CN112698158B - Partial discharge electrical positioning method and device for transformer - Google Patents
Partial discharge electrical positioning method and device for transformer Download PDFInfo
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- CN112698158B CN112698158B CN202011271487.9A CN202011271487A CN112698158B CN 112698158 B CN112698158 B CN 112698158B CN 202011271487 A CN202011271487 A CN 202011271487A CN 112698158 B CN112698158 B CN 112698158B
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- 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
- G01R31/1227—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 of components, parts or materials
Abstract
The application discloses a partial discharge electrical positioning method and device for a transformer, which are used for solving the technical problems that an existing partial discharge positioning method has errors and positioning accuracy is difficult to guarantee. The method comprises the following steps: determining that partial discharge of the transformer occurs in the main insulation of the transformer according to the polarity of the first current signal and the polarity of the second current signal; the first current signal and the second current signal are pulse current signals collected by two high-frequency current transformers; respectively calculating frequency spectrums of the first current signal and the second current signal, and determining the energy occupation ratio of the intermediate frequency region of the first current signal and the energy occupation ratio of the intermediate frequency region of the second current signal based on the frequency spectrums; and determining the distance ratio of the partial discharge according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, thereby determining the position of the partial discharge. The method realizes the positioning of the partial discharge of the transformer and simultaneously ensures the accuracy of the positioning of the partial discharge.
Description
Technical Field
The application relates to the technical field of power equipment detection, in particular to a partial discharge electrical positioning method and device for a transformer.
Background
A transformer is one of important devices in an electric power system, and the healthy operation of the transformer is related to the operation state of the whole electric power system. At present, the insulation form of a large transformer is mainly oil-paper composite insulation, insulation defects are inevitably generated in the production, manufacturing and equipment operation processes, and the partial discharge phenomenon can be generated under the action of a high electric field. The long-term development of partial discharges can lead to a gradual deterioration of the insulation material, eventually leading to failure of the entire insulation system, causing serious accidents. Therefore, it is very important to detect and locate the partial discharge position of the transformer.
The existing transformer partial discharge positioning method is mainly an ultrasonic method. But the ultrasonic wave can be refracted when meeting obstacles in the transmission process, and the propagation speeds of the ultrasonic wave in different media are different. Therefore, the accuracy of the localization of the partial discharge cannot be guaranteed by localizing the partial discharge by the ultrasonic wave.
Disclosure of Invention
The embodiment of the application provides a partial discharge electrical positioning method and device for a transformer, and aims to solve the technical problems that an existing partial discharge positioning method has errors and accurate partial discharge positioning is difficult to guarantee.
In one aspect, an embodiment of the present application provides a method for electrically positioning partial discharge of a transformer, including: determining that partial discharge of the transformer occurs in the main insulation of the transformer according to the polarity of the first current signal and the polarity of the second current signal; the first current signal is a pulse current signal collected by a first high-frequency current transformer; the second current signal is a pulse current signal collected by a second high-frequency current transformer; calculating a frequency spectrum of the first current signal, and determining an intermediate frequency region energy ratio of the first current signal based on the frequency spectrum; calculating the frequency spectrum of the second current signal, and determining the energy ratio of the intermediate frequency region of the second current signal based on the frequency spectrum; determining the distance ratio of partial discharge according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, thereby determining the position of the partial discharge; wherein the distance ratio is used for indicating the ratio of the distances from the positions of the partial discharge to the left and right ends of the transformer winding.
According to the electrical positioning method for partial discharge of the transformer, the main insulation of the transformer at the partial discharge position is determined according to the polarity relationship between the first current signal and the second current signal, and the partial discharge position is preliminarily positioned. Aiming at the partial discharge occurring in the main insulation, the ratio of the distance from the discharge position to the left end and the distance from the discharge position to the right end of the transformer winding is determined by calculating the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, and then the occurrence position of the partial discharge can be accurately determined according to the physical parameters of the winding. The positioning of the partial discharge of the transformer is realized, and the accuracy of the positioning of the partial discharge is ensured. Moreover, the positioning is carried out according to the current signals generated by the partial discharge, so that the problem that the traditional ultrasonic waves have errors in the propagation process is solved, and the positioning method provided by the embodiment of the application is more feasible.
In one implementation manner of the present application, determining that a partial discharge of the transformer occurs in a main insulation of the transformer according to a polarity of the first current signal and a polarity of the second current signal specifically includes: respectively determining the polarity of the first current signal and the polarity of the second current signal; in case the polarity of the first current signal is the same as the polarity of the second current signal, it is determined that a partial discharge of the transformer occurs in the main insulation of the transformer.
In an implementation manner of the present application, a frequency spectrum of the first current signal is calculated, and an energy ratio of an intermediate frequency region of the first current signal is determined based on the frequency spectrum, specifically: by the formula
Obtaining a frequency spectrum of the first current signal; wherein x is1(t) denotes a first current signal, X1(ω) represents a frequency spectrum of the first current signal; determining the energy ratio of the intermediate frequency region of the first current signal by the following formula;
wherein the content of the first and second substances,
representing the energy fraction in the intermediate frequency region of the first current signal, E1MRepresenting the energy of the intermediate frequency region of the first current signal, E1Representing the total energy of the first current signal.
In an implementation manner of the present application, a frequency spectrum of the second current signal is calculated, and an energy ratio of an intermediate frequency region of the second current signal is determined based on the frequency spectrum, specifically: by the formula
Obtaining a frequency spectrum of the second current signal; wherein x is2(t) represents a second current signal, X2(ω) represents a frequency spectrum of the second current signal; determining the energy ratio of the intermediate frequency region of the second current signal by the following formula;
wherein the content of the first and second substances,
representing the energy fraction in the intermediate frequency region of the second current signal, E2MRepresenting the energy of the intermediate frequency region of the second current signal, E2Representing the total energy of the second current signal.
According to the partial discharge electric positioning method, the energy ratio of the intermediate frequency region is determined through the integral of the signal frequency spectrum in the specific frequency range, the convenience and the accuracy of the calculation of the signal energy and the signal energy ratio are guaranteed, and the accuracy of the partial discharge position determined through the energy ratio subsequently is further guaranteed.
In an implementation manner of the present application, determining a distance ratio of partial discharge according to an energy ratio of an intermediate frequency region of a first current signal and an energy ratio of an intermediate frequency region of a second current signal, so as to determine a position of the partial discharge specifically includes: by the formula
Determining a distance ratio of the partial discharge; wherein the content of the first and second substances,
represents the energy fraction of the intermediate frequency region of the first current signal,
represents the energy-to-energy ratio of the intermediate frequency region of the second current signal, and z represents the distance ratio; acquiring physical parameters of a transformer winding; and determining the position of the partial discharge according to the distance ratio and the physical parameters.
In one implementation of the present application, the intermediate frequency region of the first current signal or the second current signal ranges from 10khz to 1 Mhz.
In one implementation of the present application, the method further comprises: determining that a polarity of the first current signal is different from a polarity of the second current signal; calculating the first peak arrival time of the first current signal, calculating the first peak arrival time of the second current signal and calculating the time ratio between the first current signal and the second current signal; and determining the distance ratio of the partial discharge according to the time ratio, thereby determining the position of the partial discharge.
According to the electrical positioning method for partial discharge of the transformer, the longitudinal insulation of the transformer where the partial discharge occurs is determined through the polarity relationship between the first current signal and the second current signal, and the position of the partial discharge can be positioned even if the partial discharge of the transformer occurs in the longitudinal insulation. And then, determining a time ratio based on the first peak arrival time of the first current signal and the second current signal, further determining the distance ratio of the partial discharge position to the left end and the right end of the transformer winding, further determining the specific position of partial discharge, and simultaneously ensuring the accuracy of positioning of longitudinal insulation partial discharge.
In one implementation manner of the present application, determining a distance ratio of the partial discharge according to the time ratio, so as to determine a position of the partial discharge specifically includes: by the formula
Determining a distance ratio of the partial discharge; wherein z represents a distance ratio, T represents a time ratio, T1Representing the first peak arrival time, t, of the first current signal2Represents a first peak arrival time of the second current signal; acquiring physical parameters of a transformer winding; and determining the position of the partial discharge according to the distance ratio and the physical parameters.
In one implementation of the present application, the physical parameters include any one or more of: winding height, winding diameter, winding mode, number of wire cakes and number of coil turns.
On the other hand, this application embodiment still provides a transformer partial discharge electrical positioning device, includes: the first determination module is used for determining that partial discharge of the transformer occurs in main insulation of the transformer according to the polarity of the first current signal and the polarity of the second current signal; the first current signal is a pulse current signal collected by a first high-frequency current transformer; the second current signal is a second pulse current signal collected by a second high-frequency current transformer; the calculating module is used for calculating the frequency spectrum of the first current signal, determining the energy occupation ratio of the intermediate frequency region of the first current signal based on the frequency spectrum, calculating the frequency spectrum of the second current signal and determining the energy occupation ratio of the intermediate frequency region of the second current signal based on the frequency spectrum; the second determining module is used for determining the distance ratio of the partial discharge according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, so as to determine the position of the partial discharge; wherein the distance ratio is used for indicating the ratio of the distance from the position of partial discharge to the left end distance and the right end distance of the transformer winding.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:
fig. 1 is a flowchart of a partial discharge electrical positioning method for a transformer according to an embodiment of the present disclosure;
fig. 2 is a schematic diagram of an internal structure of a partial discharge electrical positioning apparatus for a transformer according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The power transformer is one of the most important devices in the power system, and the operation state of the power transformer directly affects the safe operation of the power system. At present, the insulation form of a large transformer is mainly oil-paper composite insulation, and local insulation defects are inevitably formed due to various factors in the processes of production, manufacturing and equipment operation. And the insulation defect can generate partial discharge under the action of a high electric field. The long-term development of partial discharge can lead to the gradual degradation of the insulating material, and finally lead to the failure of the whole insulating system, thereby causing serious accidents and causing huge economic and safety losses. Therefore, the detection and the positioning of the partial discharge of the power transformer are of great significance to the optimization of the insulation design of the equipment and the maintenance of the safe operation of the equipment.
The current common method for positioning partial discharge of the transformer is an ultrasonic method. When a partial discharge occurs, vibration is caused at the discharge position to generate ultrasonic waves, and the ultrasonic waves propagate from the partial discharge point to the periphery as spherical waves. By arranging a plurality of ultrasonic sensors on the transformer housing, the discharge position can be calculated according to the time difference of the ultrasonic waves reaching the ultrasonic sensors.
However, when the ultrasonic wave encounters an obstacle in the process of propagation, the ultrasonic wave is refracted or reflected, and the propagation speeds of the ultrasonic wave in different media are different. These factors all bring errors to the positioning process of the partial discharge, and it is difficult to ensure the accuracy of the partial discharge positioning.
In order to solve the above technical problems, embodiments of the present application provide an electrical positioning method and apparatus for partial discharge of a transformer, current signals caused by partial discharge are collected at two ends of a winding of the transformer, a primary insulation or a longitudinal insulation where the partial discharge occurs is preliminarily determined according to a polarity relationship of the current signals at the two ends, and then a distance ratio is determined according to an energy ratio or a first peak arrival time in an intermediate frequency region, so as to determine a position of the partial discharge. The method not only realizes the positioning of the partial discharge of the transformer, but also ensures the accuracy of the positioning of the partial discharge position.
The technical solutions proposed in the embodiments of the present application are described in detail below with reference to the accompanying drawings.
Fig. 1 is a flowchart of a partial discharge electrical positioning method for a transformer according to an embodiment of the present disclosure. As shown in fig. 1, the positioning method provided in the embodiment of the present application specifically includes the following processes:
it should be noted that, in the method for electrically positioning partial discharge of a transformer provided in the embodiments of the present application, the execution main body may be any device having a data calculation processing function, such as a computer, a tablet power supply, and the like. It should be further noted that, in the embodiment of the present application, the transformer is in a power-on use state to perform partial discharge detection and positioning.
Step 101, collecting current signals at the left end and the right end of a transformer winding.
In the method for electrically positioning partial discharge of the transformer provided by the embodiment of the application, when the partial discharge of the transformer is detected and positioned, firstly, a high-frequency current transformer is respectively installed on a grounding wire of a transformer winding and a leading-out wire of a high-voltage end. For convenience of description, in the embodiments of the present application, a high-frequency current transformer mounted on a ground line is referred to as a first high-frequency current transformer, and a high-frequency current transformer mounted on a high-voltage terminal outgoing line is referred to as a second high-frequency current transformer.
Specifically, whether pulse current signals exist at the left end and the right end of a transformer winding or not is respectively acquired through a first high-frequency current transformer and a second high-frequency current transformer. And when the first high-frequency current sensor and the second high-frequency current signal do not acquire the pulse current signal, determining that the partial discharge phenomenon does not occur in the transformer.
Further, when the first high-frequency current transformer and the second high-frequency current transformer acquire pulse current signals, the transformer is determined to have a partial discharge phenomenon. When partial discharge occurs in the transformer winding, the pulse current generated by the partial discharge propagates to the left and right ends along the winding. Due to the different propagation distances, the transformer windings also have different distorting effects on the discharge pulse. Therefore, the high-frequency current transformers arranged at the two ends of the transformer winding are used for analyzing and comparing the difference of pulse current signals at the two ends, and the positioning of partial discharge can be realized.
For convenience of description, in the embodiment of the present application, a pulse current signal collected by a first high-frequency current transformer is referred to as a first current signal, and a pulse current signal collected by a second high-frequency current transformer is referred to as a second current signal.
As will be apparent to those skilled in the art, the insulation structure of the transformer is divided into main insulation and longitudinal insulation. The main insulation refers to insulation of the transformer winding to the ground and insulation among the windings; longitudinal insulation refers to insulation between turns and between cakes in a transformer winding.
Partial discharge of the transformer winding occurs at different positions, so that discharge loops are different, and pulse current signals detected at two ends of the winding are different. When partial discharge occurs in the main insulation, the polarities of pulse current signals detected at two ends of the winding are the same; when the longitudinal insulation is partially discharged, the polarities of pulse current signals detected at the two ends of the winding are opposite. Therefore, whether partial discharge occurs in the main insulation or the longitudinal insulation can be judged by identifying the difference of the polarities of the pulse current signals at the two ends of the winding. In other words, in the electrical positioning method for partial discharge of the transformer provided in the embodiment of the present application, it can be determined that partial discharge occurs in the main insulation or the longitudinal insulation of the transformer by determining whether the polarity of the first current signal is the same as the polarity of the second current signal.
And 102, determining the polarity relation between the first current signal and the second current signal.
After the first high-frequency current transformer collects the first current signal and the second high-frequency current transformer collects the second current signal, the polarity relation between the first current signal and the second current signal is determined.
Further, if it is determined that the polarity of the first current signal is the same as the polarity of the second current signal, step 103 is performed to determine a partial discharge position by the energy ratio in the intermediate frequency region; if it is determined that the polarity of the first current signal is different (opposite) from the polarity of the second current signal, step 104 is performed to determine the location of the partial discharge by the first peak arrival time.
It should be noted that, in an actual application process, the polarity of the first current signal and the polarity of the second current signal may be determined by an existing method or device according to the method for positioning electrical partial discharge of a transformer provided in the embodiment of the present application, which is not described again in the embodiment of the present application.
And 103, determining the position of the partial discharge according to the energy ratio of the intermediate frequency region.
And under the condition that the polarity of the first current signal is determined to be the same as that of the second current signal, determining the partial discharge position of the transformer through the energy occupation ratio in the intermediate frequency region. The specific implementation process is as follows:
first, the frequency spectrum of the first current signal is calculated, and the frequency spectrum of the second current signal is calculated. Specifically, the first current signal is denoted as x1(t), the second current signal is denoted as x2(t) of (d). Respectively calculating the frequency spectrum of the first current signal and the frequency spectrum of the second current signal by the following formulas:
wherein, X1(ω) represents x1(t) frequency spectrum, X2(ω) represents x2(t) spectrum.
Further, after the frequency spectrum is calculated, the frequency spectrum of the first current signal and the frequency spectrum of the second current signal are divided into a low frequency region (0,10kHz), an intermediate frequency region (10kHz, 1MHz), and a high frequency region (1MHz, + ∞).
Then, according to the paswal theorem: the total energy of the signal can be calculated as an integral of the energy per unit time over time or as an integral of the energy per unit frequency over a frequency range. Namely:
where E represents the total energy of the current signal, X (t) represents the current signal, and X (ω) represents the frequency spectrum of the current signal.
Therefore, in the embodiment of the present application, the total energy of the first current signal and the energy of the intermediate frequency region of the first current signal, and the total energy of the second current signal and the energy of the intermediate frequency region of the second current signal are determined by a spectrum integration method, so as to determine the energy duty ratio of the intermediate frequency region of the first current signal and the energy duty ratio of the intermediate frequency region of the second current signal.
Specifically, the energy-to-energy ratio of the intermediate frequency region of the first current signal is determined by the following formula
And the energy ratio of the second current signal in the intermediate frequency region
Wherein E is1MRepresenting the energy of the intermediate frequency region of the first current signal, E1Representing the sum of the first current signalsEnergy; e2MRepresenting the energy of the intermediate frequency region of the second current signal, E2Representing the total energy of the second current signal; x1(ω) represents x1(t) frequency spectrum, X2(ω) represents x2(t) spectrum.
Further, the distance ratio is determined according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal. The distance ratio is used for indicating the ratio of the distance from the position of partial discharge to the left end of the transformer winding and the distance from the position of partial discharge to the right end of the transformer winding.
Specifically, the distance ratio is determined by the following formula:
wherein z represents a distance ratio.
And finally, acquiring physical parameters of the transformer winding, and determining the position of partial discharge according to the distance ratio and the physical parameters. For example, if the distance ratio is 2 and the number of windings of the transformer is 30, it is determined that the partial discharge is located at the 20 th winding.
In one embodiment of the application, the physical parameter comprises any one or more of: winding height, winding diameter, winding mode, number of wire cakes and number of coil turns.
And step 104, determining the position of the partial discharge through the arrival time of the first peak.
In case it is determined that the polarity of the first current signal is different (opposite) to the polarity of the second current signal, the location of the partial discharge of the transformer is determined by the first peak arrival time. The specific implementation process is as follows:
first, a first peak arrival time of the first current signal and a first peak arrival time of the second current signal are determined. It should be noted that, in the process of acquiring the first current signal by using the first high-frequency current signal and acquiring the second current signal by using the second high-frequency current signal, the first peak arrival time of the first current signal and the first peak arrival time of the second current signal may be determined by using an existing method or an existing device, which is not described in detail herein.
Then, a distance ratio is calculated based on the first peak arrival time of the first current signal and the first peak arrival time of the second current signal. Wherein the distance ratio is used for indicating the ratio of the distance from the position of partial discharge to the left end distance and the right end distance of the transformer winding. Since the first peak arrival time of the pulse current signal generated by the partial discharge is proportional to the discharge distance, the distance ratio can be determined by the following formula:
wherein, t1Is the first peak arrival time, t, of the first current signal2Is the first peak arrival time of the second current signal; t is the time ratio of the arrival times of the two first peaks, and z is the distance ratio.
And finally, after the distance ratio is determined, acquiring physical parameters of the transformer winding, and determining a specific partial discharge position according to the physical parameters and the distance ratio.
In summary, no matter whether partial discharge occurs in main insulation or longitudinal insulation of the transformer, the position can be positioned by the transformer partial discharge electrical positioning method provided by the embodiment of the application, and the accuracy of the partial discharge position positioning can be ensured.
Based on the same inventive concept, the embodiment of the present application further provides a partial discharge electrical positioning apparatus for a transformer, and the structure of the partial discharge electrical positioning apparatus is shown in fig. 2.
Fig. 2 is a schematic diagram of an internal structure of a partial discharge electrical positioning apparatus for a transformer according to an embodiment of the present application.
As shown in fig. 2, the apparatus includes: a first determining module 201, configured to determine that partial discharge of the transformer occurs in the main insulation of the transformer according to the polarity of the first current signal and the polarity of the second current signal; the first current signal is a pulse current signal collected by a first high-frequency current transformer; the second current signal is a pulse current signal collected by a second high-frequency current transformer; a calculating module 202, configured to calculate a frequency spectrum of the first current signal, and determine an intermediate frequency energy ratio of the first current signal based on the frequency spectrum, and to calculate a frequency spectrum of the second current signal, and determine an intermediate frequency energy ratio of the second current signal based on the frequency spectrum; a second determining module 203, configured to determine a distance ratio of partial discharge according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, so as to determine a position of the partial discharge; wherein the distance ratio is used for indicating the ratio of the distance from the position of partial discharge to the left end distance and the right end distance of the transformer winding.
The method and the device for electrically positioning the partial discharge of the transformer not only realize the positioning process of the partial discharge position of the transformer, avoid the problem of positioning errors caused by ultrasonic waves in the transmission process, but also ensure the positioning accuracy of the partial discharge position of the transformer.
The embodiments in the present application are described in a progressive manner, and the same and similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the apparatus embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.
Claims (9)
1. A method for electrical localization of partial discharges in a transformer, the method comprising:
determining that partial discharge of the transformer occurs in the main insulation of the transformer according to the polarity of the first current signal and the polarity of the second current signal; wherein the first current signal is a pulse current signal collected by a first high-frequency current transformer; the second current signal is a pulse current signal collected by a second high-frequency current transformer;
calculating the frequency spectrum of the first current signal, and determining the energy ratio of the intermediate frequency region of the first current signal based on the frequency spectrum of the first current signal; calculating the frequency spectrum of the second current signal, and determining the energy ratio of the intermediate frequency region of the second current signal based on the frequency spectrum of the second current signal; wherein the range of the intermediate frequency region of the first current signal or the second current signal is 10khz to 1 Mhz;
determining the distance ratio of the partial discharge according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, so as to determine the position of the partial discharge; wherein the distance ratio is used for indicating the ratio of the distance from the position of the partial discharge to the left end distance and the right end distance of the transformer winding.
2. The method of claim 1, wherein the partial discharge of the transformer is detected by the sensor,
according to the polarity of the first current signal and the polarity of the second current signal, the method for determining the partial discharge of the transformer to occur in the main insulation of the transformer specifically comprises the following steps:
determining the polarity of the first current signal and the polarity of the second current signal, respectively;
in case the polarity of the first current signal is the same as the polarity of the second current signal, it is determined that a partial discharge of the transformer occurs in the main insulation of the transformer.
3. The electrical positioning method for partial discharge of transformer according to claim 1, wherein a frequency spectrum of the first current signal is calculated, and an energy ratio of an intermediate frequency region of the first current signal is determined based on the frequency spectrum, specifically:
by the formula
Obtaining a frequency spectrum of the first current signal; wherein x is1(t) denotes a first current signal, X1(ω) represents a frequency spectrum of the first current signal;
determining the energy ratio of the intermediate frequency region of the first current signal by the following formula;
wherein the content of the first and second substances,
representing the energy fraction in the intermediate frequency region of the first current signal, E1MRepresenting the energy of the intermediate frequency region of the first current signal, E1Representing the total energy of the first current signal.
4. The electrical positioning method for partial discharge of transformer according to claim 1, wherein a frequency spectrum of the second current signal is calculated, and an energy ratio of an intermediate frequency region of the second current signal is determined based on the frequency spectrum, specifically:
by the formula
Obtaining a frequency spectrum of the second current signal; wherein x is2(t) represents a second current signal, X2(ω) represents a frequency spectrum of the second current signal;
determining the energy ratio of the intermediate frequency region of the second current signal by the following formula;
wherein the content of the first and second substances,
representing the energy fraction in the intermediate frequency region of the second current signal, E2MRepresenting the energy of the intermediate frequency region of the second current signal, E2Representing the total energy of the second current signal.
5. The method according to claim 1, wherein the step of determining the position of the partial discharge comprises determining a distance ratio of the partial discharge according to an energy ratio of an intermediate frequency region of the first current signal and an energy ratio of an intermediate frequency region of the second current signal, and specifically comprises:
by the formula
Determining a distance ratio of the partial discharges; wherein the content of the first and second substances,
represents the energy fraction of the intermediate frequency region of the first current signal,
represents the energy-to-energy ratio of the intermediate frequency region of the second current signal, and z represents the distance ratio;
acquiring physical parameters of the transformer winding;
and determining the position of the partial discharge according to the distance ratio and the physical parameters.
6. The method of claim 1, further comprising:
determining that a polarity of the first current signal is different from a polarity of the second current signal;
calculating the first peak arrival time of the first current signal, calculating the first peak arrival time of the second current signal and calculating the time ratio between the first current signal and the second current signal;
and determining the distance ratio of the partial discharge according to the time ratio, thereby determining the position of the partial discharge.
7. The method according to claim 6, wherein the step of determining the position of the partial discharge comprises determining a distance ratio of the partial discharge according to the time ratio, and specifically comprises:
by the formula
Determining a distance ratio of the partial discharges; wherein z represents a distance ratio, T represents a time ratio, T1Representing the first peak arrival time, t, of the first current signal2Represents a first peak arrival time of the second current signal;
acquiring physical parameters of the transformer winding;
and determining the position of the partial discharge according to the distance ratio and the physical parameters.
8. The method according to claim 7, wherein the physical parameters include any one or more of the following: winding height, winding diameter, winding mode, number of wire cakes and number of coil turns.
9. A partial discharge electrical positioning apparatus for a transformer, the apparatus comprising:
the first determination module is used for determining that partial discharge of the transformer occurs in main insulation of the transformer according to the polarity of the first current signal and the polarity of the second current signal; wherein the first current signal is a pulse current signal collected by a first high-frequency current transformer; the second current signal is a pulse current signal collected by a second high-frequency current transformer;
the calculating module is used for calculating the frequency spectrum of the first current signal and determining the energy ratio of the intermediate frequency region of the first current signal based on the frequency spectrum of the first current signal; and a frequency spectrum for calculating the second current signal and determining the energy fraction of the second current signal in the intermediate frequency region based on the frequency spectrum; wherein the range of the intermediate frequency region of the first current signal or the second current signal is 10khz to 1 Mhz;
the second determining module is used for determining the distance ratio of the partial discharge according to the energy ratio of the intermediate frequency region of the first current signal and the energy ratio of the intermediate frequency region of the second current signal, so as to determine the position of the partial discharge; wherein the distance ratio is used for indicating the ratio of the distance from the position of the partial discharge to the left end distance and the right end distance of the transformer winding.
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| CN202011271487.9A CN112698158B (en) | 2020-11-13 | 2020-11-13 | Partial discharge electrical positioning method and device for transformer |
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