Influence of current error controller on commutation failures and system recovery

Abstract

Constant extinction angle control based on prediction is a basic control strategy of inverter in line-commutated converter high-voltage direct current (HVDC) system. However,system commutation failure suppression ability and system recovery are determined by the proportionality coefficient in the current error control. To clarify the influence mechanism and propose countermeasures,the function of current error controller is analyzed based on the basic control strategy. Then the influence mechanism of proportional coefficient in current error controller is studied at both the initial stage of fault and fault recovery stage. It can be concluded that the mitigation effect of commutation failure would perform worse if the proportion coefficient of current error control is set to positive. Nevertheless,the recovery performance of the HVDC system would be better. Based on this a novel adaptive current error control is proposed,which can quickly identify the system state through detection modules and output an appropriate proportional coefficient to take into account the commutation failure suppression ability and recovery process of the system. Finally,high-voltage direct current test model is built based on PSCAD/EMTDC,and the correctness of the theoretical analysis and the effectiveness of the proposed countermeasures are verified by simulation test.

Keywords

• constant extinction angle control
• current error control
• high-voltage direct current
• commutation failure
• adaptive current error control
• dynamic fault recovery characteristic