Control and Fault Protection Strategy in DC Distribution Network

Abstract

This article provides a detailed analysis of the dynamic characteristics of DC pole-to-pole faults in modular multilevel converters and proposes a protection and control strategy based on the current rate of change. By detecting the current rate of change, a resistance current limiter is put into operation to achieve DC bipolar short circuit non-blocking fault crossing. The fault current is cut off by the DC circuit breaker. This method is an active current limiting control method that adds current limiting devices before fault current identification, leading to fault identification. Finally, a single-ended flexible DC distribution network model was built by using a real-time simulation system. The simulation results verified the effectiveness and accuracy of the protection and control strategy in the case of pole-to-pole faults.