Superposition technique for MOV-protected series capacitors in short-circuit calculations

A new method for modeling series capacitors protected by metal oxide varistors is developed using superposition on sequence networks. This technique is incorporated in a short-circuit program within an iterative process which allows the consideration of the nonlinear characteristic of metal oxide varistor (MOV) protected series capacitors. The iterative process is rendered dynamic by evaluating the voltage and current of the series capacitors and by adjusting the state of the varistors at each iteration without reformulating the network nodal admittance matrix. The 60 Hz impedance characteristic of the nonlinear MOV protected series capacitors is simulated by fictive shunt current sources across varistors. Results show that the proposed procedure can adequately and efficiently model MOV protected series capacitors in a standard short-circuit program