Method for voltage sag source location based on the internal resistance sign in a single-port network

摘要

Locating the voltage sag source is to determine on which side of a monitoring device the voltage sag originates. By analysing power network faults, observing from fault points to monitoring devices, power network at both sides of the device can be equivalent to two single-port networks. Based on the polarity of real part of internal impedance in these two single-port networks, the voltage sag source location can be identified accurately. If the real part of internal impedance is positive, the voltage sag source location is consistent with the reference direction, i.e. downstream. If the real part of internal impedance is negative, the voltage sag source location is opposite to the reference direction, i.e. upstream. The calculation of the real part of internal impedance is presented. The method proposed in this study has a solid theoretical basis. Simulation results show the method can locate voltage sag source with an accuracy of 100%, in power networks with various topologies (e.g. radial power system fed from one-source or multiple-source, interconnected power system, ring type network etc.), and the network adopted neutral grounded effectively or ineffectively. It is a practical method with high reliability for voltage sag source location.