System identification of an interconnected power system with an energy storage system for robust stability improvement

This paper presents the use of the system identification method to find the appropriate transfer function of an interconnected power system with an energy storage system (ESS) and to design the robust ESS controller with the identified power system transfer function for robust stability improvement. The gradient search methodology is implemented to obtain an optimal power system transfer function for the ESS controller design. Then, the H-infinite loop shaping control (HLSC) and the phase lead-lag compensator (LLC) techniques are used to design the ESS controllers. The performance comparisons of the controllers by HLSC and LLC are done to illustrate the robustness of the ESS controllers under the inter-area oscillations with different load conditions. The study on the multi-machine power system is performed by DIgSILENT PowerFactory software. The simulation results show that the system identification technique can be applied for the ESS controller design. Furthermore, it is found that the ESS with HLSC can enhance the power system oscillation damping with a superior capability.