乒乓式励磁绕组接地保护若干问题的探讨

Issues of Ping-Pong Type Protection for Ground Fault in Field Winding

乒乓式励磁绕组接地保护由于自身的优点而被广泛应用,但是该保护在应用中存在2个问题:一是由于切换电路中元件参数选取不合适,会对保护精度造成较大影响;二是接地电阻数值的变化会影响保护动作的准确性。针对第1个问题,文中对若干影响保护精度的因素进行了分析,并采用建模仿真对分析结果加以验证,得出元件参数选取的依据;对于第2个问题,分析了接地电阻在不同变化趋势下对保护的影响,并根据分析结果提出了相应解决办法,从而减小了阻值变化对保护的不良影响。

Ping-Pong type protection for ground fault in field winding is widely used for its merits. However, there are still some problems in protection applications. One of those is that the improper choice of component parameter in switch circuit can have a great impact on the protection precision, and another is that the accuracy of protection operation will be influenced by the change of ground resistance value. To solve the first problem, this paper studies some factors that can affect the protection precision, and proposes a simulation model to verify the analytical results, then obtains the rule of component parameter selection. For the solution of the second problem mentioned above, the influence of different change trends of ground resistance on protection are analyzed, and the related methods are provided such that the adverse influence of the change of ground resistance value on protection is reduced.