Frequency-Locked Loop based New Automatic Phase-Shift Method for Active Islanding Detection of Three-Phase MicroGrid

Abstract

This paper proposes an active Islanding Detection Method (IDM) integrating Frequency Locked-Loop (FLL) for detection of voltage phase and frequency at the point of common coupling (PCC) and modified Auto Phase Shift (APS) method for three phase Distributed Energy Resource (DER) serving a local RLC load. The FLL is composed of a double second-order generalized integrator (DSOGI) to attenuate the harmonics and pass the fundamental positive sequence components in a frequency adaptive manner. Different from traditional APS methods, a new variable frequency term with an exponential factor is injected into the phase shift algorithm to reduce the Non-detection Zone (NDZ) during the case of DER power matching with the local load demand. This modified approach enables the decentralized power generation system to detect the islanding phenomenon more quickly. Simulations and experimental tests conducted on a DG system on OPALRT (OP5600) and hardware test-bed demonstrate the behaviour of the proposed model within IEEE Standards.