提高三次谐波电压式定子接地保护动作可靠性的措施

通过三次谐波电压式定子接地保护2次误动案例分析,说明发电机的机型、一次设备的参数及一次回路的接线方式对发电机机端及中性点、三次谐波电压的大小和相位均有影响,在三次谐波电压式定子接地保护的设计选型时应予以考虑。提出了提高可靠性的措施:当发电机变压器按扩大单元接线时,或当发电机机端有断路器且断路器断口两侧并有接地电容时,宜采用绝对值比较式原理或采用不同工况下的自适应整定方案。

Reliability of stator grounding protection based on 3rd harmonic voltage

Case analysis of the stator grounding protection based on 3rd harmonic voltage shows that,the generator types,parameters and wire connection modes all have influences on the amplitudes and phases of generator terminal,neutral point and 3rd harmonic voltages,which should be considered in its design.Measures to improve its reliability are proposed:the absolute value comparison principle or the adaptive setting scheme should be applied when generator and transformer are connected as enlarged unit or when a breaker with parallel grounding capacitors is connected to generator terminal.