845 / 2019-04-29 22:45:46

An Islanding Detection Method for Multiple Inverter-based Distributed Generators Based on Harmonic Injection and RPD

Islanding detection,inverter-based distributed generator,harmonic injection,reactive power distrubance

In this paper, a novel active island detection method for multiple inverter-based distributed generators (IBDGs) is presented. The method contains two steps to accurately identify islanding. First, each IBDG injects its output current with a specific harmonic current. For the IBDGs at the same point of common coupling (PCC), the harmonic currents of the same specific frequency are injected when the PCC voltage is equal to zero. The injected harmonic frequency and injected time are analyzed in detail. On the other hand, for the IBDGs located at different PCCs, the harmonic frequencies should be different. Therefore, the injected harmonic currents will not be offset with each other, which can eliminate the nondetection zone (NDZ). When the harmonic voltage at the PCC variates outside its thresholds, the suspected islanding can be judged and the following step is activated. Considering that the PCC voltage and its frequency have the acknowledged thresholds for islanding detection, the second step is to inject the reactive power disturbance (RPD) to force the frequency to deviate, and islanding can be finally determined. The effectiveness of the proposed method is verified according to simulation results.