Improved criterion for differential protection of T-shaped line

Abstract

The invention discloses an improved criterion for differential protection of a T-shaped line. The improved criterion specifically comprises the following steps of: adopting double-end line R-L single-phase out-of-region and in-region fault component models; combining the different fault characteristics of the longitudinal impedance in out-of-region and in-region faults of the double-end line to obtain a protection improved criterion of the double-end line on the R-L single-phase line; according to the similarity, obtaining the protection improved criterion of the T-shaped line on the R-L single-phase line during the occurrence of out-of-region and in-region faults, the protection improved criterion of the T-shaped line during the occurrence of in-region faults after the decoupling of a three-phase line, and the protection improved criterion of the T-shaped line during the occurrence of out-of-region faults after the decoupling of the three-phase line. According to the invention, the improved criterion for differential protection of the T-shaped line solves the following problems in the prior art: the traditional current differential protection is difficult to set and is easily subjected to the influence of the capacitive current and the transient saturation of a current transformer.

Description

technical field [0001] The invention belongs to the technical field of relay protection for AC transmission lines, and in particular relates to an improved criterion for T-type line differential protection. Background technique [0002] With the access of large-scale distributed power sources, T-shaped or multi-terminal distributed power plants (including wind farms) are more and more appearing in the grid frame structure, which makes the operation mode of the grid system more complicated, resulting in The relay protection of conventional system configurations faces great challenges. Therefore, it is of great significance to study the reliability, selectivity and sensitivity of multi-terminal transmission line fault protection. [0003] At present, most T-shaped or multi-terminal transmission lines adopt current differential protection as the main protection configuration. According to the different forms of differential current and braking current in differential protecti...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide an improved criterion for T-type line differential protection, which can accurately and sensitively identify the fault and act effectively after the T-type high-voltage transmission line fails, and overcomes the difficulty in setting the traditional current differential protection, which is vulnerable Problems with capacitive currents and transient saturation of current transformers

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