Transition of Inverter Generating Plants to Unintentional Island Operation in Part of the Distribution Network

This paper deals with the issue of unintentional islanding in distribution networks with inverter-interfaced decentralized sources. Typically, these are photovoltaic power plants in low or medium voltage networks. A part of the research framework is presented in which the authors are concerned with verifying the ability of inverters to prevent unintentional islanding. A number of inverters from several manufacturers applying various techniques to detect islanded operation have been verified. The tests were carried out at the test facility at Brno University of Technology and the test methodology is based on well-known standards designed for this verification. The obtained results are presented and evaluated; the conclusion provides their summarization as well as recommendations for further research directions.