Selection method of faulty branch of t-connection line

Abstract

The invention discloses a teed line fault branch selection method. The method of the invention comprises the following steps of firstly measuring fault phase positive sequence voltages and fault phase positive sequence currents of protection installation positions of three branches of the teed line; calculating a fault current of an injection fault point of the three branches; calculating fault phase positive sequence voltages of T connection nodes of the three branches respectively; subtracting an average value of a sum of the fault phase positive sequence voltages of the T connection nodes of the other two branches from the fault phase positive sequence voltage of the T connection node of the third branch so as to obtain a voltage difference value; then calculating whether an angle of voltage difference value exceeding fault current is less than zero; if the angle is less than zero, determining that the third branch is the fault branch of the teed line. The method of the invention is suitable for fault branch selection of a whole fault process after the teed line has the fault. A selection result is not influenced by a transition resistor, a fault type, a load current and a fault position and the fault branch of the teed line can be accurately determined.

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. 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 relay protection devices, voltage transformers, current transformers and other electrical quantity acquisition equipment. After a fault occurs on the T-connection line, it is necessary to first determine which branch of the T-connection line is the fault point. On the road, and then use the double-terminal fault location method of the transmission line to perform fault location on the fault location. Therefore, whether the selection result of the fault branch is correct or not is directly related to the accuracy of th...

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Problems solved by technology

When the fault point is close to the T-junction of the T-connection line, due to the influence of the transition resistance, the voltage mutation amplitudes of the three branches at the T-junction of the T-connection line have a small difference in magnitude, plus the transmission error of the voltage transformer and current transformer Due to the influence of harmonic components, the amplitude of the voltage mutation of the fault branch at the T node of the T-connection line is smaller than the amplitude of the voltage mutation of the normal branch at the T-node of the T-connection line, which causes the fault branch of the traditional T-connection line The path selection method judges the fault branch to be wrong, resulting in the failure of T-connection line fault location measurement

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