Challenges in Fault Detection and Discrimination in Multi-terminal HVDC Grids and Potential Solutions

By simulating a multi-terminal high voltage DC grid using a detailed electro-magnetic transient simulation model, challenges in fault detection and discrimination are demonstrated. To select the most appropriate signal for fast and reliable detection of faults, behavior of the DC grid during the faults is observed by means of various terminal measurements. By simulating different scenarios, challenging situations for discriminating faults in the protected line from the reverse faults, faults on the other pole, and from the remote breaker opening events are demonstrated. Influence of such disturbances on fault detection algorithms is evaluated and a method to discriminate faults in the protected line from the faults behind the relay is presented. Time taken to detect various faults in a typical high voltage DC grid is evaluated.