Review of Power Electronics Technologies in the Integration of Renewable Energy Systems

Abstract

Power electronics (PE) technology has become integral across various applications, playing a vital role in sectors worldwide. The integration of renewable energy (RE) into modern power grids requires highly efficient and reliable power conversion systems, especially with the increasing demand for grid controllability and flexibility. Advanced control and information technologies have established power electronics converters as essential enablers of large-scale RE generation. However, their widespread use has introduced challenges to conventional power grids, including reduced system inertia and stability issues. This article studies the critical role of power electronics in the grid integration of RE systems, addressing key technical challenges and requirements. A special focus is given to the integration of wind energy, solar photovoltaic, and energy storage systems. This paper reviews essential aspects of energy generation and conversion, including the control strategies for individual power converters and system-level coordination for large-scale energy systems. This article additionally includes grid codes that pertain to wind and photovoltaic systems, as well as power conversion and control technologies. Finally, it outlines the future research directions, aimed at overcoming emerging challenges and advancing the seamless integration of RE systems into the grid, thereby contributing to the development of more sustainable and resilient energy infrastructure.

1. Introduction

Power electronics technology plays a key role in renewable energy applications, authorizing the efficient control, conversion, and integration of RE sources into the electric utility grid. The demand for electrical energy is at the highest point ever globally, and since fossil fuels are starting to run out, experts are constantly searching for the most efficient alternative energy sources to support sustainable growth. In addition, the main drivers of carbon emissions, which add to global warming, are conventional power plants. Renewable energy sources (RESs) have gained attention as well, and are widely recognized as the best alternative energy sources available today [1,2,3].

The depletion of raw materials and environmental pollution caused by conventional energy sources, such as coal and oil, present significant barriers to achieving global sustainability goals. In alignment with the 2015 Paris Agreement, there is a pressing need to transition towards renewable energy sources (RESs) to support global energy sustainability. In response, many nations are intensifying their efforts to shift their energy paradigms, significantly increasing the integration of RESs—such as wind, solar photovoltaics (PV), bioenergy, and ocean wave energy—into their national energy systems [1,2,3]. For example, Denmark aims to achieve 100% energy independence from fossil fuels and become carbon-neutral through the use of RESs by 2050 [2]. The International Energy Agency (IEA) reported that Germany has significantly expanded its share of renewable energy in its electricity generation due to robust policy support [3]. Over the past two decades, the RES capacity has surged significantly far and wide, as shown in Figure 1 [4]. Furthermore, the growth rates of wind and solar PV technologies have been most rapid among RES systems developed between 2000 and 2020 [4].

Despite this progress, the widespread integration of RESs presents two primary challenges. The first is ensuring the integration of large-scale RESs into the electrical grid while maintaining the system’s reliability during fluctuations in renewable energy power generation. Second, the use of improved power electronics can help with the efficient, intelligent, and sustainable conversion, transmission, distribution, and consumption of electrical power. Consequently, power electronics technologies have evolved rapidly, and the grid integration standards for RESs, particularly for wind and PV systems, are continuously being updated [5,6,7,8,9,10,11,12,13]. The cumulative capacity of RESs is depicted in Figure 2.

The development of power electronics technologies has been closely linked to advancements in power semiconductor devices, as shown in Figure 3 [14]. From the introduction of thyristors in 1957 to the third-generation of fully controlled semiconductor devices, such as insulated gate bipolar transistors (IGBTs) and metal–oxide semiconductor field-effect transistors (MOSFETs), in the 2000s [15,16], the research has focused on the gate drivers, circuit configuration, design, and control performance to achieve high switching frequencies, low losses, and high power handling capability in power-electronics-based converters. The advent of wide-bandgap (WBG) devices, including with silicon carbide (SiC) and gallium nitride (GaN), has marked a second revolution in power electronics, offering superior results in all aspects of the system’s performance [17,18]. However, WBG devices also introduce new challenges related to their packaging, thermal management, and electromagnetic interference (EMI).

Although reducing system costs remains an issue, technological advances in semiconductor technology have made integrating RESs into the grid on a wide scale easier. In the past, the emphasis for small-scale RES power converter architectures was attaining high power densities and efficiency to preserve the electrical isolation between the grid and the low-voltage side [19]. Transformer-based and transformer-less topologies are the two primary groups into which these grid-connected converters fall. Transformer-less topologies are now preferred over transformer-based converters due to their increased efficiency, affordability, and simplicity. The other benefits of microinverters for low-power PV systems include their plug-and-play capability, high voltage gains, and capacity to track each PV panel’s maximum power point (MPPT) [20]. For large-scale RESs, such as wind power facilities, the power converters provide high power levels, high voltages, and high reliability [21]. Despite allowing more control and flexibility, the use of power electronics in wind turbine systems has evolved from partial-scale to full-scale systems in practical applications.

Multiport converters have been looked into for use with energy storage devices to improve the grid integration even more [22]. These converters are becoming increasingly popular because of their capacity for increased system efficiency and flexibility. They are primarily created for low-power, grid-connected RESs.

The key research investigations are as follows:

• Several investigations (e.g., [3,6,10,22]) highlight grid instability and low inertia as impediments to integrating high-penetration renewables. The importance of mitigation techniques (grid-forming inverters, smart loads, and hybrid control) is escalating.
• The development of boost converter topologies [23,24] and multilevel and switched-capacitor inverters [2,8] is remarkable.
• Conventional MPPT methodologies [25,26] are progressively giving way to AI/ML-based strategies [27,28,29]. Standardized benchmarking within different MPPT scenarios appears to be lacking, according to comparative reviews [29,30,31]. A number of studies emphasize converter design, control under grid failures, and PMSG-based wind systems [32,33]. Vehicle applications, cold starts, and hybridization with batteries or ultracapacitors are the main priorities of fuel cell research [34,35,36,37,38,39,40,41,42,43].

The major research gaps are found to be as follows:

• Power electronics converters have failed to provide high efficiency under fluctuating or variable conditions.
• There is not much in the literature on coordinated control for multi-source hybrid systems, despite the fact that many studies prioritize single systems (PV, wind, and FC).
• The demand-side management and power flow in both directions play important roles and act as the functionalities in smart grid integration; however, many power electronics converters have not shown good compatibility over attaining these functionalities.
• Additionally, it was found that there is a need of to achieve proper coordination between the energy storage phenomenon and power converters in order to avoid reliability issues. As the smart grid is highly associated with IOT platforms, proper monitoring devices have to be installed to avoid safety issues.
• A lack of validation and real-world datasets for AI-based MPPT [28].

With an emphasis on wind and solar power technologies, this article thoroughly reviews the advancements in power electronics for dependable and effective energy conversion from RESs. The reference papers have been chosen and categorized as follows: (a) Grid connectivity and the stability of clean energy sources with a primary emphasis on the following topics: power system operation under high RE penetration, mitigating techniques, and challenges. (b) Inverters and power electronics for renewable inclusion, with a particular emphasis on grid converters, fault-handling, control strategies, and switched-capacitor inverters. (c) MPPT methods for solar PV systems, with a particular emphasis on hybrid, AI-based, traditional, and comparative MPPT approaches. (d) Energy storage systems and hybrid configurations, with a focus on supercapacitors, hydrogen, battery integration, and hybrid storage. (e) Wind energy systems, with an eye on fault handling, offshore wind, grid impact, control, and interfacing. (f) Fuel cell power systems, with a special emphasis on fuel cell management, hybridization, and integration. (g) Intelligent energy management, smart control, and fault tolerance are the main fields of focus for AI, control, and optimization in RE systems. (h) Methods of control and converter architecture. The selected references are shown in

Table 1. Selected references.

Number of Literature Section	References	Area
(a)	[1,3,6,7,10,11,12,13,16,19,22,44,45]	Grid Integration and Stability of Renewable Energy Sources
(b)	[2,4,8,13,46,47,48,49,50,51,52,53,54,55]	Inverters and Power Electronics for Renewable Integration
(c)	[25,26,27,28,29,30,31,56,57,58]	MPPT Techniques for Solar PV Systems
(d)	[9,18,20,21,23,24,32,59,60,61,62,63,64]	Energy Storage Systems and Hybrid Configurations
(e)	[32,33,65,66,67,68,69,70,71]	Wind Energy Systems
(f)	[34,35,36,37,38,39,40,41,42,43]	Fuel Cell Power Systems
(g)	[15,17,53,72,73,74]	AI, Control, and Optimization in RE Systems
(h)	[14,75,76,77,78,79]	Control Techniques and Converter Design

.

An examination of the specifications for wind and photovoltaic systems follows the introduction of the typical RES infrastructure in Section 2. The technologies utilized in wind and photovoltaic power systems, such as the converter topologies and control programs, are covered in detail in Section 3. The challenges and recent advances in power electronics research for the extensive grid integration of RESs are addressed in Section 4. Finally, the conclusions are offered in Section 5.

2. Demand of Renewable Energy Generation

2.1. RES Architecture

In a typical renewable energy source (RES) system, as shown in Figure 4, the power electronics converter is a critical connection between the utility grid, end users, devices for storing energy, and renewable energy sources. With the voltage amplitude and frequency fixed, the power electronics devices have responsibility for adding shifted amounts of renewable energy to the utility grid, as shown in Figure 5.

Consequently, the demands placed on power electronics are both diverse and complex. These needs can be summarized in three main parts: first, maximizing energy harvesting based on renewable energy characteristics; second, optimizing energy production at the most affordable rate using power converters; third, requesting grid support features such as flexible power control and power management. The following sections discuss the particular needs for wind and PV power systems and also the related grid integration requirements.

2.2. Demands for PV Power Generation

The photovoltaic effect permits solar energy to be directly captured by PV cells or panels, avoiding the need for a mechanical energy conversion stage, which is necessary in wind power systems. As a result, PV power systems often have lower operating requirements than wind power systems. However, far superior results and regulatory requirements have resulted from the rapid expansion of solar PV installations [25,27,56,57]. As shown in Figure 4, these demands for PV power systems can be divided roughly into different groups.

Side of the PV Panel: Achieving high energy usage and prolonging the system’s lifespan requires optimizing energy harvesting and ensuring regular maintenance, such as PV panel monitoring, is performed. A DC–DC converter usually acts as the initial step to enhance the flexibility of PV inverters.

PV Power Conversion System Side: PV panels continue to get cheaper, and the system-wide power capacity per generating unit is still reasonably priced. Therefore, it is crucial to consider ways to lower the total expenses while increasing the power converter efficiency. With their high efficiency and power density, transformer-less PV inverters at lower power levels present an acceptable alternative [28,56]. However, in these systems, the parasitic capacitance between the PV panels [5,80] and the ground creates a leakage current, which is a serious problem. This is addressed by grid codes such as those in [6,29], which require that the leakage current be suppressed below predefined limitations (for example, the RMS value must be less than 300 mA) to protect both pieces of equipment.

Utility Grid Side: As demonstrated in Figure 4, the requirements for PV systems have strengthened, with a particular emphasis on power quality, voltage, and frequency regulation and protection and recovery during exceptional grid voltage scenarios. In this case, the grid current’s total harmonic distortion (THD) must be less than 5% [7,12,57]. Furthermore, because of their growing power capacity, PV systems require several grid support tasks that were previously solely necessary for wind power systems. IEEE Std. 1547–2018, updated as IEEE Std. 1547–2003 [5,26,30,31,58], specifies these as reactive power injection, frequency regulation, and low-voltage ride-through (LVRT) support tasks.

Requirements of Grid Integration: The inherent uncertainty and unpredictability of wind and solar energy derives from the reliance on weather conditions. Renewable energy sources (RESs), such as wind and photovoltaic power systems, are required to contribute to the grid to lessen the intermittency effects [11]. Forecasting power production, changing promptly to changing operating and weather conditions, and establishing flexible power control skills are essential strategies.

As is the case under high levels of renewable penetration, a sudden drop in grid voltage could cause an unplanned disconnection, compromising the equipment and system stability and possibly resulting in widespread outages. To overcome these difficulties, RESs must facilitate voltage and frequency regulation during fault ride-through operations. Voltage-reactive and frequency-active power regulation are examples of this [5,57].

In particular, RESs may employ one of the reactive power regulation modes listed below while operating in low-voltage ride-through (LVRT) mode:

• Mode of constant power factor;
• Active power-reactive power mode;
• Voltage-reactive power mode;
• Mode of constant reactive power [5].

Operators of transmission systems can also submit orders for reactive power injection to stabilize and support the grid voltage. The output of wind turbines spinning at lower power levels can be changed up or down to control the frequency flexibly [80]. This illustrates how wind turbines can use power modulation for improved grid frequency regulation.

In several nations, the grid codes have been modified to improve the grid support capabilities of renewable energy systems to guarantee reliable and steady large-scale grid integration. These upgrades make more resilient and durable energy infrastructure possible.

2.3. Demands for Wind Power Generation

The wind turbine uses wind energy to generate mechanical energy, which a generator uses to create electrical energy in wind power systems. After this, a power converter controls this electrical energy to meet local loads or utility grid requirements [59,81,82]. Three main points can be employed to describe the particular demands made on wind energy facilities, which are illustrated in Figure 6.

Wind Generator Side: The power electronics converter maintains the generator’s electromagnetic torque by managing the generator’s rotor or stator current. Improving the energy harvesting and maintaining energy balance are the fundamental objectives of current control on the generator side, particularly when the mechanical and electrical power operate with distinct inertia [81].

Wind Power Conversion System Side: The power conversion system is the primary component of the wind power system, and any failure here can have a significant effect on how well the system operates as a whole, resulting in high maintenance costs, particularly for greater wind power capacity. As a result, reliability assurance is becoming increasingly crucial in wind power systems [60,72].

Utility Grid Side: The network must fulfill particular demands, such as grid synchronization, reaction under unusual grid conditions, and grid support, in order to assure safe operation even with significant amounts of wind energy integration [5,8,80]. The primary requirements are fault ride-through operation, frequency management, reactive power injection, and power quality. The practical concerns also include power forecasts, communication, ramp rate constraints, and other essential needs for offshore wind power plants [46].

A transformer typically increases the voltage level to facilitate proper power transmission when connected to the grid. However, because of the restricted physical area in the nacelle and tower of wind power systems, power density and heat dissipation issues must be resolved. In addition, it is essential to incorporate energy storage or balancing capabilities into the power conversion step to avoid extra expenses arising from temporary power imbalances between the utility grid and the wind turbine [47,81].

3. Literature Survey

Renewable energy system technology has become one of the key areas for much of the research and has been treated as the best alternative for the generation of electric power and satisfying the end-user requirements across the globe. The applications of RESs have been found to be numerous, and have made researchers focus more on this area to identify more solutions to the many complex engineering problems associated with electric power generation. The integration of RESs into grids is still challenging, and enormous research efforts have been made by researchers in this domain, as presented in [1,2,3,4,5,6,7,8,9,10]. The roles of RESs in HVDC systems, PLC, SCADA, etc., are also presented here.

As stated earlier, grid-connected RESs [10,11,12,13,14,15,16,17,18,19,20] have become vital, although with some constraints. The electricity generated by grid-connected RESs, including through the use of grid-connected PV, wind, fuel cells, and wind-hydro plants, is possible only by employing a proper power electronics circuitry [21,22,46,47,59,60,72,80,81,82] in between the source and the load. This circuitry configuration ensures the power transfer and control are achieved in an efficient manner and ensures better reliability at the end.

Another critical component in grid-connected RES is the inverter. It plays a vital role in the conversion process. There are many inverter configurations, which have been presented in brief by the authors of [45,48,49,50,51,52,53,61,75,76]. When connecting a solar PV system to an electric power grid, three types of inverter configurations, namely central inverter, string inverter, and microinverter configurations, have been employed, and an enormous amount of work has been presented by the authors in the references mentioned in this paragraph.

A DC–DC converter takes the DC voltage from the RESs as the input and provides the DC voltage as the output quantity. It may lessen the voltage or boost the voltage, depending upon the requirement of the end-user and the applications of the proposed configurations, if any. These converters are modelled through various equations. The main component in the converter is the switch, and in order to ensure proper levelling of the voltage, optimum switching is highly necessary. The role and various applications of the DC–DC boost converters have been presented in [23,24,54,55,62,63,64,73,77,78].

Maximum power harnessing is a vital task during the grid integration of RESs, as the power generated by the RESs is intermittent in nature, and to overcome this difficulty, suitable MPPT control techniques have to be employed. There are several techniques available in the literature, ranging from traditional to soft computing domains. Detailed analyses were presented by the authors of [25,26,27,28,29,30,31,56,57,58,74,79,83,84,85,86,87,88,89,90].

The role of PE technology in fuel cell systems and variable-speed wind hydropower plants has become vital, and detailed analyses were presented in [34,35,36,37,38,39,40,41,42,43] and [91,92,93,94,95,96,97,98,99,100,101,102,103,104,105], respectively.

4. Application of Power Electronics in RES

In this section, the applications of power electronics technology in various areas of electrical power system networks are presented.

4.1. DC-Powered Electric Network

Power systems connected with DC sources and converters have revolutionized the processes of generating and distributing electric power. In this kind of electric network, direct current sources, which include batteries and solar PV arrays, are employed as the generation source, and PE technology is utilized for the power control and conversion process. Solar panels generate DC power, and by connecting them directly to the system, we can avoid the losses associated with converting DC power to AC and back again to DC. This makes the overall energy conversion process more efficient. Converters play an essential role in this type of system. DC–DC converters, such as buck, boost, and buck–boost converters, are used to boost or lessen the voltage levels at the output side to ensure optimal power transfer. In addition to DC–DC converters [23,24,54,55,62,63,64,73,77,78], inverters are essential components in power systems connected with DC sources. Inverters [45,48,49,50,51,52,53,61,75,76] convert DC power into alternating current (AC) power, and are commonly seen by all domestic users. They ensure that the electricity generated by solar panels or stored in batteries is compatible with the electrical grid. These power systems also enable the integration of ESS technologies. Batteries, which store DC power, can be connected to the system through inverters, thereby ensuring the continuous flow of power into the utility grid. A grid-connected solar PV system is depicted in Figure 7. In this network, efficient power control and transfer can only be achieved with the help of a boost converter and inverter arrangement, which is a type of PE technology. The boost converter circuit arrangement is shown in Figure 8.

Furthermore, power systems connected with DC sources and converters offer benefits in terms of grid resilience and stability. They can also assist the utility grid with proper voltage regulation and frequency control, thereby intensifying the solidity of the electric grid.

A boost converter is depicted in Figure 8, composed of various components such as an inductor, switch (IGBT/MOSFET), diode, capacitor, and load resistance unit. It is used to boost the input voltage at the output side, making it highly suitable for power systems with low-voltage sources such as solar panels.

The boost converter can be modelled using the below equations.

$${\mathrm{O}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t} \mathrm{v}\mathrm{o}\mathrm{l}\mathrm{t}\mathrm{a}\mathrm{g}\mathrm{e}, V}_0={\displaystyle \frac{V_i}{1-D}}$$

(1)

$${\mathrm{A}\mathrm{v}\mathrm{e}\mathrm{r}\mathrm{a}\mathrm{g}\mathrm{e} \mathrm{v}\mathrm{a}\mathrm{l}\mathrm{u}\mathrm{e} \mathrm{o}\mathrm{f} \mathrm{i}\mathrm{n}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{t}\mathrm{o}\mathrm{r} \mathrm{c}\mathrm{u}\mathrm{r}\mathrm{r}\mathrm{e}\mathrm{n}\mathrm{t}, I}_L={\displaystyle \frac{I_0}{1-D}}$$

(2)

$${\mathrm{C}\mathrm{r}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{c}\mathrm{a}\mathrm{l} \mathrm{i}\mathrm{n}\mathrm{d}\mathrm{u}\mathrm{c}\mathrm{t}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}, L}_C={\displaystyle \frac{D{\left(1-D\right)}^2·R}{2f}}$$

(3)

$${\mathrm{C}\mathrm{r}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{c}\mathrm{a}\mathrm{l} \mathrm{c}\mathrm{a}\mathrm{p}\mathrm{a}\mathrm{c}\mathrm{i}\mathrm{t}\mathrm{a}\mathrm{n}\mathrm{c}\mathrm{e}, C}_C={\displaystyle \frac{D}{2fR}}$$

(4)

where D is the duty cycle, which refers to the ratio of the time period to the total time period; R is the resistive load [Ω]; L is the inductor in [H]; C represents the capacitor in [F]; f represents the switching frequency [Hz].

The use of DC-based power systems is not limited to renewable energy applications. They are also employed in various other sectors, such as electric vehicles and data centers. The DC power distribution within these systems reduces energy losses and improves the overall efficiency.

4.2. Power System Connected to Microturbines

AC power systems connected with microturbines and converters have turned up as a promising solution for decentralized and sustainable development. These systems utilize small-scale turbines and employ converters to efficiently convert and control the flow of electrical energy. Microturbines are compact power generators that can be powered by numerous sources, including biogas, natural gas, and even renewable fuels. They operate on the principle of converting the kinetic energy (KE) of a fluid into mechanical energy (ME), which is then converted into electrical energy. These turbines are typically connected to an AC generator, which generates AC power [32,33,44,65,66,67,68,69,70,71].

Converters play a vital role in these AC power systems. They ensure that the electrical energy generated by the microturbines is compatible with the electrical grid or the end-use applications. An electric power system network employing a microturbine is depicted in Figure 9. One of the significant advantages of AC power systems connected with microturbines and converters is their ability to provide localized power generation. In conclusion, AC power systems connected with microturbines and converters offer a decentralized and sustainable approach to energy generation. By leveraging the power of microturbines and employing efficient converters, these systems provide localized power generation, reduce transmission losses, and contribute to environmental sustainability.

4.3. Grid-Integrated Solar PV Inverters

Power systems connected with PV modules and converters have become increasingly popular as a sustainable and renewable energy solution. These systems harness the power of sunlight by converting it into electrical energy through the use of PV modules. Power systems connected with PV modules and string inverters [52,53,61] have revolutionized the way we harness solar energy, as have power systems connected with microinverters. The connections between solar panels and microinverters are crucial for optimal power generation. Each solar panel is furnished with a microinverter, which transforms the DC power into AC power. This ensures that each panel operates at its maximum potential, even if other panels in the system are shaded or experiencing different levels of sunlight.

With traditional string inverters, if one panel in the string is shaded or not performing optimally, it can significantly impact the output of the entire string. However, with micro inverters, each panel operates independently, allowing for maximum energy production even in less-than-ideal conditions. Another benefit of power systems connected with microinverters [45,76] is their scalability. Extrasolar PV panels can be easily added into the system, as each panel operates independently with its own microinverter. This makes it easier to expand the system and meet increasing energy demands. Furthermore, these power systems are reliable and require minimal maintenance. Since each solar panel has its own microinverter, any issues or malfunctions can be easily identified and addressed without affecting the performance of the entire system. This also simplifies troubleshooting and maintenance tasks. These systems are scalable, easy to maintain, and environmentally friendly, making them an excellent choice for generating clean electricity. The various inverter configurations are depicted in Figure 10. A comparison between central inverters, string inverters, and microinverters is presented in

Table 2. Comparison between central inverters, string inverters, and microinverters.

Parameter	Central Inverter	String Inverter	Microinverter
Size of the system	Large	Medium	Small
Mode of installation	Single inverter for the entire power system	One inverter for group of panels	One inverter for each solar panel
Effect during faults	Low	Moderate	Very high
Initial cost	Low	Moderate	High
Impact of disturbance	Complete shutdown	One string may be affected	One panel may be affected

.

4.4. PV Power Optimizer

Power systems connected with PV power optimizers have revolutionized the way we harness solar energy. PV power optimizers as shown in Figure 11 are the devices that are installed on each individual solar panel, with which the reliability of the system can be enhanced. PV power optimizers work by maximizing the power output of each solar panel. They perform a crucial role in the electrical power system network by optimizing the voltage and current levels of each panel, ensuring that they operate at their maximum potential [74,79,83,84,85]. This is especially beneficial in scenarios where panels may be partially shaded or experiencing different levels of sunlight. The connections between solar panels and PV power optimizers are vital for the optimal functioning of the system. Each solar panel is equipped with a PV power optimizer, which constantly monitors and adjusts the electrical characteristics of the panel.

This allows for the maximum power to be extracted from each panel, even under less-than-ideal conditions. PV power optimizers have the ability to mitigate the impact of partial shading. In a traditional solar panel system, the overall efficiency of the system is minimized when any one panel is shaded. However, with PV power optimizers, the shaded panel’s performance is isolated; therefore, the impact on the rest of the system can be curtailed [86,87,88,89,90]. This ensures that the system operates efficiently, even in challenging shading conditions. Another benefit of power systems connected with PV power optimizers is their ability for enhanced system monitoring and maintenance. Each PV power optimizer provides real-time data on the performance of individual solar panels. This allows for easy identification of any issues or malfunctions, making troubleshooting and maintenance tasks more straightforward and efficient. Furthermore, these power systems contribute to increased energy production and overall system efficiency. By optimizing the performance of each solar panel, PV power optimizers maximize the amount of electricity generated. This results in higher energy yields and a more efficient use of available sunlight. Power systems connected with PV power optimizers also offer scalability and flexibility.

4.5. Power Systems Connected to Wind Turbines

Power systems connected with wind turbines, soft starters, and transformers play a crucial role in harnessing renewable energy and ensuring efficient electricity generation. Wind turbines are devices that convert the kinetic energy of the wind into electrical energy, while soft starters and transformers help optimize the performance and transmission of this energy [44,65,66,67,68]. Wind turbines are designed to capture the power of the wind and convert it into usable electricity. The typical architecture of the wind energy conversion system (WECS) is presented in Figure 12.

Wind turbines consist of large blades that rotate when the wind blows, driving a generator to produce electrical power. Soft starters are electronic devices used to control the starting and stopping of electric motors in wind turbines. They provide gradual increases in voltage and current to the motor, reducing the mechanical stress and electrical surge that occur during start-up. This not only extends the lifespan of the motor but also improves the overall efficiency of the turbine [32,33,69,70,71].

Transformers ensure that the electricity generated by the wind turbines can be efficiently transferred without significant losses. The connections between wind turbines, soft starters, and transformers are vital for the effective operation of the power system network. The electricity generated by the wind turbines is sent to the soft starters, which control the motor’s start-up and regulate the power output. The transformed electricity is then transmitted through the transformers, which adjust the voltage levels for efficient distribution. One of the significant advantages of using power systems connected with wind turbines, soft starters, and transformers is their contribution to renewable energy generation. Soft starters and transformers can be adjusted and optimized to accommodate the increased power output, ensuring efficient transmission and distribution. Power systems connected with wind turbines, soft starters, and transformers also promote energy independence and grid stability. By diversifying our energy sources and incorporating renewable energy into the grid, we can reduce the risk of power outages and create more resilient and reliable electrical infrastructure. Furthermore, these systems have a positive environmental impact. A summary of the contributions made by various authors is given below in

Table 3. Summary of author contributions.

Reference Number	Author Details, Year of Publication	Proposed Work
[1]	Fache et al., 2025	Policies for renewable energy in the United States
[3]	Ejuh Che et al., 2025	Diverse constraints to integrating renewable energy
[6]	Ali et al., 2025	Stability and high penetration of renewable energy
[10]	Wu et al., 2023	Control and stability viewpoints in RESs
[11]	Alsokhiry, 2024	Grid-connected hybrid systems
[12]	Liu et al., 2023	Grid adaptability evaluation
[13]	Li and Zhang, 2023	Dual-mode control for grid-following/forming
[22]	Li et al., 2020	Capacity planning using SCR
[44]	Wang et al., 2023	Multi-timescale inertia evaluation
[45]	Li et al., 2020	Inertia damping in wind power integration
[19]	Rafiqi and Bhat, 2022	Power quality using UPQC
[7]	Jain et al., 2022	Grid-supportive loads
[16]	Mohammad et al., 2023	Economic dispatch with renewables
[81]	Dobeissi et al., 2021	RE potential in Lebanon
[2]	Gopal et al., 2025	Switched-capacitor multilevel inverter
[4]	Gu et al., 2020	Isolation for motor-generator pairs
[8]	Gopal et al., 2023	Reduced device count inverter
[46]	Zhang et al., 2024	Resonant circuit breaker
[47]	Amaral et al., 2024	Capacitor failure diagnosis
[13]	Li and Zhang, 2023	Dual-mode inverter control
[52]	Sangwongwanich et al., 2017	Delta power control
[53]	Ouai et al., 2024	Fault-tolerant converter
[54]	Mishra and Singh, 2021	Four-phase SRM with three-level boost
[55]	Agorreta et al., 2009	Fuzzy PWM converter
[50]	Chen et al., 2024	Buck four-leg current inverter
[48]	Sun et al., 2018	Split-capacitor inverter
[49]	Li et al., 2023	A common-mode EMI analysis
[51]	Aamri et al., 2023	DC link controller design
[56]	Katche et al., 2023	Review of MPPT techniques
[57]	Bhukya et al., 2022	Enhanced MPPT under shading
[25]	Basha and Rani, 2020	Conventional vs. soft computing
[27]	Masry et al., 2023	AI–traditional hybrid MPPT
[26]	Pandiyan et al., 2021	MPPT in PV trees
[30]	Devarakonda et al., 2022	A comparative analysis
[58]	Awan et al., 2023	Ordering technique
[31]	Ko et al., 2020	Overview in microgrids
[28]	Roy et al., 2024	Deep learning with LSTM
[29]	Abidi et al., 2023	Benchmarking MPPT techniques
[9]	Zhu et al., 2020	Energy storage in VRE systems
[59]	Amir et al., 2023	Energy storage review
[21]	Buduma et al., 2024	PV + hybrid storage in a DC microgrid
[32]	Prince et al., 2024	Wind + STATCOM + supercapacitor
[64]	Kinjo et al., 2006	EDLC-based leveling
[20]	Deshmukh et al., 2023	PV with battery integration
[60]	Montoya-Acevedo et al., 2024	Hydrogen with a DC microgrid
[18]	Dalai et al., 2022	DC microgrid management
[62]	Surulivel et al., 2024	Four-port converter with common ground
[24]	Lin et al., 2024	High-gain converter for RE
[63]	Rao and Sundaramoorthy, 2023	Coupled cascaded boost
[23]	Karthikeyan et al., 2019	High step-up DC–DC converter
[61]	Velasco-Quesada et al., 2009	PV reconfiguration strategy
[65]	Hannan et al., 2023	Wind energy review
[66]	Li et al., 2023	Grid-side fault in DC wind system
[67]	Wang et al., 2011	Small-scale grid-connected wind system
[68]	Blaabjerg and Ma, 2017	Wind energy overview
[69]	Muljadi et al., 2007	Weak grid stability
[70]	Amin and Mohammed, 2011	Variable-speed wind utilization
[33]	Raza et al., 2024	Fault handling in MMC HVDC wind system
[71]	Chinchilla et al., 2006	PMG for variable-speed wind system
[34]	Jin et al., 2009	Cold start in fuel cells
[35]	Lai and Ellis, 2017	FC systems and applications
[36]	Emadi et al., 2006	PE solutions for FC vehicles
[37]	Zhang et al., 2016	Al–air FC in EVs
[38]	Cheng et al., 2012	Interleaved converter
[39]	Wang and Li, 2010	Fuel-economy-oriented control
[40]	Kirubakaran et al., 2011	DSP control for DGs
[41]	Carreon-Bautista et al., 2015	MPPT for microbial FC
[42]	Jin et al., 2009	Hybrid fuel cell system
[43]	Wu et al., 2020	High-gain converter in FC EVs
[72]	Sasikala et al., 2024	AI in wind farm monitoring
[53]	Ouai et al., 2024	Intelligent fault-tolerant PV converter
[15]	Wang et al., 2023	Cuckoo search for an energy park
[17]	Houam et al., 2022	Economic strategy for PV + battery system
[74]	Long et al., 2022	Moth–flame optimization for control
[73]	Silva-Ortigoza et al., 2023	Flatness-based control for DC motor
[14]	Li et al., 2022	VSC-HVDC simulation
[75]	Sonti et al., 2019	Open-circuit detection
[77]	Tseng et al., 2015	Forward-flyback boost
[76]	Trinh et al., 2018	Harmonic/DC current mitigation
[78]	Kuo et al., 2013	IC design for energy harvesters
[79]	Dong et al., 2018	Power-optimizer-fed inverter

.

4.6. Power Systems Connected to Fuel Cells

AC power systems connected with fuel cell technology hold huge potential for clean and efficient energy generation. Fuel cells convert the chemical energy into electrical energy. When integrated into AC power systems, they offer enhanced grid stability. Fuel cells combine hydrogen (H2) and oxygen (O2) to generate electric power, which makes them a sustainable source of energy [34,35,36,37]. AC power systems connected with fuel cells also offer improved energy efficiency compared to traditional power generation methods. Fuel cells have higher conversion efficiency rates, as huge amounts of the fuel’s energy can be converted into electric power generation. This results in less wasted energy and increased overall system efficiency, leading to cost savings and reduced resource consumption. Moreover, integrating fuel cells into AC power systems can result in enhanced grid stability and reliability. The architecture is depicted in Figure 13.

In conclusion, AC power systems connected with fuel cells are a promising solution for clean, efficient, and reliable energy generation. By harnessing the power of fuel cells, we can reduce emissions and achieve improved energy efficiency.

4.7. Power Systems Connected to Variable-Speed Hydro–Wind Turbines

For power systems connected with variable-speed hydro–wind turbines, as shown in Figure 14, gearboxes, converters, and transformers have emerged as essential elements of modern RE infrastructure. Electric power can be generated by extracting the power both from hydro plants and wind energy systems. Variable-speed hydro–wind turbines are designed to adapt to changing wind and water conditions, maximizing energy production. The turbines are connected to gearboxes, which help increase the rotational speed of the turbine shafts to match the generator’s requirements. Gearboxes play a vital role in optimizing power generation by ensuring that the turbine operates at its most efficient speed [91,92,93,94].

They also provide mechanical protection by absorbing excessive loads and preventing damage to the turbine components. PE converters convert the AC power generated by the wind turbines at the variable frequency into a constant-frequency power, offering suitable options for transmission and distribution. These converters use power electronics to control the flow of electricity and maintain a consistent output. They also enable the integration of renewable energy sources into the existing power grid, ensuring a smooth and reliable power supply [98,99,100,101,102,103,104]. Transformers play a vital role in transmitting electricity efficiently over long distances and distributing it to consumers at appropriate voltage levels. Transformers help minimize power losses during transmission and ensure that the electricity is delivered safely and reliably to end-users.

4.8. Role of AI in Grid Integration of RESs

Artificial intelligence (AI) has shown its importance in every sector across the globe, and of course it has become more vital when integrating RESs into the grid side. Some of the key features are described in

Table 4. AI in RES integration.

Parameter	Area	Feature
Forecasting phenomenon	Solar and wind energy systems	Time series prediction analyses, weather forecasting, pattern recognition, etc.
Maximum power point tracking (MPPT)	Solar and wind energy systems	Harvesting maximum power from solar panels and wind turbines with the help of intelligent controllers
Monitoring	All RESs	Ensuring the system is free from cyber threats
Power quality	DGs connected to grid	Immediate detection of various power quality disturbances such as harmonics, interruptions, sags, swells, under- and over-voltage disturbances
Grid stabilization	DGs connected to grid	AI-powered devices ensure proper grid control and stability

.

5. Conclusions

This study has examined the applications of power electronics converter technology in renewable energy systems, analyzing 104 reference papers to highlight the significant contributions made by researchers in this field. Power electronics systems play an indispensable role in achieving efficient power control and transfer. As renewable energy sources emerge as the most viable alternatives for electricity generation, power electronics systems have become critical in addressing challenges associated with the grid integration of renewable energy sources (RESs). A detailed analysis was conducted on the role of power converters in integrating various RESs—such as solar, wind, hydro, and fuel cells—into electrical power systems. This study has emphasized their functionality and impact, demonstrating how the integration of power electronics has revolutionized the energy sector by enabling cleaner, more efficient, and reliable energy generation, storage, and distribution. Furthermore, the latest advancements and emerging trends in power electronics have been reviewed, underscoring their importance in enhancing the performance and scalability of renewable energy technologies.

The future of power electronics in renewable energy systems is set to evolve along several key directions. The adoption of artificial intelligence and machine learning (ML) technologies will drive improvements in system performance through predictive maintenance, fault detection, and optimization. The use of IoT-enabled power electronics devices will facilitate real-time monitoring and control, fostering the development of smart grids. Additionally, innovations in multi-port converters and hybrid energy systems will optimize the utilization of multiple renewable energy sources, enhancing the energy resilience and overall efficiency. By addressing the existing challenges and embracing cutting-edge technologies, power electronics systems will play a central role in shaping a sustainable energy future. These advancements are vital to the global efforts to combat climate change, ensure energy independence, and support the growing demand for electricity. Ongoing research and development in this domain will be essential to fully harness the potential of renewable energy systems and drive the transition to a more sustainable energy paradigm.