A single-phase grounding protection method for distribution network based on zero-sequence current multi-order differential transformation direction

A technology of zero-sequence current and single-phase grounding, which is applied to emergency protection circuit devices, emergency protection circuit devices, and electrical components used to limit overcurrent/overvoltage, and can solve problems such as low reliability and improve reliability , the effect of high protection reliability

Active Publication Date: 2016-03-30
KUNMING UNIV OF SCI & TECH
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Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the problem that the existing single-phase grounding protection method depends on the relevant information of other feeders to judge the problem of low reliability, and provides a single-phase distribution network based on zero-sequence current multi-order differential transformation direction Phase-to-ground protection method

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  • A single-phase grounding protection method for distribution network based on zero-sequence current multi-order differential transformation direction
  • A single-phase grounding protection method for distribution network based on zero-sequence current multi-order differential transformation direction
  • A single-phase grounding protection method for distribution network based on zero-sequence current multi-order differential transformation direction

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Embodiment 1

[0037] Embodiment 1: as figure 1 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 connected in a triangle, and there is no neutral point in the system. When the system adopts the resonant 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 numb...

Embodiment 2

[0041] Embodiment 2: as figure 1 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 3 A single-phase ground fault occurs in phase A 10km away from the busbar, the initial phase angle of the fault is 90°, the fault transition resistance is 20Ω, and the sampling frequency is 1MHz. The waveform of the zero-sequence voltage of the bus in the window at 0.1ms after the fault is as follows: Figure 6 Shown; the waveform of the zero-sequence current of each feeder is as follows Figure 7 shown; according to formulas (1) to (3), the bus zero-sequence voltage SOD transformation result and the feeder L 3 The waveform of the product of zero-sequence current SOD transformation results is as follows Figure 8 Shown; bus zero-sequence voltage SOD transformation results and feeder L 1 , L 2 , L 4 , L 5 , L 6 The waveform of the pr...

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Abstract

The invention relates to a distribution network single-phase ground protection method based on zero-sequence current sequential overlapping derivative transformation direction, belonging to the technical field of power system relay protection. For a resonant earthed system, when single-phase earth fault occurs on one feed line, firstly, a bus zero-sequence voltage in a short time window and zero-sequence currents of feed lines after the fault are intercepted and subjected to sequential overlapping derivative transformation respectively; then, a bus zero-sequence voltage sequential overlapping derivative transformation result is multiplied by zero-sequence current sequential overlapping derivative transformation results respectively to obtain a series of wave fronts on a time axis; finally, the amplitude of the first wave front in the series of wave fronts is used as a basis for protective start; when the amplitude of the first wave front is less than zero to determine positive-direction fault occurs on the feed line, a protective element acts; when the amplitude of the first wave front is larger than zero to determine reverse-direction fault occurs on the feed line, and the protective element does not act. The distribution network single-phase ground protection method is low in using difficulty and high in protection reliability.

Description

technical field [0001] The invention relates to a single-phase grounding protection method for a distribution network based on zero-sequence current multi-order differential transformation direction, and belongs to the technical field of electric power system relay protection. Background technique [0002] The distribution network directly faces users and provides them with electricity services, so it has the widest coverage. There are various types of faults in the distribution network, but according to statistics, single-phase ground faults account for about 80% of distribution network faults. The resonant grounding system of the distribution network is the neutral point through the arc suppression coil grounding system, which belongs to the small current grounding system. Most of the distribution network in my country adopts this operation mode. The single-phase grounding fault of the small current grounding system will affect the non-fault phase ground voltage and cause...

Claims

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Application Information

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