Method for measuring power-transmission circuit double-ended distance by distributing parameter

Abstract

The invention relates to a method for relay protection in the field of power systems. Disclosed is a method of synchronizing sampling current and voltage at both ends of a power system, using distributed parameter long-line equations, and realizing double-terminal fault location according to the method that the positive-sequence or negative-sequence voltages at both ends of the fault point are equal. The method includes the following main steps: the line protection device samples the secondary current of the current transformer and the secondary voltage of the voltage transformer on the side of the line to obtain the corresponding instantaneous values ​​of current and voltage, and obtains the three-phase current and the three-phase current on the side through the Fourier algorithm. The Fourier form of the phase voltage, and the phasor form of the current and voltage obtained by receiving the synchronous sampling of the opposite side protection through the optical fiber communication network and filtering and calculating, using the condition that the positive sequence voltage or negative sequence voltage on both sides of the fault point is equal, the protection is obtained. The distance from the installation to the reference point. The method is not affected by the power supply impedance and transition resistance of the line operation mode. Theory and practice have proved that the method can greatly improve the accuracy of fault location of transmission lines.

Description

technical field [0001] The 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 phasor current and voltage at both ends of the line 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 methods: single-end location measurement and double-terminal lo...

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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