SUPERPOSITION TECHNIQUE FOR MOV-PROTECTED SERIES CAPACITORS IN SHORT-CIRCUIT CALCULATIONS

A new method for modeling series capacitors protected by metal oxide v aristors is developed using superposition on sequence networks. This t echnique is incorporated in a short-circuit program within an iterativ e process which allows the consideration of the nonlinear characterist ic of metal oxide varistor (MOV) protected series capacitors. The iter ative process is rendered dynamic by evaluating the voltage and curren t 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 protec ted series capacitors is simulated by fictive shunt current sources ac ross varistors. Results show that the proposed procedure can adequatel y and efficiently model MOV protected series capacitors in a standard short-circuit program.