VDCOL Coordinated Control Strategy for Successive Commutation Failure Mitigation in Multi-infeed HVDC Systems

Control strategy improvement is an effective method for commutation failure mitigation in line-commutated-converter-based high voltage direct current (LCC-HVDC). However, for the multi-infeed HVDC system with multiple dc links located in close mutual proximity, existing strategies based on adjustment of dc current or the firing angle may lead to negative influence even commutation failure in adjacent HVDC. Therefore, in order to achieve coordinated recovery of multi-infeed HVDC systems, novel control strategy for improvement of the voltage dependent dc current order limiter (VDCOL) is put forward after analyzing the reactive power interaction between dc systems. Then crucial parameters in the proposed strategy are determined based on evaluation of influence on stability of the multi-infeed HVDC system caused by each dc system and reactive power-voltage sensitivity between ac busbar of inverters. Simulation results in PSCAD/EMTDC verify effectiveness and advantage of the method on commutation failure mitigation as well as coordinated recovery performance.