Analysis of power system QV curve by fuzzy modeling

Voltage instability of power system comes from increasing load rapidly, and causes bus voltage to drop. When voltage is out of control and it can be voltage collapse. This paper presents the fuzzy modeling approach to the description QV curve of power system for analysis of voltage stability. The QV curve can identify voltage stability limit, and it determine robustness of power system. The fuzzy system model is basically a collection of fuzzy IF-THEN rules that are combined via fuzzy reasoning for describing the features of a system under study. The method of fuzzy modeling has been proven to be well-suited for modeling nonlinear industrial processes described by input-output data. In view of the nonlinear characteristic of the QV curve, the method of fuzzy modeling is employed for representing the curve. Based on the Sugeno-type fuzzy model, various models with different numbers of modeling rules are used to describing the QV curve. It is found that such fuzzy model offers both quantitative and qualitative descriptions for the QV curve.