Zahed Zomorodikhani - Electrical Engineering Department, College of Engineering, Asadabad Branch, Islamic Azad University, Asadabad, Iran
Morteza Yousefi - Electrical Engineering Department, College of Engineering, Asadabad Branch, Islamic Azad University, Asadabad, Iran

Sub-Synchronous Resonance (SSR) Damping using various devices such as PSS and FACTS devices has been explored in detail in the literature. In such devices reactive power modulation is usually used for mitigating the SSR. Since SSR is defined by the IEEE sub-synchronous resonance working group as an electric power system condition where the series capacitor on transmission line exchange significant energy (Active Power) with a turbine-generator at one or more the natural frequencies, active power modulation through energy storage devices (ESDs) can be an efficient and effective way to maintain this destructive phenomenon and the ability of the ESDs in mitigating SSR has rarely been investigated. In this paper, the ESD capabilities will be explored for SSR mitigation and a new optimization algorithm called Teaching-Learning-Based- Optimization (TLBO) algorithm has been used for managing the optimization problems. Two similar TLBO based damping controller has been designed and added to the active and reactive control loop of ESD. a comprehensive comparison between active and reactive power modulation on ESD to SSR damping is investigated. Various Fast Fourier Transformer (FFT) and transient simulations of detailed nonlinear system are considered to investigate the performance of the controllers. Robustness of the proposed system has been analyzed by facing the system with disturbances leading to significant changes in generator and power system operating point and fault duration time. The IEEE Second Benchmark Model is considered as the system under study. All the simulations are carried out in MATLAB/SIMULINK environment.