Suppression strategy for subsequent commutation failure of DC system based on improved VDCOL

Abstract

Aiming at the problem of subsequent commutation failure during the fault recovery period after the first commutation failure of high voltage direct current system,the recovery process is divided into the first commutation failure (stage 1),the beginning of system recovery (stage 2),and the current deviation control (stage 3) based on the action logic of direct current (DC) system control link in this study. It could be found that excessive recovery of DC current will lead to subsequent commutation failure during the stage 3. On this basis,an improved strategy of voltage dependent current order limiter (VDCOL) is advanced,which uses instantaneous voltage to detect the voltage amplitude of commutation bus in real time. The minimum current instruction value of the VDCOL is dynamically adjusted in accordance with the commutation bus voltage after the alternating current (AC) faults,so as to achieve the purpose of suppressing subsequent commutation failures. Finally,the effectiveness of this strategy is proved to suppress subsequent commutation failures under different failure conditions by the simulation results based on the CIGRE benchmark model.

Keywords

• high voltage direct current
• fault recovery process
• voltage dependent current order limiter (vdcol)
• subsequent commutation failure
• suppression measures
• cigre benchmark model