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Distribution network single-phase grounding protection method based on active and passive combined detection of weak fault

A joint detection, single-phase grounding technology, applied in fault location, emergency protection circuit device, fault detection according to conductor type, etc., can solve problems such as difficulty in passive detection of weak faults, avoid multiple trips, and reduce power supply reliability. , good real-time effect

Active Publication Date: 2020-02-11
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 provide a distribution network unit based on active and passive joint detection of weak faults for the difficult passive detection of weak faults such as high-resistance faults based on steady-state information or remote faults at the end of multi-branch feeder lines in distribution networks. Phase-to-ground protection method

Method used

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  • Distribution network single-phase grounding protection method based on active and passive combined detection of weak fault
  • Distribution network single-phase grounding protection method based on active and passive combined detection of weak fault
  • Distribution network single-phase grounding protection method based on active and passive combined detection of weak fault

Examples

Experimental program
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Effect test

Embodiment 1

[0084] Example 1: Such as figure 1 As shown, a 110kV / 35kV cable hybrid power distribution network single-phase ground fault simulation model is constructed, which contains 3 pure overhead lines, 2 pure cable lines and 1 cable hybrid line. Where L 1 -L 6 The lengths are: 15km, 6km, 18km, 20km, 30km, 8km. Where feeder L 4 The lengths of branch 1, branch 2, branch 3, and branch 4 are 3km, 4km, 3km, and 4km, respectively. The main transformer is an on-load tapping transformer with a tapping range of 110±8×1.25% kV, and a total of 17 gear positions, among which the ninth gear positions are: 9a, 9b, and 9c. The neutral point of the Z-shaped transformer is grounded through the series resistance of the arc suppression coil, the arc suppression coil is over-compensated, the compensation degree is 7%, and the sampling rate of the relay protection is 10kHz.

[0085] Assuming that the single-phase ground fault is located on the feeder L 4 On branch line 4, the initial fault angle is 30°, t...

Embodiment 2

[0090] Example 2: Assume that the single-phase ground fault is located on the feeder L 4 On the main line, the initial fault angle is 90°, the fault transition resistance is 20Ω, and the fault distance is 18km from the bus. The specific steps of the single-phase grounding protection method for distribution network based on weak fault active and passive combined detection and transient SOD transformation in this example are as follows:

[0091] According to step (1), collect transient zero-sequence voltage and current components, calculate zero-sequence voltage wavelet transform low-frequency sudden change energy, sudden change energy such as Figure 8 As shown, when the zero-sequence voltage wavelet transform low-frequency sudden change energy is greater than the set threshold, it is determined that a single-phase ground fault occurs.

[0092] After determining that the system has a single-phase grounding fault, select the zero sequence current of each feeder 1ms before the fault an...

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Abstract

The invention relates to a distribution network single-phase grounding protection method based on active and passive combined detection of a weak fault, which belongs to the technical field of power system relay protection. When a distribution network operates abnormally, sudden energy under the bus zero sequence voltage wavelet transform low frequency band is used to determine whether a system has a single-phase ground fault and initiate protection; if a fault occurs, the zero-sequence voltage and zero-sequence current of a bus are sampled when a neutral point is not regulated; 6-layer wavelet decomposition is performed, and a characteristic frequency band is determined by using energy and the maximum principle; and wavelet coefficients under the characteristic frequency band are subjected to cross-overlap differential transformation to construct a passive fault detection criterion. According to whether the first non-zero value of the passive detection discriminant exceeds a threshold, whether a feeder has a single-phase ground fault is judged. According to the invention, according to whether the zero-sequence voltage can be continuously detected multiple times within a fixed time-lag, the nature of the fault can be preliminarily judged; and reduced power supply reliability caused by multiple trips is avoided.

Description

Technical field [0001] The invention relates to a distribution network single-phase grounding protection method based on active and passive combined detection of weak faults, and belongs to the technical field of power system relay protection. Background technique [0002] The resonant grounding power distribution system has high operational reliability, but after permanent single-phase grounding occurs, it is easy to cause non-fault phase voltage increase, insulation damage, and expansion of the fault range. Therefore, the fault detection and protection technology for the resonant grounded distribution network is essential to ensure the safe and reliable operation of the distribution network. The current distribution line detection methods mainly include line selection, positioning, and relay protection. After repeated studies by many scholars, the accuracy of line selection can reach 50% to 70%, but such a positive selection rate is still not up to on-site users. Requirements....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/08G01R31/52
CPCH02H7/26G01R31/086Y04S10/52
Inventor 束洪春高钰莹安娜代月梁雨婷
Owner KUNMING UNIV OF SCI & TECH
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