscholar.org/CorpusID:204846015 (accessed on 18 March 2014).
  37. Hannan, M.; Abu, S.M.; Al-Shetwi, A.Q.; Mansor, M.; Ansari, M.; Muttaqi, K.M.; Dong, Z. Hydrogen energy storage integrated battery and supercapacitor based hybrid power system: A statistical analysis towards future research directions. Int. J. Hydrogen Energy 2022, 47, 39523–39548. [Google Scholar] [CrossRef]
  38. Arsad, A.; Hannan, M.; Al-Shetwi, A.Q.; Mansur, M.; Muttaqi, K.; Dong, Z.; Blaabjerg, F. Hydrogen energy storage integrated hybrid renewable energy systems: A review analysis for future research directions. Int. J. Hydrogen Energy 2022, 47, 17285–17312. [Google Scholar] [CrossRef]
  39. Huff, G. DOE/EPRI 2013 Electricity Storage Handbook in Collaboration with NRECA; Sandia National Laboratories: Albuquerque, NM, USA, 2013. [Google Scholar]
  40. Gorman, W.; Mills, A.; Bolinger, M.; Wiser, R.; Singhal, N.; Ela, E. Motivations and options for deploying hybrid generator-plus-battery projects within the bulk power system. Electr. J. 2020, 33, 106739. [Google Scholar] [CrossRef]
  41. Petersen, L.; Altin, M.; Shahid, K.; Løvenstein Olsen, R.; Iov, F.; Hansen, A. Specifications for ReGen Plant Model and Control Architecture; DTU Library: New Delhi, India, 2018. [Google Scholar]
  42. Vázquez Pombo, D. Coordinated Frequency and Active Power Control of Hybrid Power Plants: An Approach to Fast Frequency Response; Aalborg University: Aalborg, Denmark, 2018. [Google Scholar]
  43. Vogler-Finck, P.; Früh, W. Evolution of primary frequency control requirements in Great Britain with increasing wind generation. Int. J. Electr. Power Energy Syst. 2015, 73, 377–388. [Google Scholar] [CrossRef]
  44. Tamrakar, U.; Shrestha, D.; Maharjan, M.; Bhattarai, B.; Hansen, T.; Tonkoski, R. Virtual Inertia: Current Trends and Future Directions. Appl. Sci. 2017, 7, 654. [Google Scholar] [CrossRef]
  45. Eriksson, R.; Modig, N.; Elkington, K. Synthetic inertia versus fast frequency response: A definition. IET Renew. Power Gener. 2018, 12, 507–514. [Google Scholar] [CrossRef]
  46. Afshar, Z.; Zadeh, M.; Bathaee, S.; Gharehpetian, G. Primary and Secondary Frequency Control of Low-Inertia Microgrids with Battery Energy Storage and Intermittent Renewable Energy Resources. In Proceedings of the 2020 11th Power Electronics, Drive Systems, and Technologies Conference (PEDSTC), Tehran, Iran, 4–6 February 2020; pp. 1–6. [Google Scholar]
  47. Li, P.; Hu, W.; Chen, Z. Review on integrated-control method of variable speed wind turbines participation in primary and secondary frequency. In Proceedings of the IECON 2016—42nd Annual Conference of the IEEE Industrial Electronics Society, Florence, Italy, 24–27 October 2016; pp. 4223–4228. [Google Scholar]
  48. Jahan, E.; MdR, H.; Muyeen, S.; Umemura, A.; Takahashi, R.; Tamura, J. Primary frequency regulation of the hybrid power system by deloaded PMSG-based offshore wind farm using centralised droop controller. J. Eng. 2019, 2019, 4950–4954. [Google Scholar] [CrossRef]
  49. Khooban, M.; Niknam, T. A new intelligent online fuzzy tuning approach for multi-area load frequency control: Self Adaptive Modified Bat Algorithm. Int. J. Electr. Power Energy Syst. 2015, 71, 254–261. [Google Scholar] [CrossRef]
  50. Amrouche, S.O.; Rekioua, D.; Rekioua, T.; Bacha, S. Overview of energy storage in renewable energy systems. Int. J. Hydrogen Energy 2016, 41, 20914–20927. [Google Scholar] [CrossRef]
  51. Sun, Y.; Zhang, Z.; Li, G.; Lin, J. Review on frequency control of power systems with wind power penetration. In Proceedings of the 2010 International Conference on Power System Technology, Hangzhou, China, 24–28 October 2010; pp. 1–8. [Google Scholar]
  52. Morren, J.; Haan, S.; Kling, W.; Ferreira, J. Wind turbines emulating inertia and supporting primary frequency control. IEEE Trans. Power Syst. 2006, 21, 433–434. [Google Scholar] [CrossRef]
  53. Kundur, P. Power System Stability and Control; CRC Press: Boca Raton, FL, USA, 1994; Available online: https://api.semanticscholar.org/CorpusID:109062304 (accessed on 18 March 2024).
  54. Loukarakis, E.; Margaris, I.; Moutis, P. Frequency control support and participation methods provided by wind generation. In Proceedings of the 2009 IEEE Electrical Power & Energy Conference (EPEC), Montreal, QC, Canada,, 22–23 October 2009; pp. 1–6. [Google Scholar]
  55. Moutis, P.; Loukarakis, E.; Papathanasiou, S.; Hatziargyriou, N. Primary load-frequency control from pitch-controlled wind turbines. In Proceedings of the 2009 IEEE Bucharest PowerTech, Bucharest, Romania, 28 June–2 July 2009; Volume 1–7. [Google Scholar]
  56. Lubosny, Z.; Bialek, J. Supervisory Control of a Wind Farm. IEEE Trans. Power Syst. 2007, 22, 985–994. [Google Scholar] [CrossRef]
  57. Li, W.; Joos, G. Performance Comparison of Aggregated and Distributed Energy Storage Systems in a Wind Farm For Wind Power Fluctuation Suppression. In Proceedings of the 2007 IEEE Power Engineering Society General Meeting, Tampa, FL, USA, 24–28 June 2007; pp. 1–6. [Google Scholar]
  58. Scarabaggio, P.; Carli, R.; Cavone, G.; Dotoli, M. Smart Control Strategies for Primary Frequency Regulation through Electric Vehicles: A Battery Degradation Perspective. Energies 2020, 13, 4586. [Google Scholar] [CrossRef]
  59. Shim, J.; Verbič, G.; Hur, K. Grid-supportive electric vehicle charging methodology with energy management for coordinated frequency control. IET Gener. Transm. Distrib. 2021, 15, 3474–3487. [Google Scholar] [CrossRef]
  60. Alam, M.S.; Almehizia, A.A.; Al-Ismail, F.S.; Hossain, M.A.; Islam, M.A.; Shafiullah, M. Ullah, A. Frequency Stabilization of AC Microgrid Clusters: An Efficient Fractional Order Supercapacitor Controller Approach. Energies 2022, 15, 5179. [Google Scholar] [CrossRef]
  61. Mihalic, R.; Zunko, P.; Papic, I.; Povh, D. Improvement Of Transient Stability By Insertion Of Facts Devices. In Proceedings of the Joint International Power Conference Athens Power Tech, Athens, Greece, 5–8 September 1993; pp. 521–525. [Google Scholar]
  62. Pappachen, A.; Peer Fathima, A. Load frequency control in deregulated power system integrated with SMES–TCPS combination using ANFIS controller. Int. J. Electr. Power Energy Syst. 2016, 82, 519–534. [Google Scholar] [CrossRef]
  63. Zarina, P.P.; Mishra, S. Power oscillation reduction contribution by PV in deloaded mode. In Proceedings of the 2016 IEEE 6th International Conference on Power Systems (ICPS), New Delhi, India, 4–6 March 2016; pp. 1–4. [Google Scholar]
  64. Zarina, P.; Mishra, S.; Sekhar, P. Exploring frequency control capability of a PV system in a hybrid PV-rotating machine-without storage system. Int. J. Electr. Power Energy Syst. 2014, 60, 258–267. [Google Scholar] [CrossRef]
  65. Pawar, B.; Batzelis, E.; Chakrabarti, S.; Pal, B. Grid-Forming Control for Solar PV Systems With Power Reserves. IEEE Trans. Sustain. Energy 2021, 12, 1947–1959. [Google Scholar] [CrossRef]
  66. Shayeghi, H.; Shayanfar, H.; Jalili, A. Load frequency control strategies: A state-of-the-art survey for the researcher. Energy Convers. Manag. 2009, 50, 344–353. [Google Scholar] [CrossRef]
  67. Birch, A.; Sapeluk, A.; Ozveren, C. An enhanced neural network load frequency control technique. In Proceedings of the 1994 International Conference on Control—Control ’94, Coverntry, UK, 21–24 March 1994; pp. 409–415. [Google Scholar]
  68. Wang, Y. New robust adaptive load-frequency control with system parametric uncertainties. In Proceedings of the IEE Proceedings—Generation, Transmission and Distribution; IEEE: New York City, NY, USA, 1994; Volume 141, p. 184. [Google Scholar]
  69. Sakeen, B.; Bachache, N.; Wang, S. Frequency Control of PV-Diesel Hybrid Power System Using Optimal Fuzzy Logic Controller. In Proceedings of the 2013 IEEE 11th International Conference on Dependable, Autonomic and Secure Computing (DASC’13), Chengdu, China, 21–22 December 2013; pp. 174–178. [Google Scholar] [CrossRef]
  70. Cheng, M.; Sami, S.; Wu, J. Benefits of using virtual energy storage system for power system frequency response. Appl. Energy 2017, 194, 376–385. [Google Scholar] [CrossRef]
  71. Ribeiro, P.; Johnson, B.; Crow, M.; Arsoy, A.; Liu, Y. Energy storage systems for advanced power applications. Proc. IEEE 2001, 89, 1744–1756. [Google Scholar] [CrossRef]
  72. Bolund, B.; Bernhoff, H.; Leijon, M. Flywheel energy and power storage systems. Renew. Sustain. Energy Rev. 2007, 11, 235–258. [Google Scholar] [CrossRef]
  73. Singh, S.; Verma, R.; Shakya, A.; Singh, S. Frequency stability analysis of hybrid power system based on solar PV with SMEs unit. In Proceedings of the 2016 International Conference on Emerging Trends in Electrical Electronics & Sustainable Energy Systems (ICETEESES), Sultanpur, India, 11–12 March 2016; pp. 5–11. [Google Scholar]
  74. Alam, M.S.; Chowdhury, T.A.; Dhar, A.; Al-Ismail, F.S.; Choudhury, M.S.H.; Shafiullah, M.; Hossain, M.I.; Hossain, M.A.; Ullah, A.; Rahman, S.M. Solar and Wind Energy Integrated System Frequency Control: A Critical Review on Recent Developments. Energies 2023, 16, 812. [Google Scholar] [CrossRef]
  75. Abdeen, M.; Sayyed, M.; Domínguez-García, J.; Kamel, S. Supplemental Control for System Frequency Support of DFIG-Based Wind Turbines. IEEE Access 2022, 10, 69364–69372. [Google Scholar]
  76. Lyu, X.; Jia, Y.; Dong, Z. Adaptive Frequency Responsive Control for Wind Farm Considering Wake Interaction. J. Mod. Power Syst. Clean Energy 2021, 9, 1066–1075. [Google Scholar] [CrossRef]
  77. Zhao, X.; Xue, Y.; Zhang, X. Fast Frequency Support From Wind Turbine Systems by Arresting Frequency Nadir Close to Settling Frequency. IEEE Open Access J. Power Energy 2020, 7, 191–202. [Google Scholar]
  78. Kheshti, M.; Ding, L.; Bao, W.; Yin, M.; Wu, Q.; Terzija, V. Toward Intelligent Inertial Frequency Participation of Wind Farms for the Grid Frequency Control. IEEE Trans Ind. Inf. 2020, 16, 6772–6786. [Google Scholar]
  79. Li, D.; Cai, M.; Yang, W.; Wang, J. Study of Doubly Fed Induction Generator Wind Turbines for Primary Frequency Control. In Proceedings of the 2020 IEEE 4th Conference on Energy Internet and Energy System Integration (EI2), Wuhan, China, 30 October–1 November 2020; pp. 2690–2695. [Google Scholar]
  80. Shao, C.; Li, Z.; Hao, R.; Qie, Z.; Xu, G.; Hu, J. A Wind Farm Frequency Control Method Based on the Frequency Regulation Ability of Wind Turbine Generators. In Proceedings of the 2020 5th Asia Conference on Power and Electrical Engineering (ACPEE), Chengdu, China, 4–7 June 2020; pp. 592–596. [Google Scholar]
  81. Rebello, E.; Watson, D.; Rodgers, M. Performance Analysis of a 10 MW Wind Farm in Providing Secondary Frequency Regulation: Experimental Aspects. IEEE Trans. Power Syst. 2019, 34, 3090–3097. [Google Scholar]
  82. Yang-Wu, S.; Xun, M.; Ao, P.; Yang-Guang, W.; Ting, C.; Ding, W. Load Frequency Control Strategy for Wind Power Grid-connected Power Systems Considering Wind Power Forecast. In Proceedings of the 2019 IEEE 3rd Conference on Energy Internet and Energy System Integration (EI2), Changsha, China, 8–10 November 2019; pp. 1124–1128. [Google Scholar]
  83. Tan, G.; Xu, C.; Wu, F.; Qi, C.; Wang, D.; Yang, P. Research on primary frequency regulation of wind turbine based on new nonlinear droop control. In Proceedings of the 2020 4th International Conference on HVDC (HVDC), Xi’an, China, 6–9 November 2020; pp. 170–174. [Google Scholar]
  84. Zhang, J.; Zhang, B.; Li, Q.; Zhou, G.; Wang, L.; Li, B. Fast Frequency Regulation Method for Power System With Two-Stage Photovoltaic Plants. IEEE Trans. Sustain. Energy 2022, 13, 1779–1789. [Google Scholar]
  85. Lin, K.; Wu, F.; Ju, X.; Shi, L. Coordinated Control Strategy of Concentrating Solar Power Plant for Power System Frequency Regulation. In Proceedings of the 2020 12th IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC), Nanjing, China, 20–23 September 2020; pp. 1–5. [Google Scholar]
  86. Varma, R.; Akbari, M. A Novel Reactive Power based Frequency Control by PV-STATCOMs during Day and Night. In Proceedings of the 2018 IEEE Power & Energy Society General Meeting (PESGM), Portland, OR, USA, 5–10 August 2018; pp. 1–5. [Google Scholar]
  87. Li, Y.; Choi, S.; Vilathgamuwa, D. Primary Frequency Control Scheme for a Fixed-Speed Dish-Stirling Solar–Thermal Power Plant. IEEE Trans. Power Syst. 2018, 33, 2184–2194. [Google Scholar] [CrossRef]
  88. Li, Y.; Choi, S.; Vilathgamuwa, D.; Xiong, B.; Tang, J. Combined Primary Frequency and Virtual Inertia Response Control Scheme of a Variable-Speed Dish-Stirling System. IEEE Access 2020, 8, 151719–151730. [Google Scholar]
  89. Estrice, M.; Sharma, G.; Akindeji, K.; Davidson, I. Application of AI for Frequency Normalization of Solar PV-Thermal Electrical Power System. In Proceedings of the 2020 International Conference on Artificial Intelligence, Big Data, Computing and Data Communication Systems (icABCD), Durban, South Africa, 6–7 August 2020; pp. 1–4. [Google Scholar]
  90. Popkov, E.; Seyt, R.; Feshin, A. The Possibility of Participation of Solar Power Plants in the Primary Frequency Control. In Proceedings of the 2019 IEEE Conference of Russian Young Researchers in Electrical and Electronic Engineering (EIConRus), Saint Petersburg and Moscow, Russia, 28–31 January 2019; pp. 1035–1039. [Google Scholar]
  91. Varma, R.; Akbari, M. Simultaneous Fast Frequency Control and Power Oscillation Damping by Utilizing PV Solar System as PV-STATCOM. IEEE Trans. Sustain. Energy 2020, 11, 415–425. [Google Scholar] [CrossRef]
  92. Marthi, P.R.; Debnath, S.; Xia, Q.; Crow, M.L. Model Based Predictive Control for Frequency Support in Multi-port Autonomous Reconfigurable Solar Plants. In Proceedings of the 2021 IEEE Power & Energy Society Innovative Smart Grid Technologies Conference (ISGT), Espoo, Finland, 18–21 October 2021; pp. 1–5. [Google Scholar]
  93. Peruffo, A.; Guiu, E.; Panciatici, P.; Abate, A. Aggregation and Control of a Heterogeneous Population of Solar Panels Over the Grid Frequency. IEEE Trans. Control Syst. Technol. 2021, 29, 1420–1436. [Google Scholar]
  94. Zhao, D.; Qian, M.; Ma, J.; Jiang, D.; Ding, M.; Xiang, L. A Decentralized Frequency Regulation Strategy of PV Power Plant Based on Droop Control. In Proceedings of the 2018 China International Conference on Electricity Distribution (CICED), Tianjin, China, 17–19 September 2018; pp. 1824–1828. [Google Scholar]
  95. Yu, H.; Shuai, Y.; Peng, D.; Jin, D. Bi-level Optimal Control Strategy of Energy Storage Participating in Power Grid Frequency Regulation Based on Multi ObjectiveGenetic Algorithm. In Proceedings of the 2021 Power System and Green Energy Conference PSGEC, Virtual, 21–22 August 2021; pp. 437–442. [Google Scholar]
  96. Gundogdu, B.; Gladwin, D. Bi-Directional Power Control of Grid-Tied Battery Energy Storage System Operating in Frequency Regulation. In Proceedings of the 2018 International Electrical Engineering Congress (iEECON), Krabi, Thailand, 7–9 March 2018; pp. 1–4. [Google Scholar]
  97. Ramírez, M.; Castellanos, R.; Calderón, J.; Malik, O. Battery Energy Storage for Frequency Support in the BCS Electric Power System. In Proceedings of the 2018 IEEE PES Transmission & Distribution Conference and Exhibition—Latin America (T&D-LA), Lima, Peru, 18–21 September 2018; pp. 1–5. [Google Scholar]
  98. García-Pereira, H.; Blanco, M.; Martínez-Lucas, G.; Pérez-Díaz, J.; Sarasúa, J. Comparison and Influence of Flywheels Energy Storage System Control Schemes in the Frequency Regulation of Isolated Power Systems. IEEE Access 2022, 10, 37892–37911. [Google Scholar] [CrossRef]
  99. Oshnoei, A.; Kheradmandi, M.; Muyeen, S. Robust Control Scheme for Distributed Battery Energy Storage Systems in Load Frequency Control. IEEE Trans. Power Syst. 2020, 35, 4781–4791. [Google Scholar] [CrossRef]
  100. Sun, F.; Li, P.; Liu, S.; Hao, J.; Yang, H.; Wang, S. Distributed Energy Storage Aggregator for Power System Frequency Control. In Proceedings of the 2020 International Conference on Intelligent Computing, Automation and Systems (ICICAS), Chongqing, China, 11–13 December 2020; pp. 203–206. [Google Scholar]
  101. Xian-kui, W.; Shi-hai, Z.; Peng, W.; Mi, W. Study on Primary Frequency Modulation Parameter Setting of Compressed Air Energy Storage. In Proceedings of the 2018 2nd International Conference on Green Energy and Applications (ICGEA), Singapore, Singapore, 24–26 March 2018; pp. 143–146. [Google Scholar]
  102. Albrecht, M.; Strunck, C.; Rehtanz, C. Hardware-in-the-Loop Simulation of a Battery Energy Storage System and External Storage Controller to provide Primary Control. In Proceedings of the 2019 IEEE Milan PowerTech, Milan, Italy, 23–27 June 2019; pp. 1–4. [Google Scholar]
  103. Moeini, A.; Kamwa, I.; Gallehdari, Z.; Ghazanfari, A. Optimal Robust Primary Frequency Response Control for Battery Energy Storage Systems. In Proceedings of the 2019 IEEE Power & Energy Society General Meeting (PESGM), Atlanta, GA, USA, 4–8 August 2019; pp. 1–5. [Google Scholar]
  104. Hao, C.; Yanbing, J.; Jin, Z.; Yanfang, Z.; Gang, L.; Dong, X. Energy Storage Frequency Regulation Energy Management Strategy Based on K-Means Analysis. In Proceedings of the 2019 IEEE 3rd International Conference on Green Energy and Applications (ICGEA), Taiyuan, China, 16–18 March 2019; pp. 163–166. [Google Scholar]
  105. Meng, G.; Chang, Q.; Sun, Y.; Rao, Y.; Zhang, F.; Wu, Y. Energy Storage Auxiliary Frequency Modulation Control Strategy Considering ACE and SOC of Energy Storage. IEEE Access 2021, 9, 26271–26277. [Google Scholar] [CrossRef]
  106. Ebinyu, E.; Abdel-Rahim, O.; Mansour, D.E.A.; Shoyama, M.; Abdelkader, S.M. Grid-Forming Control: Advancements towards 100% Inverter-Based Grids—-A Review. Energies 2023, 16, 7579. [Google Scholar] [CrossRef]
  107. Teng, Y.; Deng, W.; Pei, W.; Li, Y.; Dingv, L.; Ye, H. Review on grid-forming converter control methods in high-proportion renewable energy power systems. Glob. Energy Interconnect. 2022, 5, 328–342. [Google Scholar] [CrossRef]
  108. Rathnayake, D.B.; Akrami, M.; Phurailatpam, C.; Me, S.P.; Hadavi, S.; Jayasinghe, G.; Zabihi, S.; Bahrani, B. Grid Forming Inverter Modeling, Control, and Applications. IEEE Access 2021, 9, 114781–114807. [Google Scholar] [CrossRef]
  109. Mohammed, N.; Udawatte, H.; Zhou, W.; Hill, D.J.; Bahrani, B. Grid-Forming Inverters: A Comparative Study of Different Control Strategies in Frequency and Time Domains. IEEE Open J. Ind. Electron. Soc. 2024, 5, 185–214. [Google Scholar] [CrossRef]
  110. Rahman, K.; Hashimoto, J.; Orihara, D.; Ustun, T.S.; Otani, K.; Kikusato, H.; Kodama, Y. Reviewing Control Paradigms and Emerging Trends of Grid-Forming Inverters—A Comparative Study. Energies 2024, 17, 2400. [Google Scholar] [CrossRef]
  111. Li, S.; Zhou, N.; Xing, L.; Zhang, Z.; Zhang, Z.; Fang, Q. Hierarchical Voltage Control of a Wind Farm Based on Droop Control. In Proceedings of the 2020 5th Asia Conference on Power and Electrical Engineering (ACPEE), Chengdu, China, 4–7 June 2020; pp. 432–436. [Google Scholar]
  112. Solanki, N.; Patel, J. Utilization of PV solar farm for Grid Voltage regulation during night; analysis & control. In Proceedings of the 2016 IEEE 1st International Conference on Power Electronics, Intelligent Control and Energy Systems (ICPEICES), Delhi, India, 4–6 July 2016; pp. 1–5. [Google Scholar]
  113. Lund, T.; Sørensen, P.; Eek, J. Reactive power capability of a wind turbine with doubly fed induction generator. Wind Energy 2007, 10, 379–394. [Google Scholar] [CrossRef]
  114. Sarkar, M.; Hansen, A.; Sørensen, P. Quantifying robustness of Type 4 wind power plant as reactive power source. Int. J. Electr. Power Energy Syst. 2020, 122, 106181. [Google Scholar] [CrossRef]
  115. Gau, D.; Wu, Y. Overview of Reactive Power and Voltage Control of Offshore Wind Farms. In Proceedings of the 2020 International Symposium on Computer, Consumer and Control (IS3C), Taichung City, Taiwan, 13–16 November 2020; pp. 276–279. [Google Scholar]
  116. Li, Y.; Xu, Z.; Zhang, J.; Meng, K. Variable Droop Voltage Control For Wind Farm. IEEE Trans. Sustain. Energy 2018, 9, 491–493. [Google Scholar] [CrossRef]
  117. Sarkar, M.; Souxes, T.; Hansen, A.; Sørensen, P.; Vournas, C. Enhanced Wind Power Plant Control Strategy During Stressed Voltage Conditions. IEEE Access 2020, 8, 120025–120035. [Google Scholar] [CrossRef]
  118. Ramli, A.; Leh, N.; Hamid, S.; Muhammad, Z. Improvement of Voltage Stability in Power System using SVC. In Proceedings of the 2022 IEEE 12th International Conference on Control System, Computing and Engineering (ICCSC), Penang, Malaysia, 21–22 October 2022; pp. 19–24. [Google Scholar]
  119. Xu, L.; Chen, T.; Yang, L.; Chen, J.; Du, L.; Zhong, H. Reactive Power and Voltage Coordinated Control of Wind Farm for Parallel Running STATCOM. In Proceedings of the 2019 IEEE Innovative Smart Grid Technologies, Bucharest, Romania, 29 September–2 October 2019; pp. 1414–1418. [Google Scholar]
  120. Annamalai, A.; Sanavullah, M. Voltage Stability Improvement in Power System by Using Statcom. Int. J. Eng. Sci. Technol. 2012, 4, 4584–4591. [Google Scholar]
  121. Sadiq, R.; Wang, Z.; Chung, C.; Zhou, C.; Wang, C. A review of STATCOM control for stability enhancement of power systems with wind/PV penetration: Existing research and future scope. Int. Trans. Electr. Energy Syst. 2021, 31, e13079. [Google Scholar] [CrossRef]
  122. Nguyen, T.; Kim, H. Cluster-Based Predictive PCC Voltage Control of Large-Scale Offshore Wind Farm. IEEE Access 2021, 9, 4630–4641. [Google Scholar] [CrossRef]
  123. Li, J.; Huang, H.; Lou, B.; Peng, Y.; Huang, Q.; Xia, K. Wind Farm Reactive Power and Voltage Control Strategy Based on Adaptive Discrete Binary Particle Swarm Optimization Algorithm. In Proceedings of the 2019 IEEE Asia Power and Energy Engineering Conference (APEEC), Chengdu, China, 29–31 March 2019; pp. 99–102. [Google Scholar]
  124. Jiang, M.; Wang, M.; Tan, B.; Jia, L.; Guo, Q.; Tang, L. Reactive Power and Voltage Control in VSC-HVDC Connected Wind Farms Considering Stochastic Wind Power. In Proceedings of the 2018 2nd IEEE Conference on Energy Internet and Energy System Integration (EI2), Beijing, China, 20–22 October 2018; pp. 1–6. [Google Scholar]
  125. Zhang, Z.; Wang, C.; Zhang, H.; Zhang, X.; Wang, N. Coordinated Voltage Control of a Wind Farm Considering the Impact of Voltage Support Ability from the Integrated Grid. In Proceedings of the 2019 IEEE PES Asia-Pacific Power and Energy Engineering Conference (APPEEC), Macao, China, 1–4 December 2019; pp. 1–5. [Google Scholar]
  126. Al-Awaad, A.; Arwani, M. Economical benefits of supporting voltage control with large solar parks. In Proceedings of the 2010 9th International Conference on Environment and Electrical Engineering, Sibiu, Romania, 24–26 June 2010; pp. 349–352. [Google Scholar]
  127. Duan, J.; Shi, D.; Diao, R.; Li, H.; Wang, Z.; Zhang, B. Deep-Reinforcement-Learning-Based Autonomous Voltage Control for Power Grid Operations. IEEE Trans. Power Syst. 2020, 35, 814–817. [Google Scholar] [CrossRef]
  128. Gozhyj, A.; Nechakhin, V.; Kalinina, I. Solar Power Control System based on Machine Learning Methods. In Proceedings of the 2020 IEEE 15th International Conference on Computer Sciences and Information Technologies (CSIT), Zbarazh, Ukraine, 23–26 September 2020; pp. 24–27. [Google Scholar]
  129. Li, C.; Jin, C.; Sharma, R. Coordination of PV Smart Inverters Using Deep Reinforcement Learning for Grid Voltage Regulation. In Proceedings of the 2019 18th IEEE International Conference On Machine Learning And Applications (ICMLA), Boca Raton, FL, USA, 16–19 December 2019; pp. 1930–1937. [Google Scholar]
  130. Tavoosi, J.; Mohammadzadeh, A.; Pahlevanzadeh, B.; Kasmani, M.; Band, S.; Safdar, R. A machine learning approach for active/reactive power control of grid-connected doubly-fed induction generators. Ain Shams Eng. J. 2022, 13, 101564. [Google Scholar] [CrossRef]
  131. Cao, D.; Hu, W.; Zhao, J.; Huang, Q.; Chen, Z.; Blaabjerg, F. A Multi-Agent Deep Reinforcement Learning Based Voltage Regulation Using Coordinated PV Inverters. IEEE Trans. Power Syst. 2020, 35, 4120–4123. [Google Scholar] [CrossRef]
  132. Padullaparthi, V.; Nagarathinam, S.; Vasan, A.; Menon, V.; FALCON, S.D. FArm Level CONtrol for wind turbines using multi-agent deep reinforcement learning. Renew Energy 2022, 181, 445–456. [Google Scholar] [CrossRef]
  133. Zhao, H.; Liu, H.; Hu, W.; Yan, X. Anomaly detection and fault analysis of wind turbine components based on deep learning network. Renew. Energy 2018, 127, 825–834. [Google Scholar] [CrossRef]
  134. Coumont, M.; Hanson, J. Analysis of Voltage Support during Fault Ride Through of Converter-Interfaced Distributed Generation Considering the Grid Impedance. In Proceedings of the NEIS 2018; Conference on Sustainable Energy Supply and Energy Storage Systems, Hamburg, Germany, 20–21 September 2018; pp. 1–6. [Google Scholar]
  135. Rokrok, E.; Shafie-khah, M.; Catalão, J. Review of primary voltage and frequency control methods for inverter-based islanded microgrids with distributed generation. Renew. Sustain. Energy Rev. 2018, 82, 3225–3235. [Google Scholar] [CrossRef]
  136. Kundur, P.; Paserba, J.; Ajjarapu, V.; Andersson, G.; Bose, A.; Canizares, C. Definition and classification of power system stability IEEE/CIGRE joint task force on stability terms and definitions. IEEE Trans. Power Syst. 2004, 19, 1387–1401. [Google Scholar]
  137. Ahmed, K.; Seyedmahmoudian, M.; Mekhilef, S.; Mubarak, N.; Stojcevski, A. A Review on Primary and Secondary Controls of Inverter-interfaced Microgrid. J. Mod. Power Syst. Clean Energy 2021, 9, 969–985. [Google Scholar] [CrossRef]
  138. Göksu, Ö.; Teodorescu, R.; Bak, C.; Iov, F.; Kjær, P. Instability of Wind Turbine Converters During Current Injection to Low Voltage Grid Faults and PLL Frequency Based Stability Solution. IEEE Trans. Power Syst. 2014, 29, 1683–1691. [Google Scholar] [CrossRef]
  139. Tian, X.; Cheng, P.; Wei, L.; Chi, Y.; Liu, H. Self-damping fault ride-through control of DFIG for weak grid. In Proceedings of the The 10th Renewable Power Generation Conference (RPG 2021), Online, 1–2 March 2021; pp. 862–868. [Google Scholar]
  140. Ramakrishna, R.; Miao, Z.; Fan, L. Dynamic Performance of Type-4 Wind with Synchronous Condenser during Weak Grids and Faults. In Proceedings of the 2021 IEEE Power & Energy Society General Meeting (PESGM), Washington, DC, USA,, 26–29 July 2021; pp. 1–5. [Google Scholar]
  141. Kim, J.; Muljadi, E.; Park, J.; Kang, Y. Adaptive Hierarchical Voltage Control of a DFIG-Based Wind Power Plant for a Grid Fault. IEEE Trans. Smart Grid. 2016, 7, 2980–2990. [Google Scholar] [CrossRef]
  142. Niu, L.; Wang, X.; Wu, L.; Yan, F.; Xu, M.; Hu, X. Low Voltage Ride-through Strategy for Wind Farm and VSC-HVDC. In Proceedings of the 2018 International Conference on Power System Technology (POWERCON), Guangzhou, China, 6–9 November 2018; pp. 2183–2188. [Google Scholar]
  143. Alsaif, A.; Miao, Z.; Fan, L. Inner Current Controls of Grid-Connected PV for Unbalanced Grid Conditions. In Proceedings of the 2021 North American Power Symposium (NAPS), College Station, TX, USA, 14–16 November 2021; pp. 1–6. [Google Scholar]
  144. Kim, D.; Ramadhan, U.; Islam, S.; Jung, S.; Yoon, M. Design and Implementation of Novel Fault Ride through Circuitry and Control for Grid-Connected PV System. Sustainability 2022, 14, 9736. [Google Scholar] [CrossRef]
  145. Al-Shetwi, A.; Sujod, M.; Blaabjerg, F.; Yang, Y. Fault ride-through control of grid-connected photovoltaic power plants: A review. Sol. Energy 2019, 180, 340–350. [Google Scholar] [CrossRef]
  146. El Moursi, M.S.; Xiao, W.; Kirtley, J.L., Jr. Fault ride through capability for grid interfacing large scale PV power plants. IET Gener. Transm. Distrib. 2013, 7, 1027–1036. [Google Scholar] [CrossRef]
  147. Mahdavi, S.; Panamtash, H.; Dimitrovski, A.; Zhou, Q. Predictive and Cooperative Voltage Control with Probabilistic Load and Solar Generation Forecasting. In Proceedings of the 2020 International Conference on Probabilistic Methods Applied to Power Systems (PMAPS), Liège, Belgium, 18–21 August 2020; pp. 1–6. [Google Scholar]
  148. Khadkikar, V.; Varma, R.; Seethapathy, R. Grid voltage regulation utilizing storage batteries in PV solar—Wind plant based distributed generation system. In Proceedings of the 2009 IEEE Electrical Power & Energy Conference (EPEC), Montreal, QC, Canada, 22–23 October 2009; pp. 1–6. [Google Scholar]
  149. Jamroen, C.; Pannawan, A.; Sirisukprasert, S. Battery Energy Storage System Control for Voltage Regulation in Microgrid with High Penetration of PV Generation. In Proceedings of the 2018 53rd International Universities Power Engineering Conference (UPEC), Glasgow, UK, 4–7 September 2018; pp. 1–6. [Google Scholar]
  150. Xing, L.; Mishra, Y.; Tian, Y.; Ledwich, G.; Wen, C.; He, W. Distributed Voltage Regulation for Low-Voltage and High-PV-Penetration Networks With Battery Energy Storage Systems Subject to Communication Delay. IEEE Trans. Control Syst. Technol. 2022, 30, 426–433. [Google Scholar] [CrossRef]
  151. Varetsky, Y.; Konoval, V.; Seheda, M.; Pastuh, O. Studying Voltage Fluctuations in Microgrid with Hybrid Renewable Energy System. In Proceedings of the 2019 IEEE 6th International Conference on Energy Smart Systems (ESS), Kyiv, Ukraine, 17–19 April 2019; pp. 239–242. [Google Scholar]
  152. Alam, M.; Muttaqi, K.; Sutanto, D. Battery Energy Storage to Mitigate Rapid Voltage/Power Fluctuations in Power Grids Due to Fast Variations of Solar/Wind Outputs. IEEE Access 2021, 9, 12191–12202. [Google Scholar] [CrossRef]
  153. Chandran, A.; Lenin, P. A review on active & reactive power control strategy for a standalone hybrid renewable energy system based on droop control. In Proceedings of the 2018 International Conference on Power, Signals, Control and Computation (EPSCICON), Thrissur, India, 6–10 January 2018; pp. 1–10. [Google Scholar]
  154. Rahman, M.M.; Mohammad, S.; Hossain, M.S. Frequency control in micro grid system using solar, wind, fuel cell and biomass energy. In Proceedings of the 2018 International Conference on Innovation in Engineering and Technology (ICIET), Dhaka, Bangladesh, 27–28 December 2018; pp. 1–6. [Google Scholar]
  155. Datta, A.; Konar, S.; Singha, L.; Singh, K.; Lalfakzuala, A. A study on load frequency control for a hybrid power plant. In Proceedings of the 2017 Second International Conference on Electrical, Computer and Communication Technologies (ICECCT), Tamil Nadu, India, 22–24 February 2017; pp. 1–5. [Google Scholar]
  156. Pandey, A.; Tyagi, N. Frequency control of an autonomous hybrid generation system. In Proceedings of the 2017 IEEE International Conference on Power, Control, Signals and Instrumentation Engineering (ICPCSI), Chennai, India, 21–22 September 2017; pp. 2688–2893. [Google Scholar]
  157. Sato, T.; Asharif, F.; Takahashi, R.; Umemura, A.; Tamura, J. Cooperative Virtual Inertia and Reactive Power Control of PMSG Wind Generator and Battery for Improving Transient Stability of Power System Including Renewable Energy Sources. In Proceedings of the 2021 2nd International Conference on Robotics, Electrical and Signal Processing Techniques (ICREST), Dhaka, Bangladesh, 5–7 January 2021; pp. 287–292. [Google Scholar]
  158. Nikolakakos, C.; Mushtaq, U.; Palensky, P.; Cvetković, M. Improving Frequency Stability with Inertial and Primary Frequency Response via DFIG Wind Turbines equipped with Energy Storage System. In Proceedings of the 2020 IEEE PES Innovative Smart Grid Technologies Europe ISGT-Europe, The Hague, The Netherlands, 26–28 October 2020; pp. 1156–1160. [Google Scholar]
  159. Sahoo, B.; Panda, S. Load Frequency Control of Solar Photovoltaic/Wind/Biogas/Biodiesel Generator Based Isolated Microgrid Using Harris Hawks Optimization. In Proceedings of the 2020 First International Conference on Power, Control and Computing Technologies (ICPC2T), Raipur, India, 3–5 January 2020; pp. 188–193. [Google Scholar]
  160. Zadeh, M.; Afshar, Z.; Harandi, M.; Taghi Bathaee, S. Frequency Control of Low Inertia Microgids in Presence of Wind and Solar Units Using Fuzzy-neural Controllers. In Proceedings of the 2022 26th International Electrical Power Distribution Conference (EPDC), Tehran, Iran, 11–12 May 2022; pp. 54–59. [Google Scholar]
  161. Wang, Z.; Luo, D.; Li, R.; Zhang, L.; Liu, C.; Tian, X. Research on the active power coordination control system for wind/photovoltaic/energy storage. In Proceedings of the 2017 IEEE Conference on Energy Internet and Energy System Integration (EI2), Beijing, China, 26–28 November 2017; pp. 1–5. [Google Scholar]
  162. Loka, R.; Parimi, A.; Srinivas, S. Model Predictive Control Design for Fast Frequency Regulation in Hybrid Power System. In Proceedings of the 2022 2nd International Conference on Power Electronics & IoT Applications in Renewable Energy and Its Control (PARC), Mathura, India, 21–22 January 2022; pp. 1–5. [Google Scholar]
  163. Long, Q.; Das, K.; Sørensen, P. Hierarchical Frequency Control of Hybrid Power Plants Using Frequency Response Observer. IEEE Trans. Sustain. Energy 2023, 14, 504–515. [Google Scholar] [CrossRef]
  164. Bakir, H.; Kulaksiz, A. Modelling and voltage control of the solar-wind hybrid micro-grid with optimized STATCOM using GA and BFA. Eng. Sci. Technol. Int. J. 2020, 23, 576–584. [Google Scholar] [CrossRef]
  165. Moheb, A.; El-Hay, E.; El-Fergany, A. Comprehensive Review on Fault Ride-Through Requirements of Renewable Hybrid Microgrids. Energies 2022, 15, 6785. [Google Scholar] [CrossRef]
  166. Pati, S.; Subudhi, U. Frequency regulation of Solar-Wind integrated multi-area system with SMES and SSSC. In Proceedings of the 2021 IEEE International Power and Renewable Energy Conference (IPRECON), Kollam, India, 24–26 September 2021; pp. 1–4. [Google Scholar]
  167. Adib, A.; Mirafzal, B.; Wang, X.; Blaabjerg, F. On Stability of Voltage Source Inverters in Weak Grids. IEEE Access 2018, 6, 4427–4439. [Google Scholar] [CrossRef]
  168. Wang, M.; Meng, K.; Yu, L.; Yuan, L.; Liang, Z. Comparative Fault Ride Through Assessment between Grid-following and Grid-forming Control for Weak Grids Integration. In Proceedings of the 2022 IEEE Global Conference on Computing, Power and Communication Technologies (GlobConPT), Kollam, India, 24–26 September 2022; pp. 1–6. [Google Scholar]
  169. Dozein, M.; Mancarella, P.; Saha, T.; Yan, R. System Strength and Weak Grids: Fundamentals, Challenges, and Mitigation Strategies. In Proceedings of the 2018 Australasian Universities Power Engineering Conference (AUPEC), Hobart, Australia, 29 November–3 December 2018; pp. 1–7. [Google Scholar]
  170. Li, C.; Yang, Y.; Cao, Y.; Wang, L.; Blaabjerg, F. Frequency and Voltage Stability Analysis of Grid-Forming Virtual Synchronous Generator Attached to Weak Grid. IEEE J. Emerg. Sel. Top Power Electron. 2020, 10, 2662–2671. [Google Scholar] [CrossRef]
  171. Long, Q.; Das, K.; V, P.D.; Sørensen, P. Hierarchical control architecture of co-located hybrid power plants. Int. J. Electr. Power Energy Syst. 2022, 143, 108407. [Google Scholar] [CrossRef]
  172. Wang, Z.; Fan, L.; Miao, Z. Stability Analysis of Oscillations in SVCs. In Proceedings of the 2022 North American Power Symposium (NAPS), Salt Lake City, UT, USA, 9–11 October 2022; pp. 1–5. [Google Scholar]
  173. Fan, L.; Miao, Z.; Piper, D.; Ramasubramanian, D.; Zhu, L.; Mitra, P. Analysis of 0.1-Hz Var Oscillations in Solar Photovoltaic Power Plants. IEEE Trans. Sustain. Energy 2023, 14, 734–737. [Google Scholar] [CrossRef]
  174. Fan, L.; Miao, Z.; Wang, Z. A New Type of Weak Grid IBR Oscillations. IEEE Trans. Power Syst. 2023, 38, 988–991. [Google Scholar] [CrossRef]
  175. Sørensen, P.; Hansen, A.; Christensen, P.; Mieritz, M.; Bech, J.; Bak-Jensen, B. Simulation and Verification of Transient Events in Large Wind Power Installations; DTU Library: New Delhi, India, 2003. [Google Scholar]
  176. Shah, C.; Vasquez-Plaza, J.; Campo-Ossa, D.; Patarroyo-Montenegro, J.; Guruwacharya, N.; Bhujel, N. Review of Dynamic and Transient Modeling of Power Electronic Converters for Converter Dominated Power Systems. IEEE Access 2021, 9, 82094–82117. [Google Scholar] [CrossRef]
  177. Irwin, G. Intricacies in PSCAD/EMT Analysis: A Discussion of Intricacies in EMT Simulation of Power Electronic Controllers, Which Can Lead to Varying Results and Poor Benchmark/Comparisons; Technical Report; Electranix: Winnipeg, MB, Canada, 2020. [Google Scholar]
  178. Shahnazian, F.; Das, K.; Yan, R.; Sørensen, P. Challenges of renewable energy integration to weak grids. In Proceedings of the 22nd Wind and Solar Integration Workshop (WIW 2023), Copenhagen, Denmark, 26–28 September 2023; Volume 2023, pp. 529–536. [Google Scholar] [CrossRef]
Energies 17 06353 g001
Figure 1. Different integration and operation configurations of various generating modules in HPPs, (a) WPP and SPP sharing the same grid connection, (b) PV panels integrated with the turbines.
Figure 1. Different integration and operation configurations of various generating modules in HPPs, (a) WPP and SPP sharing the same grid connection, (b) PV panels integrated with the turbines.
Energies 17 06353 g001
Energies 17 06353 g002
Figure 2. Frequency response contribution stages [41].
Figure 2. Frequency response contribution stages [41].
Energies 17 06353 g002
Energies 17 06353 g003
Figure 3. Generic structure of hierarchical HPP control.
Figure 3. Generic structure of hierarchical HPP control.
Energies 17 06353 g003
Table 1. Overview of pros and cons of HPP projects [33,36].
Table 1. Overview of pros and cons of HPP projects [33,36].
proscons
Better grid utilization by increasing capacity factorReduced operational flexibility of the battery
Potential reduction in variabilityUncertainty related to future policy schemes
Potential increase in Net Present Value of investment (NPV/CAPEX)Metering needs to be standardized
Increase in availabilitySizing the plant
Increase in ancillary service capability
Table 2. Overview of proposed frequency control methods in single technology power plants.
Table 2. Overview of proposed frequency control methods in single technology power plants.
Ref.FFCPFCSFCWind Power PlantSolar Power PlantStorage Technology
PAPA
[75] ✓ ✓
[76]✓✓ ✓
[77]✓ ✓
[78]✓ ✓
[79] ✓ ✓
[80]✓✓ ✓✓
[81] ✓✓
[82]✓ ✓
[83] ✓ ✓
[84]✓ ✓
[85] ✓ ✓
[86]✓ ✓
[87] ✓ ✓
[88]✓✓ ✓
[89]✓ ✓
[90] ✓ ✓
[91]✓ ✓
[92] ✓ ✓
[93]✓ ✓
[94]✓ ✓
[95]✓ Battery
[96] ✓ Battery
[97] ✓ Battery
[98] ✓ Flywheel
[99] ✓ Battery
[100]✓✓ Distributed
[101] ✓ Compressed Air
[102] ✓ Battery
[103] ✓ Battery
[104] ✓ Battery
[105] ✓ Battery
Table 3. Overview of proposed voltage control methods in single-technology power plants.
Table 3. Overview of proposed voltage control methods in single-technology power plants.
Ref.FRTPrVCSeVCWind Power PlantSolar Power PlantStorage Technology
PAPA
[138]✓ ✓
[139]✓ ✓
[140]✓ ✓
[141]✓ ✓
[142]✓ ✓
[119] ✓✓
[111]✓✓ ✓
[115] ✓✓ ✓
[116] ✓ ✓
[117] ✓ ✓
[27] ✓✓✓✓
[122] ✓✓
[123] ✓✓
[124] ✓✓
[125] ✓✓
[143]✓ ✓
[144]✓ ✓
[145]✓ ✓
[146]✓ ✓
[112] ✓ ✓
[126] ✓ ✓
[147] ✓✓ ✓✓
[148] ✓ Battery in SPP or WPP
[149] ✓ Battery in SPP
[150] ✓ Battery in SPP
Table 4. Overview of proposed frequency and voltage control objectives in hybrid power plants.
Table 4. Overview of proposed frequency and voltage control objectives in hybrid power plants.
Ref.Frequency ControlVoltage ControlIncluded Technologies
FFCPFCSFCFRTPrVCSeVC
[164] ✓Wind + solar + STATCOM
[165] ✓ Wind + solar
[151] ✓ Wind + solar +generalized energy storage
[152] ✓ Wind + solar + storage
[153] ✓ ✓ Wind + solar + battery
[154]✓✓ Wind + solar+ fuel cell + biomass
[155]✓✓ Wind + solar + conventional energy sources
[156]✓ Wind + diesel generator + aqua electrolyzer+ fuel cell + battery
[157]✓ ✓ Wind + battery
[158]✓✓ Wind + energy storage
[159]✓ Wind + solar + biogas + biodiesel generators + flywheel + battery
[160]✓ Wind + solar + battery + diesel generator
[161]✓✓ Wind + solar + energy storage
[46]✓✓ Wind + solar + energy storage
[162] ✓ Wind + thermal power system + battery + fuel cell +aqua electrolyzer + diesel generator
[163]✓✓✓ Wind + solar + energy storage
[166]✓✓ Wind + solar + diesel generator + energy storage + Superconducting Magnetic Energy storage (SMES) + static synchronous series compensator (SSSC)
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Shahnazian, F.; Das, K.; Yan, R.; Sørensen, P. Aspects of Relevance of Hybrid Power Plants in Control and Stability of Weak Grids. Energies 2024, 17, 6353. https://doi.org/10.3390/en17246353

AMA Style

Shahnazian F, Das K, Yan R, Sørensen P. Aspects of Relevance of Hybrid Power Plants in Control and Stability of Weak Grids. Energies. 2024; 17(24):6353. https://doi.org/10.3390/en17246353

Chicago/Turabian Style

Shahnazian, Fatemeh, Kaushik Das, Ruifeng Yan, and Poul Sørensen. 2024. "Aspects of Relevance of Hybrid Power Plants in Control and Stability of Weak Grids" Energies 17, no. 24: 6353. https://doi.org/10.3390/en17246353

APA Style

Shahnazian, F., Das, K., Yan, R., & Sørensen, P. (2024). Aspects of Relevance of Hybrid Power Plants in Control and Stability of Weak Grids. Energies, 17(24), 6353. https://doi.org/10.3390/en17246353

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop