Current THD reduction and anti-islanding detection in distributed generation with grid voltage distortion

Abstract

Phase angle in grid-connected inverter for DPGS(Distributed Power Generation Systems) is important information for current control. When different loads are connected to PCC(Point of Common Coupling) of grid, distorted grid voltage is taken place by load utility generating distorted current. Especially, in case the grid voltage is distorted by low order frequency such as 3rd, 5th harmonic, phase angle of PLL(Phase Locked Loop) output is distorted. This paper analyze problem of current THD(Total Harmonic Distortion) due to distorted phase angle by distorted grid voltage, and propose control method compensating this problem. Also proposed anti-islanding detection method using distorted grid voltage is proposed in this paper. These proposed methods are verified by simulation and experiment.