直流馈入后交流线路故障对换相失败瞬态特征的影响

Influence of AC line faults on HVDC commutation failure transient characteristics in DC/AC interconnected power grid

高压直流(HVDC)输电系统故障会使交流系统电气故障特性复杂化。在PSCAD/EMTDC环境下,基于含宁东—山东直流输电系统的山东电网的电磁暂态模型,研究当青岛换流站附近交流线路不同位置发生不同故障时,直流系统换相失败对交流系统电气瞬态特征的影响。直流系统换相失败对故障线路的平行线路影响最为严重,重点研究交流线路不同故障引起直流换相失败对平行线路电气特性的影响。仿真分析结果表明,平行线路的故障相电流畸变程度随着故障位置和故障类型的不同而不同,在线路中间发生故障比线路两端故障时畸变严重,发生单相接地短路故障比三相接地短路故障时畸变严重,故在线路中间发生单相接地短路故障时畸变最严重。

The faults of HVDC power transmission system make the electrical characteristics of AC system more complex.In PSCAD/EMTDC environment,based on the electromagnetic transient model of Shandong grid containing Ningdong-Shandong DC transmission system,the influence of HVDC commutation failure on the electrical transient characteristics of AC system is studied for different faults occurring at different positions of AC line near Qingdao substation.During the period of commutation failure,the parallel line of the faulty line is most affected.The influence of commutation failure,caused by different faults of AC line,on the electrical transient characteristics of parallel line is detailed.According to the comparative analysis of simulative results,the current distortion of the faulty phase of parallel line varies with the fault positions and fault types.It is more serious when the fault occurs in the middle of the line than that when the fault occurs at terminals;it is more serious during single-phase grounding fault than that during three-phase grounding fault.When single-phase grounding fault occurs in the middle of the line,the current distortion of the parallel line is most serious.