CN112986775A - Active calibration method for partial discharge pulse phase - Google Patents
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- CN112986775A CN112986775A CN202110514074.7A CN202110514074A CN112986775A CN 112986775 A CN112986775 A CN 112986775A CN 202110514074 A CN202110514074 A CN 202110514074A CN 112986775 A CN112986775 A CN 112986775A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
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Abstract
The invention relates to an active calibration method of a partial discharge pulse phase, which comprises the steps of firstly measuring and obtaining a power frequency phase shift of a partial discharge coupling device by using a power frequency high-voltage generator, a capacitive voltage divider and an oscilloscope through an off-line test, then extracting a power frequency component in an online monitoring output signal of the partial discharge coupling device and correcting the power frequency component, further correcting the corrected power frequency component by using the power frequency phase shift of the partial discharge coupling device, then extracting a partial discharge pulse from the online monitoring output signal of the partial discharge coupling device, and finally obtaining the partial discharge pulse phase according to the corrected power frequency component. The invention combines the characteristics of the partial discharge coupling device and the power frequency component output by the partial discharge coupling device to realize the active calibration of the partial discharge pulse phase, thereby avoiding the problem of additionally arranging a power frequency sensor or a trigger device in the current partial discharge monitoring and realizing the economical and reliable monitoring of the partial discharge.
Description
Technical Field
The invention belongs to the field of power equipment monitoring, and particularly relates to an active calibration method for a partial discharge pulse phase.
Background
With the improvement of energy structure transformation and carbon peak reaching and carbon neutralization targets in China, renewable energy resource installation such as hydropower, wind power and the like can be rapidly developed. However, the operation conditions of hydroelectric and wind power generation sets are complex, and high-voltage equipment such as generators and transformers will age rapidly, so that it is very important to accurately monitor and evaluate the states of the high-voltage equipment. Partial discharge monitoring is an effective insulation assessment means for high-voltage power equipment, and the type of partial discharge is generally identified through a partial discharge phase distribution mode, so pulse phase identification is a key step of partial discharge monitoring. At present, two methods are mainly adopted at home and abroad to realize the phase calibration of partial discharge pulse, firstly, a power frequency voltage sensor is additionally arranged, the outputs of the partial discharge sensor and the power frequency voltage sensor are synchronously collected, and the pulse phase is determined by utilizing the corresponding relation of pulse and power frequency signals; and secondly, a trigger module is additionally arranged, phase voltage or line voltage is used as the input of the trigger module, and partial discharge signal acquisition is triggered when the voltage crosses zero. The chinese patent application, published under the name of partial discharge signal triggered phase synchronous clock source, published under the name of CN103605062A, published under the name of 2014, 26, discloses a synchronous clock source for triggering partial discharge acquisition. The voltage reduction and shaping module and the microprocessor are additionally arranged, so that the construction cost is high, and the popularization and the application are not facilitated. The Chinese patent application with the name of a partial discharge pulse phase angle measuring method based on Fourier series is published in publication number CN102508031B, published in 2014, 8, 27 and discloses a method for realizing partial discharge pulse phase calibration by additionally installing a power frequency sensor. The system has the disadvantages that a power frequency sensor needs to be additionally arranged on a high-voltage secondary circuit, and two acquisition systems need to be configured, so that the construction cost is high, and the popularization and the application are not facilitated.
Disclosure of Invention
The invention aims to overcome the defects and shortcomings in the existing partial discharge monitoring, and provides a partial discharge pulse phase active calibration method which is combined with the characteristics of a partial discharge coupling device and power frequency components in output signals thereof to realize active phase calibration of partial discharge pulses. Compared with the prior art, the method has the advantages that the complexity and equipment requirements of the partial discharge monitoring system are reduced, the popularization and application of partial discharge monitoring are facilitated, the running safety of renewable energy units such as hydropower and wind power can be effectively guaranteed, and the national carbon peak reaching and carbon neutralization target realization is promoted.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for active calibration of partial discharge pulse phase, comprising:
step (1): obtaining power frequency phase shift of partial discharge coupling device through off-line testφ m ；
Step (2): on-line collecting output signal of partial discharge coupling device to obtain sampling sequenceSn；
And (3): from the sequence of samplesSnExtracting industrial frequency component fromS PF ；
And (4): for the extracted power frequency componentS PF Carrying out phase calibration to obtain a power frequency synchronous signalS ’ PF ；
And (5): for the sampling sequenceSnDenoising processing is carried out to obtain a denoising signal sequenceS；
And (6): de-noising a signal sequenceSExtracting a partial discharge pulse signal;
and (7): the phase of each partial discharge pulse is determined.
Furthermore, the partial discharge coupling device is formed by connecting a partial discharge sensor and a partial discharge signal conditioner in series, and comprises an input end and an output end.
Further, the partial discharge sensor may be a high voltage capacitive coupler or a high frequency current transformer.
Further, the step (1) includes:
step (1-1): the output of the power frequency high-voltage generator is simultaneously connected with the input end of the partial discharge coupling device and the input end of the capacitive voltage divider, and the output ends of the partial discharge coupling device and the capacitive voltage divider are connected with two input channels of the oscilloscope;
step (1-2): electrifying the power frequency high-voltage generator, and adjusting the power frequency voltage output by the power frequency high-voltage generator to the rated voltage of the partial discharge sensor;
step (1-3): synchronously measuring the outputs of the capacitive voltage divider and the local discharge coupling device by using an oscilloscope;
step (1-4): and reading the power frequency phase shift of the partial discharge coupling device from the oscilloscope.
Further, the step (3) includes:
step (3-1): obtaining a sampling sequence through Hanning window Fourier transformSnWindowed spectrumf H (n)；
Step (3-2): obtaining power frequency component by ratio correction methodS PF Frequency of (2)fAmplitude, amplitudeAAnd phaseφ；
Step (3-3): reconstructing to obtain power frequency components in the sampling sequenceS PF The formula is shown below
Further, the step (4) is to obtain the power frequency phase shift of the sensor according to the step (1)φ m And the power frequency component obtained in the step (3-2)S PF Phase ofφCalculating to obtain corrected phaseφ ’ =φ m +φThereby obtaining a power frequency synchronous signalS ’ PF Is composed of
Further, the step (5) includes:
step (5-1): sampling sequence using waveletsSnPerforming wavelet decomposition;
step (5-2): carrying out hard threshold processing on wavelet coefficients of each layer obtained by decomposition by using a classical threshold;
step (5-3): reconstructing by utilizing wavelet coefficients of each layer and scale coefficient of the highest layer after threshold processing to obtain a de-noised signal sequenceS。
Further, the step (7) includes:
step (7-1): searching the position of the maximum value of the pulse amplitude absolute valueP m ；
Step (7-2): determiningP m Corresponding power frequency synchronous signalS ’ PF The phase of (2) is the pulse phase.
The invention has the beneficial effects that: according to the invention, the local discharge pulse phase calibration is carried out by utilizing the characteristics of the local discharge coupling device and the power frequency component in the output signal thereof, so that an additional power frequency sensor or a trigger module is avoided, the complexity and the construction cost of a monitoring system can be effectively reduced, and the application of local discharge monitoring in renewable energy power generation high-voltage equipment such as hydropower, wind power and the like can be remarkably promoted.
Drawings
Fig. 1 is a schematic flow chart of an active calibration method for partial discharge pulse phase according to the present invention.
Fig. 2 is a schematic diagram of power frequency phase shift measurement of the partial discharge coupling device.
Fig. 3 is a waveform diagram of power frequency phase shift measurement of a partial discharge coupling device.
Fig. 4 is a waveform diagram of a measured signal of the partial discharge coupling device on the outlet bus of the generator.
Fig. 5 is a waveform diagram of the partial discharge pulse and the power frequency synchronizing signal.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings and embodiments:
as shown in fig. 1, the present invention provides an active calibration method for partial discharge pulse phase, which includes:
step (1): obtaining a power frequency waveform diagram of the input end and the output end of the partial discharge coupling device shown in fig. 3 by using the off-line test structure shown in fig. 2, wherein a curve marked with 1 in the diagram is the output of a capacitive voltage divider, namely the input of the partial discharge coupling device, a curve marked with 2 in the diagram is the output of the partial discharge coupling device, and obtaining the power frequency phase shift of the partial discharge coupling device according to the power frequency phase difference of the two waveformsφ m . The off-line test structure comprises a partial discharge coupling device, a capacitive voltage divider, a power frequency high-voltage generator and an oscilloscope, wherein the partial discharge coupling device is formed by connecting a high-voltage capacitive coupler and a partial discharge signal conditioner in series and comprises an input end and an output end. The output end of the power frequency high-voltage generator is simultaneously connected with the input end of the partial discharge coupling device and the input end of the capacitive voltage divider, and the output ends of the partial discharge coupling device and the capacitive voltage divider are respectively connected with two input channels of the oscilloscope.
Step (2): the input end of the partial discharge coupling device is connected with an A-phase outlet bus of the motor, signals output by the partial discharge coupling device are collected on line to obtain waveforms shown in figure 4, and the corresponding sampling sequence of the signals isSn；
And (3): from the sequence of samplesSnExtracting industrial frequency component fromS PF ；
And (4): for the extracted power frequency componentS P Carrying out phase calibration to obtain a power frequency synchronous signalS ’ PF ；
And (5): for the sampling sequenceSnDenoising processing is carried out to obtain a denoising signal sequenceS；
And (6): de-noising a signal sequenceSExtracting a partial discharge pulse signal, as shown in fig. 5, wherein a curve labeled 3 in the figure is a partial discharge pulse waveform, and a curve labeled 4 in the figure is a power frequency synchronous signal waveform;
and (7): the phase of each partial discharge pulse is determined.
The step (1) comprises the following implementation steps:
step (1-1): as shown in fig. 2, the output of the power frequency high voltage generator is simultaneously connected with the input end of the partial discharge coupling device and the input end of the capacitive voltage divider, and the output ends of the partial discharge coupling device and the capacitive voltage divider are respectively connected with two input channels of the oscilloscope;
step (1-2): electrifying the power frequency high-voltage generator, and regulating the output power frequency voltage to the rated voltage of the high-voltage capacitive coupler by 30 kV;
step (1-3): the outputs of the partial discharge coupling device and the capacitive voltage divider are synchronously measured by using an oscilloscope, and the measured waveforms are shown in FIG. 3;
step (1-4): the power frequency phase shift of the partial discharge coupling device is read as 82 ° advanced from the resulting waveform shown in fig. 3.
The step (3) comprises the following implementation steps:
step (3-1): obtaining a sampling sequence through Hanning window Fourier transformSnWindowed spectrumf H (n)；
Step (3-2): obtaining frequency of power frequency signal by ratio correction methodfAmplitude, amplitudeAAnd phaseφ；
Step (3-3): reconstructing to obtain power frequency components in the sampling sequenceS PF The formula is shown below
The step (4) is to obtain the power frequency phase shift of the partial discharge coupling device according to the step (1)φ m And the phase of the power frequency component obtained in the step (3-2)φCalculating to obtain corrected phaseφ ’ =φ m +φThereby obtaining a power frequency synchronous signalS ’ PF Is composed of
The step (5) comprises the following implementation steps:
step (5-1): sampling with db2 waveletSequence ofSnPerforming 10-layer wavelet decomposition;
step (5-2): carrying out hard threshold processing on wavelet coefficients of each layer obtained by decomposition by using a classical threshold;
step (5-3): reconstructing by utilizing wavelet coefficients of each layer and scale coefficient of the highest layer after threshold processing to obtain a de-noised signal sequenceS。
The step (7) comprises the following implementation steps: :
step (7-1): searching the position of the maximum value of the pulse amplitude absolute valueP m ；
Step (7-2): determiningP m Corresponding power frequency synchronous signalS ’ PF The phase of (2) is the pulse phase.
It will be understood by those skilled in the art that the foregoing is illustrative of specific embodiments of this invention and is not to be construed as limiting the scope of the invention, which is defined by the appended claims.
Claims (8)
1. A method for active calibration of partial discharge pulse phase, comprising:
step (1): obtaining power frequency phase shift of partial discharge coupling device through off-line testφ m ；
Step (2): on-line collecting output signal of partial discharge coupling device to obtain sampling sequenceSn；
And (3): from the sequence of samplesSnExtracting industrial frequency component fromS PF ；
And (4): for the extracted power frequency componentS PF Carrying out phase calibration to obtain a power frequency synchronous signalS ’ PF ；
And (5): for the sampling sequenceSnDenoising processing is carried out to obtain a denoising signal sequenceS；
And (6): de-noising a signal sequenceSExtract part of Chinese medicinal materialsA discharge pulse signal;
and (7): the phase of each partial discharge pulse is determined.
2. The method of claim 1, wherein the partial discharge coupling device comprises a partial discharge sensor and a partial discharge signal conditioner connected in series, and comprises an input terminal and an output terminal.
3. The active calibration method for partial discharge pulse phase according to claim 2, wherein the partial discharge sensor is a high voltage capacitive coupler or a high frequency current transformer.
4. The active calibration method for partial discharge pulse phase according to claim 1, wherein the step (1) comprises:
step (1-1): the output of the power frequency high-voltage generator is simultaneously connected with the input end of the partial discharge coupling device and the input end of the capacitive voltage divider, and the output ends of the partial discharge coupling device and the capacitive voltage divider are connected with two input channels of the oscilloscope;
step (1-2): electrifying the power frequency high-voltage generator, and adjusting the power frequency voltage output by the power frequency high-voltage generator to the rated voltage of the partial discharge sensor;
step (1-3): synchronously measuring the outputs of the capacitive voltage divider and the local discharge coupling device by using an oscilloscope;
step (1-4): and reading the power frequency phase shift of the partial discharge coupling device from the oscilloscope.
5. The active calibration method for partial discharge pulse phase according to claim 1, wherein the step (3) comprises:
step (3-1): obtaining a sampling sequence through Hanning window Fourier transformSnWindowed spectrumf H (n)；
Step (3-2): obtaining a sampling sequence by using a ratio correction methodSnFrequency of medium power frequency signalfAmplitude, amplitudeAAnd phaseφ；
Step (3-3): reconstructing to obtain a sampling sequenceSnMedium power frequency componentS PF The formula is shown below
6. The active calibration method for partial discharge pulse phase according to claim 5, wherein the step (4) is performed according to the phase shift of the power frequency of the partial discharge coupling device obtained in the step (1)φ m And the sampling sequence obtained in the step (3-2)SnMedium power frequency componentS PF Phase ofφCalculating to obtain corrected phaseφ ’ =φ m +φThereby obtaining a power frequency synchronous signalS ’ PF Is composed of
7. The active calibration method for partial discharge pulse phase according to claim 1, wherein said step (5) comprises:
step (5-1): sampling sequence using waveletsSnPerforming wavelet decomposition;
step (5-2): carrying out hard threshold processing on wavelet coefficients of each layer obtained by decomposition by using a classical threshold;
step (5-3): reconstructing by utilizing wavelet coefficients of each layer and scale coefficient of the highest layer after threshold processing to obtain a de-noised signal sequenceS。
8. The active calibration method for partial discharge pulse phase according to claim 1, wherein said step (7) comprises:
step (7-1): searching the position of the maximum value of the pulse amplitude absolute valueP m ；
Step (7-2): determiningP m Corresponding power frequency synchronous signalS ’ PF The phase of (2) is the pulse phase.
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| CN114280441A (en) * | 2021-12-10 | 2022-04-05 | 武汉三江中电科技有限责任公司 | Local discharge signal simulation method and device convenient to expand and readable medium |
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