高灵敏度的三次谐波式发电机定子接地保护

A HIGHLY SENSITIVE RELAY AGAINST GENERATOR STATOR GROUND FAULTS WITH THIRD HARMONIC VOLTAGE

常规的三次谐波式定子接地保护一般采用｜Ｕ３Ｔ＋ＫＰＵ３Ｎ｜＞β｜Ｕ３Ｎ｜作为动作条件，正常运行时动作量与发电机工况有关，限制了灵敏度。文中采用微机自适应原理实时自动跟踪Ｕ３Ｔ及Ｕ３Ｎ的变化，将发电机各种工况下动作量降至最低，既提高了灵敏度又节省了现场调整工作量。

The conventional stator ground relay often uses |U· 3 T +K· P U· 3 N |>β|U· 3 N | as the criterion. The criterion relates to the output power of generator, and so the sensitivity is limited. By utilizing the adaptive protection principle, the action can be reduced to minimum under normal conditions. It not only improved the sensitivity but also reduced the adjustment work in the field. The field test shows that the new protection scheme has high sensitivity.