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• Recursive least squares and generalized regression neural network are used to build a real-time dynamic system model for adaptive control. • A static var compensator additional dual-channel damping controller structure is proposed for the dominant mode of low-frequency oscillation. • Static var compensator additional damping controller parameters tuning problem converted Markov decision process and a soft actor-critic algorithm is also introduced to solve the Markov decision process. As the access rate of wind energy in a power system has significantly increased, stabilizing the power system has become challenging. Among these challenges, low-frequency oscillation is one of the most harmful problems, effectively resolved by adding a damping controller according to the relevant properties of the low-frequency oscillation. However, the controller often fails to adapt to the constantly changing wind energy system owing to the lack of a targeted dynamic change strategy. Thus, to address this issue, an adaptive stabilization strategy that uses a static var compensator with an additional damping controller structure is proposed. Specifically, the entire power system is equivalently represented as a generalized regression neural network, with a deep reinforcement learning algorithm called soft actor-critic introduced to train the agent based on the generalized regression neural network model. After the training process, the agent can provide additional efficient static var compensator damping controller parameters under different operating conditions, vastly improving the system stability. Simulation results verify the improved performance using the proposed strategy compared to other optimization methods, regardless of whether the low-frequency oscillations were suppressed in the time or frequency domains. [ABSTRACT FROM AUTHOR]

• Improving the voltage in a wind farm by a self-corrective static VAR compensator. • Considering the steady-state and transient modes under harsh faults in analysis. • Enhancing the system performance by employing an optimized Battery Energy Storage. • Reporting the results in different cases, with or without the mentioned equipment. Maintaining synchronism and voltage stability, especially in the presence of wind farms, has a crucial role in confirming the reliability requirements of the power grid, as the natural fluctuations of wind speed result in intermittency and uncontrollability of power generation. To this end, an optimized Battery Energy Storage System (BESS) was suggested to make an equilibrium between the generation and consumption in wind farms under harsh conditions. Additionally, the instability of wind farms is very likely after transmission line faults occur. To overcome this problem, in this paper, the impact of a constant capacitor bank, connected in parallel with the wind generators, is investigated. Also, a novel self-corrective Static Volt-ampere reactive Compensator (SVC) is proposed to overcome the variations of voltage and damp the reactive power oscillations after occurring the faults. The proposed SVC compares the network voltage profile as the reference voltage with the voltage deviations in a control block diagram. For this purpose, three similar wind farms of Permanent Magnet Synchronous Generator (PMSG) type are considered in a wind park. The simulation case studies are performed in Matlab/Simulink under different conditions of transient and steady-state voltage stabilities in the presence of proposed BESS including, only capacitor bank (without self-corrective SVC), and with self-corrective SVC. The results authenticate the ability of the proposed SVC strategy to correct the voltage deviations, and voltage stability improvement of the under study system. [ABSTRACT FROM AUTHOR]

• A modified minimum switch count magnetic energy recovery switch (MERS) topology has been proposed as a shunt static VAr compensator (SVC-MERS). • The conduction loss of the switch is reduced due to the minimum switch count and thus promises a high-efficiency compensator. • An equivalent harmonic model using mathematical equations has been developed by introducing switching functions for performance analysis of the proposed compensator. • A suitable ratio of resonant angular frequency to line angular frequency has been chosen to select the optimum L and C parameter of MERS unit for low harmonic injection. In this paper, a minimum switch count modified magnetic energy recovery switch (MERS) topology has been proposed as a shunt static VAr compensator (SVC-MERS). Whereas, the existing scheme uses four active switches for the same purpose. Thus, conduction loss of the switch is reduced in the proposed scheme due to the minimum switch count and thus promises a high-efficiency compensator. Moreover, a coupling inductor (L) and a capacitor (C) are used in the proposed scheme for reactive energy storing and exchanging. Improper selection of L and C may instigate harmonic resonance. To examine its impact on modified MERS performance, an equivalent harmonic model using mathematical equations has been developed by introducing switching functions. The characteristics analysis of the proposed modified MERS has been done by using this harmonic model. Based on the above analysis a suitable ratio (S) of resonant angular frequency to line angular frequency and corresponding optimum L , C parameters have been selected for low harmonic injection. The key features of this proposed scheme are low current total harmonic distortion (THD), lesser switching losses, reduced cost, and low voltage rating of the switch as compared to the existing MERS scheme. To verify the proposed concept simulation has been carried out using a 6 kVA rating inductive load in MATLAB Simulink environment. The both analytical and simulation results confirm that the proposed reduced switch count compensator model with optimum L = 30 m H and C = 150 μ F can be used efficiently for power quality improvement in a low voltage grid. \ [ABSTRACT FROM AUTHOR]

• Categorization of FACTS devices as HSRF, MSRF, and LSRC devices by response speed. • Mathematical modelling for the coordination of MCR with SVC and FC. • Control strategy to enhance the compensation capacity of high response speed SVC. • Control strategy to enhance the low compensation speed of MCR and FC. • The proposed strategy is suitable for full range of compensation for power system. Traditional devices in flexible AC transmission system (FACTS) like magnetically controllable reactor (MCR), and fixed capacitors (FC) are less expensive and have medium or low response speed that can only provide excessive inductive or capacitive reactive power compensation. However, modern FACTS devices like static var compensators (SVC) are expensive and have high response speed which can provide limited inductive to capacitive reactive power compensation as compared to the MCR and FC. In addition, if there is no proper coordination between these traditional and modern FACTS devices they absorb each other's reactive power and may results in the decrease of compensation margin and wastage of the resources. Therefore, to make an effective use of these categories of FACTS devices in the existing power system, the coordination control that shares high speed and excessive compensation ability without wastage of resources is essential. This paper presents coordinated control of multi-FACTS devices to provide efficient reactive power compensation based voltage regulation. At first, the characteristics of various categorical FACTS devices are presented in relation to response speed by incorporating high speed response FACTS (HSRF), medium speed response FACTS (MSRF) and low speed response compensator (LSRC). Finally, the MCR with SVC and MCR with FC coordination controls have been developed sequentially with minimal efforts of compatibility issues and compensation speed while ensuring an increase in the reactive power reserves for the SVC. The simulation is carried out on PSCAD/EMTDC to test the coordination control efficiency of several three phase multi-FACTS devices with series and parallel configurations and validated on a modified IEEE 30 bus power system. The results show that multi-FACTS coordination control increases the SVC reserves and is promising in providing voltage regulation for the power system under various scenarios. [ABSTRACT FROM AUTHOR]

• Basic flicker effect mitigation techniques description. • SVC control system adjusted for industrial applications, especially for industrial system with EAF. • Study and comparison of different signal processing techniques od input SVC controller signals. • Using of field measured data for testing proposed techniques by laboratory scale SVC system. • Evaluation flicker effect for proposed techniques and comparison with results of previous works. The work focuses on the possibilities of improving the Static Var Compensator (SVC) control system for more effective reduction of the flicker effect. The studied SVC control system consists of an open control loop, which provides a fast response to dynamic changes in Electric Arc Furnace (EAF) power, and a closed control loop, which provides precise control to ensure the required value of the power factor in the Point of Common Coupling (PCC). The improvement consists in the use of alternative techniques for signal processing of input control variables. The first alternative technique is the use of Second Order Generalized Integrator (SOGI), which is also used in other related applications. The second alternative technique is to use the flicker weighting function, which corresponds to the function used to measure the flicker effect using a standardized flicker meter. Experimental laboratory equipment and theoretical model in frequency domain was used to verify the properties of the proposed techniques. To simulate the dynamic behavior of EAF, data measured from real operation were used, which were implemented into an experiment using VSC. Analysis of measured data and data obtained from laboratory apparatus shows high similarity. The experiments were carried out in several variants to reflect the differences in the various stages of the production process in the EAF. For all variants, the resulting flicker effect was evaluated and the individual techniques were compared with each other and with the results of other works. [ABSTRACT FROM AUTHOR]