Protection of Converter-Interfaced Microgrids Using Modified Short-Time Correlation Transform

Abstract

The limited and bidirectional fault current of inverter interfaced islanded microgrids make the fault detection and faulty feeder identification the major challenges for conventional overcurrent-based protection systems. To address the first challenge, this article proposes a fault detection strategy based on the modified short-time correlation transform (MSTCT) of feeder current. Using the superimposed component of MSTCT, a new directional element is defined to address the second challenge. The developed strategy relies on an intelligent electronic device in each feeder, making it a cost-effective scheme. The proposed scheme is effective for all types of fault and can differentiate normal switching events from the fault conditions. Also, it properly operates in the presence of nonlinear loads and measurement noises. The reliable performance of the proposed protection scheme is assessed on the MATLAB/Simulink simulation model of the CIGRE benchmark low-voltage microgrid network.