特高压直流单极故障引发送端接地极引线过电压计算方法及影响因素分析

Calculation Method and Influencing Factors of Overvoltage on Ground Electrode Line on Sending End Caused by Monopolar Fault in UHVDC Transmission System

接地极引线是特高压直流输电系统的重要组成部分,其运行状态与特高压直流输电工程运行的可靠性密切相关。针对特高压直流单极故障后接地极引线所出现的过电压风险,研究了过电压幅值及振荡频率的计算方法,并基于仿真算例探讨了影响过电压幅值及振荡频率的影响因素。首先,计及特高压直流一次系统以及控制系统行为,推导了特高压直流单极故障后接地极引线首端电压扰动的传递函数,提出了基于传递函数求解过电压峰值及电压振荡频率的方法。其次,利用西南某实际±800k V特高压直流系统实际录波,验证了传递函数的有效性。最后,基于仿真算例分析了直流线路故障位置、接地极引线的长度、电流控制器参数以及故障前直流的正常运行电压等因素对故障后接地极引线过电压峰值及振荡频率的影响。

Ground electrode line is an important part of UHVDC transmission system,whose operating condition determines reliability of UHVDC transmission system.Calculation method and influencing factors of amplitude and oscillation frequency of overvoltage on ground electrode line at sending end caused by monopolar fault in UHVDC transmission system are studied in this paper.Firstly,transfer function of voltage on ground electrode line head-end under monopolar fault of UHVDC transmission system is investigated.In this function,parameters of primary equipment and DC current control link are both considered.Secondly,based on the transfer function,a method solving amplitude and oscillation frequency of overvoltage is proposed.Finally,validity of the voltage-calculating method is proved using waveform records of a real ±800 kV UHVDC system in Southwestern area of China.Factors influencing amplitude and oscillation frequency,such as transmission line fault location,ground electrode line length,parameters of current control link and normal DC voltage,are analyzed with a case study.