AN ISLANDING DETECTION ENHANCER FOR A SYSTEM WITH MULTIPLE PHOTOVOLTAIC INVERTERS

Islanding is one important concern for grid connected distributed resources. Inverter-resident active islanding detection methods (IDM) inject disturbances into the grid to detect islanding. Although very effective in systems with a single inverter, these IDMs might interact with each other in multi-inverter systems thus failing to detect islanding. This paper discusses the use of a small dedicated STATCOM for drifting the frequency of an islanded system composed of multiple inverters equipped with passive IDM. The STACOM is designed to eliminate the non-detection zone (NDZ) of the multi-inverter system. The effectiveness of this technique is demonstrated with simulation and experimental results.