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Intermittent single-phase earth fault protection method and device

A single-phase ground fault and ground fault technology, which is applied to emergency protection circuit devices, fault locations, and parts of emergency protection devices, can solve problems such as fault expansion, multi-pulse width duration, and faults that cannot be quickly removed. Achieve the effect of solving the expansion of the accident

Active Publication Date: 2019-12-20
NANJING GUODIAN NANZI POWER GRID AUTOMATION CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The existing technology does solve the problems caused by some intermittent ground faults, but due to the use of a fixed stretching time, the time for the entire protection action must be relatively long. For intermittent ground faults in a short period of time, there are more pulses or the pulse width duration Longer faults may expand into phase-indirect faults because the fault cannot be removed quickly, resulting in the expansion of the fault

Method used

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  • Intermittent single-phase earth fault protection method and device
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  • Intermittent single-phase earth fault protection method and device

Examples

Experimental program
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Effect test

Embodiment 1

[0056] This embodiment is an intermittent single-phase ground fault protection method, including:

[0057] Real-time acquisition of line zero-sequence current data;

[0058] In response to the zero-sequence current of the line being greater than the intermittent overcurrent protection setting value, the intermittent overcurrent protection is started and executed within the intermittent overcurrent protection action time setting value:

[0059] a. Calculate the time accumulation criterion for intermittent ground faults;

[0060] b. Calculate the number of statistical criteria for intermittent ground faults;

[0061] c. Calculate the time interval between adjacent intermittent ground fault pulses, and in response to the time interval being greater than the set time interval threshold, end the calculation of the time accumulation criterion and the calculation of the number of statistical criteria, and perform intermittent overcurrent Protection start returns;

[0062] In respo...

Embodiment 1-1

[0067] Based on Example 1, combined with figure 1 As shown, this embodiment specifically includes the following steps in performing intermittent single-phase-to-ground fault discrimination and realizing intermittent single-phase-to-ground fault protection:

[0068] Step S1: Collect and calculate the zero-sequence current of the line in real time. When the zero-sequence current is greater than the intermittent overcurrent protection setting value I set When the corresponding zero-sequence current pulse is regarded as an intermittent ground fault pulse, the protection is started and transferred to step S2; wherein in the process of real-time acquisition and monitoring of the line zero-sequence current, the calculation of the line zero-sequence current is a prior art .

[0069] Step S2: At the preset intermittent overcurrent protection action time setting value t set In the zero-sequence current pulse, calculate the time accumulation criterion and the counting criterion respect...

Embodiment 2

[0089] This embodiment is an intermittent single-phase ground fault protection device, including:

[0090] Zero-sequence current real-time acquisition module, used for real-time acquisition of line zero-sequence current data;

[0091] The fault discrimination module within the fixed value of the protection action time is used to start the intermittent over-current protection in response to the zero-sequence current of the line being greater than the set value of the intermittent over-current protection, and execute within the set value of the intermittent over-current protection action time:

[0092] a. Calculate the time accumulation criterion for intermittent ground faults;

[0093] b. Calculate the number of statistical criteria for intermittent ground faults;

[0094] c. Calculate the time interval between adjacent intermittent ground fault pulses, and in response to the time interval being greater than the set time interval threshold, end the calculation of the time accu...

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Abstract

The invention discloses an intermittent single-phase earth fault protection method and device, and the method and device are suitable for the detection and protection of an intermittent single-phase earth fault of a power distribution network line. The method comprises the steps: obtaining the zero-sequence current of a line in real time, and starting the protection when the zero-sequence currentis greater than an intermittent overcurrent protection action fixed value; after the protection is started, respectively calculating a time accumulation criterion and a frequency statistics criterionfor the zero-sequence current pulse within the delay time of the protection action, and judging the protection starting return; when the starting return condition is not met and the delay time is up,carrying out the fault current detection if any criterion is met; if the fault current is detected within a certain period of time, judging that a single-phase earth fault occurs in the line, and outputting an alarm signal or a tripping action. By adopting the method, the intermittent single-phase grounding fault of the power distribution network line can be accurately identified and removed, andthe defect of accident expansion caused by the fact that the intermittent grounding fault cannot be removed in time in the conventional zero-sequence overcurrent protection can be effectively solved.

Description

technical field [0001] The invention relates to the technical field of relay protection for power system distribution networks, in particular to an intermittent single-phase ground fault protection method and device. Background technique [0002] At present, the grounding method of the neutral point of the medium and low voltage distribution network through a small resistance has been widely used in some areas. However, in the actual application process, there have also been accidents where intermittent single-phase ground faults caused the neutral point grounding resistor to burn out. The main reason is that when an intermittent single-phase ground fault occurs on the line, the fault is instantaneous and the ground current is usually not large. The traditional relay protection device does not operate for the zero-sequence overcurrent protection configured for outgoing lines, and the fault cannot be removed in time. This in turn leads to the development and expansion of fau...

Claims

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Application Information

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IPC IPC(8): H02H7/26H02H1/00G01R31/08G01R31/02
CPCG01R31/086H02H1/0007H02H7/26
Inventor 齐以年胡兵李玉平康丰张玮王闰羿陈栋
Owner NANJING GUODIAN NANZI POWER GRID AUTOMATION CO LTD