Current restrained undervoltage protection scheme of converter dominated microgrids

Paper in proceeding, 2020

This paper presents a current restrained undervoltage protection method for converter dominated microgrids. Current magnitude based conventional protection fails to detect a fault in converter dominated microgrid due to current limiting capability of converters. Fault detection becomes more complicated during islanded operation of such a microgrid. This is because, the current does not exceed the rated value and remains below pickup setting of overcurrent relay during the fault. One alternative is to use undervoltage relay. However, this may not function correctly in the case of a fault at the end of a long cable or a high impedance fault. The current restrained undervoltage based proposed method does not rely on communication and the selectivity can be achieved by using a blinder in a VI-plane. Subsequently, the operating time of the relay is calculated using the index obtained from change in current and voltage inside the blinder. The performance of the proposed method is tested at different fault types and locations with different fault resistance in a converter dominated microgrid.