35kv substation 10kv line small grounding current device

Abstract

The invention discloses a small current grounding device for a 10KV line of a 35KV transformer substation. One end of the device is connected with a 10KV bus bar of the transformer substation, and the other end of the device is connected with a grounding grid of the transformer substation; the small current grounding device comprises three split-phase vacuum switches, an outgoing line zero sequence current transformer, a grounding protection device, a grounding line selecting device and a driving locking unit, wherein the grounding protection device and the grounding line selecting device are respectively connected to the outgoing line zero sequence current transformer; the three split-phase vacuum switches are respectively connected to the driving locking unit and are connected with the 10KV bus bar; when a circuit is grounded, the split-phase vacuum switches are started, and the grounding phases of the split-phase vacuum switches are directly connected to the ground. The small current grounding device is based on the fact that much inconvenience is brought to line patrol personnel of a power supply station and accidents are easily caused as a single phase of the circuit in a rural network power supply system is easily grounded due to the factors of lightning stroke, trees and the like; through the introduction of the low current grounding device, the petrol time is shortened to a greater extent, and convenience is brought to the safe operation of equipment.

Description

technical field [0001] The invention relates to the technical field of power systems, in particular to a small grounding current device for a 10KV line in a 35KV substation. Background technique [0002] In the 6KV, 10KV, 35KV, 66KV and other networks of the power system, the neutral point of the transformer adopts the operation mode of not grounding or grounding through the arc suppression coil. The capacitance current to ground, the line voltage of the system still maintains symmetry, does not affect the power supply to the load, the ground protection does not act on the trip but acts on the signal, and generally allows a little ground fault to run for 1-2 hours, which can reduce the number of power outages and improve power supply reliability. The disadvantage of the neutral point ungrounded system is that there is a single-phase ground arc overvoltage, which is easy to cause two fault trips due to arcing, and expand the accident. Especially when personal induction occur...

AI Technical Summary

Problems solved by technology

The disadvantage of the neutral point ungrounded system is that there is a single-phase ground arc overvoltage, which is easy to cause two fault trips due to arcing, and expand the accident. Especially when personal induction occurs, the power can only be cut off artificially, and the response is not timely. Can cause fatal injury to electrocuted persons

[0003] In response to these problems, grounding through the arc suppression coil is used to reduce the grounding current, but the arc suppression coil usually operates in an overcompensated state, and there is still residual current. In some cases, the arc overvoltage cannot be effectively eliminated. The arc suppression coil It will amplify the unbalanced voltage at the neutral point, generate phantom grounding or series resonance overvoltage, and at the same time increase the difficulty of line selection, complex structure, high cost, and large maintenance, especially the problem of personal induction cannot be solved; The neutral point is grounded through a small resistance. When the grounding current exceeds a certain limit, the grounding protection trips, which increases the number of trips and reduces the reliability of power supply.

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