Power transmission line overload false operation prevention phase-to-phase distance backup protection method

Abstract

The invention relates to a power transmission line overload false operation prevention phase-to-phase distance backup protection method. The method comprises the steps that a fault phase-to-phase voltage, a fault phase-to-phase current and a fault phase-to-phase negative-sequence current at a power transmission line protective installation position are measured firstly, voltage drop along a power transmission line is calculated, the voltage drop along the power transmission line is subtracted from the fault phase-to-phase voltage at the power transmission line protective installation position to obtain voltage drop of phase-to-phase arc light at a phase-to-phase short-circuit fault point of the power transmission line, and then the voltage drop of the phase-to-phase arc light and a rated phase-to-phase voltage of the power transmission line are utilized to form a power transmission line phase-to-phase distance backup protection criterion. By means of the power transmission line overload false operation prevention phase-to-phase distance backup protection method, the power transmission line phase-to-phase distance backup protection criterion is formed by utilizing the amplitude characteristics of the voltage drop of the phase-to-phase arc light, motion performance is not affected by transition resistance, load current and operating modes of an electric power system, large-area power outage of a power grid caused by great shift of power grid tidal current due to phase-to-phase distance backup protection false operations under the condition of overload of the power transmission line is effectively prevented, and operation safety and stability of the power grid are reinforced.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for back-up protection of transmission line overload and anti-misoperation phase-to-phase distance. Background technique [0002] The power frequency variation distance protection constitutes the distance protection by reflecting the sudden change of the working voltage amplitude. This method has the advantages of being less affected by the operation mode of the power system and having a strong ability to resist transition resistance. However, since the mutation of the working voltage amplitude used in this method only exists in the initial stage of the fault, it cannot be used as a backup protection for high-voltage transmission lines. [0003] Impedance distance protection reflects the fault distance according to the measured impedance to distinguish whether the fault point is inside or outside the protection zone. Impedance distance pro...

AI Technical Summary

Problems solved by technology

In fact, in the power system, in addition to the artificially constructed metallic phase-to-phase short-circuit fault, the transition resistance of the actual phase-to-phase short-circuit fault point is not zero, and the additional impedance generated by the transition resistance will seriously affect the operating performance of the impedance distance protection

If the additional impedance generated by the transition resistance is resistive and inductive, it is easy to cause the impedance distance protection to refuse to operate when there is a phase-to-phase fault in the protection zone; if the additional impedance generated by the transition resistance is resistive and capacitive, it is easy to cause the impedance distance protection to exceed when there is a phase-to-phase fault outside the protection zone

[0005] High / super / extreme voltage AC transmission lines are often also heavy-duty transmission lines. Heavy-load currents will cause the impedance distance protection to malfunction or refuse to operate. The influence of heavy-load currents on the performance of impedance distance protection cannot be ignored.

Under the condition of overload transmission, the line has no faults. The measured impedance of the traditional distance protection will seriously deviate from the actual measured impedance due to the influence of the overload current, which will easily lead to the misoperation of the traditional distance protection, resulting in the expansion of the power grid blackout range, and even causing a large number of load transfers to threaten the normality of the line. operation, causing a huge security risk to the grid security

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