A method of distinguishing short-term voltage stability from rotor angle stability and its application

To solve the short-term voltage stability problem of power systems, a method which applies controlling unstable equilibrium point (CUEP) to distinguish short-term voltage stability from rotor angle stability is proposed. This paper adopts modal analysis of power flow snapshots to propose the concepts of controlling generator bus and controlling motor bus. Based on this, the CUEP can be solved by Thevenin equivalent method. Compared to time domain simulation, the proposed method is less time consuming. Finally, we can identify the corresponding instability style by comparing the slips of controlling induction motor or the power angles of controlling generator in the CUEP and the stable equilibrium point (SEP).