A new type of MW and MVar dispatch index for meeting voltage stability margin criteria based on normal vector of limit surface

this paper presents a new type of index for improving the power system economical dispatch from a voltage stability margin perspective. The proposed index is based on normal vector of voltage stability limit surface, which are supplement and enhancement of participation factor. Firstly, the rationality of this index is proved mathematically. Then numerical simulation on IEEE 39 system demonstrate the validity of the proposed index. Compared to the traditional indexes, proposed index has a wider range of application since it can deal with the critical point of voltage stability, both saddle node bifurcation and limit induced bifurcation. The proposed index can be utilized in active/reactive dispatch for normal operation, and also minimum load shedding strategies in case of critical contingencies.