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Identification method of single-phase ground fault and phantom ground fault based on full-cycle energy ratio

A single-phase ground fault and phantom grounding technology, which is applied in the direction of measuring electricity, measuring devices, and measuring electrical variables, can solve the problems of unfavorable detection of single-phase ground faults, long time windows, etc., and achieve good timeliness and hardware sampling rate. The effect of low requirements and simple principle

Active Publication Date: 2016-02-24
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing methods for identifying single-phase ground faults and phantom ground faults that require a long time window and are not conducive to timely discovery of single-phase ground faults

Method used

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  • Identification method of single-phase ground fault and phantom ground fault based on full-cycle energy ratio
  • Identification method of single-phase ground fault and phantom ground fault based on full-cycle energy ratio
  • Identification method of single-phase ground fault and phantom ground fault based on full-cycle energy ratio

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Embodiment 1: as figure 1 Shown: 110kV / 35kV distribution network single-phase ground fault simulation model, the power supply voltage in the figure is 110kV, which is changed to 35kV by the transformer and then sent to the load end. It has 6 feeders, and the neutral point of the Z-shaped transformer passes through the arc suppression Coil series resistor to ground. overhead feeder L 1 =15km, L 3 =18km, L 5 =30km, wire-cable hybrid feeder L 4 =17km, the overhead feeder is 12km, the cable is 5km, and the cable feeder L 2 =6km, L 6=8km. Among them, the overhead feeder is JS1 rod type, LGJ-70 type conductor, the span is 80m, and the cable feeder is YJV23-35 / 95 type cable. G in the power grid is an infinite power source; T is the main transformer, the transformation ratio is 110kV / 35kV, and the connection group is Y N / d11;T Z Is a zigzag transformer; L is the arc suppression coil; R is the damping resistance of the arc suppression coil. The feeder adopts th...

Embodiment 2

[0042] Embodiment 2: The single-phase ground fault simulation model of the 110kV / 35kV distribution network is the same as that of Embodiment 1, and the distance from the feeder L 1 A single-phase ground fault occurs at 5km from the beginning, the ground resistance is 20Ω, the fault angle is 90°, and the sampling frequency is 10kHz.

[0043] According to the same method as in Example 1, the feeder L 1 The zero-sequence voltage waveform is as image 3 Shown, and obtain the highest frequency energy value ratio of the first cycle and the second cycle =13198> ρ set =1.5, so it can be judged that the feeder L 1 It is a single-phase ground fault feeder.

Embodiment 3

[0044] Embodiment 3: The simulation model of the 110kV / 35kV distribution network system is the same as in Embodiment 1. After the voltage value exceeds the limit, two cycles of zero-sequence voltage data are obtained.

[0045] The steps of the single-phase ground fault and phantom ground fault identification method based on the full-cycle energy ratio are the same as those in Embodiment 1.

[0046] The zero-sequence voltage waveform obtained by the simulation experiment is as follows: Figure 4 Shown, and obtain the highest frequency energy value ratio of the first cycle and the second cycle =1.2943 =1.5, so it can be judged that the phantom grounding phenomenon has occurred in the system.

[0047] In addition, the highest frequency energy ratio of the first cycle and the second cycle after the fault under different fault angles and phantom grounding conditions is shown in Table 1. The ratio is much greater than 1 in the case of a single-phase ground fault, and close to 1 i...

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Abstract

The invention relates to a method for identifying a single-phase earth fault and visional grounding based on a whole cyclic wave energy ratio and belongs to the technical field of electric power system relay protection. Zero sequence voltage data of two cyclic waves are extracted after the fault, wavelet transformation is respectively conducted on the zero sequence voltage data, and summation is conducted on the square number of each wavelet reconstruction coefficient in each dimension after transformation, so that the highest frequency energy value is obtained. The highest frequency energy value of a first cyclic wave is compared with the highest frequency energy value of a second cyclic wave, so that identification of the single-phase earth fault and visional grounding of a power distribution network is reliably achieved according to the value relationship of the highest frequency energy values and a set threshold value. The method for identifying the single-phase earth fault and visional grounding based on the whole cyclic wave energy ratio has the advantages of being simple in principle, capable of identifying visional grounding in short time, good in robustness, free of influence by an arc fault, non-linear load and the like, capable of greatly reducing the requirements for a hardware sampling rate and high in practicality.

Description

technical field [0001] The invention relates to a single-phase ground fault and phantom ground fault identification method based on full-cycle energy ratio, and belongs to the technical field of electric power system relay protection. Background technique [0002] Under normal operation, the neutral point is usually in an overcompensated state through the arc suppression coil grounding distribution network. When the number of feeders put into operation in the busbar increases or the system operation mode changes and other factors cause the capacitive current to increase, the automatic tuning device will automatically track The change of the capacitor current adjusts the input value of the arc suppression coil. At this time, the system may enter the full compensation state, thereby generating a resonant overvoltage. The resonant overvoltage may be close to or even exceed the neutral point displacement voltage of the single-phase ground fault. The phenomenon is called phantom ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/02
Inventor 束洪春龚石磊冯海欧董俊
Owner KUNMING UNIV OF SCI & TECH