A CPAT Simulation Analysis on the Effect of Islanding Protection under Clustered PV Application 500 PV Systems

Since the FY2003, the demonstration site Josai-no-mori including over 500 residences with PV system has been under construction at the Ota City, Gunma prefecture in Japan. It is important to clear the safety of islanding protection. However, it is very difficult to verify the islanding phenomena including many PV systems on the actual utility grid, where the people are leading life actually. Therefore, it becomes important to develop a technique employing simulation analysis for the safety evaluation.

Purpose of our study is to clear the details of dangerous islanding phenomena and the effects of various protection methods under clustered installation of over 500 PV systems within a partial area of utility grid. To solve these problems, a new analysis method has been developed, that is based on the CRIEPI's Power system Analysis Tools (CPAT) technology implemented by CRIEPI, so called “Y-method".

As a noteworthy result, it has been confirmed that the new simulation method has a capability to expand to the large-scale clustered installation model including 500 PV systems on utility grid. The validity of simulation analysis has been verified by comparing with preliminary indoor tests. In addition, it has been clarified that the combination of passive and active protection methods is very effective to avoid the islanding phenomena.