Assessment Modeling of Series Capacitors Protected by Metal Oxide Varistors in Power System Studies

This paper presents assessments of two models for MOV protected series capacitors. The first model is empirical and the second is analytically developed by solving the nonlinear system and applying the describing function (DF). The models are assets in short-circuit and transient stability studies. For short-circuit analysis, symmetrical and unsymmetrical faults are considered on simplified circuits using a compensation technique. For the transient stability analysis, the model is evaluated on simplified circuits with a single machine system and an infinite bus. The evaluation of the model is done using an equal area criterion and numerical solutions of nonlinear differential equations. Comparing the model with the results obtained from electromagnetic transient simulations and the empirical model proves the accuracy and flexibility of the DF model.