Impact of DC protection strategy of large HVDC network on frequency response of the connected AC system

Abstract

Integration of renewable energy generations requires the transmission of bulky power over long distance, and high‐voltage direct current (HVDC) transmission systems become a more preferable choice compared to conventional HVAC systems. For HVDC systems, one of the important concerns is the DC protection strategy which can significantly impact on the connected AC system performance, e.g. system frequency. The maximum loss‐of‐infeed for a AC network is highly dependent on the duration of the power outage, and the impacts of DC fault protection arrangements which result in different speed of power restoration on the connected AC system, on the system frequency, have not been properly understood. Different DC protection arrangements using DC disconnectors, fast and slow DC circuit breakers on frequency response of the connected AC networks are investigated. A three‐terminal meshed HVDC system is studied to demonstrate system behaviour during DC faults.