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Single-phase grounding fault determining, protecting method and system of neutral-point uneffective earthed electric grid

A single-phase ground fault and non-effective grounding technology, which is applied to emergency protection circuit devices, fault locations, and emergency protection circuit devices for limiting overcurrent/overvoltage, and can solve misjudgments or missed judgments of high-resistance ground faults , unable to provide effective protection, misunderstanding of single-phase ground fault judgment, etc.

Active Publication Date: 2009-01-07
孙嘉宁 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Aiming at the existing misunderstanding of single-phase ground fault discrimination, which may easily cause misjudgment or missed judgment of high-resistance ground faults and fail to provide effective protection, a kind of neutral point non-effectively grounded power grid is invented to detect single-phase ground faults. Discrimination and protection method and system

Method used

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  • Single-phase grounding fault determining, protecting method and system of neutral-point uneffective earthed electric grid
  • Single-phase grounding fault determining, protecting method and system of neutral-point uneffective earthed electric grid
  • Single-phase grounding fault determining, protecting method and system of neutral-point uneffective earthed electric grid

Examples

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example 1

[0038] When single-phase grounding occurs in a 6kV neutral point non-effectively grounded grid system, the measured zero-sequence voltage is 2kV, while the normal phase voltage of the system is 3.6kV. It can be seen from the discrimination method described in claim 1 that the single-phase The ground fault satisfies the condition of characteristic area 1, therefore, it can be judged that the lowest phase of the three-phase voltage is the fault phase at this time, and immediately put into ground protection on the busbar of this phase (the ground protection can be grounded through the reactor L, or other methods grounding), if the fault current is less than 20A, the reactor Ln will not be used, and only the switch-on reactor L will complete the protection; if it is greater than 20A, the reactor Ln will be adjusted to an appropriate position according to the current value measured by CT2 to drive the high voltage The switch Ko is closed, and the neutral point of the power supply is...

example 2

[0040] When single-phase grounding occurs in a 6kV neutral point non-effectively grounded power grid system, the measured zero-sequence voltage is 1.8kV, while the normal phase voltage of the system is 3.6kV. It can be seen from the discrimination method described in claim 1 that the single The phase-to-ground fault satisfies the condition of characteristic area 2. Therefore, it can be judged that the phase voltage lagging behind the zero-sequence voltage by 90° at this time is the fault phase, and the grounding protection is immediately put into use on the busbar of this phase (the grounding protection can be grounded through the reactor L, or other means of grounding), if the fault current is less than 20A, the reactor Ln will not be put into use, and only the switching-off reactor L will complete the protection; if it is greater than 20A, the reactor Ln will be adjusted to an appropriate position according to the current value measured by CT2 , drive the high-voltage switch ...

example 3

[0042] When single-phase grounding occurs in a 6kV neutral point non-effectively grounded grid system, the measured zero-sequence voltage is 1.2kV, while the normal phase voltage of the system is 3.6kV. It can be seen from the discrimination method described in claim 1 that the single The phase-to-ground fault satisfies the condition of characteristic area 3, therefore, it can be judged that the second lowest phase of the three-phase voltage is the fault phase at this time, and immediately put into ground protection on the busbar of this phase (the ground protection can be grounded through the reactor L, or grounding in other ways), if the fault current is less than 20A, the reactor Ln will not be put into use, and only the switch-on reactor L will complete the protection; if it is greater than 20A, the reactor Ln will be adjusted to an appropriate position according to the current value measured by CT2, Drive the high-voltage switch Ko to close, ground the neutral point of the...

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Abstract

The invention discloses a distinguishing, protective method and a protective system of single-phase grounding faults of a neutral point non-effectively grounded power network in view of the judgment wrong regions of the single-phase grounding faults of a neutral point non-effectively grounded system; wherein, the distinguishing method of the single-phase grounding faults distinguishes the fault phase according to the relationship between the zero sequence voltage and phase voltage as well as the relationship between the phase voltages to provide bases for right throwing and withdrawing of grounding protection, and the distinguishing method can particularly distinguish the weak signals of unobservable high resistance grounding faults to eliminate the faults in the bud; a grounding comprehensive protection method and a grounding comprehensive protection system combine a voltage limiting and bypass protection method of fault phase voltage and a current compensation protection method of inductance-current compensation grounding capacitor and current so as to achieve the ideal effects of reliably eliminating the faults such as arc grounding without being influenced by ground current as well as reducing the grounding fault current without accurately tracing and adjusting the compensation current values. The method and the system of the invention have the advantages of strong practicality, simple measurement and control and reliable protection.

Description

technical field [0001] The invention relates to a comprehensive protection method and comprehensive protection system for comprehensive discrimination and elimination of single-phase grounding faults in neutral point non-effectively grounded power grids, in particular to a single-phase grounding protection system for neutral point non-effectively grounded power grids. Fault discrimination, protection method and system. Background technique [0002] In the power system, single-phase grounding is the main fault form in the operation of the power grid, accounting for more than 60% of the total faults in the entire power grid, and a considerable part of interphase short-circuit faults are developed from single-phase grounding faults. The safety and reliability of the power system, when other conditions are the same, only depends on the working mode of the neutral point of the power system. To study the grounding mode of the neutral point of the power system, it is mainly to cor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H9/08G01R31/02G01R31/08
Inventor 孙嘉宁
Owner 孙嘉宁
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