A new fault location method based on the correlation of zero mode current

A new earth fault location method for non-effective earthed neutral network using transient signals measured at the bus terminal is presented. Based on the mode network of the single phase to ground fault, the s-domain equation of the faulty feeder is derived and the discrete difference equation is obtained by z-transform. Then fault distance is evaluated form transient data using the least square estimation. The adoption of Γ-mode equivalent circuit reduces the number of the parameters to be estimated and simplifies the distance estimation algorithm. The algorithm is effective on intermittence faults as it makes use of transient signals and, consequently, a shorter than half cycle data window. EMTP software was used for simulating the typical distribution system and MATLAB was used for data process. The simulation and calculation results proved the accuracy and reliability of the correlation coefficient method and entropy method. The fault location scheme proposed in this paper is valuable in practical application.