System and method for testing partial discharge of transformer winding

Abstract

The invention discloses a transformer winding partial discharge test system and method, and belongs to the technical field of transformers, the system comprises an AC voltage source, a to-be-tested winding, a laser emitter, an ultrahigh frequency sensor, a temperature sensor, an oscilloscope and a temperature display, applying an AC voltage to the winding to be tested by controlling the AC voltage source; controlling a laser transmitter to continuously transmit laser to a preset target position on the winding to be measured; monitoring an oscilloscope and a temperature display, recording the local temperature displayed by the temperature sensor when determining that the oscilloscope displays the electromagnetic wave signal, and taking the local temperature as a target temperature for causing the partial discharge of the winding to be detected, the problem that in the prior art, it is difficult to measure the key temperature when partial discharge is caused by a local hot spot area can be solved.

Description

Technical Field

[0001] The present invention relates to the field of transformers, and in particular to a system and method for testing partial discharge of transformer windings. Background Art

[0002] Power transformers are critical equipment in power grids, and their safe operation is crucial to the overall safety of the grid. Transformer windings are a frequent site of accidents. This is primarily due to the current flowing through the conductors within the windings, which generates magnetic fields and easily produces localized hot spots. When these hot spots develop to a certain extent, they can damage the winding insulation, leading to partial discharges, short circuits, and serious accidents. Therefore, understanding the critical temperatures that trigger winding insulation damage and partial discharges is crucial for designing transformer insulation structures and determining the extent of insulation degradation.

[0003] The conventional method for simulating thermal damage to windings is to place a closed metal ring around the winding. Under the action of AC voltage, the magnetic field around the winding passes through the closed metal ring. Due to the action of eddy currents, the metallization heats up, generating a thermal effect. However, this method causes the entire metal ring to heat up, and the resulting hot spots in the winding are random, making it difficult to measure the critical temperature when the local hot spots trigger partial discharge. Summary of the Invention

[0004] The present invention provides a system and method for testing partial discharge of transformer windings, which can solve the problem in the prior art that it is difficult to measure the critical temperature when a local hot spot area triggers partial discharge.

[0005] An embodiment of the present invention provides a transformer winding partial discharge test system, comprising: an AC voltage source, a winding to be tested, a laser transmitter, a UHF sensor, a temperature sensor, an oscilloscope, and a temperature display;

[0006] The AC voltage source is connected to the winding to be measured; the UHF sensor is connected to the oscilloscope; the temperature sensor is connected to the temperature display;

[0007] The AC voltage source is used to apply an AC voltage to the winding to be tested;

[0008] The laser emitter is used to continuously emit laser light toward a preset target position on the winding to be tested;

[0009] The UHF sensor is used to monitor the target position for electromagnetic waves, and when electromagnetic waves are detected, send electromagnetic wave signals to the oscilloscope for display;

[0010] The temperature sensor is used to monitor the local temperature of the target location and send the monitored local temperature to the temperature display for display.

[0011] Furthermore, the transformer winding partial discharge testing system described in the above embodiment further includes: a test chamber;

[0012] The winding to be tested, the laser transmitter, the temperature sensor, and the ultra-high frequency sensor are located in the experimental cavity.

[0013] Furthermore, the temperature sensor is arranged at the center of the surface of the UHF sensor.

[0014] Furthermore, the transformer winding partial discharge testing system described in the above embodiment further includes: an electrical connection device; the electrical connection device is composed of a high-voltage conductor and a bushing;

[0015] The electrical connection device has one end connected to the AC voltage source and the other end connected to the winding to be measured, and is used to transmit the AC voltage output by the AC voltage source to the winding to be measured.

[0016] Furthermore, the transformer winding partial discharge testing system described in the above embodiment further includes: a laser controller;

[0017] The laser controller is connected to the laser emitter and is used to control the irradiation angle, irradiation duration, and intensity of the emitted laser of the laser emitter.

[0018] Furthermore, the transformer winding partial discharge testing system described in the above embodiment further includes: a signal amplifier;

[0019] The input end of the signal amplifier is connected to the UHF sensor, and the output end is connected to the oscilloscope;

[0020] The signal amplifier is used to amplify the electromagnetic wave signal monitored by the UHF sensor.

[0021] Furthermore, the transformer winding partial discharge test system described in the above embodiment further includes: a pulse generator, and a discharge amount monitoring device;

[0022] The pulse generator is used to inject a preset calibration pulse into the winding to be tested after the target position is damaged;

[0023] The UHF sensor is further used to monitor the pulse signal at the target position and send the pulse signal to the discharge amount monitoring device for display;

[0024] The discharge amount monitoring device is further used to calculate the discharge amount at the target position based on the pulse signal and the calibration pulse.

[0025] Another embodiment of the present invention further provides a method for testing partial discharge of a transformer winding, which is applicable to a system for testing partial discharge of a transformer winding as described in any one of the above embodiments, comprising:

[0026] Controlling the AC voltage source to apply AC voltage to the winding to be measured;

[0027] Controlling the laser transmitter to continuously emit laser light toward a preset target position on the winding to be measured;

[0028] The oscilloscope and the temperature display are monitored. When it is determined that the oscilloscope displays an electromagnetic wave signal, the local temperature displayed by the temperature sensor is recorded, and the local temperature is used as the target temperature for inducing partial discharge in the winding to be tested.

[0029] Furthermore, the controlling the laser emitter to continuously emit laser light toward a preset target position on the winding to be measured comprises:

[0030] determining an irradiation angle of the laser emitter according to the target position;

[0031] generating a laser irradiation instruction according to the irradiation angle;

[0032] The laser irradiation instruction is input into the laser controller to enable the laser emitter to emit laser light toward the target position.

[0033] Furthermore, after taking the local temperature as the target temperature for inducing partial discharge in the winding to be tested, the method further includes:

[0034] Controlling the AC voltage source to sequentially apply working voltages of different magnitudes to the winding to be tested;

[0035] Monitoring the temperature display and recording the heating time required for the winding to be tested to reach the target temperature at each operating voltage;

[0036] The plurality of heating time periods are used as operating time thresholds of the winding to be tested at each operating voltage.

[0037] The following beneficial effects are achieved by implementing the present invention:

[0038] The present invention provides a system and method for testing partial discharge of transformer windings. The system includes: an AC voltage source, a winding to be tested, a laser transmitter, a UHF sensor, a temperature sensor, an oscilloscope, and a temperature display. The AC voltage source is controlled to apply an AC voltage to the winding to be tested; the laser transmitter is controlled to continuously emit a laser at a preset target position on the winding to be tested; the oscilloscope and the temperature display are monitored. When it is determined that the oscilloscope displays an electromagnetic wave signal, the local temperature displayed by the temperature sensor is recorded, and the local temperature is used as the target temperature for inducing partial discharge in the winding to be tested.

[0039] Therefore, the present invention utilizes a laser emitter to irradiate a target position of a winding to create local damage at the target position, and simultaneously utilizes a UHF sensor to monitor the electromagnetic wave signal caused by partial discharge. Then, when it is determined that the oscilloscope displays the electromagnetic wave signal, the local temperature displayed by the temperature sensor is the target temperature that causes partial discharge in the winding to be tested. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the implementation. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0041] Figure 1 1 is a schematic structural diagram of a transformer winding partial discharge testing system provided by one embodiment of the present invention;

[0042] Figure 2 The figure is a flow chart of a method for testing partial discharge of a transformer winding provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0043] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions in this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0045] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0046] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0047] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0048] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0049] In the description of the embodiments of the present application, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; internal connections between two components or interactions between two components. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0050] See also Figure 1To address the problem that existing technologies have difficulty measuring the critical temperature at which a local hotspot region triggers partial discharge, an embodiment of the present invention provides a transformer winding partial discharge testing system, comprising: an AC voltage source 1, a winding to be tested 2, a laser transmitter 3, a UHF sensor 4, a temperature sensor 5, an oscilloscope 6, and a temperature display 7;

[0051] The AC voltage source 1 is connected to the winding to be measured 2; the UHF sensor 4 is connected to the oscilloscope 6; the temperature sensor 5 is connected to the temperature display 7;

[0052] The AC voltage source 1 is used to apply an AC voltage to the winding 2 to be tested;

[0053] The laser emitter 3 is used to continuously emit laser light toward a preset target position on the winding 2 to be tested;

[0054] The UHF sensor 4 is used to monitor the target position for electromagnetic waves, and when electromagnetic waves are detected, the electromagnetic wave signal is sent to the oscilloscope 6 for display;

[0055] The temperature sensor 5 is used to monitor the local temperature of the target location and send the monitored local temperature to the temperature display 7 for display.

[0056] In a preferred embodiment of the present invention, an AC voltage source 1 serves as an excitation voltage, generating an AC test voltage of 30 Hz to 300 Hz. The winding 2 to be tested utilizes a conductor-wrapped insulating paper structure consistent with that of an actual transformer, with the first end of the winding 2 connected to high voltage and the second end grounded. During testing, an AC voltage is applied to the winding 2 to be tested, while a laser emitter 3 is used to illuminate the insulation surface of the winding. The laser irradiation time and intensity are continuously increased to create localized insulation damage in the winding 2 to be tested. While this localized damage is being created, a UHF sensor 4 and a temperature sensor 5 are used to measure localized discharge electromagnetic waves and localized temperature. When the damage is sufficient to cause localized discharge, the localized discharge electromagnetic wave and temperature signal values are obtained.

[0057] Preferably, the transformer winding partial discharge test system further includes: an experimental cavity 8; the winding to be tested 2, the laser emitter 3, the temperature sensor 5, and the ultra-high frequency sensor 4 are located in the experimental cavity 8.

[0058] In a preferred embodiment of the present invention, the experimental cavity 8 uses a metal shell to simulate an actual transformer shell and provide an actual working environment for the winding 2 to be tested.

[0059] Preferably, the temperature sensor 5 is arranged at the center of the surface of the UHF sensor 4 .

[0060] In a preferred embodiment of the present invention, the UHF sensor 4 and the temperature sensor 5 are arranged in an integrated manner, that is, the temperature sensor 5 is arranged at the center position of the surface of the flat-plate UHF sensor 4, and the integrated sensor is set inside the experimental cavity 8 and is directly opposite the insulation damage point (target position). The signal transmission lines of the UHF sensor 4 and the temperature sensor 5 are led out to the outside of the experimental cavity 8, and are connected to an oscilloscope 6 to display the UHF signal, and are connected to a temperature display 7 to display the real-time temperature of the insulation damage point.

[0061] Preferably, the transformer winding insulation damage and partial discharge testing system further comprises: an electrical connection device; the electrical connection device 9 is composed of a high-voltage conductor 91 and a bushing 92;

[0062] The electrical connection device 9 has one end connected to the AC voltage source 1 and the other end connected to the winding 2 to be measured, and is used to transmit the AC voltage output by the AC voltage source to the winding 2 to be measured.

[0063] In a preferred embodiment of the present invention, in order to prevent the risk of electric shock caused by excessive voltage when simulating the working voltage of the transformer, the AC voltage source 1 is introduced into the experimental cavity 8 through an electrical connection device 9 composed of a high-voltage conductor 91 and an insulating sleeve 92.

[0064] Preferably, the transformer winding partial discharge testing system further includes: a laser controller 10;

[0065] The laser controller 10 is connected to the laser emitter 3 and is used to control the irradiation angle, irradiation duration, and intensity of the emitted laser of the laser emitter 3 .

[0066] In a preferred embodiment of the present invention, an internal laser emitter 3 is arranged in an experimental cavity 8, with its emission end located inside the experimental cavity. A control line is led out of the cavity and connected to a laser controller 10. The laser controller 10 can adjust the emission angle, irradiation time, and laser intensity of the laser emitter. In a specific implementation, the laser controller 10 is aimed at the oil-paper insulation on the winding surface, and the intensity and irradiation time of the laser emitter 3 are continuously increased. This can create an insulation temperature rise point at the irradiation point on the winding insulation surface and form an insulation damage point.

[0067] It's understandable that partial discharge in windings primarily arises from two factors: voltage and laser damage. Normally, in the absence of laser damage, partial discharge only occurs when the voltage reaches a certain (high) threshold. However, with laser irradiation, the destructive effect of the laser significantly lowers this threshold, allowing partial discharge to occur at lower voltages. Therefore, the testing steps are as follows: 1. Maintain a constant applied AC voltage while performing partial discharge testing. No partial discharge occurs. 2. Increase the laser intensity using a stepwise method: Apply a laser beam with an intensity of P for a time of T, then continue with a laser beam with an intensity of P + δP for a time of T, and so on, until the UHF sensor detects the occurrence of partial discharge.

[0068] Preferably, the transformer winding partial discharge testing system further comprises: a signal amplifier 11;

[0069] The input end of the signal amplifier 11 is connected to the UHF sensor 4, and the output end is connected to the oscilloscope 6;

[0070] The signal amplifier 11 is used to amplify the electromagnetic wave signal monitored by the UHF sensor 4 .

[0071] In a preferred embodiment of the present invention, the signal amplifier 11 can receive an electrical signal and convert it into a larger current or voltage signal. Such a device is very critical in various electronic systems and is used to enhance the amplitude of the signal for further processing or transmission.

[0072] Preferably, the transformer winding partial discharge test system further comprises: a pulse generator 12, and a discharge amount monitoring device 13;

[0073] The pulse generator 12 is used to inject a preset calibration pulse into the winding 2 to be tested after the target position is damaged;

[0074] The UHF sensor 4 is also used to monitor the pulse signal at the target position and send the pulse signal to the discharge amount monitoring device 13 for display;

[0075] The discharge amount monitoring device 13 is further configured to calculate the discharge amount at the target position according to the pulse signal and the calibration pulse.

[0076] In a preferred embodiment of the present invention, the insulation damage degree of the insulation-damaged winding under different operating times is measured at various operating voltages, thereby determining the maximum operating time of the transformer with insulation damage.

[0077] By injecting a calibration pulse (e.g., 10pC, 100pC) into the winding using a pulse generator 12 with a known discharge capacity, the pulse amplitude output by the UHF sensor is recorded. The transfer function of the sensor system is determined by fitting an amplitude-discharge curve (linear or nonlinear) using the calibration data:

[0078] Q=k*V peak +C;

[0079] Where Q is the discharge capacity (pC), Vpeak is the pulse amplitude measured by the oscilloscope, and k and C are calibration factors, which are set according to the calibration pulse and AC voltage.

[0080] See also Figure 2 , a transformer winding partial discharge testing method provided in another embodiment of the present invention, applicable to a transformer winding partial discharge testing system as described in any of the above-mentioned invention embodiments, comprising:

[0081] S1, control the AC voltage source to apply AC voltage to the winding to be tested;

[0082] S2, controlling the laser transmitter to continuously emit laser light toward a preset target position on the winding to be tested;

[0083] S3. Monitoring the oscilloscope and the temperature display. When it is determined that the oscilloscope displays an electromagnetic wave signal, recording the local temperature displayed by the temperature sensor, and using the local temperature as the target temperature for inducing partial discharge in the winding to be tested.

[0084] Preferably, controlling the laser emitter to continuously emit laser light toward a preset target position on the winding to be measured comprises:

[0085] S21. Determine the irradiation angle of the laser emitter according to the target position;

[0086] S22, generating a laser irradiation instruction according to the irradiation angle;

[0087] S23, inputting the laser irradiation instruction into the laser controller to enable the laser emitter to emit laser toward the target position.

[0088] In a preferred embodiment of the present invention, an AC voltage is applied to the winding to be measured through an AC voltage source, and a laser emitter is used to irradiate the insulating surface of the winding to be measured, and the laser irradiation time and intensity are continuously increased to produce local damage to the winding insulation. While producing the local damage, local discharge electromagnetic waves and local temperature measurements are performed using ultra-high frequency and temperature sensors facing the irradiation point. When the damage is sufficient to cause local discharge, the local discharge electromagnetic wave signal and temperature signal values at this time are obtained.

[0089] By manually controlling the generation of insulation damage points and using non-contact methods to measure ultra-high frequency partial discharge and temperature, this method avoids the safety issues associated with contact methods used in high-voltage testing. It also avoids the difficulty in determining the location of hotspots created using conventional methods. This method is easy to implement, safe and controllable, and produces accurate measurement results.

[0090] Preferably, after taking the local temperature as the target temperature for inducing partial discharge in the winding to be tested, the method further includes:

[0091] S4, controlling the AC voltage source to sequentially apply working voltages of different magnitudes to the winding to be tested;

[0092] S5. Monitor the temperature display and record the heating time required for the winding to reach the target temperature at each operating voltage;

[0093] S6. Using the plurality of heating time periods as operating time thresholds of the winding to be tested at each operating voltage.

[0094] In a preferred embodiment of the present invention, different operating voltages of the transformer are simulated during operation, the winding to be tested is tested, and the heating time required for the winding to be tested to reach the target temperature at each operating voltage is recorded. Specifically, considering the different initial temperatures in different months, the initial temperature of the experimental cavity is initially set to the initial temperature of the different months, for example, in July and August in summer, the initial temperature is set to 35°C, and in December in winter, it is set to -10°C. Then, the heating time required for the winding to be tested to reach the target temperature at each operating voltage at different initial temperatures is recorded, and the maximum operating time threshold of the winding to be tested at each operating voltage is determined.

[0095] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A transformer winding partial discharge testing system, characterized in that: include: AC voltage source, winding to be tested, laser transmitter, UHF sensor, temperature sensor, oscilloscope, and temperature display; The AC voltage source is connected to the winding to be measured; The UHF sensor is connected to the oscilloscope; the temperature sensor is connected to the temperature display; The AC voltage source is used to apply an AC voltage to the winding to be tested; The laser emitter is used to continuously emit laser light toward a preset target position on the winding to be tested; The UHF sensor is used to monitor the target position for electromagnetic waves, and when electromagnetic waves are detected, send electromagnetic wave signals to the oscilloscope for display; The temperature sensor is used to monitor the local temperature of the target location and send the monitored local temperature to the temperature display for display.

2. A transformer winding partial discharge testing system as claimed in claim 1, characterized in that: Also includes: Experimental chamber; The winding to be tested, the laser transmitter, the temperature sensor, and the ultra-high frequency sensor are located in the experimental cavity.

3. A transformer winding partial discharge testing system as claimed in claim 2, characterized in that: The temperature sensor is arranged at the center of the surface of the UHF sensor.

4. A transformer winding partial discharge testing system as claimed in claim 3, characterized in that: Also includes: electrical connection device; The electrical connection device is composed of a high-voltage conductor and a bushing; The electrical connection device has one end connected to the AC voltage source and the other end connected to the winding to be measured, and is used to transmit the AC voltage output by the AC voltage source to the winding to be measured.

5. A transformer winding partial discharge testing system as claimed in claim 4, characterized in that: Also includes: Laser controller; The laser controller is connected to the laser emitter and is used to control the irradiation angle, irradiation duration, and intensity of the emitted laser of the laser emitter.

6. A transformer winding partial discharge testing system as claimed in claim 5, characterized in that: Also includes: signal amplifier; The input end of the signal amplifier is connected to the UHF sensor, and the output end is connected to the oscilloscope; The signal amplifier is used to amplify the electromagnetic wave signal monitored by the UHF sensor.

7. A transformer winding partial discharge testing system as claimed in claim 6, characterized in that: Also includes: Pulse generator and discharge amount monitoring device; The pulse generator is used to inject a preset calibration pulse into the winding to be tested after the target position is damaged; The UHF sensor is further used to monitor the pulse signal at the target position and send the pulse signal to the discharge amount monitoring device for display; The discharge amount monitoring device is further used to calculate the discharge amount at the target position based on the pulse signal and the calibration pulse.

8. A method for testing partial discharge of transformer windings, characterized in that: A transformer winding partial discharge testing system according to any one of claims 1 to 7, comprising: Controlling the AC voltage source to apply AC voltage to the winding to be measured; Controlling the laser transmitter to continuously emit laser light toward a preset target position on the winding to be measured; The oscilloscope and the temperature display are monitored. When it is determined that the oscilloscope displays an electromagnetic wave signal, the local temperature displayed by the temperature sensor is recorded, and the local temperature is used as the target temperature for inducing partial discharge in the winding to be tested.

9. A method for testing partial discharge of transformer windings according to claim 8, characterized in that: The controlling the laser emitter to continuously emit laser light toward a preset target position on the winding to be measured comprises: determining an irradiation angle of the laser emitter according to the target position; generating a laser irradiation instruction according to the irradiation angle; The laser irradiation instruction is input into the laser controller to enable the laser emitter to emit laser light toward the target position.

10. A method for testing partial discharge of transformer windings according to claim 9, characterized in that: After taking the local temperature as the target temperature for inducing partial discharge in the winding to be measured, the method further includes: Controlling the AC voltage source to sequentially apply working voltages of different magnitudes to the winding to be tested; Monitoring the temperature display and recording the heating time required for the winding to be tested to reach the target temperature at each operating voltage; The plurality of heating time periods are used as operating time thresholds of the winding to be tested at each operating voltage.

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