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25 pages, 9548 KiB

Open AccessArticle

Optimization of Costs and Self-Sufficiency for Roof Integrated Photovoltaic Technologies on Residential Buildings

by Guglielmina Mutani and Valeria Todeschi

Energies 2021, 14(13), 4018; https://doi.org/10.3390/en14134018 - 3 Jul 2021

Cited by 10 | Viewed by 3095

Abstract

It is common practice, in the production of photovoltaic energy to only use the south-exposed roof surface of a building, in order to achieve the maximum production of solar energy while lowering the costs of the energy and the solar technologies. However, using [...] Read more.

It is common practice, in the production of photovoltaic energy to only use the south-exposed roof surface of a building, in order to achieve the maximum production of solar energy while lowering the costs of the energy and the solar technologies. However, using the south-exposed surface of a roof only allows a small quota of the energy demand to be covered. Roof surfaces oriented in other directions could also be used to better cover the energy load profile. The aim of this work is to investigate the benefits, in terms of costs, self-sufficiency and self-consumption, of roof integrated photovoltaic technologies on residential buildings with different orientations. A cost-optimal analysis has been carried out taking into account the economic incentives for a collective self-consumer configuration. It has emerged, from this analysis, that the better the orientation is, the higher the energy security and the lower the energy costs and those for the installation of photovoltaic technologies. In general, the use of south-facing and north-facing roof surfaces for solar energy production has both economic and energy benefits. The self-sufficiency index can on average be increased by 8.5% through the use of photovoltaic installations in two directions on gable roofs, and the maximum level that can be achieved was on average 41.8, 41.5 and 35.7% for small, medium and large condominiums, respectively. Therefore, it could be convenient to exploit all the potential orientations of photovoltaic panels in cities to improve energy security and to provide significant economic benefits for the residential users. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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17 pages, 1654 KiB

Open AccessArticle

A Progressive Period Optimal Power Flow for Systems with High Penetration of Variable Renewable Energy Sources

by Zongjie Wang and C. Lindsay Anderson

Energies 2021, 14(10), 2815; https://doi.org/10.3390/en14102815 - 14 May 2021

Cited by 15 | Viewed by 3197

Abstract

Renewable energy sources including wind farms and solar sites, have been rapidly integrated within power systems for economic and environmental reasons. Unfortunately, many renewable energy sources suffer from variability and uncertainty, which may jeopardize security and stability of the power system. To face [...] Read more.

Renewable energy sources including wind farms and solar sites, have been rapidly integrated within power systems for economic and environmental reasons. Unfortunately, many renewable energy sources suffer from variability and uncertainty, which may jeopardize security and stability of the power system. To face this challenge, it is necessary to develop new methods to manage increasing supply-side uncertainty within operational strategies. In modern power system operations, the optimal power flow (OPF) is essential to all stages of the system operational horizon; underlying both day-ahead scheduling and real-time dispatch decisions. The dispatch levels determined are then implemented for the duration of the dispatch interval, with the expectation that frequency response and balancing reserves are sufficient to manage intra-interval deviations. To achieve more accurate generation schedules and better reliability with increasing renewable resources, the OPF must be solved faster and with better accuracy within continuous time intervals, in both day-ahead scheduling and real-time dispatch. To this end, we formulate a multi-period dispatch framework, that is, progressive period optimal power flow (PPOPF), which builds on an interval optimal power flow (IOPF), which leverages median and endpoints on the interval to develop coherent coordinations between day-ahead and real-time period optimal power flow (POPF). Simulation case studies on a practical PEGASE 13,659-bus transmission system in Europe have demonstrated implementation of the proposed PPOPF within multi-stage power system operations, resulting in zero dispatch error and violation compared with traditional OPF. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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30 pages, 19949 KiB

Open AccessArticle

CO₂ Intensities and Primary Energy Factors in the Future European Electricity System

by Sam Hamels

Energies 2021, 14(8), 2165; https://doi.org/10.3390/en14082165 - 13 Apr 2021

Cited by 23 | Viewed by 4043

Abstract

The European Union strives for sharp reductions in both CO₂ emissions as well as primary energy use. Electricity consuming technologies are becoming increasingly important in this context, due to the ongoing electrification of transport and heating services. To correctly evaluate these technologies, [...] Read more.

The European Union strives for sharp reductions in both CO₂ emissions as well as primary energy use. Electricity consuming technologies are becoming increasingly important in this context, due to the ongoing electrification of transport and heating services. To correctly evaluate these technologies, conversion factors are needed—namely CO₂ intensities and primary energy factors (PEFs). However, this evaluation is hindered by the unavailability of a high-quality database of conversion factor values. Ideally, such a database has a broad geographical scope, a high temporal resolution and considers cross-country exchanges of electricity as well as future evolutions in the electricity mix. In this paper, a state-of-the-art unit commitment economic dispatch model of the European electricity system is developed and a flow-tracing technique is innovatively applied to future scenarios (2025–2040)—to generate such a database and make it publicly available. Important dynamics are revealed, including an overall decrease in conversion factor values as well as considerable temporal variability at both the seasonal and hourly level. Furthermore, the importance of taking into account imports and carefully considering the calculation methodology for PEFs are both confirmed. Future estimates of the CO₂ emissions and primary energy use associated with individual electrical loads can be meaningfully improved by taking into account these dynamics. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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19 pages, 645 KiB

Open AccessArticle

Day-Ahead Energy and Reserve Dispatch Problem under Non-Probabilistic Uncertainty

by Keivan Shariatmadar, Adriano Arrigo, François Vallée, Hans Hallez, Lieven Vandevelde and David Moens

Energies 2021, 14(4), 1016; https://doi.org/10.3390/en14041016 - 15 Feb 2021

Cited by 4 | Viewed by 2636

Abstract

The current energy transition and the underlying growth in variable and uncertain renewable-based energy generation challenge the proper operation of power systems. Classical probabilistic uncertainty models, e.g., stochastic programming or robust optimisation, have been used widely to solve problems such as the day-ahead [...] Read more.

The current energy transition and the underlying growth in variable and uncertain renewable-based energy generation challenge the proper operation of power systems. Classical probabilistic uncertainty models, e.g., stochastic programming or robust optimisation, have been used widely to solve problems such as the day-ahead energy and reserve dispatch problem to enhance the day-ahead decisions with a probabilistic insight of renewable energy generation in real-time. By doing so, the scheduling of the power system becomes, production and consumption of electric power, more reliable (i.e., more robust because of potential deviations) while minimising the social costs given potential balancing actions. Nevertheless, these classical models are not valid when the uncertainty is imprecise, meaning that the system operator may not rely on a unique distribution function to describe the uncertainty. Given the Distributionally Robust Optimisation method, our approach can be implemented for any non-probabilistic, e.g., interval models rather than only sets of distribution functions (ambiguity set of probability distributions). In this paper, the aim is to apply two advanced non-probabilistic uncertainty models: Interval and

ϵ

-contamination, where the imprecision and in-determinism in the uncertainty (uncertain parameters) are considered. We propose two kinds of theoretical solutions under two decision criteria—Maximinity and Maximality. For an illustration of our solutions, we apply our proposed approach to a case study inspired by the 24-node IEEE reliability test system. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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19 pages, 471 KiB

Open AccessArticle

A Two-Stage Stochastic Optimisation Methodology for the Operation of a Chlor-Alkali Electrolyser under Variable DAM and FCR Market Prices

by Jens Baetens, Jeroen D. M. De Kooning, Greet Van Eetvelde and Lieven Vandevelde

Energies 2020, 13(21), 5675; https://doi.org/10.3390/en13215675 - 30 Oct 2020

Cited by 8 | Viewed by 2898

Abstract

The increased penetration of renewable energy sources in the electrical grid raises the need for more power system flexibility. One of the high potential groups to provide such flexibility is the industry. Incentives to do so are provided by variable pricing and remuneration [...] Read more.

The increased penetration of renewable energy sources in the electrical grid raises the need for more power system flexibility. One of the high potential groups to provide such flexibility is the industry. Incentives to do so are provided by variable pricing and remuneration of supplied ancillary services. The operational flexibility of a chlor-alkali electrolysis process shows opportunities in the current energy and ancillary services markets. A co-optimisation of operating the chlor-alkali process under an hourly variable priced electricity sourcing strategy and the delivery of Frequency Containment Reserve (FCR) is the core of this work. A short term price prediction for the Day-Ahead Market (DAM) and FCR market as input for a deterministic optimisation shows good results under standard DAM price patterns, but leaves room for improvement in case of price fluctuations, e.g., as caused by Renewable Energy Sources (RES). A two-stage stochastic optimisation is considered to cope with the uncertainties introduced by the exogenous parameters. An improvement of the stochastic solution over the deterministic Expected Value (EV) solution is shown. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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19 pages, 10220 KiB

Open AccessArticle

An Adjusted Weight Metric to Quantify Flexibility Available in Conventional Generators for Low Carbon Power Systems

by Saleh Abujarad, Mohd Wazir Mustafa, Jasrul Jamani Jamian, Abdirahman M. Abdilahi, Jeroen D. M. De Kooning, Jan Desmet and Lieven Vandevelde

Energies 2020, 13(21), 5658; https://doi.org/10.3390/en13215658 - 29 Oct 2020

Cited by 5 | Viewed by 2657

Abstract

With the increasing shares of intermittent renewable sources in the grid, it becomes increasingly essential to quantify the requirements of the power systems flexibility. In this article, an adjusted weight flexibility metric (AWFM) is developed to quantify the available flexibility within individual generators [...] Read more.

With the increasing shares of intermittent renewable sources in the grid, it becomes increasingly essential to quantify the requirements of the power systems flexibility. In this article, an adjusted weight flexibility metric (AWFM) is developed to quantify the available flexibility within individual generators as well as within the overall system. The developed metric is useful for power system operators who require a fast, simple, and offline metric. This provides a more realistic and accurate quantification of the available technical flexibility without performing time-consuming multi-temporal simulations. Another interesting feature is that it can be used to facilitate scenario comparisons. This is achieved by developing a new framework to assure the consistency of the metric and by proposing a new adjusted weighting mechanism based on correlation analysis and analytic hierarchy process (AHP). A new ranking approach based on flexibility was also proposed to increase the share of the renewable energy sources (RESs). The proposed framework was tested on the IEEE RTS-96 test-system. The results demonstrate the consistency of the AWFM. Moreover, the results show that the proposed metric is adaptive as it automatically adjusts the flexibility index with the addition or removal of generators. The new ranking approach proved its ability to increase the wind share from 28% to 37.2% within the test system. The AWFM can be a valuable contribution to the field of flexibility for its ability to provide systematic formulation for the precise analysis and accurate assessment of inherent technical flexibility for a low carbon power system. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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29 pages, 2833 KiB

Open AccessArticle

Test Grids for the Integration of RES—A Contribution for the European Context

by Anna Traupmann and Thomas Kienberger

Energies 2020, 13(20), 5431; https://doi.org/10.3390/en13205431 - 17 Oct 2020

Cited by 8 | Viewed by 3660

Abstract

A long-term sustainable energy transition can only be achieved by technological advancements and new approaches for efficiently integrating renewable energies into the overall energy system. Significantly increasing the share of renewable energy sources (RES) within the overall energy system requires appropriate network models [...] Read more.

A long-term sustainable energy transition can only be achieved by technological advancements and new approaches for efficiently integrating renewable energies into the overall energy system. Significantly increasing the share of renewable energy sources (RES) within the overall energy system requires appropriate network models of current transmission and distribution grids, which, as limiting factors of energy infrastructures, confine this share due to capacity constraints. However, especially regarding electrical network models, data (e.g., geographical data, load and generation profiles, etc.) is rarely available since it usually includes user-specific information and is, therefore, subject to data protection. Synthetically obtained electrical networks, on the other hand, may not be representative and may fail to replicate real grid structures due to the heterogeneous properties of currently operated networks. To account for this heterogeneity, this paper offers a contribution for the European electrical energy system and presents the development of four synthetic test networks at different voltage levels which are representative and include non-confidential time-series data. The test network development is based on an extensive literature research on a multitude of different network parameters for grids within the ENTSO-E (European Network of Transmission System Operators for Electricity) interconnected system in Europe. These parameters are then used to design the networks in NEPLAN^®. Then, these networks are provided with load and generation profiles for enabling time-series calculations. To validate the representativeness of the test networks, a short-circuit analysis is conducted and the obtained results are compared to short-circuit parameters common for Austrian and German literature values as well as for value ranges for European ENTSO-E grids. The analysis shows that the presented test networks replicate European electrical network behavior accurately and can, therefore, be utilized for various application purposes to assess technological impacts on European ENTSO-E grids. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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19 pages, 4390 KiB

Open AccessArticle

Indirect Matrix Converter-Based Grid-Tied Photovoltaics System for Smart Grids

by Thomas Geury, Sonia Ferreira Pinto, Johan Gyselinck and Patrick Wheeler

Energies 2020, 13(20), 5405; https://doi.org/10.3390/en13205405 - 16 Oct 2020

Cited by 1 | Viewed by 2347

Abstract

This paper proposes an Indirect Matrix Converter (IMC)-based grid-tied Photovoltaic (PV) system for Smart Grids (SGs). The PV array injects current in the ‘dc link’ of the IMC through an inductive link, and is connected to the SG with shunt and series connections, [...] Read more.

This paper proposes an Indirect Matrix Converter (IMC)-based grid-tied Photovoltaic (PV) system for Smart Grids (SGs). The PV array injects current in the ‘dc link’ of the IMC through an inductive link, and is connected to the SG with shunt and series connections, allowing for the compensation of current- and voltage-related Power Quality (PQ) issues, respectively, for the sensitive loads and the SG connection. A direct sliding mode-based controller is proposed to guarantee nearly sinusoidal currents in the connection to the SG, and sinusoidal voltages guaranteeing compliance with international standards, when supplying the sensitive loads. Additionally, a novel control approach for the ‘dc link’ voltage is synthesised to allow for the control of both the PV array current and the power flow to the SG. To guarantee the semiconductors safe commutation an asynchronous commutation strategy is derived. Simulation and experimental results show that the proposed system significantly improves PQ in the SG, minimizing the total harmonic distortion of the currents injected in the SG, and guaranteeing the quality of the voltage supplied to the sensitive loads, even in the occurrence of voltage sags or overvoltages. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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21 pages, 15183 KiB

Open AccessArticle

The Impact of Pitch-To-Stall and Pitch-To-Feather Control on the Structural Loads and the Pitch Mechanism of a Wind Turbine

by Arash E. Samani, Jeroen D. M. De Kooning, Nezmin Kayedpour, Narender Singh and Lieven Vandevelde

Energies 2020, 13(17), 4503; https://doi.org/10.3390/en13174503 - 1 Sep 2020

Cited by 14 | Viewed by 4465

Abstract

This article investigates the impact of the pitch-to-stall and pitch-to-feather control concepts on horizontal axis wind turbines (HAWTs) with different blade designs. Pitch-to-feather control is widely used to limit the power output of wind turbines in high wind speed conditions. However, stall control [...] Read more.

This article investigates the impact of the pitch-to-stall and pitch-to-feather control concepts on horizontal axis wind turbines (HAWTs) with different blade designs. Pitch-to-feather control is widely used to limit the power output of wind turbines in high wind speed conditions. However, stall control has not been taken forward in the industry because of the low predictability of stalled rotor aerodynamics. Despite this drawback, this article investigates the possible advantages of this control concept when compared to pitch-to-feather control with an emphasis on the control performance and its impact on the pitch mechanism and structural loads. In this study, three HAWTs with different blade designs, i.e., untwisted, stall-regulated, and pitch-regulated blades, are investigated. The control system is validated in both uniform and turbulent wind speed. The results show that pitch-to-stall control enhances the constant power control for wind turbines with untwisted and stall-regulated blade designs. Stall control alleviates the fore-aft tower loading and the blades flapwise moment of the wind turbine with stall-regulated blades in uniform winds. However, in turbulent winds, the flapwise moment increases to a certain extent as compared to pitch-to-feather control. Moreover, pitch-to-stall control considerably reduces the summed blade pitch movement, despite that it increases the risk of surface damage in the rolling bearings due to oscillating movements with a small amplitude. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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12 pages, 2613 KiB

Open AccessArticle

Fault Ride-Through Characteristics of Small Wind Turbines

by Junji Kondoh, Hidetoshi Mizuno and Takuji Funamoto

Energies 2019, 12(23), 4587; https://doi.org/10.3390/en12234587 - 2 Dec 2019

Cited by 3 | Viewed by 3677

Abstract

There is significant potential for an increase in the use of kilowatt-class small wind turbines (SWTs) in Japan due to reduced limitations with respect to installation, despite their high cost. At this stage, the Japanese grid code has not been considered sufficiently with [...] Read more.

There is significant potential for an increase in the use of kilowatt-class small wind turbines (SWTs) in Japan due to reduced limitations with respect to installation, despite their high cost. At this stage, the Japanese grid code has not been considered sufficiently with respect to grid-connected SWTs, and the addition of fault ride-through (FRT) requirements for SWTs has been requested. Moreover, the FRT of SWTs is challenging to achieve owing to the low inertia constants when compared with those of large-scale wind turbines, which result in significant acceleration of the rotor speed and an increase in the input voltage of the power conditioning system (PCS) during FRT operation. In this study, FRT field tests were conducted on SWT systems against a voltage dip with a duration of

~ 1

s, and it was confirmed that the SWT systems satisfied the FRT requirements for photovoltaic (PV) systems connected to low-voltage distribution lines in Japan. The behaviors of the rotational speed of the SWTs and the PCS input voltage in an FRT operation were then analyzed, and it was noted that the increase in the PCS input voltage with the overspeed of the turbine can reach the upper limit and make the PCS cease operation, which indicates failure of the FRT. The overvoltage, therefore, requires restriction using a method such as pitch control, furling, and electrical and/or mechanical brakes. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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20 pages, 2859 KiB

Open AccessArticle

Generation Expansion Planning Based on Dynamic Bayesian Network Considering the Uncertainty of Renewable Energy Resources

by Xiangyu Kong, Jingtao Yao, Zhijun E and Xin Wang

Energies 2019, 12(13), 2492; https://doi.org/10.3390/en12132492 - 28 Jun 2019

Cited by 8 | Viewed by 3846

Abstract

In generation expansion planning, sustainable generation expansion planning is gaining more and more attention. Based on the comprehensive consideration of generation expansion planning economics, technology, environment, and other fields, this paper analyzes the sustainable development of power supply planning evaluation indicators and builds [...] Read more.

In generation expansion planning, sustainable generation expansion planning is gaining more and more attention. Based on the comprehensive consideration of generation expansion planning economics, technology, environment, and other fields, this paper analyzes the sustainable development of power supply planning evaluation indicators and builds a multi-objective generation expansion planning decision model considering sustainable development. According to the target variables in the model, the variables such as attribute variables are divided into different subsets, and the logical relationship analysis method between different nodes is obtained based on Dynamic Bayesian network theory, which reduces the complexity of the planning model problem. The application examples show the feasibility and effectiveness of the proposed model and the solution method. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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14 pages, 4836 KiB

Open AccessArticle

Research of the Fundamental Wave of Wound-Rotor Brushless Doubly-Fed Machine

by Zhenming Li, Xuefan Wang, Lezhi Ou, Xinmai Gao and Fei Xiong

Energies 2019, 12(6), 1172; https://doi.org/10.3390/en12061172 - 26 Mar 2019

Viewed by 2490

Abstract

The brushless doubly-fed machine (BDFM) is a special type of machine with two sets of stator windings and one set of rotor winding. The magnetic field of the BDFM is considered to be complex with no regularity. To study the principles of magnetic [...] Read more.

The brushless doubly-fed machine (BDFM) is a special type of machine with two sets of stator windings and one set of rotor winding. The magnetic field of the BDFM is considered to be complex with no regularity. To study the principles of magnetic fields for the BDFM, a general expression of the fundamental wave is deduced, which shows that the fundamental wave can be regarded as a standing wave when it is observed from rotor reference; also, some discussions about the characteristics of the fundamental wave are presented in the paper. Next, a model of wound-rotor BDFM prototype is established, and the enveloping line and the relations between rotor position and its electrical angle of the magnetic field are figured out in the paper. Finally, after detecting the induced electromotive force (EMF) of measurement coils embedded in the corresponding prototype machine, the validity of the proposed conclusions is verified. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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16 pages, 3180 KiB

Open AccessArticle

Analysis of the Propagation Characteristic of Subsynchronous Oscillation in Wind Integrated Power System

by Zhiping Wen, Shutao Peng, Jing Yang, Jun Deng, Hanqing He and Tong Wang

Energies 2019, 12(6), 1081; https://doi.org/10.3390/en12061081 - 20 Mar 2019

Cited by 10 | Viewed by 3103

Abstract

This paper proposes oscillation propagation factors to analyze power oscillations caused by the interharmonics of doubly fed induction generators (DFIG) at different points in the power system. First, a dynamic model of the DIFG is built, including the asynchronous generator, its transmission system, [...] Read more.

This paper proposes oscillation propagation factors to analyze power oscillations caused by the interharmonics of doubly fed induction generators (DFIG) at different points in the power system. First, a dynamic model of the DIFG is built, including the asynchronous generator, its transmission system, converters and the control systems. Then, the state space expression is formed by deducing the input and output matrices. From this, the oscillation propagation factor is proposed and denoted to exhibit the propagation mechanism of interharmonics in the view of frequency domain, by deducing the multi-input-multi-output transfer functions matrix. Along with this, the sensitivity of propagation is calculated for adjusting the parameters to block the oscillation propagating path. Finally, the modified four machine system with two DFIGs and the New-England 39 bus system with two DFIGs is used as a test system to verify the effectiveness of the oscillation propagation factor. From this the simulation results demonstrate that the subsynchronous interharmonics of DFIGs injected into the grid will propagate to the different points of the system and results in oscillation of the power. The oscillation propagation factor could quantize the oscillation magnitude propagating from one point to other point in the wind integrated power system. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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12 pages, 2566 KiB

Open AccessArticle

Power Loss Minimization and Voltage Stability Improvement in Electrical Distribution System via Network Reconfiguration and Distributed Generation Placement Using Novel Adaptive Shuffled Frogs Leaping Algorithm

by Arun Onlam, Daranpob Yodphet, Rongrit Chatthaworn, Chayada Surawanitkun, Apirat Siritaratiwat and Pirat Khunkitti

Energies 2019, 12(3), 553; https://doi.org/10.3390/en12030553 - 11 Feb 2019

Cited by 109 | Viewed by 6174

Abstract

This paper proposes a novel adaptive optimization algorithm to solve the network reconfiguration and distributed generation (DG) placement problems with objective functions including power loss minimization and voltage stability index (VSI) improvement. The proposed technique called Adaptive Shuffled Frogs Leaping Algorithm (ASFLA) was [...] Read more.

This paper proposes a novel adaptive optimization algorithm to solve the network reconfiguration and distributed generation (DG) placement problems with objective functions including power loss minimization and voltage stability index (VSI) improvement. The proposed technique called Adaptive Shuffled Frogs Leaping Algorithm (ASFLA) was performed for solving network reconfiguration and DG installation in IEEE 33- and 69-bus distribution systems with seven different scenarios. The performance of ASFLA was compared to that of other algorithms such as Fireworks Algorithm (FWA), Adaptive Cuckoo Search Algorithm (ACSA) and Shuffled Frogs Leaping Algorithm (SFLA). It was found that the power loss and VSI provided by ASFLA were better than those given by FWA, ACSA and SFLA in both 33- and 69-bus systems. The best solution of power loss reduction and VSI improvement of both 33- and 69-bus systems was achieved when the network reconfiguration with optimal sizing and the location DG were simultaneously implemented. From our analysis, it was indicated that the ASFLA could provide better solutions than other methods since the generating process, local and global searching of this algorithm were significantly improved from a conventional method. Hence, the ASFLA becomes another effective algorithm for solving network reconfiguration and DG placement problems in electrical distribution systems. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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22 pages, 3634 KiB

Open AccessArticle

Model Reduction of DFIG Wind Turbine System Based on Inner Coupling Analysis

by Pingping Han, Yu Zhang, Lei Wang, Yan Zhang and Zihao Lin

Energies 2018, 11(11), 3234; https://doi.org/10.3390/en11113234 - 21 Nov 2018

Cited by 9 | Viewed by 3913

Abstract

The doubly-fed induction generator (DFIG) wind turbine system, which is composed of the wind turbine, generator, rotor-side converter, grid-side converter, and so on, is a typical multi-time scale system. The dynamic processes at different time scales do not exist in isolation. Furthermore, neglecting [...] Read more.

The doubly-fed induction generator (DFIG) wind turbine system, which is composed of the wind turbine, generator, rotor-side converter, grid-side converter, and so on, is a typical multi-time scale system. The dynamic processes at different time scales do not exist in isolation. Furthermore, neglecting the coupling of parameters of different time scales to reduce the order of the model will lead to deviation between the simulation results and the actual results, which may not be suitable for power system transient analysis. This paper proposes an electromechanical transient model and an electromagnetic transient model of the DFIG wind turbine system that consider the interaction of multiple time-scale dynamic processes. Firstly, the paper applies the modal analysis method to explain the multi-time scale characteristics of the DFIG wind turbine system. Secondly, the variation in the eigenvalues of the DFIG wind turbine system before and after the order reduction and the coupling between variables and the system, as well as the coupling between variables of different time scales, are analyzed to obtain the preliminary 21-order simplified model. Thirdly, considering the weak coupling characteristics between the mechanical part and the electromagnetic part of the DFIG wind turbine system, the 21-order simplified model is decomposed into a 15-order electromagnetic transient model and a six-order electromechanical transient model on the basis of their time scales. Then, according to the balance between simulation time and simulation accuracy, the 14-order electromagnetic transient model and the 10 or 12-order electromechanical transient model are finally obtained. Finally, the rationality of the simplified models is verified by simulations under two large disturbance conditions, namely wind speed abrupt change and voltage sag. The obtained simplified models have reference significance for improving the simulation speed of a wind power grid-connected system and analyzing the internal mechanism of the DFIG wind turbine system’s stability. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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41 pages, 8522 KiB

Open AccessReview

Wind and Solar Intermittency and the Associated Integration Challenges: A Comprehensive Review Including the Status in the Belgian Power System

by Siavash Asiaban, Nezmin Kayedpour, Arash E. Samani, Dimitar Bozalakov, Jeroen D. M. De Kooning, Guillaume Crevecoeur and Lieven Vandevelde

Energies 2021, 14(9), 2630; https://doi.org/10.3390/en14092630 - 4 May 2021

Cited by 48 | Viewed by 7160

Abstract

Renewable Energy Sources (RES) have drawn significant attention in the past years to make the transition towards low carbon emissions. On the one hand, the intermittent nature of RES, resulting in variable power generation, hinders their high-level penetration in the power system. On [...] Read more.

Renewable Energy Sources (RES) have drawn significant attention in the past years to make the transition towards low carbon emissions. On the one hand, the intermittent nature of RES, resulting in variable power generation, hinders their high-level penetration in the power system. On the other hand, RES can aid not only to supply much more eco-friendly energy but also it allows the power system to enhance its stability by ancillary service provision. This article reviews the challenges related to the most intermittent RES utilised in Belgium, that is, wind energy and solar energy. Additionally, wind speed and solar irradiance variations, which are the cause of wind and solar intermittency, are studied. Then, recent techniques to forecast their changes, and approaches to accommodate or mitigate their impacts on the power system, are discussed. Finally, the latest statistics and future situation of RES in the Belgian power system are evaluated. Full article

(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)

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