A single-phase ground fault distance protection method for transmission lines

A single-phase ground fault, transmission line technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as power outage accidents, faults that cannot be isolated from the power grid in time, and large power flow transfers in the power grid

Active Publication Date: 2015-08-26
STATE GRID CORP OF CHINA +3
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The additional fault impedance caused by the transition resistance is likely to cause the traditional grounding distance protection to refuse or malfunction
The refusal of the traditional grounding distance protection will make the fault unable to be isolated from the power grid in time, which is not good for the safe and stable operation of the power grid; the wrong operation of the traditional grounding distance protection will lead to the expansion of the fault range, and even lead to a large shift of the power grid power flow, which will lead to large-scale power outages in the power grid

Method used

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  • A single-phase ground fault distance protection method for transmission lines
  • A single-phase ground fault distance protection method for transmission lines
  • A single-phase ground fault distance protection method for transmission lines

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Embodiment Construction

[0014] The technical solution of the present invention will be further described in detail according to the accompanying drawings.

[0015] figure 1 It is a schematic diagram of the line transmission system applying the present invention. figure 1 Among them, PT is a voltage transformer, and CT is a current transformer. The protection device samples the voltage waveform of the voltage transformer PT and the current waveform of the current transformer CT at the installation place of the transmission line protection to obtain the instantaneous value of the voltage and current, and calculates the instantaneous value of the voltage and current obtained by sampling using the Fourier algorithm Fault phase voltage at transmission line protection installation , fault phase negative sequence voltage , fault phase current and zero sequence current , as the input quantity; among them, φ=A phase, B phase, C phase.

[0016] The protection device uses the transmission line to prot...

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Abstract

The invention discloses a single-phase earth fault distance protection method of a power transmission line, which comprises the steps that additional fault impedance due to transition resistance is calculated by using fault phase electrical quantity; line fault impedance between a protection mounting part of the power transmission line and a single-phase earth fault point is obtained by a ratio of fault phase voltage to zero sequence compensation current minus the additional fault impedance; whether an amplitude of the line fault impedance between the protection mounting part of the power transmission line and the single-phase earth fault point is less than that of line fault impedance between the protection mounting part of the power transmission line and a protection setting range is judged; and if so, a protection device sends an action trip signal. With the adoption of the method, an effect of the additional fault impedance due to the transition resistance on the protection action performance is avoided, and the method can act correctly and reliably and cannot reject to act or act incorrectly when the power transmission line has a single-phase high-impedance earth fault.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a distance protection method for a single-phase grounding fault of a power transmission line. Background technique [0002] The calculation formula of measuring line fault impedance z for traditional grounding distance protection is ,because ,therefore , that is, the line fault impedance z measured by the traditional grounding distance protection is composed of two parts, one part is the line fault impedance xz reflecting the real fault distance 1 , the other part is the additional fault impedance caused by the transition resistance . In the above formula, is the fault phase voltage; is the fault point voltage; is the fault phase current; is the zero-sequence current; φ is the fault phase: A phase, B phase, C phase; z 1 is the positive sequence impedance of the transmission line per unit length; z 0 is the zero-sequence impedance...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
Inventor 林富洪曾惠敏
Owner STATE GRID CORP OF CHINA
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