High Precision Distance Relaying Algorithm for Transmission Line Protection by Optimal Integral Approximation Technique

抄録

This paper presents a new distance relaying algorithm for transmission line protection and the method of estimating integral coefficients in this algorithm. The presented algorithm is based on the differential equation that satisfies the relation between the voltage and the current of transmission line. This algorithm calculates impedance values by approximating the integral term of the integro-differential equation, which is obtained by taking integral to differential equation. Spectrums of voltage and current due to faults of transmission lines are obtained by Prony's analysis. To find optimal integral coefficients in a least-square-error sense in the frequency domain, each weighting function of voltage and current coefficients can be derived by considering these spectrums and analog filter together. These weighting functions give the optimal coefficients appropriate to transient voltage and current after faults. The simulation and the test result show that the proposed algorithm can be used successfully to protect transmission lines.