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A distribution network single-phase ground protection method based on active and passive joint detection of weak faults

A technology of joint detection and single-phase grounding, which is applied in the direction of fault location, emergency protection circuit device, fault detection according to conductor type, etc., can solve the problems such as the difficulty of passive detection of weak faults, achieve good real-time performance, strengthen fault characteristics, and improve reliability effect

Active Publication Date: 2021-06-08
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • A distribution network single-phase ground protection method based on active and passive joint detection of weak faults
  • A distribution network single-phase ground protection method based on active and passive joint detection of weak faults
  • A distribution network single-phase ground protection method based on active and passive joint detection of weak faults

Examples

Experimental program
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Effect test

Embodiment 1

[0084] Embodiment 1: as figure 1 As shown, a single-phase ground fault simulation model of a 110kV / 35kV cable hybrid distribution network is constructed, including 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 the 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 tap-changing transformer with a tap range of 110±8×1.25%kV and a total of 17 gears, of which the ninth gear is: 9a, 9b, 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 overcompensated, the compensation degree is 7%, and the sampling rate of the relay protection is 10kHz.

[0085] Assume that the single-phase-to-earth fault is located on the feeder L 4 On branch line 4, the initial fault angle is 30°, the fault transition resistanc...

Embodiment 2

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

[0091] According to step (1), the transient zero-sequence voltage and current components are collected, and the zero-sequence voltage wavelet transform low-frequency band mutation energy is calculated. The mutation energy is as follows: Figure 8 As shown in , when the zero-sequence voltage wavelet transform low-frequency band mutation energy is greater than the set threshold, it is determined that a single-phase ground fault occurs.

[0092] After confirming that a single-phase ground fault occurs in the system, select the zero-sequence current of each f...

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Abstract

The invention relates to a distribution network single-phase grounding protection method based on active and passive joint detection of weak faults, and belongs to the technical field of electric power system relay protection. When the distribution network is running abnormally, use the bus zero-sequence voltage wavelet transform mutation energy in the low frequency band to judge whether the system has a single-phase ground fault, and start protection; if a fault occurs, the bus zero-sequence voltage when the neutral point is not regulated The zero-sequence current is sampled, decomposed by 6-layer wavelet, and the characteristic frequency band is determined by using the energy and maximum principle; the fault passive detection criterion is constructed after the wavelet coefficients under the characteristic frequency band are cross-overlapped and differentially transformed. According to whether the first non-zero value of the passive detection discriminant exceeds the threshold, it is judged whether a single-phase ground fault occurs in the feeder. The present invention utilizes whether the zero-sequence voltage can be continuously detected multiple times within a fixed time limit, can preliminarily judge the nature of the fault, and avoid repeated tripping to reduce power supply reliability.

Description

technical field [0001] The invention relates to a distribution network single-phase grounding protection method based on active and passive joint detection of weak faults, and belongs to the technical field of electric power system relay protection. Background technique [0002] The operation reliability of the resonant grounded power distribution system is high, but after the permanent single-phase grounding occurs, it is easy to cause the non-faulty phase voltage to rise, the insulation to be damaged, and the fault range to expand. Therefore, the fault detection and protection technology for resonant grounded distribution network is very important to ensure the safe and reliable operation of distribution network. The current distribution line detection methods mainly include line selection, positioning, relay protection and other methods. After repeated research by many scholars, the correct rate of line selection can reach 50% to 70%, but such a positive selection rate is...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26G01R31/08G01R31/52
CPCG01R31/086H02H7/26Y04S10/52
Inventor 束洪春高钰莹安娜代月梁雨婷
Owner KUNMING UNIV OF SCI & TECH
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