Impacts of rectifier circuit loads on islanding detection of photovoltaic systems

Simulation analysis of the islanding tests with the rectifier circuit load is performed. The rectifier circuit load has the impacts to the harmonic voltage after the islanding operation, and reduces the frequency and fundamental voltage greater than if no rectifier circuit loads. It is probable that total harmonic voltage distortion occurs more than 2V in a balanced three-phase circuit, if the ratio of the rectifier circuit load is at least 10%. However, the changes in the harmonic voltage after the islanding operation are dependent on the difference between the harmonic voltage included in the system power supply and the harmonic voltage by the rectifier circuit load. The characteristics on the islanding detection time are clarified in case of using the new active islanding detection method that is called “a frequency feedback method with step reactive power injection”.

I. Introduction

When a large penetration of the distributed generators such as photovoltaic (PV) systems is growing up in distribution systems, it is very important for PV systems to quickly detect islanding caused by power system fault in order to ensure electrical safety.