Sequence Measurement-Based Islanding Detection of DGs in Microgrid With Enhanced Power Quality

Abstract

Maintaining the power quality (PQ) of supply in a microgrid is a challenge due to the massive integration of inverter interfaced distributed generators (IIDGs). Supply’s PQ and IIDG controller’s transient performance degrade due to continuous, uncontrolled, and nondecaying injections in active methods for islanding detection. Also, active methods have limited application due to increased total harmonic distortion (THD) of current during microgrid’s operation. In this article, a novel sequence measurement-based identification of grid disturbance by sensing voltage and current is proposed to control the disturbance injection cycle in the IIDG controller during islanding detection. The disturbance is a low-frequency decaying current injection in the IIDG controller with controlled input. The proposed method is experimentally verified in controller hardware in loop (CHIL) with real-time digital simulator (RTDS) using the TMSF28335 microcontroller and compared with several previous methods. The impact on PQ due to change in the injection points with controlled and uncontrolled injections is also analyzed. The results indicate that the islanding detection time is low. Also, the proposed closed-loop method is effective and reliable due to two-stage screening. The nondetection zone (NDZ) is eliminated with negligible impact on the PQ of supply.