输电线路相间故障引发直流双极换相失败分析

Analysis of Bipolar Commutation Failure of HVDC Caused by An Interphase Fault of Transmission Line

对一起220 kV交流线路相间故障引发直流双极换相失败的原因开展了分析,分析结果表明,220 kV线路AB相故障后,直流换流站500 kV交流母线电压遭受扰动,主要表现为故障相电压幅值跌落、换相电压过零点偏移,二者叠加引发了直流换相失败。并且,作为实际工程中预防换相失败的主要手段,换相失败预测控制在所提事件中未能及时识别故障,对于第一次换相失败并未起到预防作用。此外,换相失败受故障时刻等偶然因素与控制响应的复杂交互影响,所提事件中,正常的换相过程后紧跟换相失败,无过渡换相过程可供控制参考调节,情况较为不利。最后,结合所提事故案例,针对换相失败分析与抑制提出了相关建议。

The reason for a bipolar commutation failure(CF)caused by a 220 kV AC line interphase fault is analyzed,and the results show that 500 kV AC bus voltage of DC converter station suffers from disturbance after AB-phase failure of the 220 kV line.This disturbance is mainly manifested in the drop of fault phase voltage amplitude and the zero-crossing offset of commutation voltages.As a result,the combination of these two factors triggers CF.Furthermore,the commutation failure prevention(CFPREV)control,as the main method used to prevent CF in actual projects,fails to recognize the fault in time in this fault event and does not play a preventive role for the first CF.Additionally,CF is affected by the complex interaction of control response and accidental factors such as fault moment.In this fault event,the normal commutation process is immediately followed by CF and lacks a transition commutation process which can be adjusted for control reference,which is unfavorable.Finally,based on this fault case,some relevant suggestions are proposed for the analysis and mitigation of CF.