±800 kV云广特高压直流输电系统中,在各种特殊工况下,如投切滤波器、直流功率调整、电网扰动等,由于交流滤波器中大量电容器件的充放电过程,会导致交流滤波器上流过较大的冲击电流,该冲击电流将导致交流滤波器高压电容器不平衡电流增大,从而使不平衡保护发生误动作.准确的识别交流滤波器高压电容器故障与冲击干扰,对交流滤波器不平衡保护的准确动作具有非常重大的意义.通过对不平衡电流采样值进行小波变换,利用小波变化模极大值,提出一种新的交流滤波器高压电容器故障识别方法.通过PSCAD/EMTDC软件仿真验证,该方法能快速、准确、有效的识别交流滤波器高压电容器故障与冲击干扰,提高了交流滤波器不平衡保护的可靠性和准确性.%In ±800kV YUN-GUANG UHVDC transmission system, in various special conditions, such as investing and cutting filter, adjusting dc power, power grid disturbance, etc, since the charging and discharging process of a lot of capacitors of AC filter, large surge current will flow thought the AC filter, the surge current cause the unbalanced current of high-voltage capacitor of AC filter increased, and cause the unbalanced protection mistake action. So accurately distinguishing the fault and surge of high-voltage capacitor of AC filter is very important to unbalanced protection of AC filter. Though the unbalanced current wavelet transforming and the wavelet transformation modulus maximum, the paper present a new fault distinguishing method of high-voltage capacitor of AC filter. Though PSCAD/EMTDC simulation checking, this method can rapidly, accurately and effective distinguishing the fault and surge of high-voltage capacitor of AC filter, and improve the reliability and validity of unbalanced protection of AC filter.
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