Evaluation of Fault Voltage and Current in a Symmetric Power System Network

Abstract: The subject of Evaluation of Fault voltages and currents in a power system network is very important part of power system analysis for stable and economical operations of a Power System. The main objective of the short circuit fault analysis is to simulate short circuit faults on different buses of a power system network and to estimate the state of the power system before and after a fault, which includes various bus voltages and current flow on various transmission lines. The analysis of power systems under faulted condition provides information regarding circuit breaker selection, relay setting, and the stability of the systems operation. Two different MATLAB based programs were written; one program was for Load Flow Studies to determine the pre-fault conditions based on Newton-Raphson method, while the other was for three-phase short-circuit studies. It was observed that the fault currents were mostly excessively high. In this paper, three-phase symmetrical fault was simulated on the standard IEEE 6 bus and IEEE 30 bus system and fault voltage and fault current level is calculated and short circuit MVA rating for the circuit breaker has been chosen.

Keywords: Evaluation of fault analysis, NR method, symmetrical fault (LLL) calculation, short circuit MVA.