Determination of impedance of fault current limiter in distribution system with generator based on linear network analysis

This paper describes a linear network analysis for determining the suitable value of limiting impedance of fault current limiter installed in a medium voltage power system with a synchronous generator. In the linear network analysis, the impedance of generator was approximated with a direct axis transient reactance and the limiting impedance was constant although the impedance of generator after a short circuit varies with time and the limiting impedance was generated after the fault current limiter detected an excessive short circuit current. It was assumed that a three-phase short circuit appeared in the power system. The limiting impedance suppressing the short circuit current under 0.3 pu was estimated. It was found that the method of linear network analysis can be useful for determining the required limiting impedance since the results of computer simulation agree with those of linear network analysis.