Small current grounding line selection method

Abstract

The invention discloses a small current grounding line selection method. When the first time of anticipation on a fault line is wrong, the second line selection is performed by a line incremental algorithm of line switching through the switching function of a switch cabinet and accordingly the accuracy of the fault line selection is improved, the repeated line switching is avoided, an additional primary device does not need to be added, the automation level of a power system is improved, and the safe and stable operation of a system is ensured.

Description

technical field [0001] The present invention relates to the technical field of small current grounding, more specifically, it relates to the occurrence of single-phase grounding in a power grid with a voltage level of 6kV to 66kV where the neutral point is not grounded, the neutral point is grounded through a resistor, and the neutral point is grounded through an arc suppressing coil. A method for discriminating the faulty line in the event of a fault. Background technique [0002] The small ground current power grid refers to the power system where the neutral point is not grounded or grounded through the arc suppression coil. This grounding method does not form a short circuit when a single-phase ground fault occurs, and the fault current is very small. The regulations stipulate that it can continue to run for 1 to 2 hours after a single-phase ground fault occurs. In our country, in the power grid with voltage level of 6kV ~ 66kV, the low current grounding method is gener...

AI Technical Summary

Problems solved by technology

Due to the particularity of the small current grounding system, such as the system whose neutral point is compensated by the arc suppression coil, when a single-phase ground fault occurs, the current of the fault line will vary due to the compensation degree of the arc suppression coil, and it will be affected by external interference. The influence of the signal leads to the misjudgment of the algorithm

The success rate of conventional line selection method is less than 50%

Under some extreme conditions, the correct rate of judgment is less than 20%, which often results in the embarrassing situation of multiple switching lines for power outage judgment

The low accuracy rate of judgment has become the short board of the current conventional line selection method, which cannot well meet the actual needs of the project.

[0004] At present, the application effect of incremental algorithm in ground fault discrimination has been relatively ideal. However, due to the need to add primary equipment such as resistors and capacitors, or to cooperate with other equipment such as arc suppression, it will not only increase equipment investment costs, but also increase additional in the power system. The device is not conducive to the safe and reliable operation of the system, and its application is also limited

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