CN203025307U

CN203025307U - Smart line selector of small-current earthing system

Info

Publication number: CN203025307U
Application number: CN 201220712657
Authority: CN
Inventors: 宣自平; 于天浪; 范成龙
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-12-21
Filing date: 2012-12-21
Publication date: 2013-06-26
Anticipated expiration: 2022-12-21

Abstract

The utility model relates to a smart line selector of a small-current earthing system. The smart line selector comprises an integrated controller, wherein the signal input end of the integrated controller is connected with a voltage transformer PT for acquiring the bus voltage and the zero-sequence voltage of the protected device and a current transformer CT for acquiring the zero-sequence current of a line selecting circuit, respectively; the signal output end of the integrated controller is connected with the three-phase bus of the protected device through a vacuum circuit breaker DLQ; the other end of the vacuum circuit breaker is grounded through the primary coil of a single-phase transformer T; at least two line selecting circuits are connected in parallel to the secondary coil of the single-phase transformer T; and the signal output end of the integrated controller is connected with the control end of the line selecting circuits. The smart line selector of the small-current earthing system is capable of accurately selecting out the faulted feeder line with the relative phases of the zero-sequence current and the zero-sequence voltage, the trend of amplitude changes of transient current and voltage and the principle of gradual transfer of the zero-sequence current as criterion, and also capable of automatically removing the faulted feeder line; after the system returns to normal, the selector automatically exits from the energy-consuming equipment and waits for bein put in service in next fault.

Description

A kind of small current neutral grounding system intelligent route selection device

Technical field

The utility model relates to a kind of small current neutral grounding system, especially a kind of small current neutral grounding system intelligent route selection device.

Background technology

At present, existing line selection apparatus, depend on original PT(voltage transformer (VT) in system) open delta voltage and the variable quantity of circuit zero sequence CT judge, when the PT open delta voltage rises and a certain circuit zero sequence CT electric current when occurring, think that just certain circuit of this section bus breaks down.There is following defective in this line selection apparatus: the first, and all judgement data rely on the output of other equipment, rely on electric system existing equipment precision and configuration fully, if the equipment precision in original system is low, can causes error in judgement and can't select faulty line; The second, after selecting faulty line, owing to there is no the output of node action signal, can't directly cut off processing to faulty line, must manually carry out site disposal, the mute time of having strengthened fault, failure accident is enlarged, and take time and effort.

The utility model content

The purpose of this utility model is to provide a kind of small current neutral grounding system intelligent route selection device that can select exactly faulty line, also automatically faulty line be excised.

for achieving the above object, the utility model has adopted following technical scheme: a kind of small current neutral grounding system intelligent route selection device, comprise general controller, its signal input part respectively with the voltage transformer pt that is used for gathering protected equipment busbar voltage and residual voltage, the Current Transmit that be used for to gather route selection loop zero-sequence current is connected, its signal output part connects the three-phase bus of protected equipment by vacuum circuit breaker DLQ, the other end of vacuum circuit breaker is by the primary coil ground connection of single transformer T, at least two route selection loops are attempted by on the secondary coil of single transformer T, the signal output part of general controller is connected with the control end in route selection loop, the route selection loop is attempted by on the feeder line of protected equipment.

Described route selection loop is comprised of electronic switch V, current transfer resistance R, divider resistance R0, trigger KCF, be connected across on the secondary coil of single transformer T after electronic switch V and the series connection of current transfer resistance R, the signal output part of general controller is connected with the input end of trigger KCF, the output terminal of trigger KCF is connected with the control end of electronic switch V, trigger KCF be connected across on the secondary coil of single transformer T after divider resistance R0 connects.

The signal output part of described general controller is connected with the end of vacuum circuit breaker DLQ, and the other end of vacuum circuit breaker DLQ is connected with the end of disconnector GL, the three-phase bus of the protected equipment of another termination of disconnector GL.

Cross-over connection single-phase circuit breaker K on the primary coil of described single transformer T, the primary coil of single transformer T and single-phase circuit breaker K are altogether.

Current Transmit passes from the circuit between resistance R and ground.

as shown from the above technical solution, the utility model collects change in voltage by voltage transformer pt, during judgement small current neutral grounding system generation earth fault, the vacuum circuit breaker DLQ of fault phase is closed in the pass, drop into single transformer T and route selection loop, relative phase according to zero-sequence current and residual voltage, the principle that the trend that the transient current voltage magnitude changes and zero-sequence current progressively shift is as basis for estimation, select exactly the fault feeder circuit, can automatically excise faulty line after finding out the fault feeder circuit, after system recovers normally, this device withdraws from energy consumption equipment automatically, wait for that putting into operation appears in next fault again.

Description of drawings

Fig. 1 is electrical schematic diagram of the present utility model.

Embodiment

a kind of small current neutral grounding system intelligent route selection device, comprise general controller 2, its signal input part respectively with the voltage transformer pt that is used for gathering protected equipment busbar voltage and residual voltage, the Current Transmit that be used for to gather route selection loop 1 zero-sequence current is connected, its signal output part connects the three-phase bus of protected equipment by vacuum circuit breaker DLQ, the other end of vacuum circuit breaker is by the primary coil ground connection of single transformer T, at least two route selection loops 1 are attempted by on the secondary coil of single transformer T, the signal output part of general controller 2 is connected with the control end in route selection loop 1.As shown in Figure 1.Single transformer T is used for providing enough capacity and voltage to route selection loop 1.When earth fault occured, three-phase voltage is balance no longer, and opening voltage rises, and zero-sequence current occurs.

As shown in Figure 1, described route selection loop 1 is comprised of electronic switch V, current transfer resistance R, divider resistance R0, trigger KCF, be connected across on the secondary coil of single transformer T after electronic switch V and the series connection of current transfer resistance R, the signal output part of general controller 2 is connected with the input end of trigger KCF, the output terminal of trigger KCF is connected with the control end of electronic switch V, trigger KCF be connected across on the secondary coil of single transformer T after divider resistance R0 connects.Electronic switch V is connected on the secondary side of single transformer T, is used for switching current transfer resistance R, closes and closes without arc light, and reaction velocity is fast; Current transfer resistor R is connected on the lower end of electronic switch V, is used for calculating the trend data that shifts; Trigger KCF is used for triggering in real time, conducting electronic switch V.

The signal output part of described general controller 2 is connected with the end of vacuum circuit breaker DLQ, and the other end of vacuum circuit breaker DLQ is connected with the end of disconnector GL, the three-phase bus of the protected equipment of another termination of disconnector GL.Cross-over connection single-phase circuit breaker K on the primary coil of described single transformer T, the primary coil of single transformer T and single-phase circuit breaker K altogether, short circuit single transformer T when single-phase circuit breaker K is used for normally moving in system.Described Current Transmit passes from the circuit between resistance R and ground.

Below in conjunction with Fig. 1, the utility model is further described.

when certain singlephase earth fault occurs in system, general controller 2 collects the residual voltage of voltage transformer pt, when busbar voltage changes, general controller 2 is sent steering order, close should phase vacuum circuit breaker DLQ, disconnect simultaneously single-phase circuit breaker K, drop into single transformer T, send for simultaneously trigger KCF with it and open signal, progressively access the current transfer resistance R between the bus of Earth Phase and ground, the resistance of regular adjusting current transfer resistance R, the number of current transfer resistance R can progressively increase, the number of the current transfer resistance R that drops into is decided according to actual situation about breaking down,

When the current transfer resistance R when diminishing greatly, the electric current that flows through non-fault line can become large gradually, direction is by a straight edge line flow line road, the electric current that flows through faulty line can diminish gradually, because fault ground point all can have certain resistance usually, when the resistance of current transfer resistance R is little of certain degree, the counter-rotating of the zero-sequence current generation direction of faulty line is become by bus to bus by line flows and flows to circuit; Otherwise, when opposite variation tendency appears in the current transfer resistance R Shi Zehui that changes from small to big.

As seen, as long as in the process that zero-sequence current shifts, the zero-sequence current of each feeder line of continuous monitoring changes, just can select accurately faulty line, after selecting faulty line, general controller 2 is just sent action command to the fault phase isolating switch, makes fault phase out of service.

When normal operation recovered in system, general controller 2 was just sent switching signal to single-phase circuit breaker K, closed and closed single-phase circuit breaker K, made the equipment such as single transformer T out of service.Simultaneously, when the current transfer resistance R is reduced to zero resistance, be also system to be carried out the function of extinguishing arc, can effectively carry out extinguishing arc, avoid the arc overvoltage that produces to the injury of the insulation of system equipment.

In the situation that there is no condition, Current Transmit is not installed, directly measure the electric current of each feeder line, the curent change of faulty line and non-fault line also has diverse characteristics, as long as measuring system has enough sensitivity to the variation of electric current, just can be according to different variation tendency failure judgement circuits, these all correlatives take zero-sequence current at other are all impossible in the method for criterion.

Earth fault might be single-phase multipoint earthing, can find faulty line for this fault without any technological means at present, even the way of operating a switch by circuit one by one, also can't find out many faulty lines, adopt the utility model can by faulty line different variations in the zero-sequence current transfer process from non-fault line, can find accurately and reliably many faulty lines equally.

In some cases, if when high resistance ground occured, zero-sequence current was very little, the fault-signal that may record is not enough to reliable failure judgement circuit, the situation that might judge by accident this moment.When the utility model carries out route selection, if do not detect reliable fault-signal, just can not carry out the route selection operation, can constantly carry out subsequently the operation of repetition route selection extinguishing arc, until find faulty line.

Consider the requirement of fast line selection and assurance system stability, the resistance that the utility model adopts electronic switch V to control the current transfer resistance R is regulated, can satisfy the requirement of fast line selection, and owing to regulating resistance at current zero-crossing point, system does not have the transient state transient process, directly reach steady state (SS), except satisfying the requirement of fast line selection, also satisfied the requirement that guarantees system stability

In sum, the principle that the trend that the utility model changes according to the relative phase of zero-sequence current and residual voltage, transient current voltage magnitude and zero-sequence current progressively shift is as basis for estimation, select exactly the fault feeder circuit, can automatically excise faulty line after finding out the fault feeder circuit, after system recovers normally, this device withdraws from energy consumption equipment automatically, waits for that putting into operation appears in next fault again.

Claims

1. small current neutral grounding system intelligent route selection device, it is characterized in that: comprise general controller (2), its signal input part respectively with the voltage transformer pt that is used for gathering protected equipment busbar voltage and residual voltage, be connected for the Current Transmit that gathers route selection loop (1) zero-sequence current, its signal output part connects the three-phase bus of protected equipment by vacuum circuit breaker DLQ, the other end of vacuum circuit breaker is by the primary coil ground connection of single transformer T, at least two route selection loops (1) are attempted by on the secondary coil of single transformer T, the signal output part of general controller (2) is connected with the control end in route selection loop (1), route selection loop (1) is attempted by on the feeder line of protected equipment.

2. small current neutral grounding system intelligent route selection device according to claim 1, it is characterized in that: described route selection loop (1) is comprised of electronic switch V, current transfer resistance R, divider resistance R0, trigger KCF, be connected across on the secondary coil of single transformer T after electronic switch V and the series connection of current transfer resistance R, the signal output part of general controller (2) is connected with the input end of trigger KCF, the output terminal of trigger KCF is connected with the control end of electronic switch V, trigger KCF be connected across on the secondary coil of single transformer T after divider resistance R0 connects.

3. small current neutral grounding system intelligent route selection device according to claim 1; it is characterized in that: the signal output part of described general controller (2) is connected with the end of vacuum circuit breaker DLQ; the other end of vacuum circuit breaker DLQ is connected with the end of disconnector GL, the three-phase bus of the protected equipment of another termination of disconnector GL.

4. small current neutral grounding system intelligent route selection device according to claim 1, it is characterized in that: cross-over connection single-phase circuit breaker K on the primary coil of described single transformer T, the primary coil of single transformer T and single-phase circuit breaker K are altogether.

5. small current neutral grounding system intelligent route selection device according to claim 2, it is characterized in that: Current Transmit passes from the circuit between resistance R and ground.