Optimized Coordinated Control Strategy of Assembly HVDC Breakers for MMC Based HVDC Grids

摘要

The assembly HVDC breaker (ASCB) can handle the dc-side fault efficiently. To overcome the shortcomings of the traditional strategy, two coordinated control strategies are proposed. The main idea is adopting the overcurrent in the dc-side as the criterion of pre-operation, and the ASCB will close in advance when it is satisfied. In the proposed strategies, the current that flows through the main breaker will be reduced, as well as the injecting current towards the ASCB from neighboring converters. The simulation result shows that the strategy is valid and feasible.