Continuous commutation failure suppression method based on dynamic compensation of firing angle deviation

Abstract

In the line commutated converter based high voltage direct current(LCC-HVDC) transmission system, it has important meaning to suppress continuous commutation failure(CCF) for the safe and stable operation of the system. Aiming at CCF caused by poor dynamic performance of DC control system, this paper first analyzes that firing angle deviation is an important cause of CCF in the dynamic process of recovery after first commutation failure(FCF). Then, the reasons for firing angle deviation caused by the underlying firing control at this stage are analyzed: One is the phase deviation caused by the inherent response of the phase locked loop(PLL), which is a second-order system; the other is the phase deviation of the asymmetric commutation voltage. On this basis, a CCF suppression method based on dynamic compensation of firing angle deviation is proposed. The method dynamically and adaptively compensates firing angle deviation through the actual measurement value, which improves the controllability of actual firing angle in the dynamic process, thereby suppressing CCF. Finally, it is verified that the improved method has good suppression effects on CCF in the CIGRE HVDC benchmark model.