Hopf bifurcation point identification in a power system with various static load models

Abstract

This paper covers the impact of voltage dependent load models on the small signal stability in Western States Coordinating Council (WSCC) system having Automatic Voltage Regulator (AVR) with increased generation and load scenarios. Earlier work on the same system using constant power type of load representation for locating the Hopf bifurcation point was done by the authors of this manuscript. This paper deals with the extension of the previous work to include various voltage dependent small signal load models such as Constant Current (CC),  Constant Impedance (CZ),  Industrial (IND) and large scale Electric Vehicle (EV) for evaluating damping ratios and sketching the locus of critical modes at stressed loadings by defining six cases. A thorough comparison of damping ratios of several complex modes obtained after including various voltage dependent load models in the linearization programmes with the constant power model presented in earlier work at the nominal loading is done. It is concluded that by including large scale EV load model at load buses, highest damping ratio of exciter mode corresponding to first generator of WSCC system was obtained when compared to remaining load models.