CN204129165U - A kind of change of current becomes bilateral pressurization local discharge test device - Google Patents

A kind of change of current becomes bilateral pressurization local discharge test device Download PDF

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CN204129165U
CN204129165U CN201420450306.2U CN201420450306U CN204129165U CN 204129165 U CN204129165 U CN 204129165U CN 201420450306 U CN201420450306 U CN 201420450306U CN 204129165 U CN204129165 U CN 204129165U
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transformer
test
pressure side
exciting transformer
exciting
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沈鑫
曹敏
闫永梅
马红升
王昕�
张林山
吴水军
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Yunnan Power Grid Corp Technology Branch
Yunnan Electric Power Experimental Research Institute Group Co Ltd of Electric Power Research Institute
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Yunnan Power Grid Corp Technology Branch
Yunnan Electric Power Experimental Research Institute Group Co Ltd of Electric Power Research Institute
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Abstract

The utility model discloses a kind of change of current and become bilateral pressurization local discharge test device, put detector by P1 variable-frequency power sources, T1 exciting transformer, T2 exciting transformer, L1 compensation reactor, L2 compensation reactor, C1-C6 capacitive divider, office, Em grounding terminal block, CT1-CT4 current transformer form.The utility model establishes the change of current and becomes bilateral pressurization local discharge test device and experiment process, substantially increase test effect and efficiency, through verification experimental verification, the utility model has promotional value, explores transformer partial discharge test method provide valuable guidance and experience for reference for electric system.

Description

A kind of change of current becomes bilateral pressurization local discharge test device
Technical field
The utility model belongs to electricity field, particularly relates in high pressure, extra-high voltage field, carries out a kind of device of converter power transformer bilateral pressurization shelf depreciation.
Background technology
Converter power transformer is equipment indispensable in DC transmission engineering, and its running status directly affects the safety and stability of straight-flow system.It is except having the effect of regular alternating current transformer, the mutual conversion between alternating current and direct current is also realized together with converter valve, and by straight-flow system and AC system mutually isolated, its impedance can also play the effect of short-circuit current on restriction valve arm short circuit and DC bus, makes converter valve exempt from damage.
Shelf depreciation refers to and insulate only by the electrical discharge of part bridge joint between conductor, and this electric discharge can occur also can not occur near conductor near conductor.In highfield, in the weakness existed in inside transformer insulation or production run, the defect that causes can cause shelf depreciation, the energy of this electric discharge is very little, it there is the dielectric strength not affecting electrical equipment in short-term, but once there is shelf depreciation in medium, generation cumulative effect can make the dielectric properties of insulation deteriorated gradually and local defect is expanded by these faint electric discharges, finally causes insulation breakdown.Time long, the test of induced electricity pressure zone measurement of partial discharge effectively can find the inherent shortcoming of insulating inner or test by lightning impulse or operation wave impact the local hidden danger caused, to eliminate these defects, prevents shelf depreciation from damaging insulation.Therefore will ensure the reliability of equipment long-time running, partial discharge test is absolutely necessary.Chinese scholars has carried out a lot of research to the partial discharge method of transformer, the general method adopting monolateral pressurization at present, because live end above earth potential is high, voltage is higher, the office of its own band entry loop high-volume just increases, also larger to testing equipment harm, directly threaten the life security of experimental technique personnel time serious.
Utility model content
In order to solve the problem, a kind of change of current that the utility model provides becomes bilateral pressurization local discharge test device, puts detector, Em grounding terminal block, CT1-CT4 current transformer form by P1 variable-frequency power sources, T1 exciting transformer, T2 exciting transformer, L1 compensation reactor, L2 compensation reactor, C1-C6 capacitive divider, office;
Wherein, P1 variable-frequency power sources low pressure side joint main electrical network 380V electrical source of power, its high-pressure side connects T1 exciting transformer and T2 exciting transformer low-pressure side; T1 exciting transformer high-pressure side polarity termination valve winding in converter transformer C, T2 exciting transformer high-pressure side polarity termination valve winding in converter transformer D; T1 exciting transformer and T2 exciting transformer high-pressure side non-polar end ground connection; Capacitive divider C3, C4 connect, and head end connects converter power transformer source side winding A, tail end ground connection; Capacitive divider C1, C2 connect, and head end meets C after CT3, tail end connects Em grounding terminal block; Capacitive divider C5, C6 connect, and head end meets D after CT4, tail end connects Em grounding terminal block; L1 compensation reactor head end connects C, tail end after CT1, connects Em grounding terminal block after CT3; L2 compensation reactor head end connects D, tail end after CT2, connects Em grounding terminal block after CT4; Converter power transformer source side winding B point ground connection.
Adopt said apparatus, T1 exciting transformer and T2 exciting transformer can be made to export phase 180 degree, and when ensureing symmetrical applied voltage test, valve side winding can bear the situation that puncturing and damaging does not appear in trial voltage.The test method that a kind of change of current becomes bilateral pressurization local discharge test device is undertaken by following 7 steps:
Step 1: boosting of starting from scratch, voltage rise arrives keep 5min, and record measurement of partial discharge, wherein Um is the highest travel line voltage of equipment;
Step 2: voltage rise arrives keep 5min, and record measurement of partial discharge;
Step 3: voltage rise arrives when trial voltage frequency is equal to or less than twice rated frequency, duration of test runs should be 60s, and when test frequency exceedes twice rated frequency, test duration should be t=rated frequency f n/ test frequency f s× 120S, and be not less than 15 seconds, and record measurement of partial discharge.During test, test frequency is 250Hz, and the duration is 24s;
Step 4: immediately voltage is down to U after test 2, keep 60min, period continuous coverage shelf depreciation, and record measurement of partial discharge every 5min;
Step 5: voltage is down to keep 5min, and record measurement of partial discharge;
Step 6: test complete, be depressurized to zero, and powered-down;
Step 7: trial voltage does not produce unexpected decline; Online terminal voltage is time, the continuous horizontal of partial discharge quantity should not be greater than 100pC; Online terminal voltage is time, the continuous horizontal of partial discharge quantity should not be greater than 300pC, and shelf depreciation does not present the trend of sustainable growth, and the higher magnitude pulse accidentally occurred is negligible; Online terminal voltage is time, the continuous horizontal of partial discharge quantity should not be greater than 550pC; It is qualified that oil chromatogram analysis result after local discharge test requires, and with local discharge test before analysis result no significant difference; If meet this requirement, it is qualified to judge.
The utility model compared with the existing technology, have the following advantages and beneficial effect: establish the change of current and become bilateral pressurization local discharge test device and experiment process, substantially increase test effect and efficiency, through verification experimental verification, the utility model has promotional value, explores transformer partial discharge examination provide valuable guidance and experience for reference for electric system.In addition, the utility model changes backward, outmoded local discharge test pattern, reduces the experimentation cost of electric system, has saved the man power and material of test.
Accompanying drawing explanation
Fig. 1 is wiring schematic diagram of the present utility model;
Fig. 2 is the utility model test pressurization protocols process flow diagram.
Embodiment
Below in conjunction with drawings and Examples, the technical solution of the utility model is clearly and completely described.
As shown in Figure 1, a kind of change of current becomes bilateral pressurization local discharge test device, puts detector, Em grounding terminal block, CT1-CT4 current transformer form by P1 variable-frequency power sources, T1 exciting transformer, T2 exciting transformer, L1 compensation reactor, L2 compensation reactor, C1-C6 capacitive divider, office;
Wherein, P1 variable-frequency power sources low pressure side joint main electrical network 380V electrical source of power, high-pressure side connects T1 exciting transformer and T2 exciting transformer low-pressure side; T1 exciting transformer high-pressure side polarity termination C (valve winding in converter transformer), T2 exciting transformer high-pressure side polarity termination D (valve winding in converter transformer); T1 exciting transformer and T2 exciting transformer high-pressure side non-polar end ground connection; Capacitive divider C3, C4 connect, and head end connects A (converter power transformer source side winding), tail end ground connection; Capacitive divider C1, C2 connect, and head end meets C after CT3, tail end connects Em grounding terminal block; Capacitive divider C5, C6 connect, and head end meets D after CT4, tail end connects Em grounding terminal block; L1 compensation reactor head end connects C, tail end after CT1, connects Em grounding terminal block after CT3; L2 compensation reactor head end connects D, tail end after CT2, connects Em grounding terminal block after CT4; B point (converter power transformer source side winding) ground connection.
The connected mode adopting said apparatus to have, T1 exciting transformer and T2 exciting transformer can be made to export phase 180 degree, and when ensureing symmetrical applied voltage test, valve side winding can bear the situation that puncturing and damaging does not appear in trial voltage.Test method of the present utility model, according to the block diagram shown in Fig. 2, is carried out in conjunction with following 7 steps:
Step 1: boosting of starting from scratch, voltage rise arrives keep 5min, and record measurement of partial discharge, wherein Um is the highest travel line voltage of equipment;
Step 2: voltage rise arrives keep 5min, and record measurement of partial discharge;
Step 3: voltage rise arrives when trial voltage frequency is equal to or less than twice rated frequency, duration of test runs should be 60s, and when test frequency exceedes twice rated frequency, test duration should be t=rated frequency f n/ test frequency f s× 120S, and be not less than 15 seconds, and record measurement of partial discharge.During test, test frequency is 250Hz, and the duration is 24s;
Step 4: immediately voltage is down to U after test 2, keep 60min, period continuous coverage shelf depreciation, and record measurement of partial discharge every 5min;
Step 5: voltage is down to keep 5min, and record measurement of partial discharge;
Step 6: test complete, be depressurized to zero, and powered-down;
Step 7: trial voltage does not produce unexpected decline; Online terminal voltage is time, the continuous horizontal of partial discharge quantity should not be greater than 100pC; Online terminal voltage is time, the continuous horizontal of partial discharge quantity should not be greater than 300pC, and shelf depreciation does not present the trend of sustainable growth, and the higher magnitude pulse accidentally occurred is negligible; Online terminal voltage is time, the continuous horizontal of partial discharge quantity should not be greater than 550pC; It is qualified that oil chromatogram analysis result after local discharge test requires, and with local discharge test before analysis result no significant difference; If meet this requirement, it is qualified to judge.
The item that complete process of the test should be noted is as follows:
1., before test, the net side of tested converter power transformer must install the grading ring corresponding with its electric pressure additional with value side bushing, exciting transformer middle high-pressure side sleeve pipe and compensation reactor, ensures its corona free under trial voltage; Grading ring and sleeve pipe need couple together with bare copper wire and fixed, prevent floating potential discharge.
2. each earth point in test loop must reliable ground.In test, tested transformer independent grounding, two exciting transformer independent groundings, the equipment one point earth in all the other pilot systems.In order to prevent surrounding metal object suspended discharge on the impact of test, electrical equipment, the necessary reliable ground of metal frame that test site is closed on.Ground wire must adopt Special grounding wire, or the bare copper wire of band transparent sheath.
3. because site test voltage is higher, the need of high-voltage connection are anti-corona, and the connection between exciting transformer to compensation reactor to the tested change of current becomes adopts the anti-corona wire of diameter 30cm, guarantees not occur corona phenomenon when normal assays.
4. the connecting line detecting impedance and bottom shielding of bushing should be short as far as possible.During test, detection impedance is put near converter transformer sleeve end shield, background office can be put and be reduced to below 30pC, substantially increase reliability.
In order to verify correctness of the present utility model, usability, this programme adopts embodiment to be illustrated.
Tested converter power transformer is the single-phase doublewound transformer that special power transformation work is produced, and source side winding is graded insulation, and valve side winding is all insulation structure, and rated capacity is 250MVA, and source side winding rated voltage is maximum operating voltage is valve side winding rated voltage is 170kV.
When carrying out measurement of partial discharge test, apply magnitude of voltage to reduce valve side, the shunting switch that the change of current becomes is adjusted to maximum gear and tests, namely+18 grades, its rated voltage is 642.97kV, and the voltage ratio of now netting side and valve side is during partial discharge test net side and voltage on valve side value as shown in table 1.
Each side magnitude of voltage during table 1 local discharge test
According to special power transformation work delivery test report data, tested transformer source side winding ground capacitance is C l=12800pF, valve side winding-to-earth capacity is C v=18000pF.According to formulae discovery converter transformer valve-side entrance capacitance be:
C = 1 3 C L K 2 + 1 3 C V = 1 3 × 12800 × 2.185 2 + 1 3 × 18000 = 26370 pF
Test frequency is: f = 1 2 π LC = 1 2 π 13.2 × 26.37 × 10 - 9 = 269.76 Hz , The capacity current of tested transformer is
I c=ω CU, wherein C is converter power transformer entrance capacitance, and U is trial voltage.
Under calculating different voltage, the capacity current of tested transformer is as shown in table 2.
The very important object of estimating test frequency one is got rid of " false tuning-points " exactly.During site test, the actual resonance frequency of test loop is 250Hz, is less than calculated value 269.76Hz, and the actual frequency reason different with theoretic frequency is the impact of stray capacitance in parameter estimation error, test loop etc.
Test adopts symmetrical pressuring method to carry out, so compensation reactor adopts the mode of bilateral compensation to compensate to pressurization survey in testing, and each employing rated capacity 2200kVA, rated voltage 110kV, rated current 20A, the reactor of inductance value 6.6H ± 2%.Compensation reactor compensation current is I l=U/ ω L.
The tested converter power transformer capacitance current of table 2 and offset current
When carrying out partial discharge test, the active loss computing formula of tested transformer under different voltage is as follows:
P＝(k×f N/f S) 1.9×(f S/f N) 1.6×P 0
P in formula 0for the open circuit loss of converter power transformer, 90.45kW; f nfor rated frequency, 50Hz; K is the ratio of trial voltage and rated voltage.? under trial voltage, voltage on line side value is 217.9kV, so k=217.9/169.9=1.28, now active loss is: P=(1.28 × 50/250) 1.9× (250/50) 1.6× 90.46=89.22kW, active current is:
I R＝P/U 1＝89.22/217.9＝0.41A。
When partial discharge test, separate unit excitation T1 and T2 varying capacity are 550kVA, high-pressure side rated voltage 220kV, rated current 2.5A, low pressure side joint 400V winding, and rated current 1375A, no-load voltage ratio is 550.Variable-frequency power sources capacity is 750kVA, and rated output voltage 0 ~ 400V is adjustable, output-current rating 1875A.? under trial voltage, the active current of transformer is 0.41A, and reactive current is I x=I l-I c=10.15-9.02=1.13A, so exciting transformer high-pressure side output current exciting transformer low-pressure side input current and variable-frequency power sources output current are I t'=1.445 × 550=794A; Exciting transformer low-pressure side input voltage
This test local discharge measurement is as shown in table 3, and according to test figure, result meets code relevant regulations, stand the test.Carried out oil chromatogram analysis after local discharge test, do not found acetylene, increasing does not appear in total hydrocarbon, can judge that electric discharge does not appear in converter power transformer inside, confirm this correctness of the present utility model and reliability.
Table 3 measurement of partial discharge test figure

Claims (1)

1. a change of current becomes bilateral pressurization local discharge test device, it is characterized in that, put detector by P1 variable-frequency power sources, T1 exciting transformer, T2 exciting transformer, L1 compensation reactor, L2 compensation reactor, C1-C6 capacitive divider, office, Em grounding terminal block, CT1-CT4 current transformer form; Wherein:
P1 variable-frequency power sources low pressure side joint main electrical network 380V electrical source of power, its high-pressure side connects T1 exciting transformer and T2 exciting transformer low-pressure side; T1 exciting transformer high-pressure side polarity termination valve winding in converter transformer C, T2 exciting transformer high-pressure side polarity termination valve winding in converter transformer D; T1 exciting transformer and T2 exciting transformer high-pressure side non-polar end ground connection; Capacitive divider C3, C4 connect, and head end connects converter power transformer source side winding A, tail end ground connection; Capacitive divider C1, C2 connect, and head end meets C after CT3, tail end connects Em grounding terminal block; Capacitive divider C5, C6 connect, and head end meets D after CT4, tail end connects Em grounding terminal block; L1 compensation reactor head end connects C, tail end after CT1, connects Em grounding terminal block after CT3; L2 compensation reactor head end connects D, tail end after CT2, connects Em grounding terminal block after CT4; Converter power transformer source side winding B point ground connection.
CN201420450306.2U 2014-08-12 2014-08-12 A kind of change of current becomes bilateral pressurization local discharge test device Active CN204129165U (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106443139A (en) * 2016-11-22 2017-02-22 山东电力设备有限公司 A converter transformer impedance voltage tap switch test apparatus
CN110542842A (en) * 2019-09-29 2019-12-06 广东电网有限责任公司 10kV switch cabinet partial discharge simulation device and method
CN111103516A (en) * 2019-12-24 2020-05-05 保定天威保变电气股份有限公司 Partial discharge test method for single-phase traction transformer
CN111751682A (en) * 2020-06-24 2020-10-09 国网黑龙江省电力有限公司电力科学研究院 Pressurization method for on-site partial discharge measurement of overhauled transformer

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106443139A (en) * 2016-11-22 2017-02-22 山东电力设备有限公司 A converter transformer impedance voltage tap switch test apparatus
CN110542842A (en) * 2019-09-29 2019-12-06 广东电网有限责任公司 10kV switch cabinet partial discharge simulation device and method
CN110542842B (en) * 2019-09-29 2024-04-12 广东电网有限责任公司 10kV switch cabinet partial discharge simulation device and method
CN111103516A (en) * 2019-12-24 2020-05-05 保定天威保变电气股份有限公司 Partial discharge test method for single-phase traction transformer
CN111751682A (en) * 2020-06-24 2020-10-09 国网黑龙江省电力有限公司电力科学研究院 Pressurization method for on-site partial discharge measurement of overhauled transformer

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