DL/T 911-2016 PDF English
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| DL/T 911-2016 | English | 215 |
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Frequency response analysis on winding deformation of power transformers
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| DL/T 911-2004 | English | 70 |
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Frequency response analysis on winding deformation of power transformers
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DL/T 911-2016: Frequency response analysis on winding deformation of power transformers---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/DLT911-2016
DL
ELECTRICITY INDUSTRY STANDARD
ICS 27.100
F 24
Filing No.. 53992-2016
Replacing DL/T 911-2004
Frequency response analysis on winding deformation of
power transformers
Issued on. FEBRUARY 05, 2016
Implemented on. JULY 01, 2016
Issued by. National Energy Administration
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative references... 5
3 Terms and definitions... 5
4 Detection principle... 6
5 Requirements for detection instruments... 8
6 Detection method... 9
7 Analysis and judgment of winding deformation... 11
Appendix A (Informative) Basic requirements for transformer winding deformation
tester... 14
Appendix B (Informative) Data export format of frequency response characteristic
curve... 16
Appendix C (Normative) Use the correlation coefficient R to assist in determining the
deformation of transformer windings... 18
Appendix D (Informative) Example of using the longitudinal comparison method to
determine the deformation of transformer windings... 20
Appendix E (Informative) Example of using lateral comparison method to judge
transformer winding deformation... 21
Appendix F (Informative) Example of using comprehensive analysis method to judge
transformer winding deformation... 22
Appendix G (Informative) Example of typical interference waveform when the
transformer winding is deformed... 24
Appendix H (Informative) Process for determining transformer winding deformation
using frequency response analysis method... 27
Appendix I (Informative) Typical amplitude-frequency response characteristic curves
when transformer windings are deformed... 29
1 Scope
This standard specifies the basic requirements for detecting transformer winding
deformation by frequency response analysis.
This standard applies to power transformers with voltage levels of 66kV and above and
other transformers for special purposes.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
DL/T 1093 Guide for reactance method to detect and diagnose winding deformation
of power transformer
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Winding deformation
Refers to the axial or radial dimensional changes of power transformer windings
under the action of electric or mechanical forces, when they are subjected to short-
circuit current shock or collision during transportation; it is usually manifested as
local twisting, bulging or displacement of windings.
3.2
Bilateral network
Refers to a network with a pair of input ports and a pair of output ports. If the
network is composed of linear resistors, inductors (including mutual inductance),
capacitors, meanwhile it does not contain any independent power supply inside, it
is called a passive linear bilateral network.
3.3
Transfer function
The ratio of the output to the input of a passive bilateral network, which is expressed
in Laplace transform form. The distribution of the poles and zeros of the transfer
function is closely related to the internal component parameters, connection method,
port connection impedance of the bilateral network.
3.4
Frequency response
Refers to the relationship between the transfer function H(jω) of the network and
the angular frequency ω in the sinusoidal steady state. The relationship between the
amplitude of H(jω) and the frequency ω is usually called the amplitude-frequency
response; the relationship between the phase of H(jω) and the frequency ω is called
the phase-frequency response.
4 Detection principle
Under the action of a high frequency voltage, each winding of the transformer can be
regarded as a passive linear bilateral network, which is composed of distributed
parameters such as linear resistance, inductance (mutual inductance), capacitance.
5 Requirements for detection instruments
5.1 Basic requirements for detection instruments
For the basic requirements of transformer winding deformation tester, please refer to
Appendix A.
5.2 Sweep frequency detection range
The sweep frequency detection range shall include the frequency band of 1kHz ~
1000kHz.
5.4 Sweep frequency accuracy
The frequency accuracy of the sine wave signal output by the signal source shall not
exceed 0.01%.
5.5 Scanning frequency interval
The scanning frequency interval should be 1kHz.
5.6 Impedance matching method
The output impedance RS of the sine wave signal output source US of the detection
instrument shall be 50Ω; the input impedance of the two signal detection terminals U1
and U2 shall not be lower than 1MΩ; a 50Ω matching resistor R shall be installed
between the signal response terminal and the common terminal (see Figure 1).
5.7 Detection accuracy
The detection instrument shall have a dynamic detection range of -100dB ~ 20dB; the
absolute error of detection within the range of -80dB ~ 20dB shall be less than 1dB.
5.10 Data query function
The search function can be used to query the historical data of the same model, the same
manufacturer and the transformer.
6 Detection method
6.1 Detection condition requirements
6.1.1 Detection shall not be carried out in thunderstorms, rain, snow and other weather.
The detection shall strictly implement the requirements of the power safety work
regulations; it shall strictly implement the organizational and technical measures to
ensure safety. The test personnel shall be trained and have the ability to conduct on-site
tests.
6.1.3 Before testing, all leads connected to the end of the transformer bushing shall be
removed; the removed leads shall be as far away from the tested transformer bushing
as possible.
6.2 Wiring requirements
6.2.1 All wiring shall be stable and reliable. Special wiring clamps shall be used to
reduce contact resistance.
6.2.2 The same wiring method shall be used for the same transformer or the same model.
The test cable and ground lead on the excitation end and the response end can be led
down along the porcelain sleeve of the bushing. The ground wire cannot be entangled
and shall be electrically connected to the metal box of the transformer nearby, to
maintain good high-frequency grounding performance.
6.3 Wiring method
6.3.1 According to the connection structure of the transformer winding, select the
excitation end (input end) and response end (measurement end) of the winding to be
tested according to Figure 2; the ends of other windings are suspended.
7 Analysis and judgment of winding deformation
7.1 Analysis and judgment principle
The frequency response analysis method is used to judge the deformation of transformer
windings. The frequency response data curves of three-phase windings of the same
voltage level are mainly compared longitudinally, laterally, comprehensively; the
changes in the amplitude-frequency characteristics of the transformer windings are
judged by the correlation coefficient.
7.2 Longitudinal comparison method
The longitudinal comparison method refers to comparing the amplitude-frequency
response characteristics of the same transformer, the same winding, the same tap
position, the different periods;
7.3 Lateral comparison method
The lateral comparison method refers to comparing the amplitude-frequency response
characteristics of three-phase windings of the same voltage level of the transformer. If
necessary, the amplitude-frequency response characteristics of the same model
transformer manufactured by the same manufacturer at the same time are used to judge
whether the transformer winding is deformed. This method does not require the original
amplitude-frequency response characteristics of the transformer;
7.4 Comprehensive analysis method
The comprehensive analysis method mainly compares the three-phase frequency
response fingerprints of the transformer laterally and longitudinally; makes a judgment
based on the differences in the three-phase frequency response fingerprints.
See Appendix F for an example of using the comprehensive comparison method to
judge the deformation of the transformer winding.
7.5 Analysis process
7.6 Winding deformation analysis
7.6.1 The typical amplitude-frequency response characteristic curve of transformer
winding usually contains multiple obvious peaks and troughs. The changes in the
distribution position and number of peaks or troughs are important bases for analyzing
transformer winding deformation. See Appendix I for the typical amplitude-frequency
response characteristic curve of transformer winding deformation.
DL/T 911-2016
DL
ELECTRICITY INDUSTRY STANDARD
ICS 27.100
F 24
Filing No.. 53992-2016
Replacing DL/T 911-2004
Frequency response analysis on winding deformation of
power transformers
Issued on. FEBRUARY 05, 2016
Implemented on. JULY 01, 2016
Issued by. National Energy Administration
Table of Contents
Foreword... 3
1 Scope... 5
2 Normative references... 5
3 Terms and definitions... 5
4 Detection principle... 6
5 Requirements for detection instruments... 8
6 Detection method... 9
7 Analysis and judgment of winding deformation... 11
Appendix A (Informative) Basic requirements for transformer winding deformation
tester... 14
Appendix B (Informative) Data export format of frequency response characteristic
curve... 16
Appendix C (Normative) Use the correlation coefficient R to assist in determining the
deformation of transformer windings... 18
Appendix D (Informative) Example of using the longitudinal comparison method to
determine the deformation of transformer windings... 20
Appendix E (Informative) Example of using lateral comparison method to judge
transformer winding deformation... 21
Appendix F (Informative) Example of using comprehensive analysis method to judge
transformer winding deformation... 22
Appendix G (Informative) Example of typical interference waveform when the
transformer winding is deformed... 24
Appendix H (Informative) Process for determining transformer winding deformation
using frequency response analysis method... 27
Appendix I (Informative) Typical amplitude-frequency response characteristic curves
when transformer windings are deformed... 29
1 Scope
This standard specifies the basic requirements for detecting transformer winding
deformation by frequency response analysis.
This standard applies to power transformers with voltage levels of 66kV and above and
other transformers for special purposes.
2 Normative references
The following documents are essential to the application of this document. For the dated
documents, only the versions with the dates indicated are applicable to this document;
for the undated documents, only the latest version (including all the amendments) is
applicable to this standard.
DL/T 1093 Guide for reactance method to detect and diagnose winding deformation
of power transformer
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Winding deformation
Refers to the axial or radial dimensional changes of power transformer windings
under the action of electric or mechanical forces, when they are subjected to short-
circuit current shock or collision during transportation; it is usually manifested as
local twisting, bulging or displacement of windings.
3.2
Bilateral network
Refers to a network with a pair of input ports and a pair of output ports. If the
network is composed of linear resistors, inductors (including mutual inductance),
capacitors, meanwhile it does not contain any independent power supply inside, it
is called a passive linear bilateral network.
3.3
Transfer function
The ratio of the output to the input of a passive bilateral network, which is expressed
in Laplace transform form. The distribution of the poles and zeros of the transfer
function is closely related to the internal component parameters, connection method,
port connection impedance of the bilateral network.
3.4
Frequency response
Refers to the relationship between the transfer function H(jω) of the network and
the angular frequency ω in the sinusoidal steady state. The relationship between the
amplitude of H(jω) and the frequency ω is usually called the amplitude-frequency
response; the relationship between the phase of H(jω) and the frequency ω is called
the phase-frequency response.
4 Detection principle
Under the action of a high frequency voltage, each winding of the transformer can be
regarded as a passive linear bilateral network, which is composed of distributed
parameters such as linear resistance, inductance (mutual inductance), capacitance.
5 Requirements for detection instruments
5.1 Basic requirements for detection instruments
For the basic requirements of transformer winding deformation tester, please refer to
Appendix A.
5.2 Sweep frequency detection range
The sweep frequency detection range shall include the frequency band of 1kHz ~
1000kHz.
5.4 Sweep frequency accuracy
The frequency accuracy of the sine wave signal output by the signal source shall not
exceed 0.01%.
5.5 Scanning frequency interval
The scanning frequency interval should be 1kHz.
5.6 Impedance matching method
The output impedance RS of the sine wave signal output source US of the detection
instrument shall be 50Ω; the input impedance of the two signal detection terminals U1
and U2 shall not be lower than 1MΩ; a 50Ω matching resistor R shall be installed
between the signal response terminal and the common terminal (see Figure 1).
5.7 Detection accuracy
The detection instrument shall have a dynamic detection range of -100dB ~ 20dB; the
absolute error of detection within the range of -80dB ~ 20dB shall be less than 1dB.
5.10 Data query function
The search function can be used to query the historical data of the same model, the same
manufacturer and the transformer.
6 Detection method
6.1 Detection condition requirements
6.1.1 Detection shall not be carried out in thunderstorms, rain, snow and other weather.
The detection shall strictly implement the requirements of the power safety work
regulations; it shall strictly implement the organizational and technical measures to
ensure safety. The test personnel shall be trained and have the ability to conduct on-site
tests.
6.1.3 Before testing, all leads connected to the end of the transformer bushing shall be
removed; the removed leads shall be as far away from the tested transformer bushing
as possible.
6.2 Wiring requirements
6.2.1 All wiring shall be stable and reliable. Special wiring clamps shall be used to
reduce contact resistance.
6.2.2 The same wiring method shall be used for the same transformer or the same model.
The test cable and ground lead on the excitation end and the response end can be led
down along the porcelain sleeve of the bushing. The ground wire cannot be entangled
and shall be electrically connected to the metal box of the transformer nearby, to
maintain good high-frequency grounding performance.
6.3 Wiring method
6.3.1 According to the connection structure of the transformer winding, select the
excitation end (input end) and response end (measurement end) of the winding to be
tested according to Figure 2; the ends of other windings are suspended.
7 Analysis and judgment of winding deformation
7.1 Analysis and judgment principle
The frequency response analysis method is used to judge the deformation of transformer
windings. The frequency response data curves of three-phase windings of the same
voltage level are mainly compared longitudinally, laterally, comprehensively; the
changes in the amplitude-frequency characteristics of the transformer windings are
judged by the correlation coefficient.
7.2 Longitudinal comparison method
The longitudinal comparison method refers to comparing the amplitude-frequency
response characteristics of the same transformer, the same winding, the same tap
position, the different periods;
7.3 Lateral comparison method
The lateral comparison method refers to comparing the amplitude-frequency response
characteristics of three-phase windings of the same voltage level of the transformer. If
necessary, the amplitude-frequency response characteristics of the same model
transformer manufactured by the same manufacturer at the same time are used to judge
whether the transformer winding is deformed. This method does not require the original
amplitude-frequency response characteristics of the transformer;
7.4 Comprehensive analysis method
The comprehensive analysis method mainly compares the three-phase frequency
response fingerprints of the transformer laterally and longitudinally; makes a judgment
based on the differences in the three-phase frequency response fingerprints.
See Appendix F for an example of using the comprehensive comparison method to
judge the deformation of the transformer winding.
7.5 Analysis process
7.6 Winding deformation analysis
7.6.1 The typical amplitude-frequency response characteristic curve of transformer
winding usually contains multiple obvious peaks and troughs. The changes in the
distribution position and number of peaks or troughs are important bases for analyzing
transformer winding deformation. See Appendix I for the typical amplitude-frequency
response characteristic curve of transformer winding deformation.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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