Islanding prevention performance test of Japanese manufacturers inverters

Popularization of PV systems is accelerating by the powerful policies of government and effect of cost reduction in Japan. As a result, it is feared that PV systems will be connected with high density in some local areas. In this situation, most important issues are the safety and stability of PV systems, especially because dangerous islanding phenomenon could easily occur. To clear the problems, performance tests of islanding prevention, as the safety and durability to daily fluctuation of voltage phase on utility grid or frequency swing in power system accident depends on the stability, were conducted with six types of inverters from the market in Japan at the Akagi testing center of CRIEPI. As a result of the islanding test, it was confirmed that there is no problem in the combination of passive and active islanding prevention method. On the other hand, stability test showed that most inverters are over sensitive as a power source of utility grid. The work has been promoted by NEDO as a part of New Sunshine Project in Japan.