A Control Strategy for Recovery from Commutation Failures in LCC-based HVDC Systems Based on Trajectory Prediction

Abstract

Commutation failures are very common in LCC-based HVDC systems, and many control strategies have been developed to enhance the immunity against commutation failures. Among these strategies, one key idea is to enlarge the commutation margin by firing the gate with a specific time advance. However, the controllers based on PI-scheme may induce unexpected overshoot, leading to the failure of recovery. A recovery strategy to eliminate the overshoot is proposed for improving the performance of recovery from commutation failures, where the fast-changing trend of system states including commutating voltage and dc current are considered. Case studies show the effectiveness of the proposed method.