Phase amount and zero sequence amount combined realization powerline both-end distance measuring method

Abstract

The present invention relates to the relay protection method in the field of a power system. The present invention discloses a method for realizing two-terminal fault location in the power system through two terminal synchronism sampling current and voltage according to the method of equal voltages at two ends of a fault point and using a phase current and a phase voltage without zero sequence current and zero sequence voltage. The method comprises main steps as follows: a line protection device samples to a line side current sensor secondary current and voltage sensor secondary voltage to obtain a corresponding instantaneous value of the current and the voltage. The Fourier form of a three phase current and a three phase voltage on the side is worked out using a Fourier algorithm. The phasor form of phase current and phase voltage obtained by filtering to compute of protecting synchronism sampling on the other side is received through optical fiber network of communication. The distance from the protection arranging place to the fault point is obtained using the situation that the phase voltages on two sides of the fault point is equal with each other. The method is not affected by the power supply impedance and the transition resistance in the line operation method. Theory and practice prove that the method greatly improves the accuracy of transmission line fault location.

Description

technical field [0001] The present invention relates to the field of power systems, more specifically to a method for fault location in a power system, which is a method for judging the fault location of a transmission line by using the phase current and voltage at both ends of the line, the zero-sequence current and zero-sequence voltage, and the distribution parameters of the line itself. Background technique [0002] Transmission line is the basic equipment for power generation and transmission in the power system, and occupies a very important position in the power system. When the transmission line fails, if the fault location can be carried out quickly and accurately, it will not only help to repair the fault line in time, ensure the reliable power supply of the power system, but also be very important to the safety, stability and economic operation of the power system. [0003] At present, the fault location methods of transmission lines can be divided into two method...

AI Technical Summary

Problems solved by technology

The problem brought about is that the solution of the equation is more complicated and the amount of calculation is large. For some iterative algorithms, there is still the problem of solving hyperbolic functions. The calculation results are very likely to diverge, which leads to the failure of distance measurement.

Among the algorithms using concentrated parameters, considering distributed capacitance is obviously more accurate than not considering distributed capacitance. For short lines, the influence of distributed capacitance can be ignored, but for medium and long lines, ignoring distributed capacitance will bring larger errors.

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