COMPARISON OF STEADY-STATE SVC MODELS IN LOAD FLOW CALCULATIONS

This paper compares in a load flow calculation three existing steady-state models of static var compensator (SVC), i.e. the generator-fixed susceptance model, the total susceptance model and the firing angle model. The comparison is made in terms of the voltage at the SVC regulated bus, equivalent SVC susceptance at the fundamental frequency and the load flow convergence rate when SVC is operating both within and on the limits. The latter two models give inaccurate results of the SVC susceptance due to the assumption of constant voltage when the SVC is operating within the limits This may underestimate the SVC regulating capability. Two modified models are proposed to improve the SVC regulated voltage according to its steady-state characteristic. The simulation results of the two modified models show the improved accuracy of the SVC susceptance while retaining acceptable load flow convergence rate.