Setting frequency relays and voltage relays to protect synchronous distributed generators against islanding and abnormal frequencies and voltages

摘要

This study concerns frequency relays and voltage relays applied to the protection ofsynchronous distributed generators operating in reactive power control mode withouta frequency regulation function. The effect of active and reactive powers combination,load power factor, and reactive power imbalance are investigated for their implicationfor the anti-islanding setting of the frequency relay. Results reveal that the effect ofthese factors must be considered when setting the relay for islanding detection. Forthe voltage relay, results reveal that the effect of active and reactive powerscombination, load power factor, and active power imbalance must be considered whensetting the relay for islanding detection. The effect of multi-stage tripping on thefrequency relay ability to detect island was also investigated. Results show that multistagetripping can improve the anti-islanding performance of the frequency relay.