Time difference positioning method for partial discharge inside transformer winding

Abstract

Disclosed is a method for localizing partial discharge time difference inside transformer windings. In the method, a frequency response curve of the transformer winding is measured, a resistive frequency band of signal propagation is obtained according to the frequency response curve, and a bandpass filter is established according to the resistive frequency band; a standard pulse signal is injected into the head end of the transformer winding by a calibration source, a partial discharge pulse signal is measured at the neutral point of the winding by a high-frequency current sensor, the origin of the standard pulse signal and the peak time of the signal after bandpass filtering by the bandpass filter are recorded, and the propagation time of the standard signal is calculated; a transformer partial discharge detection test is carried out, a partial discharge pulse signal is measured at the neutral point of the winding by a high-frequency current sensor, the origin of the measured partial discharge signal and the peak time of the signal after bandpass filtering by the bandpass filter are recorded, and the propagation time of the measured partial discharge signal is calculated; and the position of the partial discharge in the winding is obtained according to the propagation time of the standard signal and the propagation time of the measured partial discharge signal.

Description

Technical Field

[0001] The invention relates to the technical field of transformer detection, and in particular to a method for locating the time difference of partial discharge inside a transformer winding. Background Art

[0002] Transformers are key components in power systems, and their health status directly affects the stable operation of power systems. Partial discharge may occur inside the transformer due to problems with design and manufacturing processes or insulation aging due to long-term operation. As the degree of partial discharge increases, the overall insulation strength of the transformer decreases rapidly, which may eventually cause serious failures. Partial discharge is an important cause of transformer insulation degradation. Timely detection of partial discharge inside the transformer can effectively avoid further losses.

[0003] Most transformer faults are insulation faults, which usually occur inside the windings, so it is necessary to locate the local discharge source. However, the transformer is compact and complex in structure, and the transformer core and windings have a certain impact on signal propagation, making the localization accuracy of local discharge based on spatial positioning algorithms low and difficult to carry out.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a method for time-difference positioning of partial discharge inside a transformer winding. By measuring the time when different components of the partial discharge arrive at a detection point, the distance the partial discharge propagates in the winding is estimated, thereby achieving accurate positioning of the partial discharge inside the transformer winding.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for locating the time difference of partial discharge inside a transformer winding of the present invention comprises:

[0008] Step 1, measuring the frequency response curve of the transformer winding, obtaining the resistive frequency band of the signal propagation according to the frequency response curve, and establishing a bandpass filter according to the resistive frequency band;

[0009] Step 2, injecting a standard pulse signal at the head end of the transformer winding with a calibration source, measuring the partial discharge pulse signal at the neutral point of the winding with a high-frequency current sensor, recording the origin of the standard pulse signal and the peak time of the signal after bandpass filtering by the bandpass filter, and calculating the propagation time of the standard signal;

[0010] Step 3, carrying out a partial discharge detection test of the transformer, measuring the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, recording the origin of the measured partial discharge signal and the peak time of the signal after the bandpass filtering by the bandpass filter, and calculating the measured partial discharge signal propagation time;

[0011] Step 4: obtaining the position of the partial discharge in the winding according to the standard signal propagation time and the measured partial discharge signal propagation time.

[0012] In the method described, a high-frequency current sensor is used to measure the partial discharge pulse signal at the neutral point of the winding, the origin t01 of the standard pulse signal and the peak time tp1 of the signal after bandpass filtering by the bandpass filter are recorded, and the standard signal propagation time dt1=tp1-t01 is calculated.

[0013] In the method, a high-frequency current sensor is used to measure the partial discharge pulse signal at the neutral point of the winding, the origin t02 of the signal and the peak time tp2 of the signal after bandpass filtering by the bandpass filter are recorded, and the measured partial discharge signal propagation time dt2=tp2-t02 is calculated.

[0014] In the method described, the location of the partial discharge is expressed as x=l·dt2 / dt1, where x represents the distance between the discharge in the winding and the end of the winding, and l represents the total length of the transformer winding.

[0015] In addition, the present invention also discloses a transformer winding internal partial discharge time difference positioning system, which includes:

[0016] A unit for establishing a bandpass filter, which is used to measure a frequency response curve of a transformer winding, obtain a resistive frequency band of signal propagation according to the frequency response curve, and establish a bandpass filter according to the resistive frequency band;

[0017] A unit for calculating the propagation time of a standard signal, which is used to inject a standard pulse signal at the head end of the transformer winding using a calibration source, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, record the origin of the standard pulse signal, and the peak time of the signal after the bandpass filtering by the bandpass filter, and calculate the propagation time of the standard signal;

[0018] A unit for calculating the propagation time of a measured partial discharge signal, which is used to carry out a partial discharge detection test of a transformer, measure a partial discharge pulse signal at a neutral point of a winding using a high-frequency current sensor, record the origin of the measured partial discharge signal, and the peak time of the signal after bandpass filtering by the bandpass filter, and calculate the propagation time of the measured partial discharge signal;

[0019] A position determination unit is used to obtain the position of the partial discharge in the winding according to the standard signal propagation time and the measured partial discharge signal propagation time.

[0020] In the system, a high-frequency current sensor is used to measure the partial discharge pulse signal at the neutral point of the winding, the origin t01 of the standard pulse signal and the peak time tp1 of the signal after bandpass filtering by the bandpass filter are recorded, and the standard signal propagation time dt1=tp1-t01 is calculated.

[0021] In the system, a high-frequency current sensor is used to measure a partial discharge pulse signal at the neutral point of the winding, the origin t02 of the signal and the peak time tp2 of the signal after bandpass filtering by the bandpass filter are recorded, and the measured partial discharge signal propagation time dt2=tp2-t02 is calculated.

[0022] In the system, the location of the partial discharge is expressed as x=l·dt2 / dt1, wherein x represents the distance between the discharge in the transformer winding and the end of the winding, and l represents the total length of the transformer winding.

[0023] Beneficial Effects

[0024] The present invention measures the time when different components of partial discharge arrive at a detection point and estimates the distance that the partial discharge propagates in the winding, thereby realizing accurate positioning of the partial discharge inside the transformer winding.

[0025] The above description is only an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and to enable those skilled in the art to implement it according to the contents of the specification, and to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described below by way of example. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0027] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0028] In the attached picture:

[0029] Figure 1 It is a flow chart of the steps of a method for locating the time difference of partial discharge inside a transformer winding provided by the present invention;

[0030] Figure 2 This is a diagram of partial discharge pulse detection inside a transformer according to an embodiment of the present invention.

[0031] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0035] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0036] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0037] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0039] In order to enable those skilled in the art to better understand the technical solution of the present invention, Figure 1 to Figure 2 The present invention is further described in detail, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0040] In one embodiment, if Figure 1 to Figure 2 As shown, the present disclosure provides a method for locating the time difference of partial discharge inside a transformer winding, comprising the following steps:

[0041] Step 1, measuring the frequency response curve of the transformer winding, obtaining the resistive frequency band of the signal propagation according to the frequency response curve, and establishing a bandpass filter according to the resistive frequency band;

[0042] Step 2, injecting a standard pulse signal at the head end of the transformer winding with a calibration source, measuring the partial discharge pulse signal at the neutral point of the winding with a high-frequency current sensor, recording the origin of the standard pulse signal and the peak time of the signal after bandpass filtering by the bandpass filter, and calculating the propagation time of the standard signal;

[0043] Step 3, carrying out a partial discharge detection test of the transformer, measuring the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, recording the origin of the measured partial discharge signal and the peak time of the signal after the bandpass filtering by the bandpass filter, and calculating the measured partial discharge signal propagation time;

[0044] Step 4: obtaining the position of the partial discharge in the winding according to the standard signal propagation time and the measured partial discharge signal propagation time.

[0045] In a preferred embodiment of the method, a high-frequency current sensor is used to measure the local discharge pulse signal at the neutral point of the winding, the origin t01 of the standard pulse signal and the peak time tp1 of the signal after bandpass filtering by the bandpass filter are recorded, and the standard signal propagation time dt1=tp1-t01 is calculated.

[0046] In a preferred embodiment of the method, a high-frequency current sensor is used to measure a partial discharge pulse signal at the neutral point of the winding, the origin t02 of the signal and the peak time tp2 of the signal after bandpass filtering by the bandpass filter are recorded, and the measured partial discharge signal propagation time dt2=tp2-t02 is calculated.

[0047] In a preferred embodiment of the method, the location of the partial discharge is expressed as x=l·dt2 / dt1, wherein x represents the distance of the discharge in the winding from the end of the winding, and l represents the total length of the winding.

[0048] In one embodiment, first, a frequency response curve of a transformer winding is measured, a resistive frequency band of signal propagation is obtained according to the frequency response curve, and a bandpass filter is established according to the resistive frequency band;

[0049] Furthermore, a standard pulse signal is injected into the head end of the winding using a calibration source, and a partial discharge pulse signal is measured at the neutral point of the winding using a high-frequency current sensor, and the origin t01 of the signal and the peak time tp1 of the signal after the bandpass filtering in step 1 are recorded, and the standard signal propagation time dt1=tp1-t01 is calculated;

[0050] Furthermore, a transformer partial discharge detection test is carried out, and a partial discharge pulse signal is measured at the neutral point of the winding using a high-frequency current sensor, and the origin t02 of the signal and the peak time tp2 of the signal after the bandpass filtering in step 1 are recorded, and the measured partial discharge signal propagation time dt2=tp2-t02 is calculated;

[0051] Furthermore, according to the propagation time difference between the standard pulse signal and the measured partial discharge signal, the location of the partial discharge can be expressed as x=l·dt2 / dt1, where x represents the distance from the discharge in the winding to the end of the winding, and l represents the total length of the winding.

[0052] Figure 2This is a transformer internal partial discharge pulse detection diagram of one of the embodiments of the present application. According to the starting time t0 of the original signal and the peak time tp of the signal after the bandpass filter is established based on the winding frequency response curve, the propagation time dt=tp-t0 of the partial discharge signal inside the transformer winding can be obtained. The standard pulse is injected from the head end of the winding and detected at the neutral point of the winding. After dt1 time, its propagation distance is the entire transformer winding length l; the partial discharge signal actually occurring inside the winding only passes through a part of the winding from the partial discharge position to the neutral point. After dt2 time, its propagation distance is the length x of the winding section. Considering that the propagation speed of the current signal in the winding is basically unchanged, the discharge position x inside the winding can be expressed as x=l·dt2 / dt1.

[0053] In addition, the present invention also discloses a transformer winding internal partial discharge time difference positioning system, which includes:

[0054] A unit for establishing a bandpass filter, which is used to measure a frequency response curve of a transformer winding, obtain a resistive frequency band of signal propagation according to the frequency response curve, and establish a bandpass filter according to the resistive frequency band;

[0055] A unit for calculating the propagation time of a standard signal, which is used to inject a standard pulse signal at the head end of the transformer winding using a calibration source, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, record the origin of the standard pulse signal, and the peak time of the signal after the bandpass filtering by the bandpass filter, and calculate the propagation time of the standard signal;

[0056] A unit for calculating the propagation time of a measured partial discharge signal, which is used to carry out a partial discharge detection test of a transformer, measure a partial discharge pulse signal at a neutral point of a winding using a high-frequency current sensor, record the origin of the measured partial discharge signal, and the peak time of the signal after bandpass filtering by the bandpass filter, and calculate the propagation time of the measured partial discharge signal;

[0057] A position determination unit is used to obtain the position of the partial discharge in the winding according to the standard signal propagation time and the measured partial discharge signal propagation time.

[0058] In the system, a high-frequency current sensor is used to measure the partial discharge pulse signal at the neutral point of the winding, the origin t01 of the standard pulse signal and the peak time tp1 of the signal after bandpass filtering by the bandpass filter are recorded, and the standard signal propagation time dt1=tp1-t01 is calculated.

[0059] In the system, a high-frequency current sensor is used to measure a partial discharge pulse signal at the neutral point of the winding, the origin t02 of the signal and the peak time tp2 of the signal after bandpass filtering by the bandpass filter are recorded, and the measured partial discharge signal propagation time dt2=tp2-t02 is calculated.

[0060] In the system, the location of the partial discharge is expressed as x=l·dt2 / dt1, wherein x represents the distance between the discharge in the transformer winding and the end of the winding, and l represents the total length of the transformer winding.

[0061] The present invention utilizes the characteristics that different frequency current signals have different propagation speeds in the transformer due to different internal transmission paths. The resistive band signal propagates along the winding, with a long propagation distance and a slow speed. The capacitive band signal propagates longitudinally along the winding due to the longitudinal capacitance between the windings, so the signal propagation distance is short and the speed is fast, which can be regarded as being generated at the same time as the discharge signal. The time difference between the arrival of the resistive component and the capacitive component of the signal can be regarded as the propagation time of the local discharge inside the winding, and compared with the propagation time of the standard pulse current signal injected from the head end of the winding, the discharge position inside the winding can be determined.

[0062] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A method for localizing partial discharge time difference inside transformer windings, characterized in that: It includes the following steps: Step 1, measuring the frequency response curve of the transformer winding, and obtaining the resistive frequency band of the signal propagation according to the frequency response curve, and establishing a bandpass filter according to the resistive frequency band; Step 2: inject a standard pulse signal at the head end of the transformer winding using a calibration source, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, and calculate the propagation time of the standard signal; Step 3, carry out a partial discharge detection test of the transformer, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, calculate the measured partial discharge signal propagation time, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, record the origin t01 of the standard pulse signal, and the peak time tp1 of the signal after the band-pass filtering of the band-pass filter, calculate the standard signal propagation time dt1=tp1-t01, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, record the origin t02 of the signal, and the peak time tp2 of the signal after the band-pass filtering of the band-pass filter, calculate the measured partial discharge signal propagation time dt2=tp2-t02; Step 4, obtaining the position of the partial discharge in the winding according to the standard signal propagation time and the measured partial discharge signal propagation time, the position of the partial discharge is expressed as x=l·dt2 / dt1, wherein x represents the distance from the discharge in the transformer winding to the end of the winding, and l represents the total length of the transformer winding.

2. A time difference positioning system for partial discharge inside transformer windings, characterized in that: It includes: A unit for establishing a bandpass filter, which is used to measure a frequency response curve of a transformer winding, obtain a resistive frequency band of signal propagation according to the frequency response curve, and establish a bandpass filter according to the resistive frequency band; A unit for calculating the propagation time of a standard signal, which is used to inject a standard pulse signal at the head end of the transformer winding using a calibration source, measure a partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, and calculate the propagation time of the standard signal; A unit for calculating the measured partial discharge signal propagation time is used to carry out a transformer partial discharge detection test, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, calculate the measured partial discharge signal propagation time, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, record the origin t01 of the standard pulse signal, and the signal peak time tp1 after the band-pass filtering of the band-pass filter, calculate the standard signal propagation time dt1=tp1-t01, measure the partial discharge pulse signal at the neutral point of the winding using a high-frequency current sensor, record the signal origin t02, and the signal peak time tp2 after the band-pass filtering of the band-pass filter, and calculate the measured partial discharge signal propagation time dt2=tp2-t02; A position determination unit is used to obtain the position of the partial discharge in the winding according to the standard signal propagation time and the measured partial discharge signal propagation time. The position of the partial discharge is expressed as x=l·dt2 / dt1, wherein x represents the distance from the discharge in the transformer winding to the end of the winding, and l represents the total length of the transformer winding.

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