Method for recognizing fault in power transmission line distance protection

Abstract

The invention provides a method for recognizing a fault in a power transmission line distance protection. The method comprises the following steps that the three-phase voltage and the three-phase current at the position where the protection is installed; a positive sequence voltage, a positive sequence current, a negative sequence current and a zero sequence current with the phi phase as the reference are determined; the current asymmetry degree at the position where the protection is installed is determined; the included angle between the positive sequence voltage and the positive sequence current is determined; fault recognition is carried out according to a current asymmetry degree plane. According to method for recognizing the fault in the power transmission line distance protection, fault recognition in the distance protection is achieved through comprehensive use of the current asymmetry degree and the U1cos phi1 characteristic, and action performance of an existing power transmission line distance protection is improved when a fault happens during oscillation and overload happens.

Description

technical field [0001] The invention relates to a method in the field of distance protection, in particular to a fault identification method in the distance protection of transmission lines. Background technique [0002] The distance protection is divided into three sections. Among them, distance I and II section, after 150ms after the fault is opened, it enters the oscillation lock. The increase of the load and the transfer of the load after the line fault will cause the line overload. Area without power. [0003] In the prior art, the re-opening condition of oscillation blocking fault is to use m (open asymmetric fault) and Ucosφ (open symmetric fault) separately. For asymmetric fault, when the transition resistance of single-phase ground fault is large, it cannot be opened. For symmetrical Fault, the open time is long, in view of the problem that the distance protection may malfunction under overload, the current measures are mainly to set the load limit line on the imp...

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Problems solved by technology

[0002] The distance protection is divided into three sections. Among them, distance I and II section, after 150ms after the fault is opened, it enters the oscillation lock. The increase of the load and the transfer of the load after the line fault will cause the line overload. area blackout

[0003] In the prior art, the re-opening condition of oscillation blocking fault is to use m (open asymmetric fault) and Ucosφ (open symmetric fault) separately. For asymmetric fault, when the transition resistance of single-phase ground fault is large, it cannot be opened. For symmetrical Fault, the open time is long, in view of the problem that the distance protection may malfunction under overload, the current measures are mainly to set the load limit line on the impedance plane to avoid the load, and this method will sacrifice the sensitivity of the distance protection, and then As the load continues to increase, the action area of ​​the distance protection will be greatly reduced. For a single-phase ground fault, due to the large range of transition resistance, when the transition resistance is large, due to the influence of the load limit line, the distance protection will refuse to operate. The ability to withstand the transition resistance of the protection is greatly weakened

[0004] Therefore, it is necessary to provide a fault identification method that can quickly open distance protection for transmission line distance protection, improve the ability of distance protection to withstand transition resistance, and overcome the shortcomings of traditional methods that only use a single feature

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