Faulty branch selection method of t-connection line based on branch selection factor

Abstract

The invention discloses a method for selecting a T-junction circuit fault branch circuit based on branch circuit selection factors. The method comprises measuring respectively a fault phase voltage, fault phase current, fault phase negative-sequence current and zero-sequence current of the T-junction circuit at a protection installation position of three branch circuits; and calculating fault branch circuit selection factors at the T-junction point of the three branch circuits respectively, and determining a branch circuit to be a fault branch circuit of the T-junction circuit if a fault branch circuit selection factor of the branch circuit at the T-junction point is smaller than zero. The method is suitable for fault branch circuit selection of a whole fault process after a single-phase earth fault occurs in the T-junction circuit, and selection results are not subject to transition resistance, load current and fault positions. When a single-phase high-resistance earth fault occurs in the T-junction circuit, the fault branch circuit of the T-junction circuit can be accurately determined by using the method.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a method for selecting a faulty branch of a T-connection line based on a branch selection factor. Background technique [0002] In the case of increasingly tight land resources, T-connection lines have become a common line transmission method in power systems due to their small footprint and low cost. The T-connection node of the T-connection line is not installed with electrical quantity acquisition equipment such as voltage transformers and current transformers. After a fault occurs on the T-connection line, it is necessary to first determine which branch of the T-connection line the fault point is on, and then use the The double-terminal fault location method of transmission line performs fault location measurement on the fault location. Therefore, whether the selection result of the fault branch is correct or not is directly related to the accu...

AI Technical Summary

Problems solved by technology

When the fault point is close to the T-junction of the T-connection line, due to the influence of high transition resistance, the voltage mutation amplitudes of the three branches at the T-junction of the T-connection line have little difference in amplitude, and the voltage transformer and current transformer Due to the influence of errors and harmonic components, the voltage mutation amplitude of the faulty branch at the T node of the T-connection line is smaller than that of the normal branch at the T-junction of the T-connection line, causing traditional T-connection line faults The branch selection method judges the faulty branch incorrectly, resulting in failure of T-connection line fault distance measurement

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