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Ground fault protection method of distribution network

A ground fault and distribution network technology, applied in the field of distribution network, can solve the problems of low accuracy and reliability of ground fault protection methods

Active Publication Date: 2011-06-15
CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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Problems solved by technology

[0006] In order to solve the problem of low accuracy and reliability of the distribution network ground fault protection method, the present invention proposes a distribution network ground fault protection method, which can comprehensively utilize various fault characteristic quantities, does not need to set protection judgment setting values ​​and does not Affected by the transition resistance and system operation mode, the adaptability and reliability of the protection method can be effectively improved

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  • Ground fault protection method of distribution network

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Embodiment Construction

[0036] figure 1 It is a schematic diagram of the ground fault experiment of the present invention, with L on the busbar 1 , L 2 , L 3 , L 4 Four feeders, L 1 is an overhead line, L 2 Concentrate equivalent lines for multiple feeder lines, L 3 is the cable line, L 4 For overhead lines, in the feeder L 4 Install protection device 1 at the exit.

[0037] figure 2 is a flowchart of the present invention. see figure 2 , first calculate the effective value of the zero-sequence voltage, when the zero-sequence voltage is greater than the set value, it is judged that a ground fault has occurred in the distribution network, and the moment of zero-sequence voltage mutation is the time when the fault occurs; then record the sample data to be tested z g ,calculate and when , judge z g normal, will z g into the non-fault historical sample set, and update the non-fault historical sample center; when , judge z g fault, tripping to isolate the faulty line, will z g Cla...

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Abstract

The invention discloses a ground fault protection method of a distribution network, which comprises the following steps: continuously measuring the zero sequence voltage value of an outlet of a distribution line, and when the zero sequence voltage value exceeds a limit, recording s fault characteristic quantities defined as a sample to be measured; and computing the distance between the sample tobe measured and a fault history sample center as well as the distance between the sample to be measured and a non-fault history sample center, and judging whether the distribution line has a fault ornot according to the distance. In the method disclosed by the invention, the spatial relative distance is used as a protection criterion, and a self-learning mode is used for updating the sample centers, thus the protection method has stronger adaptability and higher reliability and can not be influenced by the change of system operation modes. The invention thoroughly solves the problems of difficult judgment and setting and lower reliability of the ground fault protection of the distribution network.

Description

technical field [0001] The invention relates to a ground fault protection method, which is especially suitable for distribution networks with large changes in operation modes. Background technique [0002] my country's distribution network generally adopts the neutral point non-effective grounding method. When a single-phase ground fault occurs on the feeder, the distribution network operating in this mode has a small fault residual current, and is affected by interference and other factors, and the ground fault protection accuracy and reliability are poor. , The line selection accuracy rate of the on-site line selection device is generally low. [0003] At present, the existing domestic distribution network ground fault protection methods mainly include the injection signal method, the steady state method and the transient state method. The main difficulties of the injection signal method are: ① Additional high-voltage coupling equipment is required, which requires a large ...

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Application Information

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IPC IPC(8): H02H7/28
Inventor 曾祥君王媛媛李泽文赵劲峰
Owner CHANGSHA UNIVERSITY OF SCIENCE AND TECHNOLOGY
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