An arc grounding overvoltage limiting device applied to medium voltage power distribution system

Abstract

The invention discloses an arc grounding overvoltage limiting device applied to a medium-voltage power distribution system, which includes a single-phase fast electronic switch controlled by an intelligent controller and a high-energy nano-zinc oxide energy-absorbing arc extinguishing device; the single-phase fast electronic switch is three Only, the main circuits of the three single-phase fast electronic switches are connected in a star shape, and the three high-voltage terminals are respectively connected to the three-phase busbar of the system, and the other ends are connected in parallel to the upper end of the high-energy nano-zinc oxide energy-absorbing arc-extinguishing device The high-energy nano-zinc oxide energy-absorbing arc-extinguishing device is composed of a high-energy zinc oxide linear resistor, a nano-damping absorber, a high-energy zinc oxide non-linear resistor and a high-voltage thyristor, wherein the high-voltage thyristor is connected in parallel to the high-energy zinc oxide Linear resistors and nano-damping absorbers at both ends. Compared with the prior art, the invention can effectively limit the single-phase intermittent arc grounding overvoltage in various operating modes of the 3-35KV neutral point non-directly grounded power grid.

Description

technical field [0001] The invention relates to the field of overvoltage limitation in medium-voltage power distribution systems, specifically an arc grounding overvoltage limiting device applied to medium-voltage power distribution systems. Background technique [0002] In the medium voltage distribution system, especially the medium and high voltage transmission and distribution power system (3-35KV), most of them adopt the neutral point non-effective grounding system. In the neutral point non-effectively grounded system, besides the lightning overvoltage, the overvoltage caused by the single-phase ground arc is the most frequent, and this kind of overvoltage has a higher amplitude and a longer duration. If the voltage cannot be effectively limited, it will cause cumulative damage to the power supply equipment in this type of grid, and may cause ground breakdown or phase-to-phase flashover at weak points in the external insulation, resulting in short-circuit accidents. ...

AI Technical Summary

Problems solved by technology

It adopts the arc suppression measure of transforming the intermittent arc grounding into direct grounding of the busbar metal, but the overvoltage limiter will cause an impact on the system at the moment of busbar grounding and disconnection, especially the momentary moment of disconnection of the grounding busbar. State overvoltage, so that the single-phase intermittent arc grounding caused by overvoltage impact may occur again when the insulation level drops, and after the grounding is disconnected, the excess stored charge on the healthy phase-to-ground capacitance will discharge through the winding of the transformer, resulting in The instantaneous magnetic saturation of the winding will still excite the ferromagnetic resonance

[0005] In addition, foreign countries (and a few areas in China have begun to adopt it) adopt the neutral point of this kind of power grid to be grounded through a small resistance to suppress this overvoltage. It is still permanent, and the faulty grounding line is cut off directly, and the operation experience of the power system shows that most of the single-phase grounding faults are instantaneous, especially in the power grid composed of overhead lines, which will inevitably lead to a sharp increase in power outages, obviously Reduced power supply reliability

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