应用解析法分析中性点接地系统中的工频铁磁谐振-谐振判据和消谐措施

STUDY OF FUNDAMENTAL FERRORESONANCE ON NEUTRAL-GROUNDED SYSTEMS BY USING ANALYTICAL METHOD-CRITERION AND ELIMINATION

该文应用解析法讨论了工频铁磁谐振发生的原因和消谐措施。谐振原因是由于非线性电感的工频励磁特性与谐振电路戴维南电源伏安特性有交点,即是由于回路电阻大于临界阻尼电阻。文中给出了临界阻尼电阻公式和消谐措施。对于已经发生谐振的变电站,建议在电压互感器的二次侧并联电阻,使回路的等效电阻小于临界阻尼电阻。应用该方法成功地分析和消除了一110kV变电站的铁磁谐振。

The cause and the elimination of fundamental ferroresonance have been discussed by using analytical method.This phenomenon is likely to happen when the power frequency excitation characteristic of the nonlinear inductor intersects the voltage-current characteristic of the Thevenin equivalent source of the resonant circuit,or to say it another way, when the circuit resistance is larger than the critical damping value.This value is given as an analytical equation.A suppression means is then proposed.For a substation subjected to ferroresonance, a resistance is added to the busbar PT抯 secondary side,so that the resultant can be less than the critical value.This means proved effective in analyzing and suppressing ferroresonance at a 110kV substation.