Description of Power System QV Curve by Fuzzy Modeling

The purpose of this paper is to study the description of power system QV curves by using the method of fuzzy modeling for analysis of voltage stability. 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. The QV curve can identify voltage stability limit, and it determine robustness of power system. The method of fuzzy modeling has been proven to be well-suited for modeling nonlinear industrial processes described by input-output data. 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. In view of the nonlinear characteristic of power system 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. Key-Words: Fuzzy Modeling, Sugeno-type, ANFIS, QV Curve, Voltage Stability, Voltage Collapse.