±1100 kV特高压直流换流站PCOV计算及影响因素分析

Calculation and Influencing Factor Analysis of PCOV in±1100 kV UHVDC Converter Station

含换相过冲的持续运行电压峰值(peak value of the continuous operating voltage, PCOV)是决定换流站直流避雷器参考电压的一个重要参数。针对昌吉—古泉±1 100kV特高压直流工程建立了换流阀、换流变压器、平波电抗器、PLC滤波器等主设备模型,基于±1 100kV特高压换流站系统等效电路模型仿真计算了各类型直流避雷器的PCOV水平。对比公式法计算结果,PCOV水平整体上一致,最大偏差为13.4%,说明公式法计算值仍留有一定的安全裕度。基于所建立的模型进一步对PCOV计算的影响因素进行分析,结果表明,换流阀的阻尼电阻、阻尼电容、饱和电抗器铁芯电感、换流变压器漏感和平波电抗器电感对PCOV计算的影响较大。

The peak value of the continuous operating voltage including commutation overshoot is an important parameter that determines the reference voltage of the DC arrester in the converter station.Based on the Changji-Guquan±1100 kV UHVDC project,the models of main equipment including converter valve,converter transformer,flat wave reactor and PLC filter are established.The PCOV level of each type of DC arrester is simulated according to the equivalent circuit model of the±1100 kV UHVDC converter station.Compared with the results calculated by the formula method,the simulated PCOV level is consistent on the whole,with the maximum deviation of 13.4%,indicating that the formula method still has a certain safety margin.Based on the models established in this paper,the influencing factors of PCOV are further analyzed,and the results show that the damping resistance,damping capacitance,the iron inductance of the saturated reactor,the leakage inductance of the converter transformer and the inductance of flat-wave reactor have a great influence on PCOV calculation.