基于阀侧电流不对称性的LCC-HVDC系统换相失败检测OA

With the widespread application of HVDC transmission technology in long-distance and large-capacity power transmission,line-commutated converter based high voltage direct current(LCC-HVDC)attracts much attention due to its unique advantages.However,the semi-controlled devices used in LCC-HVDC system lack self turning off capability,and commutation failure is easy to occur in case of fault,which greatly affects the stability and safety of the system.Therefore,the dynamic commutation process of LCC-HVDC system is researched,the variation characteristics of the valve-side current of the converter transformer under normal operation and AC system faults are analyzed in detail,and the variation features of this current are extracted.On this basis,a commutation failure criterion of LCC-HVDC system is proposed based on its asymmetry characteristics,enabling rapid and accurate identification of multiple commutation failures.Based on the PSCAD/EMTDC simulation platform,the effectiveness of this method under various operating conditions is verified by means of simulation models of CIGRE LCC-HVDC system and practical double-circuit transmission lines models on the same tower.The experimental results indicate that the proposed criterion has fast response and high detection accuracy in multi-commutation failure scenarios,demonstrating strong reliability and robustness,and providing a theoretical reference for the detection of commutation failure in practical engineering applications.