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Travelling wave differential protection method of mixed line braked by using sum of phase current

A hybrid circuit and differential protection technology, applied in the direction of emergency protection circuit devices, electrical components, etc., to achieve the effect of high sensitivity

Inactive Publication Date: 2013-10-02
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] In order to solve the problems existing in the application of traditional phase-separated current differential protection and traveling wave differential protection to hybrid lines, the present invention provides a hybrid line traveling wave differential protection method using the sum of phase currents to brake

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  • Travelling wave differential protection method of mixed line braked by using sum of phase current
  • Travelling wave differential protection method of mixed line braked by using sum of phase current
  • Travelling wave differential protection method of mixed line braked by using sum of phase current

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Embodiment Construction

[0015] The technical solution of the present invention will be further described below through a specific embodiment.

[0016] A method of traveling wave differential protection for a hybrid line utilizing the sum of phase currents to brake in the present invention comprises the following steps:

[0017] Relay protection devices are installed on both sides of the overhead line-power cable hybrid line, and for the protection devices on each side, the three-phase voltage value of the side is obtained by sampling and current value Obtain the three-phase voltage value of the opposite side through communication and current value where m and n represent the current side and contralateral side, respectively, Indicates the three phases of the line;

[0018] Using phase-to-mode transformation, the phase voltages on both sides and current Transformed into a voltage u in the modulo domain m.x (t), u n.x (t) and current i m.x (t), i n.x (t), where x=α, β, and 0 repres...

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Abstract

The invention discloses a travelling wave differential protection method of a mixed line braked by using the sum of phase current. The method comprises the steps of calculating positive refraction current travelling waves at a circuit node according to voltage and current at both sides of an overhead line-power cable mixed line, using the calculated current difference of the two sides as differential current of relay protection, and determining a trouble inside the sample space if the ratio between the fundamental current amplitude of any phase of the differential current and the fundamental current amplitude of the sum of the current at both sides of the phase is greater than a setting value occurs at any side. The travelling wave differential protection method disclosed by the invention is not influenced by distributed capacitive current, thereby being applicable to the overhead-power cable mixed line; and the sensitivity is high when an internal fault occurs through being braked by the sum of the phase current, and unbalance current can be effectively avoided when an external fault occurs.

Description

technical field [0001] The invention relates to a line protection method. Background technique [0002] In recent years, with the continuous acceleration of urbanization, the requirements for the cable rate of power lines have been increasing. It has become a trend to change overhead power lines to cables, but for a large number of overhead power lines that have been constructed in the early stage, it is required to gradually carry out cable transformation according to the plan. Therefore, hybrid lines of power cables and overhead lines are increasingly appearing in power supply networks. middle. [0003] For long-distance high-voltage and ultra-high-voltage mixed lines, the distributed capacitance current is relatively large, which seriously affects the reliability of traditional phase-separated current differential protection. Some experts proposed the principle of traveling wave differential, which solved the influence of distributed capacitance on differential protecti...

Claims

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Application Information

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IPC IPC(8): H02H7/26
Inventor 徐习东王全
Owner ZHEJIANG UNIV