Using the ratio of 3rdharms got from G-term and N-point to do the Stator Ground Fault protection, together with the way of using the ZSVolt of N-point ,can protect the whole 100% Stator Ground Fault accident.

• 用机端和中性点三次谐波电压的比值来监视定子接地保护可以弥补中性点零序电压保护的不足，可以配合中性点零序电压保护实现100%25的定子接地保护。