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A single-phase grounding protection method for distribution network based on transient power direction

A single-phase grounding, transient power technology, used in emergency protection circuit devices, emergency protection circuit devices, electrical components, etc. for limiting overcurrent/overvoltage Grounding protection principle The zero sequence current is small, and the current flow direction is difficult to distinguish, etc., to achieve the effect of high reliability

Active Publication Date: 2016-04-20
KUNMING UNIV OF SCI & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The present invention provides a single-phase grounding protection method of distribution network based on transient power direction, which is used to solve the problem of the existing single-phase grounding protection principle due to the small zero-sequence current, the difficulty of distinguishing the current flow direction, the influence of the compensation process and the The zero-sequence current of the fault line is greater than the sum of the zero-sequence currents of other lines, which causes the protection device to malfunction or refuse to operate, so as to improve the reliability of the protection device

Method used

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  • A single-phase grounding protection method for distribution network based on transient power direction
  • A single-phase grounding protection method for distribution network based on transient power direction
  • A single-phase grounding protection method for distribution network based on transient power direction

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Embodiment 1

[0035] Embodiment 1: as figure 2 Shown is a 35kV distribution network composed of 6 feeder lines whose neutral point is grounded through an arc suppression coil. G in this network is an infinite power supply; T is the main transformer with a transformation ratio of 110kV / 35kV and a connection group of YN / d11; the distribution voltage side of the main transformer in my country's distribution network is generally a delta connection, and there is no neutral point in the system. When the system adopts the resonance grounding method, it is necessary to obtain a neutral point that can be grounded by the arc suppression coil. Adding a grounding transformer is the best solution. The best way, here T Z It is a zigzag transformer specially used for grounding of the compensation grid; L is the arc suppression coil, and R is the damping resistance of the arc suppression coil. The line adopts three types of lines: overhead line, overhead line-cable hybrid line and cable line. The numbers ...

Embodiment 2

[0040] Embodiment 2: as figure 2 In the distribution network system shown in which the neutral point is grounded through the arc suppression coil, the system parameters are the same as those in Embodiment 1. Now assume the feeder L 2 A single-phase ground fault occurs in phase A at a distance of 4km from the busbar. The initial phase angle of the fault is 90°, the fault transition resistance is 20Ω, and the sampling frequency is 10kHz. The waveform diagram of the zero-sequence voltage of the bus in the window at 5ms after the fault is as follows Figure 10 Shown; feeder L 1 , L 2 , L 3 … L 6 The zero-sequence current waveform is shown in Figure 11-16 shown. Intercept the zero-sequence voltage of the busbar and the zero-sequence current value of each feeder in the 1ms time window after the fault, and calculate the transient zero-sequence power value of each feeder according to formula (1):

[0041] S ( j )=[2.00×10 5 -1.40×10 8 1.27×10 6 2.22×10 5 1.03×10 ...

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Abstract

The invention relates to a transient-power-direction-based single-phase grounding protection method for a power distribution network, belonging to the technical field of power system relay protection. For the power distribution network with a neutral point which is grounded through an arc suppression coil, the method comprises the following steps: when one feeder line has a single-phase ground fault, firstly, calculating a product integral of a zero sequence voltage of a bus and zero sequence currents of feeder lines in a short time window after the fault to obtain transient zero-order power values of the feeder lines, and then, comparing the transient zero-order power values of the feeder lines with a zero value; and when the transient zero-order power value of some feeder line is less than the zero value, judging that the line has a forward fault, wherein a protective element acts, or when the transient zero-order power value of some feeder line is greater than the zero value, judging that the line has a reverse fault, wherein the protective element does not act. The method provided by the invention is low in cost, the difficulty of using the method is reduced, and the reliability of protection is increased.

Description

technical field [0001] The invention relates to a single-phase grounding protection method of a distribution network based on a transient power direction, and belongs to the technical field of electric power system relay protection. Background technique [0002] my country's urban and rural distribution networks belong to the small current grounding system, that is, the neutral point is not grounded or the neutral point is grounded through the arc suppression coil. A fault in the small current grounding system will affect the voltage of the non-fault phase ground and cause it to rise, and the voltage rise will damage the insulation of the grid equipment; especially the intermittent arc grounding will cause arc overvoltage, which will destroy the system insulation and then It develops into phase-to-phase or multi-point grounding short circuit, causing system overvoltage, thereby damaging equipment and destroying the safe operation of the system. Therefore, it is necessary to ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H9/08
Inventor 束洪春高利段瑞敏朱梦梦黄文珍
Owner KUNMING UNIV OF SCI & TECH
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