CN104076315B

CN104076315B - On-load calibration method for polarity of high-transformation-ratio current transformer (CT)

Info

Publication number: CN104076315B
Application number: CN201410332143.2A
Authority: CN
Inventors: 闫广涛; 李明; 周文; 朱岩; 孙海玉; 孙浩然; 田志勇
Original assignee: Shangqiu Tianyu Electric Power Engineering Survey & Design Co Ltd; Shangqiu Power Supply Co of State Grid Henan Electric Power Co Ltd
Current assignee: Shangqiu Tianyu Electric Power Engineering Survey & Design Co Ltd; Shangqiu Power Supply Co of State Grid Henan Electric Power Co Ltd
Priority date: 2014-07-14
Filing date: 2014-07-14
Publication date: 2017-02-15
Anticipated expiration: 2034-07-14
Also published as: CN104076315A

Abstract

An on-load calibration method for the polarity of a high-transformation-ratio current transformer (CT) is technically characterized in that a test bed outputs large currents, the currents flow into a transformer substation through the A phase of primary equipment, return through the A phase of a bus tie CT of the transformer substation on the side, the A phase of the CT, the A phase of a circuit L, the A phase of a circuit CT of a transformer substation on the opposite side and the B phase of the three-phase connection end of a mother grounding disconnecting link of the transformer station, and flow back to the K2 end of the test bed through the B phase of the circuit CT of the transformer substation on the opposite side, the B phase of the circuit L, the B phase of the circuit CT on the side and the B phase of the bus tie CT, and therefore the currents form a complete loop. The correctness of the polarity is judged by calculating the sum of secondary current vectors of the bus tie CT and the LMCT of an M transformer station and calculating the sum of secondary current vectors of the LMCT of the M transformer station and the LNCT of an N transformer station. According to the method, wrong connection of the busbar differential protection polarity of a newly-built transformer station can be avoided, the reliably of busbar differential protection operation in the transformer station can be improved, and stable operation of an electric system can be guaranteed.

Description

A kind of high no-load voltage ratio CT polarity load test method

Technical field

The present invention relates to a kind of high no-load voltage ratio CT polarity load test method, belong to the inspection of comprehensive automation of electric power system equipment Test field.

Background technology

CT (current transformer) is transformer station, a kind of capital equipment used in electric line, mainly by system one Relation is converted into secondary current to the electric current of secondary side according to a certain percentage.It is widely used in electric power supervisory control, protection, failure wave-recording With technical fields such as fault localizations, it is current measurement in power system, system controls, particularly the important of protective relaying device sets Standby.Before CT puts into operation, typically to verify its polarity, particularly it is required with higher bus differential protection loop, longitudinal difference protection loop. And the continuous increase with China's power system capacity, electrical network scale, grid structure, short circuit current be also increasing, and CT holds very much Magnetic flux saturation easily occurs, when saturated, exciting current increases, and secondary output current is distorted, primary side current and two The ratio of secondary side electric current now, can not impact to the correct operation of protection device in strict accordance with original proportionate relationship again, It is likely to result in protective relaying maloperation work, tripping or delay voltage, also can reduce the accuracy of fault localization.For this reason, it is now more next More transformer stations and power plant adopt high no-load voltage ratio CT（Soprano has 3000/1）, so, CT is difficult to magnetic flux saturation. And high no-load voltage ratio CT is under actual normal operating mode, secondary current is very little, particularly newly-built plant stand initial operation stage, due to negative Lotus can not possibly reach the exact requirements meeting load test polarity, therefore cannot be to bus differential protection, circuit in the case of on-load Longitudinal difference protection carries out polarity verification.Cause certain hidden danger, or even the economy directly affecting operation of power networks to power grid security.

At this stage, there is the blank of equipment and technology always to high no-load voltage ratio CT polarity load test.In newly-built transformer station, one As in the case of all be change multiple substation operation modes, organize larger load verified.And in more than 220kV voltage etc. Level, the no-load voltage ratio to 3000/1, there is the difficulty of tissue load, be still difficult to meet the requirement of load test in reality. If load is less, CT bis- sub-value will very little, distinguish not out with the drift of protection device, will impact personnel judgement, or Person causes to judge by accident, when running after circuit, if there is under failure condition, it will cause bus differential protection or longitudinal difference protection by mistake Dynamic, expand power failure range, bring great hidden danger to power grid security.In addition, changing multiple substation operation modes, make Become substantial amounts of manpower and materials to waste, and during back brake, there is more dangerous spot, cause unnecessary potential safety hazard.If Can be actual according to scene, if particularly a kind of survey of simple possible can be invented according to bus arrangement mode in newly-built plant stand Method for testing is come to realize high no-load voltage ratio CT polarity load test be a very important problem.

Content of the invention

In order to avoid above various shortcoming, the present invention proposes a kind of safe and reliable, simple possible high no-load voltage ratio CT polarity The test method of load test, the method test device is simple to operate, can overhaul and can find bus differential protecting, line Rectify and improve in time during the longitudinal difference protection incorrect polarity of road, the pre-control before accident can be accomplished again；Ensure that the safe and stable operation of electrical network.

Solve the problems, such as that the present invention be employed technical scheme comprise that：Export high current with testing stand K1 end, through M side mother disconnecting link A phase flow into, respectively through the A phase of M side transformer station mother CT, the A phase of M side line road CT, the A phase of circuit L, N side power transformation station track The A phase of road CT, the B phase through N side transformer station female ground disconnecting link three-phase connection end returns, and again passes by the B of N side substation line CT Phase, the B phase of circuit L, the B phase of M side line road CT, the B phase of mother CT flow back to testing stand K2 end, make electric current form complete returning Road;Then, mother CT and the secondary current vector of M transformer station LMCT are flow through by calculating, judge that polarity is correct;Meanwhile, lead to Cross calculating and flow through M side transformer station LMCT and N side transformer station LNCT and obtain secondary current vector, judge that polarity is correct.

The positive effect of the present invention is：（1）The each branch road CT polarity of same electric pressure in transformer station can be checked secondary The missing or misconnection of wiring, it is to avoid the mistake access of newly-built substation bus bar differential protection polarity；（2）Check a circuit The missing or misconnection of CT polarity secondary connection that longitudinal difference protection uses,（3）It is impossible to on-load in the case of avoiding line load little Check the hidden danger staying.（4）Reduce protective calibration time when newly-built transformer station puts into operation, safety quick to each user's power transmission, Increase economic efficiency；（5）Improve bus differential protecting and pilot wire relays reliability of operation in transformer station, ensure electricity The stable operation of Force system.

Brief description

Fig. 1 is the wiring embodiment schematic diagram of the present invention.

Specific embodiment

Accompanying drawing 1 is the embodiment schematic diagram that can simultaneously verify bus differential protection and pilot wire relays.This embodiment is one There is the M transformer station in the double-bus loop in mother loop, via line L is to the primary connection figure of offside N transformer station.

As shown in Figure 1, disconnect mother south disconnecting link 7 and the LM south disconnecting link 9 of M transformer station 15, make in M transformer station 15 Southern bus 8 normally runs, and disconnects mother south disconnecting link 2.Close the bus connection switch 4 of M transformer station 15, mother north disconnecting link 5 and LM Northern disconnecting link 10, LM switch 11, LM first disconnecting link 13.

Disconnect the western disconnecting link of LN 20 and the LN east disconnecting link 21 of N transformer station 16, so that the double-bus in N transformer station 15 is normally transported OK.Close the LN switch 19 of N transformer station 16, LN first disconnecting link 17, and LN female ground disconnecting link 22 takes connecing of LN female ground disconnecting link 22 apart Ground terminal；It is connected with the A phase upper end of mother south disconnecting link 2 with the K1 end of testing stand 1, the K2 end of testing stand 1 southern disconnecting link 2 with mother B phase upper end be connected, wiring finishes.

Export 600A primary current from testing stand 1, the A phase input through mother south disconnecting link 2, flow separately through mother CT 3 K2 end, K1 end, the A phase of northern bus 6, the A phase K1 end of LMCT 12, K2 end, the A phase of circuit L 14, enter N transformer station 16, continue Continuous A phase K2 end through LNCT 18, K1 end, the A phase through LN female ground disconnecting link 22 enters, and because LN female ground disconnecting link is to close position, and connects Ground terminal is removed, and such electric current flows out from the B phase of LN female ground disconnecting link 22, and the B phase according to primary circuit returns to the K2 of testing stand 1 End.

The polarity of bus differential protection judges by flowing through the A phase K2 end of mother CT 3, the secondary current I1 at K1 end（It is not less than 0.02A）With the A phase K1 end of LMCT 12, the secondary current I2 Vector operation at K2 end and checking, such as undesirable, two please be search Secondary wiring, until correct.

The polarity of pilot wire relays judges by flowing through the A phase K1 end of M transformer station LMCT 12, the secondary current I2 at K2 end （Not less than 0.02A）With the secondary current I3 vector flowing through the A phase K2 end of N transformer station LNCT 12, the A phase K1 end at K1 end, K2 end Calculate and verify, such as undesirable, secondary connection please be search, until correct.

Meanwhile, B phase is verified according to the method described above.

Change test connection is B, C phase（Or A, C phase）, verify C phase polarity according to the method described above.

Claims

1. a kind of high no-load voltage ratio CT polarity load test method, exports high current, the A through M side mother disconnecting link with testing stand K1 end Mutually flow into, respectively through the A phase of M side transformer station mother CT, the A phase of M side line road CT, the A phase of circuit L, N side substation line CT A phase, the B phase through N side transformer station female ground disconnecting link three-phase connection end returns, and again passes by B phase, the line of N side substation line CT The B phase of road L, the B phase of M side line road CT, the B phase of mother CT flow back to testing stand K2 end, make electric current form a complete loop;So Afterwards, mother CT and the secondary current vector of M transformer station LMCT are flow through by calculating, judge that polarity is correct;Meanwhile, by calculating Flow through M side transformer station LMCT and N side transformer station LNCT and obtain secondary current vector, judge that polarity is correct.