Stator bar corona discharge detection method

Abstract

The invention discloses a stator bar corona discharge detection method. The method adopted by the invention comprises the following steps: placing a measured sub-bar at the upper part of a supporting and reflecting unit, carrying out acoustic imaging detection by adopting an acoustic imaging detection unit, respectively analyzing and judging sound sources with different frequencies on the premise that acoustic images with different frequencies are not overlapped with one another, and confirming graphic characteristics of each sound source in an acoustic imaging picture; as sound sources formed by further analyzing discharge, the sound sources comprise a point-shaped sound source located at a non-supporting and reflecting unit insulator, a point-shaped sound source located at a supporting and reflecting unit insulator, and a strip-shaped sound source with one end point located at the supporting and reflecting unit insulator. Discharge of the back of the stator bar can be effectively detected, a judgment and positioning method for different discharge positions of the front face and the back face of the bar is given, and the detection efficiency and accuracy of a corona test are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of motor detection, and in particular to a stator wire bar corona discharge detection method. Background Art

[0002] Accurately detecting the corona discharge of stator wire bars is of great significance to ensure the safe and stable operation of the unit. In the current corona discharge detection standards for stator wire bars, the detection methods used for corona discharge are darkroom visual inspection and ultraviolet imaging. The above methods are based on visual and optical principles and can only detect the discharge of stator wire bars in the direction facing the test personnel. If it is necessary to accurately detect whether there is corona discharge and corona inception voltage and other test information on the back of the stator wire bar, it is necessary to add test personnel and instruments on the back of the stator wire bar.

[0003] At the same time, the above problems also exist in the detection of corona discharge of stator end windings of large units. The existing darkroom visual inspection method and ultraviolet imaging method can only effectively detect the corona discharge on the front of the upper wire rod of the stator end winding. Due to the location of the obstruction and other reasons, it is difficult to effectively detect the corona discharge on the back of the upper wire rod and the lower wire rod. Summary of the invention

[0004] In view of this, the present invention provides a stator wire bar corona discharge detection method, which is based on the acoustic imaging method. Through the test device, while completing the stator wire bar support, a reflection source of the back corona discharge acoustic signal is formed, and the back discharge source is located. At the same time, since acoustic detection is easily affected by factors such as the test environment, a method for confirming the detection result is proposed to avoid interference from factors such as the test environment and ensure the accuracy of discharge signal detection.

[0005] To achieve the above object, the present invention adopts the following technical solution: a stator bar corona discharge detection method and device, which comprises the following steps:

[0006] Step 1), placing the sub-wire rod to be measured on the upper part of the support and reflection unit, wherein the support and reflection unit includes a plurality of insulators with adjustable heights; using an acoustic imaging detection unit to perform acoustic imaging detection, and on the premise that acoustic images of different frequencies do not overlap with each other, analyzing and judging the sound sources of different frequencies respectively, and confirming the graphic features of each sound source in the acoustic imaging diagram;

[0007] Step 2), for a strip sound source with one end point located at the insulator of the support and reflection unit, it is preliminarily determined that the discharge point is located on the back of the stator wire rod, and the discharge point is the end point of the strip sound source located at the insulator of the non-support and reflection unit, and a discharge signal verification process is carried out: the strip sound source is located between the first insulator of the support and reflection unit and the adjacent second insulator, wherein the first insulator is the end point of the strip sound source, the length of the stator wire rod passed by the strip sound source is L1, and the length of the stator wire rod between the end point of the strip sound source located at the insulator of the non-support and reflection unit and the second insulator is L2, and when L2≥L1, the next step of judgment is carried out;

[0008] Step 3), lowering the first insulator, without any contact with the stator wire rod and with a clear gap, when the sound imaging of the strip sound source changes, the sound imaging endpoint of the strip sound source located at the non-support and reflection unit insulator remains unchanged, and the sound imaging endpoint of the strip sound source originally located at the first insulator changes to the second insulator, and it is judged that the discharge point is located at the back of the stator wire rod, and the specific position of the discharge point is the end position of the strip sound source located at the non-support and reflection unit insulator;

[0009] Step 4), when there are multiple point sound sources at the same frequency, all the insulators of the support and reflection units are raised to the same height at the same time. If the position of the point sound source acoustic imaging on the stator bar changes, it is determined to be an interference signal;

[0010] Step 5), after preliminary elimination of interference signals in step 4), for the point sound source located at the insulator of the support and reflection unit, it is preliminarily determined that the discharge point is located on the front or back of the stator bar where the point sound source is located, and the discharge signal verification process is carried out: the insulator at the location of the point sound source is lowered until there is no contact with the stator bar and there is a clear gap;

[0011] Step 6), after preliminary elimination of interference signals in step 4), for point sound sources located at the insulator of the non-support and reflection units, the discharge point is directly determined to be the front side of the stator bar where the point sound source is located.

[0012] Furthermore, in step 1), the number of insulators in the support and reflection unit satisfies the redundant configuration. Since the number of insulators is redundantly configured, the lowering of the height of any insulator will not affect the support of the support and reflection unit to the stator bar.

[0013] Furthermore, in step 1), the distance between each insulator in the support and reflection unit is equal.

[0014] Furthermore, the upper surface of the insulator is smooth, has no sharp corners or burrs, and has chamfered edges, which can prevent the insulator surface from discharging during the detection process to form interference signals and affect the detection results.

[0015] Furthermore, in the discharge signal verification process of step 5), if the acoustic imaging of the point sound source disappears, it is determined to be an interference signal.

[0016] Furthermore, in the discharge signal verification process of step 5), if the point sound source characteristics do not change, it is determined that the discharge point is located in front of the stator bar position where the point sound source is located.

[0017] Furthermore, in the discharge signal verification process of step 5), if the point sound source is changed into a strip sound source, one end point of the sound imaging of the strip sound source is the location of the previous point sound source, and the other end point is located at the insulator closest to the point sound source, then it is judged that the discharge point is located on the back side of the stator wire rod where the point sound source is located.

[0018] Furthermore, in step 1), a pressurizing unit is used to pressurize the stator wire rod to be measured, and the imaging frequency range of the acoustic imaging detection unit is adjusted to a typical frequency range of corona discharge of the stator wire rod.

[0019] Furthermore, in step 1), the pressurization process is the same as the corona test standard requirements.

[0020] Furthermore, in step 1), by adjusting the imaging display dynamic range and gradually narrowing the imaging frequency range, it can help confirm the specific shape characteristics of the sound source.

[0021] Compared with traditional technologies, the present invention can effectively detect the discharge on the back of the stator wire bar, and provides a method for judging and locating different discharge positions on the front and back of the wire bar; and provides a method for identifying interference signals, which can save manpower and instrument investment in detection, and can be applied to corona detection of stator cable windings, and can also be further extended to corona detection of stator end windings of the generator, to make up for the current problem of difficulty in effectively detecting corona discharge on the back of the upper wire bar and the lower wire bar. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The following is a brief introduction to the drawings required for describing the specific embodiments of the present invention.

[0023] Figure 1 It is a schematic diagram of the stator wire bar corona discharge detection device of the present invention during detection;

[0024] Figure 2 It is a flow chart of the stator wire bar corona discharge detection method of the present invention;

[0025] Figure 3 Schematic diagram of acoustic signal propagation of stator bar front discharge in an embodiment of the present invention;

[0026] Figure 4 Schematic diagram of acoustic signal propagation of discharge on the back side of a stator bar in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0028] The present invention provides a stator wire bar corona discharge detection method, which uses a stator wire bar corona discharge detection device to achieve detection. The stator wire bar corona discharge detection device is composed of three parts: a pressurizing unit, a support and reflection unit, and an acoustic imaging detection unit. Figure 1 shown.

[0029] The stator bar corona discharge detection method is as follows Figure 2 As shown, the steps are as follows:

[0030] Step 1), using a pressurizing unit to pressurize the sub-wire rod to be measured, adjusting the imaging frequency range of the acoustic imaging detection unit to the typical frequency range of corona discharge of the stator wire rod, and adjusting the imaging display dynamic range and gradually narrowing the imaging frequency range, which can help confirm the specific shape characteristics of the sound source; placing the sub-wire rod to be measured on the upper part of the support and reflection unit, using the acoustic imaging detection unit to perform acoustic imaging detection, and on the premise that the acoustic imaging of different frequencies does not overlap with each other, respectively analyze and judge the sound sources of different frequencies, and confirm the graphic characteristics of each sound source in the acoustic imaging diagram;

[0031] The following three sound sources can be further analyzed as sound sources formed by discharge, namely: a point sound source located at the insulator of the non-support and reflection unit, a point sound source located at the insulator of the support and reflection unit, and a strip sound source with one end point located at the insulator of the support and reflection unit.

[0032] The support and reflection unit is composed of a plurality of insulators with adjustable heights, and the height of each insulator can be adjusted individually. The number of insulators in the support and reflection unit satisfies the redundant configuration, and the distance between each insulator is equal. If the height of any insulator decreases, it will not affect the support effect of the support and reflection unit on the stator wire rod. The upper surface of the insulator is smooth, without sharp corners and burrs, and the edges are chamfered, which can largely prevent surface discharge during the detection process and form interference signals that affect the test results; the above-mentioned pressurization process is the same as the requirements of the corona test standard, and the acoustic imaging diagram is formed by superposition of the visible light image and the sound field distribution cloud diagram.

[0033] Step 2), for a strip sound source with one end point located at the insulator of the support and reflection unit, it is preliminarily determined that the discharge point is located on the back of the stator wire rod, and the discharge point is the end point of the strip sound source located at the insulator of the non-support and reflection unit, and a discharge signal verification process is carried out: the strip sound source is located between the first insulator of the support and reflection unit and the adjacent second insulator, wherein the first insulator is the end point of the strip sound source, the length of the stator wire rod passed by the strip sound source is L1, and the length of the stator wire rod between the end point of the strip sound source located at the insulator of the non-support and reflection unit and the second insulator is L2, and when L2≥L1, the next step of judgment is carried out;

[0034] When the discharge position is located at the back of the stator bar, the sound signal generated by the discharge propagates along the solid, that is, the surface of the stator bar. The sound signal reaches the surface of the nearest support and reflection unit insulator and is detected by the acoustic imaging detection unit.

[0035] Step 3), lowering the first insulator, without any contact with the stator wire rod and with a clear gap, when the sound imaging of the strip sound source changes, the sound imaging endpoint of the strip sound source located at the non-support and reflection unit insulator remains unchanged, and the sound imaging endpoint of the strip sound source originally located at the first insulator changes to the second insulator, and it is judged that the discharge point is located at the back of the stator wire rod, and the specific position of the discharge point is the end position of the strip sound source located at the non-support and reflection unit insulator;

[0036] The first insulator is lowered. Since the distance between the insulators in each support and reflection unit is equal, the shortest distance that the acoustic signal formed by the discharge is transmitted along the solid surface also changes. The acoustic signal is transmitted along the back surface of the stator bar to the second insulator 2 and is detected by the acoustic imaging detection unit.

[0037] Step 4), when there are multiple point sound sources at the same frequency, all the insulators of the support and reflection units are raised to the same height at the same time. If the position of the acoustic imaging of the point sound source on the stator bar changes, it is determined to be an interference signal.

[0038] Step 5), after preliminary elimination of interference signals in step 4), for the point sound source located at the insulator of the support and reflection unit, it is preliminarily determined that the discharge point is located on the front or back of the stator bar where the point sound source is located, and the discharge signal verification process is carried out: the insulator at the location of the point sound source is lowered until there is no contact with the stator bar and there is a clear gap;

[0039] If the acoustic imaging of the point sound source disappears, it is judged to be an interference signal;

[0040] If the characteristics of the point-shaped sound source do not change, it is judged that the discharge point is located in front of the stator bar where the point-shaped sound source is located;

[0041] If the point sound source changes into a strip sound source, one end point of the sound imaging of the strip sound source is the location of the previous point sound source, and the other end point is located at the insulator closest to the point sound source, then it is judged that the discharge point is located on the back of the stator wire rod where the point sound source is located.

[0042] Step 6), after preliminary elimination of interference signals in step 4), for point sound sources located at the insulator of the non-support and reflection units, the discharge point is directly determined to be the front side of the stator bar where the point sound source is located.

[0043] Example 1

[0044] This embodiment provides a stator bar corona discharge detection method, the steps of which are as follows:

[0045] 1. Place the sub-wire rod to be measured on the upper part of the support and reflection unit, pressurize the sub-wire rod to be measured through the pressurizing unit, adjust the imaging frequency range of the acoustic imaging detection unit to the typical frequency range of corona discharge of the stator wire rod, adjust the imaging display dynamic range and gradually narrow the imaging frequency range, and analyze and judge the sound sources of different frequencies separately on the premise that the acoustic imaging of different frequencies does not overlap with each other, and confirm the graphic characteristics of each sound source in the acoustic imaging diagram;

[0046] 2. It is found that there is a point sound source located at the insulator of the non-support and reflection unit, and there is only one point sound source with the same frequency characteristics. It is judged that the discharge point is the front of the stator bar where the point sound source is located, such as Figure 3 shown.

[0047] Example 2

[0048] This embodiment provides a stator bar corona discharge detection method, the steps of which are as follows:

[0049] 1. Place the sub-wire rod to be measured on the upper part of the support and reflection unit, pressurize the sub-wire rod to be measured through the pressurizing unit, adjust the imaging frequency range of the acoustic imaging detection unit to the typical frequency range of corona discharge of the stator wire rod, adjust the imaging display dynamic range and gradually narrow the imaging frequency range, and analyze and judge the sound sources of different frequencies separately on the premise that the acoustic imaging of different frequencies does not overlap with each other, and confirm the graphic characteristics of each sound source in the acoustic imaging diagram;

[0050] 2. It is found that there are multiple point sound sources with the same frequency characteristics, namely the first point sound source and the second point sound source; all the insulators of the support and reflection units are raised to the same height at the same time. If the position of the acoustic imaging of the second point sound source on the stator bar changes, the second point sound source is judged to be an interference signal;

[0051] 3. If the first point sound source is located at the non-support and reflection unit insulator, the discharge point is determined to be the front side of the stator bar where the point sound source is located.

[0052] Example 3

[0053] This embodiment provides a stator bar corona discharge detection method, the steps of which are as follows:

[0054] 1. Place the sub-wire rod to be measured on the upper part of the support and reflection unit, pressurize the sub-wire rod to be measured through the pressurizing unit, adjust the imaging frequency range of the acoustic imaging detection unit to the typical frequency range of corona discharge of the stator wire rod, adjust the imaging display dynamic range and gradually narrow the imaging frequency range, and analyze and judge the sound sources of different frequencies separately on the premise that the acoustic imaging of different frequencies does not overlap with each other, and confirm the graphic characteristics of each sound source in the acoustic imaging diagram;

[0055] 2. When a point sound source is found at the insulator of the support and reflection unit, and there is only one point sound source with the same frequency characteristics, it is preliminarily determined that the discharge point is located on the front or back of the stator bar where the point sound source is located, and the discharge signal verification process is carried out: lower the insulator at the location of the point sound source until there is no contact with the stator bar and there is a clear gap;

[0056] 3. If the acoustic imaging of the point sound source disappears, the signal is judged to be an interference signal; if the characteristics of the point sound source do not change, the discharge point is judged to be located in front of the stator wire rod position where the acoustic imaging of the point sound source is located.

[0057] Example 4

[0058] This embodiment provides a stator bar corona discharge detection method, the steps of which are as follows:

[0059] 1. Place the sub-wire rod to be measured on the upper part of the support and reflection unit, pressurize the sub-wire rod to be measured through the pressurizing unit, adjust the imaging frequency range of the acoustic imaging detection unit to the typical frequency range of corona discharge of the stator wire rod, adjust the imaging display dynamic range and gradually narrow the imaging frequency range, and analyze and judge the sound sources of different frequencies separately on the premise that the acoustic imaging of different frequencies does not overlap with each other, and confirm the graphic characteristics of each sound source in the acoustic imaging diagram;

[0060] 2. When a point sound source is found at the insulator of the support and reflection unit, and there is only one point sound source with the same frequency characteristics; preliminarily judge that the discharge point is located on the front or back of the stator bar where the point sound source is located, and carry out the discharge signal verification process: lower the insulator where the point sound source is located until there is no contact with the stator bar and there is a clear gap;

[0061] 3. If the point sound source is changed into a strip sound source, one end point of the sound imaging of the strip sound source is the location of the previous point sound source, and the other end point is located at the insulator closest to the point sound source. It is judged that the discharge point is located on the back of the stator wire rod where the point sound source is located.

[0062] Example 5

[0063] This embodiment provides a stator bar corona discharge detection method, the steps of which are as follows:

[0064] 1. Place the sub-wire rod to be measured on the upper part of the support and reflection unit, pressurize the sub-wire rod to be measured through the pressurizing unit, adjust the imaging frequency range of the acoustic imaging detection unit to the typical frequency range of corona discharge of the stator wire rod, adjust the imaging display dynamic range and gradually narrow the imaging frequency range, and analyze and judge the sound sources of different frequencies separately on the premise that the acoustic imaging of different frequencies does not overlap with each other, and confirm the graphic characteristics of each sound source in the acoustic imaging diagram;

[0065] 2. It is found that there is a strip sound source with one end point located at the insulator of the support and reflection unit. It is preliminarily judged that the discharge point is located on the back of the stator wire rod. The discharge point is the end point of the strip sound source located at the insulator of the non-support and reflection unit. The discharge signal verification process is carried out: the strip sound source is located between the first insulator of the support and reflection unit and the adjacent second insulator, where the first insulator is the end point of the strip sound source, the length of the stator wire rod passed by the strip sound source is L1, and the length of the stator wire rod between the end point of the strip sound source located at the insulator of the non-support and reflection unit and the second insulator is L2. When L2≥L1, the next step of judgment is carried out;

[0066] 3. Lower the first insulator, which has no contact with the stator bar and has an obvious gap. When the sound imaging of the strip sound source changes, the end point of the sound imaging of the strip sound source located at the non-support and reflection unit insulator remains unchanged, and the end point of the sound imaging of the strip sound source originally located at the first insulator changes to the second insulator. It can be judged that the discharge point is located at the back of the stator bar. The specific position of the discharge point is the end point of the strip sound source located at the non-support and reflection unit, such as Figure 4 shown.

[0067] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention.

Claims

1. A method for detecting corona discharge of a stator bar, characterized in that: include: Step 1), placing the sub-wire rod to be measured on the upper part of the support and reflection unit, wherein the support and reflection unit includes a plurality of insulators with adjustable height; The acoustic imaging detection unit is used to perform acoustic imaging detection. On the premise that the acoustic images at different frequencies do not overlap with each other, the sound sources at different frequencies are analyzed and judged respectively to confirm the graphic features of each sound source in the acoustic imaging diagram; Step 2), for a strip sound source with one end point located at the insulator of the support and reflection unit, it is preliminarily determined that the discharge point is located on the back of the stator wire rod, and the discharge point is the end point of the strip sound source located at the insulator of the non-support and reflection unit, and a discharge signal verification process is carried out: the strip sound source is located between the first insulator of the support and reflection unit and the adjacent second insulator, wherein the first insulator is the end point of the strip sound source, the length of the stator wire rod passed by the strip sound source is L1, and the length of the stator wire rod between the end point of the strip sound source located at the insulator of the non-support and reflection unit and the second insulator is L2, and when L2≥L1, the next step of judgment is carried out; Step 3), lowering the first insulator, without any contact with the stator wire rod and with a clear gap, when the sound imaging of the strip sound source changes, the sound imaging endpoint of the strip sound source located at the non-support and reflection unit insulator remains unchanged, and the sound imaging endpoint of the strip sound source originally located at the first insulator changes to the second insulator, and it is judged that the discharge point is located at the back of the stator wire rod, and the specific position of the discharge point is the end position of the strip sound source located at the non-support and reflection unit insulator; Step 4), when there are multiple point sound sources at the same frequency, all the insulators of the support and reflection units are raised to the same height at the same time. If the position of the point sound source acoustic imaging on the stator bar changes, it is determined to be an interference signal; Step 5), after preliminary elimination of interference signals in step 4), for the point sound source located at the insulator of the support and reflection unit, it is preliminarily determined that the discharge point is located on the front or back of the stator bar where the point sound source is located, and the discharge signal verification process is carried out: the insulator at the location of the point sound source is lowered until there is no contact with the stator bar and there is a clear gap; Step 6), after preliminary elimination of interference signals in step 4), for point sound sources located at the insulators of non-support and reflection units, the discharge point is directly determined to be the front side of the stator bar where the point sound source is located.

2. The stator bar corona discharge detection method according to claim 1, characterized in that: In step 1), the number of insulators in the support and reflection unit satisfies the redundant configuration.

3. The stator bar corona discharge detection method according to claim 1, characterized in that: In step 1), the distance between each insulator in the support and reflection unit is equal.

4. The stator bar corona discharge detection method according to claim 1, characterized in that: The upper surface of the insulator is smooth, has no sharp corners or burrs, and has chamfered edges.

5. The stator bar corona discharge detection method according to claim 1, characterized in that: In the discharge signal verification process of step 5), if the acoustic imaging of the point sound source disappears, it is determined to be an interference signal.

6. The stator bar corona discharge detection method according to claim 1, characterized in that: In the discharge signal verification process of step 5), if the characteristics of the point sound source do not change, it is determined that the discharge point is located in front of the stator bar position where the point sound source is located.

7. The stator bar corona discharge detection method according to claim 1, characterized in that: In the discharge signal verification process of step 5), if the point sound source is changed into a strip sound source, one end point of the sound imaging of the strip sound source is the location of the previous point sound source, and the other end point is located at the insulator closest to the point sound source, then it is judged that the discharge point is located on the back of the stator wire rod where the point sound source is located.

8. The stator bar corona discharge detection method according to claim 1, characterized in that: In step 1), a pressure unit is used to pressurize the stator wire rod to be measured, and the imaging frequency range of the acoustic imaging detection unit is adjusted to the typical frequency range of corona discharge of the stator wire rod.

9. The stator bar corona discharge detection method according to claim 1, characterized in that: In step 1), the pressurization process is the same as the corona test standard requirements.

10. The stator bar corona discharge detection method according to claim 1, characterized in that: In step 1), by adjusting the imaging display dynamic range and gradually narrowing the imaging frequency range, it is possible to help confirm the specific shape characteristics of the sound source.

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