Voltage collapse assessment incorporating fuzzy static load representation and dynamic models of induction motors

In this paper a fuzzy-static load model is incorporated, together with the induction motor load, into voltage stability assessment procedure in order to simulate the more realistic scenario of voltage collapse phenomena. Active and reactive static loads are treated as fuzzy variables, with different membership functions associated with that part of the total load. The objective is to propose a mathematical formulation for the voltage collapse analysis of load buses taking into account uncertainty of static load values expressed through their linguistic declarations. Simulation results are presented by means of corresponding distribution diagrams of maximal active load powers and critical voltage values. The effectiveness of the proposed approach is demonstrated by the voltage collapse analysis of different static/dynamic structures of the load bus in an environment of uncertainty and vagueness. Test cases and numerical results have shown the applicability of the proposed approach.