Problems and countermeasures on safety of utility grid with a number of small-scale PV systems

摘要

Utility interconnection and control technologies for small-scale dispersed PV (photovoltaic) systems are being studied at the Rokko Island 200 kV PV test facility in Kobe, Japan. Some safety problems of the utility grid are being investigated. Some results of experiments conducted to date are reported. It was found that the operation of the protective relay installed in the utility substation is influenced by the PV systems' power output on a short-circuit fault of the distribution line. In addition, it was confirmed that the automatic reclosing operation of the grid to separate the line fault section is interfered with by an islanding phenomenon. Some methods for preventing the run-on or islanding phenomenon on the distribution line with a number of PV systems were demonstrated, and results are reported.