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Power systems are becoming more and more complex in nature due to the integration of several power electronic devices. Protection of such systems and augmentation of reliability as well as stability highly depend on limiting the fault currents. Several fault current limiters (FCLs) have been applied in power systems as they provide rapid and efficient fault current limitation. This paper presents a comprehensive literature review of the application of different types of FCLs in power systems. Applications of superconducting and non-superconducting FCLs are categorized as: (1) application in generation, transmission and distribution networks; (2) application in alternating current (AC)/direct current (DC) systems; (3) application in renewable energy resources integration; (4) application in distributed generation (DG); and (5) application for reliability, stability and fault ride through capability enhancement. Modeling, impact and control strategies of several FCLs in power systems are presented with practical implementation cases in different countries. Recommendations are provided to improve the performance of the FCLs in power systems with modification of its structures, optimal placement and proper control design. This review paper will be a good foundation for researchers working in power system stability issues and for industry to implement the ongoing research advancement in real systems.

In this paper, a multi‐objective tuning algorithm is proposed for the voltage/current controllers of the dynamic voltage restorer (DVR) in an optimal manner in order to improve the fault‐ride‐through (FRT) capability of the grid‐connected doubly‐fed induction generators. An active crowbar protection (ACB_P) coupled with the rotor of the DFIG, provides a very little compensation, on blocking the high rotor current during fault condition. Control of DVR is achieved through use of multiple PI controllers. This paper presents a novel multi‐objective tuning known as Autonomous Group Particle Swarm Optimisation (AGPSO) to optimally tune the PI controllers. The optimisation algorithm uses diverse autonomous groups confined within a common target to achieve more directed and randomised search results for any population. Voltage sag compensation, total harmonic distortion (THD), RMS value of signal are the three major indices for comparison study during fault. Finally, the performance improvement in FRT of the DFIG with optimised controller was studied through DFIG responses on comparing with normal controller. Efficacy of the proposed controller proposed is verified by a simulation model of DFIG System with 1.5 MW rating in MATLAB. The results are analysed and comparative data are placed to ensure the enhanced FRT capability of the system.

A multi‐microgrid (MMG) system comprises of a cluster of microgrids interconnected for reliable and efficient operation in grid connected as well as islanded modes. In this study, the fault‐ride‐through capability of an MMG system is addressed. A solution to under‐voltage and over‐current scenarios arising due to severe short‐circuit faults in inverter‐interfaced MMG system is proposed for grid‐connected and islanded modes. The MMG system has the primary sources as the solar photovoltaic system, static synchronous compensator, and wind energy‐based generation units with an additional battery as the backup source at the dc link of individual microgrids. Gate turn‐off thyristors based fault‐current limiters are considered at the individual microgrid level of the MMG system. A sliding‐mode control is employed in the decentralised controllers of the interfacing voltage‐source converters and bidirectional buck–boost converters for output current control. Accurate voltage, current, and frequency control are achieved during the fault by incorporating the proposed control strategies. The proposed decentralised control in the MMG system is experimentally verified in real time using a real‐time digital simulator (OP4510) from OPAL‐RT.

The world is interested in applying grid codes to increase the reliability of power systems through a micro-grid (MG). In a common practice, the MG comprises a wind farm, and/or photovoltaic (PV) arrays that are integrated with diesel generators and energy storage devices. Fault ride-through (FRT) capability is an important requirement of grid codes. FRT means that the MG is still connected to the grid during numerous disturbances such as faults. This is required to ensure that there is no loss of power generated due to grid faults. Reactive currents must be injected into the grid to increase the power system stability and restore voltage. To enhance FRT for doubly fed induction generator (DFIG) based WT installation, internal control modifications of rotor-side converters and grid-side converters are applied. The solutions that depend on these modifications are traditional and advanced control techniques. Advanced control techniques are needed due to the non-linear nature and less robustness of traditional ones. External hardware devices are also added to improve the FRT of DFIG which are classified into protection devices, reactive power injection devices, and energy storage devices. A comprehensive review of FRT enhancements of DFIG-based WTs, PV systems, and MGs using hardware and software methods is presented in this effort. A classification of FRT of PV systems is characterized plus various inverter control techniques are indicated. Several FRT methods for hybrid PV-WT are presented, with full comparisons. The overall operation and the schematic diagrams of the DFIG-WT with FRT methods are discussed and highlighted. Many Robust control methods for controlling grid connected AC, DC and hybrid AC/DC MGs in power systems are addressed. A total of 210 reported articles were review, including the most up-to-date papers published in the literature. This review may be used as the basis to improve system reliability for those interested in FRT methods. Various traditional and advanced control techniques to improve the FRT abilities are summarized and discussed, including protection devices, reactive power injection devices, and energy storage. In addition, the classifications of FRT hardware methods for DFIG are presented, including grid code requirements.

This paper proposes a control strategy for grid-following inverter control and grid-forming inverter control developed for a Solar Photovoltaic (PV)–battery-integrated microgrid network. A grid-following (GFL) inverter with real and reactive power control in a solar PV-fed system is developed; it uses a Phase Lock Loop (PLL) to track the phase angle of the voltages at the PCC and adopts a vector control strategy to adjust the active and reactive currents that are injected into the power grid. The drawback of a GFL inverter is that it lacks the capability to operate independently when the utility grid is down due to outages or disturbances. The proposed grid-forming (GFM) inverter control with a virtual synchronous machine provides inertia to the grid, generates a stable grid-like voltage and frequency and enables the integration of the grid. The proposed system incorporates a battery energy storage system (BESS) which has inherent energy storage capability and is independent of geographical areas. The GFM control includes voltage and frequency control, enhanced islanding and black start capability and the maintenance of the stability of the grid-integrated system. The proposed model is validated under varying irradiance conditions, load switching, grid outages and temporary faults with fault ride-through (FRT) capability, and fast frequency response and stability are achieved. The proposed model is validated under varying irradiance conditions, load switching, grid outages and line faults incorporating fault ride-through capability in GFM-based control. The proposed controller was simulated in a 100 MW solar PV system and 60 MW BESS using the MATLAB/Simulink 2023 tool, and the experimental setup was validated in a 1 kW grid-connected system. The percentage improvement of the system frequency and voltage with FRT-capable GFM control is 69.3% and 70%, respectively, and the percentage improvement is only 3% for system frequency and 52% for grid voltage in the case of an FRT-capable GFL controller. The simulation and experimental results prove that GFM-based inverter control achieves fast frequency response, and grid stability is also ensured.

Converters of permanent magnet synchronous generator (PMSG), driven by wind turbines, are controlled by a classical proportional–integral controller. However, many research studies highlighted the challenge in PMSG due to the poor performance of the classical proportional–integral controller, especially in the event of faults or wind speed variations. This article proposes a solution for the limitations of the classical proportional–integral controller with PMSG driven by a wind turbine. The proposed solution includes two optimization techniques: gray wolf optimizer and whale optimizer algorithm. To ensure the effectiveness of the proposed techniques, step change and random variation of wind speed are studied. Moreover, fault ride-through capability of the PMSG is studied with gray wolf optimizer and whale optimizer algorithm techniques during the occurrence of a three-phase fault incident. In this case, a braking chopper controlled by a hysteresis controller is connected to the DC-link capacitor. The simulated results show that compared with the classical proportional–integral controller, gray wolf optimizer and whale optimizer algorithm techniques are greatly efficient in improving the dynamic behavior of the PMSG during wind speed variations. Moreover, gray wolf optimizer and whale optimizer algorithm techniques present their effectiveness during the fault incident by suppressing the transient variations of all the PMSG parameters, improving the fault ride-through capability, and decreasing the total harmonic distortion of the current waveforms. All simulations are performed with MATLAB/ Simulink program package.

Wind energy is a critical component of renewable energy systems, but the stochastic nature of wind speed poses significant challenges for consistent power generation. This paper addresses these challenges by proposing advanced control strategies to enhance the performance of wind turbine blade angle systems. We compare two optimization algorithms: harmony search algorithm (HSA) and exponential distribution optimizer (EDO) for tuning proportional‐integral‐derivative (PID) controllers under various operating conditions, including normal operation and fault scenarios. The EDO algorithm demonstrates superior performance in optimizing blade angle control, leading to improved system stability and faster response times. Building on this, we further evaluate three controllers: PID, proportional‐derivative‐derivative, and adaptive proportional‐integral (API) using the EDO algorithm. The API controller, with its adaptive gains, outperforms both PID and proportional double derivative (PD 2 ) controllers, achieving smoother pitch angle adjustments and more stable active power output under varying wind conditions. The results highlight the API controller’s ability to maintain rated power levels with minimal oscillations, even during rapid wind speed changes and fault conditions. This study provides valuable insights into the optimization of wind turbine blade angle systems, offering a robust framework for improving power extraction efficiency and system reliability. The findings suggest that the combination of EDO optimization and API control represents a promising approach for enhancing wind turbine performance in dynamic environments.

Integration of dynamic grid support is required for distributed power systems that are interconnected with medium voltage grids. This study proposes a comprehensive control solution to enhance fault ride through (FRT) capability for utility-scale photovoltaic (PV) power plants. Based on positive and negative sequence control schemes and PV characteristics, the approach alleviates dc-bus double-line-frequency ripples, reduces voltage stress on inverter power switches and DC-link capacitors, and minimises undesirable low-order voltage and current harmonics that are presented on the ac side. The study proposes a new feature to achieve superior FRT performance by using the overload capability of grid-tied inverters. A weak electric grid is used for the test case including a wind turbine induction generator, diesel engine driven synchronous generators and various loads. A comprehensive simulation verified the capability of the proposed control schemes for mitigating the voltage dip, enhancing the voltage response and further improving the stability of interconnected distributed generation in reaction to severe unbalanced voltage conditions because of asymmetrical grid faults.

This work presents a fault ride-through control scheme for a non-isolated power topology used in a hybrid energy storage system designed for DC microgrids. The hybrid system is formed by a lithium-ion battery bank and a supercapacitor module, both coordinated to achieve a high-energy and high-power combined storage system. This hybrid system is connected to a DC bus that manages the power flow of the microgrid. The power topology under consideration is based on the buck-boost bidirectional converter, and it is controlled through a bespoke modulation scheme to obtain low losses at nominal operation. The operation of the proposed control scheme during a DC bus short-circuit failure is shown, as well as a modification to the standard control to achieve fault ride-through capability once the fault is over. The proposed control provides a protection to the energy storage systems and the converter itself during the DC bus short-circuit fault. The operation of the converter is developed theoretically, and it has been verified through both simulations and experimental validation on a built prototype.

Modular multilevel converter-based solid-state transformers (MMC-SST) usually use the input series output parallel structure or the dual active bridge (DAB) structure. These two structures suffer from low power supply reliability and high economic costs, respectively. Therefore, based on hybrid frequency modulation, this paper proposes an arm integrated double capacitor submodule (AIDCSM)-type MMC-SST topology. This topology effectively reduces the number of switching devices by integrating the submodule arms, while enabling the topology to possess DC short-circuit fault ride-through capability. When compared to the DAB-type MMC-SST with half-bridge submodules, the proposed AIDCSM-type MMC-SST saves 2/5 switching devices and 1/2 high-frequency transformers, and enables uninterrupted operation under DC short-circuit faults. At the same time, the control strategy of the proposed AIDCSM-type MMC-SST is thoroughly investigated under both normal operating and DC short-circuit conditions. Simulation and experimental results demonstrate the correctness and effectiveness of the proposed topology and control method.