Comprehensive Investigation of Anti-Islanding Voltage Relay

What is it about?

This paper shows that in some conditions, a voltage relay can be a better choice for islanding detection of synchronous distributed generation (SDG) than a frequency relay. The voltage relay is adjusted and evaluated using application region (AR) and power imbalance application region (PIAR), respectively, in both single- and multi-DG scenarios. The goals of the relay adjustment are: to detect islanding condition in appropriate time; to satisfy safe and abnormal voltage variation criteria; and not to operate wrongly in the cases of non-islanding disturbances including load shedding, load restoration, and three-phase short-circuit fault, as far as possible. The voltage relay false operation for the non-islanding disturbances is investigated in the worst condition which is associated with a combination of the control mode of SDG excitation system and the load type causing the highest risk of the relay false operation.

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Why is it important?

The reasons why this work is important are as follows. - The necessity of utilizing the voltage relay for the SDG islanding detection in some conditions is discussed; - The PIAR of the voltage-based relays is presented and used for evaluating the performance of voltage relay adjusted by AR; - The voltage relay false operation is studied in the worst condition; and - The voltage relays of SDGs of a multi-DG system are adjusted using both AR and PIAR.