Re-switch on method for electric tansmission device

Abstract

This invention relates to reclosing method for power transmission line. For joint parallel double circuit type: each circuit being equiped with individual protector, main protection being phase-splitting current differential protection or phase-command longitudinal protection; for various type single circuit fault or overline fault withni a zone, tripping fault being detected, determinnig no serious permanent fault, sequentially reclosing the tripping phases. For double-circuit fault, there must be two different type circuit being of no fault for reclosing, if not, two circuits must be tripped-off. This invention method increases the reclosing rate, together with minimizing the shock to the system after reclosing permanent fault.

Description

technical field [0001] The invention relates to a reclosing method of a power transmission line, in particular to a relay protection method for double-circuit lines paralleled on the same pole and a novel reclosing protection method. Background technique [0002] With the development of the electricity market and the construction of the power grid, the ability of the line to transmit electricity is required to be fully utilized; compared with two single-circuit lines, the double-circuit line paralleled on the same pole has lower project cost, smaller outlet corridor width, shorter construction period, and obvious economic benefits. Therefore, in the case of high land acquisition costs and tight exit corridors, double-circuit lines on the same pole are often used. [0003] Overseas ultra-high voltage transmission lines have successful operation experience in this respect. For example, in the power grids of Japan and European countries, most of the high-voltage and ultra-high ...

AI Technical Summary

Problems solved by technology

Impedance and other phase selection methods, although most of them can correctly select the phase, but when a double-circuit line on the same pole and a double-circuit line with a different name phase cross-line fault occurs near the two terminals of the line, the phase selection element far away from the fault side will be misjudged as a phase-to-phase fault , so that the double circuit is misjudged as a multi-phase fault, causing all the double circuit to trip, which seriously threatens the safe and stable operation of the system

[0008] 2. Zero-sequence mutual inductance problem

[0009] The zero-sequence mutual inductance coefficient of double-circuit lines paralleled on the same pole is relatively large, so that the residual voltage of the busbar is not only determined by the current of the main line when the ground fault occurs, but also affected by the zero-sequence current of the adjacent line, which affects the action range of the grounding distance protection on both sides; At the same time, when the faulty line is close to the fault point and the switch trips first, due to the influence of zero-sequence mutual inductance, the zero-sequence current protection range of the adjacent line of the faulty line will also change, which may cause protection malfunction or refusal to operate

[0010] 3. Reclosing problem

Although the probability of cross-line failure is small, it cannot be ruled out

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