Medium-voltage power grid neutral point arc suppression coil and resistor combined grounding method

Abstract

The invention discloses a medium-voltage power grid neutral point arc suppression coil and resistor combined grounding method. On the basis of a mode that a neutral point is grounded in a resonance way through an arc suppression coil, a median resistor and a small resistor with different resistance values are connected in parallel to the arc suppression coil, and the connection and disconnection of the median resistor and the small resistor are controlled by a switch connected with a controller, so that the mutual switching among different neutral point grounding modes is achieved in the following mode. According to the invention, a neutral point grounding mode of automatically tracking the combination of the arc suppression coil system and the grounding resistor is adopted, so that transient faults and permanent faults are distinguished while overvoltage is limited, and the grounding line selection of the permanent faults is achieved, namely the advantages of suppressing overvoltage by the middle resistor, reducing the grounding current of the fault point and extinguishing arc of the arc suppression coil are fully exerted, the grounding mode of the small resistor having the good relay protection selectivity is adopted to rapidly cut off the permanent earth fault so as to improve the power supply reliability, safety and economical efficiency.

Description

Technical field: [0001] The invention relates to the field of power transmission and transformation control, in particular to a combined grounding method of a neutral point arc suppressing coil and a resistor in a medium-voltage power grid. Background technique: [0002] The neutral point grounding method of urban distribution network is a complex comprehensive problem, which is related to power supply reliability, personal safety, equipment safety and so on. However, the current neutral point grounding method has the following problems: the overvoltage limit of the arc suppression coil grounding method is insufficient, and the detection of ground fault lines is difficult. , leading to an increase in the residual current of the ground fault; series resonance overvoltage that may occur in disconnection; the small resistance grounding method, the system will trip quickly when a single-phase grounding occurs, which will affect the reliability of power supply, distribution netwo...

AI Technical Summary

Problems solved by technology

[0010] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, to combine the advantages of the small resistance grounding method and the arc suppressing coil grounding method, to overcome the shortcomings of the original grounding method, and to improve the ability to limit overvoltage; Difficult problems in line selection and identification; improving the adaptability of arc-suppression coils and the arc-suppression coils can be under-compensated for safe operation, and the grounding method of neutral point arc-suppression coils and resistors in medium-voltage power grids

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