|
US$279.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email.
DL/T 1999-2019: (Field test method for DC partial discharge measurement of converter transformer)
Status: Valid
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| DL/T 1999-2019 | English | 279 |
Add to Cart
|
3 days [Need to translate]
|
(Field test method for DC partial discharge measurement of converter transformer)
| Valid |
DL/T 1999-2019
|
PDF similar to DL/T 1999-2019
Basic data | Standard ID | DL/T 1999-2019 (DL/T1999-2019) | | Description (Translated English) | (Field test method for DC partial discharge measurement of converter transformer) | | Sector / Industry | Electricity & Power Industry Standard (Recommended) | | Classification of Chinese Standard | K41 | | Word Count Estimation | 12,131 | | Date of Issue | 2019-06-04 | | Date of Implementation | 2019-10-01 | | Regulation (derived from) | Natural Resources Department Announcement No. 7 of 2019 | | Issuing agency(ies) | National Energy Administration | DL/T 1999-2019: (Field test method for DC partial discharge measurement of converter transformer)
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Method of On-site DC Partial Discharge Test for Converter Transformer
ICS 29.180
K 41
Record number. 63143-2018
People's Republic of China Electric Power Industry Standard
DC partial discharge measurement of converter transformer
2019-06-04 released
2019-10-01 implementation
Issued by National Energy Administration
Table of contents
Preface...2
1 Scope...3
2 Normative references...3
3 Terms and definitions...3
4 Test conditions...4
5 Test equipment and test instruments...4
6 Test wiring...5
7 Test voltage and test procedure...7
8 DC partial discharge measurement...8
9 Judgment of test results...8
10 Identification and suppression of common interference sources...8
Appendix A (informative appendix) The structure and dimensions of the equalizing ring of the valve side casing...10
Appendix B (informative appendix) Differential signal method to suppress spatial interference...12
Appendix C (informative appendix) Interference identification method for DC partial discharge measurement of converter transformer...13
Foreword
This standard is compiled for the first time.
This standard is compiled in accordance with the rules given in GB/T 1.1-2009 "Guidelines for Standardization Work Part 1.Standard Structure and Compilation".
This standard was proposed by the China Electricity Council.
This standard is under the jurisdiction of the National High Voltage Test Standardization Sub-Technical Committee (DL/T C 02).
Drafting organizations of this standard. State Grid Hubei Electric Power Research Institute, China Electric Power Research Institute Co., Ltd., State Grid
Shaanxi Electric Power Research Institute, State Grid Electric Power Research Institute Wuhan Nanrui Co., Ltd., State Grid Liaoning Electric Power Co., Ltd.
Electric Power Research Institute, State Grid Gansu Electric Power Company Electric Power Research Institute, Power Industry Electrical Equipment Quality Inspection and Testing Center, Tsinghua
University, TBEA Hengyang Transformer Co., Ltd., Baoding Tianwei Baobian Electric Co., Ltd., Changzhou Toshiba Transformer Co., Ltd., ABB
Chongqing Transformer Co., Ltd., Guangzhou Siemens Transformer Co., Ltd., TBEA Co., Ltd., Xi'an Xidian Transformer Co., Ltd.
Company, TBEA Shenyang Transformer Group Co., Ltd., Datang Huainan Luohe Power Plant.
The main drafters of this standard. Xie Qijia, Wang Tao, Zhang Shuzhen, Liu Xiaowei, Cheng Lin, Ying Yong, Hu Chunjiang, Wang Xinsheng, Chen Jiang
Bo, Zhao Linjie, Zhou Yuanxiang, Wu Zhiyuan, Liu Xuemin, Xu Huafeng, Wang Liejun, Lu Xiaodong, Li Wengang, Zhang Jian, Liu Feng, Wang Mizhu.
The opinions or suggestions during the implementation of this standard are fed back to the Standardization Management Center of China Electricity Council (No. 2 Baiguang Road, Beijing)
One, 100761).
Field test method for DC partial discharge measurement of converter transformer
1 Scope
This standard specifies the test conditions, test methods, judgment of test results, and routine tests for DC partial discharge measurement of converter transformers.
See identification and suppression of interference sources.
This standard applies to on-site DC partial discharge measurement of single-phase converter transformers used in DC transmission projects with voltage levels of ±800kV and below.
The ±1100kV converter transformer can be implemented by reference.
2 Normative references
The following documents are indispensable for the application of this standard. For dated reference documents, only the dated version applies to this standard
quasi. For undated reference documents, the latest version (including all amendments) is applicable to this standard.
GB/T 2900.33-2004 Electrical Engineering Terminology Power Electronics Terminology
GB/T 2900.95-2015 Electrotechnical terminology transformers, voltage regulators and reactors
GB/T 7354 Partial discharge measurement
GB/T 18494.2-2007 Converter Transformer Part 2.Converter Transformer for HVDC Transmission
DL/T 274 ±800kV HVDC equipment handover test
DL/T 377 HVDC equipment acceptance test
DL/T 417 Partial discharge field measurement guidelines for power equipment
DL/T 1243 On-site partial discharge test technology for converter transformers
3 Terms and definitions
The following terms and definitions as well as those defined in GB/T 2900.33-2004 and GB/T 2900.95-2015 and the following terms and definitions apply to this
standard.
3.1
DC partial discharge
Electrical discharge in which the insulation between conductors is only partially bridged under a DC electric field.
3.2
DC partial discharge measurements for converter transformer
Apply the specified DC voltage to the valve side winding of the converter transformer and measure whether the partial discharge meets the specified requirements under the DC voltage
test.
Note. This definition is consistent with the DC withstand voltage test of the winding and bushing in DL/T 377, the DC withstand voltage test of the valve-side winding and bushing in DL/T 274, and DL/T 1243
The partial discharge test under DC voltage is consistent.
3.3
Valid pulses of partial discharge
The partial discharge from the converter transformer in the DC partial discharge measurement of the converter transformer, and the apparent partial discharge is greater than the standard given threshold
Value of partial discharge pulse.
3.4
Partial discharge detect device for DC voltage
A digital partial discharge test instrument for continuous detection, recording and statistics of partial discharge under DC voltage.
3.5
Differential signal method
The difference between the analog signals received by two different paths is connected to the partial discharge meter for detection.
4 Test conditions
4.1 Test environment
The test environment conditions should meet.
a) Ambient temperature. 0℃～40℃;
b) Relative humidity. less than or equal to 80%;
c) There is no significant dust, smoke, corrosive gas, steam, smoke pollutants or sand in the surrounding air;
d) There is no significant interference pulse source around.
4.2 The tested converter transformer
The tested converter transformer shall meet the following requirements before the test.
a) The appearance of the equipment is good, and there is no obvious pollution or damage to the outer insulating surface;
b) The equipment has completed other routine test items, and all the results are qualified;
c) The converter transformer that has undergone hot oil circulation treatment should be allowed to stand still before the test, and should be fully exhausted in time during the standing period, and the exhaust should be no less than
2 times, keep the vacuum if necessary; when the ambient temperature is lower than 5℃, heat preservation measures should be taken to avoid the oil temperature dropping too fast during the standing period;
d) Standing time requirements. 500kV and below grade equipment should be no less than 72h, 800kV (including 600kV) grade equipment should be no less than 96h,
When the manufacturer provides otherwise, it shall be implemented according to the manufacturer's requirements;
e) All bushing terminals, fuel tanks, iron cores and clamps shall be reliably grounded, and shall be grounded continuously for at least 2h before the start of the test;
f) The body oil surface temperature should be in the range of 10℃～30℃ during the test.
5 Test equipment and test instruments
5.1 DC high voltage generator
5.1.1 Rated parameters
The rated parameters of the DC high voltage generator should meet.
a) The rated output current should not be less than 10mA;
b) The rated output voltage should not be less than 120% of the DC partial discharge measurement test voltage of the converter transformer under test;
c) Under the rated output voltage, the partial discharge of the DC high-voltage generator body should not exceed 800pC;
d) Under the conditions of rated output voltage and rated output current, the allowable continuous working time should not be less than 150min.
5.1.2 Polarity, ripple factor and short-term stability of the output voltage waveform
The waveform of the HVDC generator should meet.
a) The output voltage polarity should be positive (or switchable polarity);
b) The ripple factor should be less than 3%;
c) The short-term stability within 5 minutes should not exceed 1%.
5.1.3 Main components
The main components of the DC high voltage generator should meet.
a) The charging power supply should be a push-pull variable frequency power supply (or other variable frequency power sources that do not generate high frequency pulses), and the frequency conversion range should be selected
30Hz～300Hz, and continuously adjustable.
b) The body of the voltage doubler rectifier device and the high-voltage DC divider should be connected as a whole, and the body support tube should adopt an umbrella skirt structure; the total height of the device
(Including the equalizing ring) should not exceed 20m; the device body should adopt a structure suitable for on-site rapid assembly and long-distance transportation.
c) The equalizing ring should adopt a double-ring structure, and the designed surface field strength of the equalizing ring should not be greater than 13kV/cm under the rated voltage.
d) The output of the main body should adopt blocking filter.
5.2 Test equipment
5.2.1 Voltage measuring device
The total uncertainty of the test voltage value (arithmetic average) measured by the voltage measuring device should not be greater than 5%, and the total uncertainty of the ripple amplitude measurement should not be greater than 10%.
5.2.2 Current measuring device
When a current measuring device is installed, the uncertainty of measuring current should not be greater than 0.5%.
5.2.3 DC partial discharge tester
In addition to meeting the requirements of GB/T 7354, the DC partial discharge tester should also meet.
a) There should be at least 2 independent channels;
b) With the automatic statistics function of pulse partial discharge and pulse number;
c) It has the function of continuous storage and playback of partial discharge signals, and the continuous storage time is not less than 150min.
6 Test wiring
6.1 Test the main circuit
The two terminals of the tested valve side winding of the converter transformer are short-circuited and connected to the high-voltage output terminal of the high-voltage DC generator via the pressurized lead, and the other non-tested terminals
The sub and converter transformer oil tank, iron core, clamps, etc. should all be reliably grounded.
Taking a two-winding converter transformer as an example, the field test wiring of the DC partial discharge measurement of the converter transformer is shown in Figure 1.Grounding wire should be used
Copper wire with transparent insulating sheath, and there should be only one connection point with the ground network.
6.2 Partial discharge measurement wiring
The partial discharge detection impedance should be connected between the two bushing end screen terminals of the side winding of the tested valve and the ground, and the impedance should be grounded nearby. Figure 1
As shown; the connection line between the impedance and the final screen should be a shielded wire, and the shielding layer of the shielded wire should be grounded nearby.
6.3 Pressure equalizing ring for test
The two bushings of the side winding of the tested valve shall be equipped with a pressure equalizing ring to prevent corona during the test..200kV, 250kV, 400kV, 500kV,
Refer to Appendix A for the size parameters of the equalizing ring required for the DC partial discharge measurement of 600kV and 800kV converter transformers.
Since the installation of the equalizing ring reduces the minimum distance between the high-voltage part and the grounding part, the maximum electric field strength on the surface of the equalizing ring may increase.
Therefore, the electric field calculation and verification should be carried out when selecting the equalizing ring, and the calculated maximum surface field strength should not be greater than 13kV/cm.
6.4 Pressure leads
The pressurized lead should be selected with a larger diameter according to the test voltage and the surface roughness of the lead. DC Partial Discharge Measurement of 500kV Converter Transformer
Conductive telescopic hose with a diameter of not less than 500mm through cable can be used for field test. 800kV converter transformer DC partial discharge measurement field test can be
Use conductive telescopic hose with a diameter of not less than 600mm, or a metal tube with a diameter of not less than 350mm with a smooth surface and no burrs.
6.5 Test circuit layout
The layout of test products and test equipment should meet.
a) The distance between all high-voltage parts in the test circuit and the grounding body or adjacent objects should not be less than the larger of the following two distances.
1) 1.5 times the minimum distance between the end of the winding on the valve side of the sample under test (not including the pressure equalizing ring for testing) and the grounding part of the sample
2) The distance obtained by dividing the test voltage Ud (unit. kV) of the sample by.200 (unit. kV/m).
b) The angle between the pressure lead and the high-voltage DC generator (vertical direction) should not be less than 60°.
7 Test voltage and test procedure
7.1 Test voltage
The test voltage should be a positive voltage. When performing handover test or diagnostic test on site, voltage cannot be pre-applied. The test voltage is factory
85% of the test voltage (or the value specified in the contract).
7.2 Test procedure
The test procedure is shown in Figure 2, and the requirements are as follows.
a) After the test power supply is switched on, the test voltage should be applied at a steady, uniform speed and continuously to the test voltage value.
Apply a lower voltage. The boost time t1 should be no more than 1min. The output current change of the DC generator should be monitored during the boost process,
In the event of a sudden increase or decrease in the current value, the test should be stopped immediately to find out the cause.
b) After the voltage rises to the specified level, it is maintained and the partial discharge detection is performed at the same time. The continuous test time t2 is 90min. During the test,
The voltage fluctuation should not exceed ±3% (arithmetic mean). When the test circuit equipment and the tested converter transformer have an external flashover,
In the event of abnormalities such as discharge, abnormal noise, and sudden current changes, stop the test immediately to find out the cause.
c) After the test is completed, the voltage should be reduced quickly. The depressurization time t3 should be no more than 1 min. Wait for the voltage measuring device to show close to "zero"
It can be discharged and grounded.
7.3 Grounding after the test
After the DC partial discharge measurement test of the converter transformer, sufficient discharge should be carried out to reduce the residual charge that may exist in the insulating structure
Impact on the remaining tests. After the DC partial discharge measurement of the converter transformer, if the AC partial discharge measurement is performed, the grounding time should not be less than 12h.
8 DC partial discharge measurement
8.1 Calibration of apparent partial discharge
To complete the test wiring, according to the method specified in GB/T 7354 and DL/T 417, inject a.2000pC square wave into the end of the winding sleeve on the valve side under test
Perform calibration and verify its linearity at 1000pC.
8.2 Measurement and recording
When the test power is turned on, the background noise level of the channel should be recorded. Under 50% test voltage, the detected pulse level should not be greater than
1000pC, otherwise measures should be taken to suppress interference pulses. During the continuous test time t2, the number of pulses and the
Should be amplitude and polarity.
9 Judgment of test results
9.1 Eligibility criteria
When the following conditions are all satisfied, the test result is considered to be passed.
a) In the last 30 minutes of the test, the number of effective discharge pulses not less than.2000pC recorded should not exceed 30, and at the end
Within 10min, the number of effective discharge pulses not less than.2000pC should not exceed 10.If this condition is not met, you can try
The test was extended by 30 minutes.
b) The test with an extension of 30 minutes is allowed to be carried out only once. Within this 30 minutes, the number of effective discharge pulses not less than.2000pC should not exceed
More than 30, and within the last 10 minutes, the number of effective discharge pulses not less than.2000pC should not exceed 10.
c) After the test, the chromatographic analysis result is qualified and there is no obvious change before and after the test.
9.2 Treatment of unqualified results
Partial discharge measurement is a non-destructive test. When the measurement result fails, but no breakdown occurs and the oil chromatographic data and test after the test
When there is no significant difference before, the sample should not be rejected immediately, and the user and the manufacturer should negotiate further measures.
10 Identification and suppression of common interference sources
10.1 Corona discharge or floating potential discharge
Corona discharge may occur in the test circuit, the outside of the test equipment, the pressure lead and the end of the valve side bushing of the converter transformer under test.
Ungrounded metal conductors near the test loop may have floating potential discharge, which will cause interference to partial discharge measurement. Using ultraviolet imaging and other methods
The method scans the parts where discharge may occur, and can identify corona discharge or floating potential discharge.
The electric field distribution can be improved by increasing the diameter of the wire, installing or optimizing the equalizing ring, and cleaning the surface burrs of the conductive part to eliminate the corona
Discharge; measures such as shielding or grounding can eliminate floating potential discharge.
10.2 Internal discharge of test equipment
The charging transformer, main capacitor, voltage divider and other components of the high-voltage DC generator may cause internal discharge and cause interference to the partial discharge measurement.
Disturb. Using ultrasonic partial discharge detection technology, ultrasonic probes are placed on the external surfaces of components such as charging transformers, main capacitors and voltage dividers to monitor
Test the internal discharge of the loop equipment. At the same time, place an ultrasonic probe near the oil tank of the tested converter transformer and the elevated seat of the tested valve side bushing to monitor
The internal discharge of the tested converter transformer is used as an auxiliary judgment method for partial discharge measurement.
If it is found that the internal discharge of the test equipment interferes with the partial discharge measurement, the test equipment should be repaired or replaced, or a blocking filter should be added.
The gain of the wave device suppresses the source of interference.
10.3 Power interference pulse
The interference pulse of the field test power supply may cause interference to the partial discharge measurement. In order to reduce the interference of the test power supply, the following measures should be taken.
a) The test power supply does not share the bus with other frequent start power supplies;
b) The working power supply of the DC partial discharge tester is connected with an isolation transformer;
c) Adjust the charging frequency of the high-voltage DC generator to reduce the rectification interference pulse of the DC high-voltage generator.
10.4 Electrostatic discharge
In the DC partial discharge measurement test of the converter transformer, the surface of the high-voltage part such as the equalizing ring is tired due to the electrostatic adsorption of dust, smoke and other small particles.
If it accumulates to a certain extent, an instantaneous discharge will occur, which will affect the partial discharge measurement.
To prevent interference caused by electrostatic dust collection, the surface of the DC generator body should be cleaned before the test;
Remove objects and protruding tips, keep the ground moist if necessary, and strengthen ventilation near the test circuit.
10.5 Space interference
Before the square wave calibration is completed and the pressure is not closed, the background noise level of the measurement channel reflects the spatial interference signal level. When the space is dry
When the interference level exceeds 1000pC or affects the partial discharge measurement, the differential signal method should be adopted to reduce the spatial interference. See Appendix B for specific implementation methods.
10.6 External interference pulse
Connect a detection impedance in series between the ground wires of the grid-side winding terminal and connect the signal of the detection impedance to the DC partial discharge tester.
Another detection channel (auxiliary channel), by distinguishing the polarity of the pulse in the partial discharge measurement channel and the auxiliary channel, to identify the external interference pulse
Rush. See Appendix C for specific implementation methods.
Appendix A
(Informative appendix)
Structure and size of pressure equalizing ring of valve side casing
In the field test of the DC partial discharge measurement of the converter transformer, the pressure equalizing ring should be installed on the bushing on the side of the valve under pressure. Figure A.1 provides a
The pressure equalizing ring structure used in the valve side bushing of the converter transformer of the double-ring structure, referring to the size parameters in Table A.1, can be applied to.200kV, 250kV,
400kV, 500kV, 600kV and 800kV converter transformer DC partial discharge measurement field test, Figure A.2 provides another
The structure and size of the 800kV equalizing ring.
Appendix B
(Informative appendix)
Differential signal method to suppress spatial interference
The differential signal method refers to the use of a nearby converter transformer (or voltage divider) to couple spatial interference signals, and achieve interference through signal difference.
The interference signals cancel each other out and suppress spatial interference. The method of realizing signal difference can be divided into impedance polarity reverse connection method and balanced impedance method. impedance
The reverse polarity connection is to use two impedances to connect to the end screen of the valve side bushing of the converter transformer under test and a nearby valve side bushing end of the converter transformer.
On the screen (or at the end of the voltage divider), the polarity of the two impedances is reversed and connected through a three-way cable connector, and the output is connected to the partial amplifier. Balanced impedance method
The wires are wired in accordance with GB/T 7354.Part of the wiring of the measurement system is shown in Figure B.1.
Appendix C
(Informative appendix)
Interference identification method for DC partial discharge measurement of converter transformer
The characteristic parameters of DC partial discharge are the apparent discharge volume and the number of pulses, and the number of pulses of DC partial discharge depends on the oil-paper insulation material.
The electrical time constant is much lower than the cycle repetition time of the AC partial discharge pulse. In the actual measurement, due to the DC partial discharge pulse present
Randomness, no phase reference, low repetition rate, so the pulse identification method in AC partial discharge measurement cannot be fully adopted. But DC PD pulse
It is related to the polarity of the applied DC voltage, and the polarity judgment method is used to distinguish the partial discharge signal inside the tested equipment from external interference
Come, it is the main technical means to solve the field test.
The external interference enters the transformer from the lead wire, and its transmission loop flows into the earth through the ground wire of the end screen of the bushing, and the other is through the network.
The grounding wires of the side windings, iron cores and other grounding parts merge into the earth. The internal discharge transmission circuit of the converter transformer can be passed from the discharge point to the end of the bushing.
The screen, the earth, and the core are grounded to the discharge point t...
|