Evaluation of Distance Relay Behavior under Faults in Two-Machine Systems with Fuzzy-PI Based Series STATCOM

Abstract

The growing demand for energy, coupled with constraints on expanding transmission infrastructure, poses significant challenges to the sustainable operation of power systems. Flexible AC Transmission Systems (FACTS), particularly the Static Synchronous Compensator (STATCOM), offer an effective solution for enhancing system stability and voltage control. This study designs and implements fuzzy logic-based and hybrid fuzzy-PI controllers for STATCOM to improve the transient stability of a two-machine power system. Simulations conducted in MATLAB/SIMULINK compare the performance of these controllers with a conventional PI controller. The results demonstrate that the proposed controllers not only enhance voltage stability but also outperform the traditional PI controller in damping transient oscillations. Additionally, this study investigates the impact of STATCOM on distance relay operation, revealing that STATCOM alters the apparent impedance observed by the relay, thus affecting its protective behavior. Consequently, careful consideration of interactions between FACTS devices and protection systems is critical for ensuring the reliable operation of modern power networks.