Method for implementing distance measurement between two ends of electric transmission line using interphase electrical quantities

Abstract

The invention relates to a relay protection method in power system, which is characterized in that the distance at the two fault points can be measured through synchronous sampling current and voltage between phases at two fault points, since the voltage between phases at two fault points is the same. The method comprises the procedures as follows: current and voltage instant values are obtained by a circuit protection unit through secondary current sampling of a current transformer and secondary voltage sampling of a voltage transformer on the circuit side; the Fourier three-phase current and voltage relation is calculated using Fourier algorithm; the sampling signal of the opposite side is received via optical fiber communication network and then filtered; phasor current and voltage is obtained through calculation; distance between the protection point and the fault point can be obtained. The invention has the advantages that the method is not affected by the source impedance and transition resistance of circuit operation mode; the influence on the distance measurement caused by poor earthing points and multipoint earthing is reduced due to the adoption of interphase value; as is proved by the theory and practice of single fault-related interphase value at the fault point, accuracy of fault distance measurement of the electric transmission line is greatly improved fault-related interphase value.

Description

technical field [0001] The present invention relates to the field of power systems, and 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-to-phase current and phase-to-phase voltage at both ends of the fault point when a fault occurs in the line area, 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 divi...

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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