Method for identifying out-of-zone fault in power transmission line protection zone of electric power system

Abstract

The present invention discloses a method for identifying an out-of-zone fault in a power transmission line protection zone of an electric power system. The method comprises the following steps: in step 1, an initial traveling wave voltage and a pre-fault voltage at each point of a protection line are obtained; in step 2, correlation between the initial traveling wave voltage and the pre-fault voltage at each point of the protection line is calculated, absolute values of correlation coefficients are obtained and a curve of the absolute values of the correlation coefficients is formed; in step 3, according to the curve of the absolute values of the correlation coefficients, whether the fault occurs within a scope of protection or outside the scope of protection is determined; if the curve of the absolute values of the correlation coefficients has an extreme point, that the fault occurs within the scope of protection is determined; otherwise, the fault occurs outside the scope of protection. Via the method disclosed in the technical solution of an embodiment of the present invention, an in-the-zone fault and the out-of-zone fault in traveling wave distance protection can be identified, a problem that the in-the-zone fault and the out-of-zone fault cannot be identified in a single-ended traveling wave protection can be solved, great pioneering effects are exerted, and reliability of traveling wave distance protection can be ensured.

Description

technical field [0001] The invention relates to a method for identifying faults inside and outside the protection range of a power system, in particular to a method for identifying faults inside and outside the protected area of ​​a power system transmission line, and belongs to the technical field of ultra-high voltage transmission line protection of a power system. Background technique [0002] The principle of fast protection of EHV transmission lines is an important field in power system operation management technology. Quickly and accurately identify faults within the protection area or outside the protection area of ​​the fault point, which can ensure fast action of protection, remove hidden faults in time, and ensure power supply reliability and stability of the power system. [0003] Traveling wave distance protection is one of the fast protection methods for power systems, especially UHV transmission lines. Compared with differential protection, it can not only real...

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Problems solved by technology

[0005] Aiming at the deficiency that the existing single-ended traveling wave distance protection cannot distinguish internal and external faults, the present invention proposes an identification method for internal and external faults in the power system transmission line protection area, which can fundamentally solve the problem of the existing single-ended faults. Insufficient distance traveling wave protection method

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