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A single-phase ground fault phase selection and transition resistance measurement method

A single-phase ground fault and transition resistance technology, which is applied in the electrical field, can solve the problems of not considering transition resistance, different phase selection methods, and no distinction, so as to achieve the effect of improving operation safety

Active Publication Date: 2017-08-25
HOHAI UNIV +1
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Problems solved by technology

The phase selection method described in this patent is a traditional phase selection method, which does not consider the influence of transition resistance and grid asymmetry on the phase selection accuracy, and the small current grounding system is divided into a neutral point ungrounded system and a resonant grounding system, the phase selection method different, the patent does not distinguish between

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  • A single-phase ground fault phase selection and transition resistance measurement method
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  • A single-phase ground fault phase selection and transition resistance measurement method

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Embodiment Construction

[0021] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0022] Such as figure 1 , 2 As shown, the implementation of the present invention can directly obtain the grid bus zero-sequence voltage signal from the secondary side of the PT. The following uses phase A of the grid as a reference phase to specifically introduce a measurement and phase selection method for a single-phase ground fault transition resistance. The steps are as follows:

[0023] Step ①: When the power grid is running normally, measure the neutral point voltage

[0024]

[0025] In the above formula: α=e 120° , where C A 、C B and C C is the total distributed capacitance of the three phases, G A , G B and G C is the total conductance of the three-phase distribution; ω is the angular frequency of the system; ...

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Abstract

The invention discloses a single-phase grounding fault phase selection and transition resistance measurement method, which predicts the size of the single-phase grounding fault current according to the neutral point voltage before and after the power grid fault, and realizes it by comparing the phases of the grounding current and the three-phase phase voltage of the power grid Fault phase selection, the transition resistance is calculated according to the amplitude of single-phase ground fault current and fault phase voltage. A single-phase ground fault phase selection and transition resistance measurement method proposed by the present invention can predict the single-phase ground fault current value, and realize fault phase selection by comparing the phase of the ground current and the voltage of each phase. Compared with the traditional phase selection based on phase voltage amplitude characteristics, the accuracy of phase selection is higher, and the transition resistance can be measured after the fault phase is determined. The method is not affected by grid asymmetry and load changes, and improves the operation safety of the grid.

Description

technical field [0001] The invention relates to a single-phase grounding fault phase selection and transition resistance measurement method, which belongs to the field of electricity. Background technique [0002] Small current grounding system, including neutral point ungrounded and neutral point grounded by arc suppressing coil, can continue to supply power even when a single-phase ground fault occurs. The distribution network in my country is dominated by small current grounding. Most of the power grid faults are single-phase ground faults, and are generally grounded through transition resistance. The transition resistance will weaken the fault characteristics of the power grid, prolong the fault transient process, and cause the protection to refuse to operate. However, it is relatively difficult to measure the transition resistance of a small current grounding system. [0003] At present, the traditional phase selection criterion of the small current grounding system is...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
Inventor 刘宝稳王春宁许洪华马宏忠施恂山张琳汪金荣杨兰英
Owner HOHAI UNIV
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