Coordinated fuzzy operation of battery energy storage and resistive brake for mitigation of SSR oscillations

The work presented herein is focusing on mitigating sub-synchronous-resonance (SSR) oscillatory torque and speed responses developed in power network equipped with series capacitor compensation as an outcome of the network perturbations. The mitigation effect of a battery-energy-storage (BES) controlled via a fuzzy-logic-controller (FLC) is explored. It is also explored accompanied by a fuzzy-bases resistor brake controlled via FLC. The IEEE second benchmark system is selected as a test grid under the MATLAB™/Simulink simulation environment. The signal utilized for the propositioned controller is the alternator rotor speed deviation. The key conclusions of this investigation are the employment of a BES in the discharging mode alone might be utilized to alleviate the SSR relative speed, and torque oscillations, the BES employment accompanied with dynamic resistive brake is supplying faster-decaying rates for the SSR oscillations in observation with the BES employment only.

Analysis and Mitigation of Sub-Synchronous Resonance for Doubly Fed Induction Generator under VSG Control

This paper presents the analysis and mitigation of sub-synchronous resonance (SSR) for doubly fed induction generators (DFIG) under virtual synchronous generator (VSG) control, based on impedance methods. VSGs are considered to have grid-supporting ability and good stability in inductance-based weak grids, and are implemented in renewable power generations, including DFIG systems. However, stability analyses of VSGs for DFIG connecting with series capacitor compensation are absent. Therefore, this paper focuses on the analysis and mitigation of SSR for DFIG under VSG control. Impedance modeling of DFIG systems is used to analyze SSR stability. Based on impedance analysis, the influence of VSG control parameters and the configuration of damping factor of reactive power are discussed. Next, a parameter configuration method to mitigate SSR is proposed. Finally, time-domain simulation and fast fourier transform (FFT) results are given to validate the correctness and effectiveness of the impedance model and parameter configuration methods.

Optimal Series Capacitor Compensation for Transmission Lines

Nowadays, voltage stability issues are the main problems around the world and therefore it is important that to maintain stable voltage stability. Series capacitor compensation plays an important role in the transmission line because it can improve the voltage stability as compared to shunt compensation. The Thyristor-Controlled Series Capacitor (TCSC) is selected in this project for providing capacitor compensation because its ability to control the amount of compensation in the transmission line, and operating in three different mode of region, which are resonance, capacitive, and inductive regions. The Fast Voltage Stability Index (FVSI) is used to determine the system’s stability and determine the weakest line in the system for TCSC placement. The TCSC sizing is optimized by using Differential Evolution (DE) optimization technique. All these processes are simulated on Institute of Electrical and Electronics Engineer (IEEE) 14-bus test system by using MATLAB. The proposed methodology was carried out in few tests, which are system contingency test, line outage test, power loss test, voltage profile improvement test and variable TCSC location. Based on the results, the overall voltage stability of the system was improved. The voltage magnitude for each bus had improved and the total power losses also reduced. Therefore, the optimization is successful and the study’s aim is achieved.