Improved transformer partial discharge rapid detection system
By combining ultrasonic, ultra-high frequency and infrared detection methods, accurate positioning and type determination of transformer partial discharge can be achieved, solving the problem of large errors in existing detection devices, improving detection accuracy and reliability, and supporting early fault diagnosis and maintenance.
Patent Information
- Application Number
- CN202422708752.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-07
- Publication Date
- 2025-09-09
- Estimated Expiration
- 2034-11-07
AI Technical Summary
Existing transformer partial discharge detection devices have large errors, making it difficult to accurately judge the actual discharge situation of the transformer and are easily affected by electrical interference.
By combining ultrasonic, UHF and infrared detection methods and comprehensively analyzing ultrasonic, UHF and infrared signals through the data processing module, the location and type of partial discharge of transformers can be determined, thus enhancing the accuracy and reliability of detection.
It improves the accuracy and reliability of transformer partial discharge detection, can diagnose faults at an early stage, reduce the misjudgment rate, provide preliminary positioning of the fault point, provide a basis for maintenance work, extend equipment life and reduce downtime.
Smart Images
Figure CN223320525U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of transformer detection, and in particular relates to an improved transformer partial discharge rapid detection system. Background Art
[0002] A complete power transmission system encompasses multiple links, from power generation at power plants, transmission via transmission lines, voltage conversion at substations, to final distribution via transformers. Transformers therefore play a central role in power distribution within the power grid and are crucial to its stable and safe operation. A transformer failure could severely impact the transmission function of the entire power grid, or even lead to systemic paralysis. According to statistics, insulation failure is the primary factor hindering transformer operation, while partial discharge is the primary cause of transformer insulation degradation. Therefore, monitoring transformer partial discharge is crucial to the stable operation of the power system, and the demand for continuously updating and optimizing transformer partial discharge detection devices has also increased.
[0003] Currently, some transformer partial discharge detection devices on the market are isolated systems that only detect certain variables generated during partial discharge. The partial discharge results detected in this way may be accompanied by interference in the field, resulting in large errors between the detection results and the actual situation, making it difficult for technicians to accurately judge the actual discharge situation of the transformer. Utility Model Content
[0004] In response to the shortcomings of the existing technology, the utility model provides an improved transformer partial discharge rapid detection system. Based on ultrasonic detection method, ultra-high frequency detection method and infrared detection method, it realizes the positioning of transformer partial discharge and the judgment of partial discharge type through combined detection, thereby enhancing the accuracy and reliability of partial discharge detection.
[0005] An improved transformer partial discharge rapid detection system, an ultrasonic detection module, is used to collect ultrasonic signals generated by transformer partial discharge, and transmit the signals to the data processing module after signal processing; during the processing process, a bandpass filter is used for filtering;
[0006] The UHF detection module is used to collect the UHF electromagnetic waves generated by partial discharge of the transformer, and transmit the signals to the data processing module after signal conversion; during the processing, a bandpass filter is used for filtering;
[0007] Infrared detection module, used to monitor and observe the transformer to be inspected and collect thermal signals, and transmit the information to the data processing module for display;
[0008] The data processing module determines whether there is abnormal discharge inside the transformer and determines the discharge location based on the analysis of ultrasonic signals, ultra-high frequency signals and thermal signals; the data processing module is connected to the PC host computer through wireless communication.
[0009] The ultrasonic detection module includes a plurality of piezoelectric ultrasonic sensors installed on the transformer housing.
[0010] The signal processing of the ultrasonic detection module includes amplification, filtering, and rectification, and is transmitted to the data processing module after conversion by an analog-to-digital converter; the bandpass filter used in the filtering process is a 70-140kHz Butterworth bandpass filter composed of a cascade of a second-order active low-pass filter and a second-order active high-pass filter, and the circuit topology is a SallenKey type.
[0011] A low-pass filter is used at the input to allow signals within 140kHz to pass through, and a high-pass filter is used at the output to allow signals above 70kHz to pass through.
[0012] In the rectifier circuit, the AC signal flows through D1 in half a cycle and flows through D2 in the second half cycle. D1 and D2 can make the AC signal flow through the load in the same direction.
[0013] The UHF detection module includes a UHF sensor, which is arranged in an area where the transformer can emit electromagnetic waves.
[0014] The signal processing of the UHF detection module includes amplification, filtering, and digital detector conversion output, which is then converted by an analog-to-digital converter and transmitted to the data processing module; the bandpass filter used in the filtering process is a cascade of a second-order Butterworth bandpass filter with a frequency band of 300 to 1500 MHz and a second-order Butterworth bandstop filter with a center frequency of 900 MHz and a stop band of 100 MHz.
[0015] The improved transformer partial discharge rapid detection system further comprises an alarm device electrically connected to the data processing module via an alarm circuit.
[0016] The data processing module is externally connected to a display device, including a display screen, for displaying the image captured by the infrared detection module.
[0017] The improved transformer partial discharge rapid detection system provided by the present utility model utilizes three detection technologies: ultrasonic, ultra-high frequency (UHF), and infrared. The ultrasonic sensor, a contact sensor, is placed directly on the transformer casing during detection. An additional UHF sensor is located in the area where the transformer emits electromagnetic waves to enhance detection of internal discharges. The infrared detection method acquires data without physical contact, and the image provides a visual display of temperature distribution. The ultrasonic detection method is less susceptible to electrical interference and is suitable for detection in complex electromagnetic environments. By measuring the time difference of sound wave propagation between each sensor relative to a reference sensor, combined with sound velocity and ultrasonic sensor position information, the ultrasonic sensor can achieve preliminary localization of the discharge location. This facilitates rapid fault location and facilitates subsequent inspection and maintenance. UHF detection can capture weak partial discharge signals, facilitating early diagnosis. Combined with the PRPD characteristic spectrum, the UHF signature of known discharge types can be compared to determine the type and severity of the discharge. The combined detection of these three methods corroborates the changes in different physical quantities, reducing false positives and enabling preliminary localization and discharge type identification.
[0018] The utility model combines data from multiple detection methods to more comprehensively evaluate the health status of equipment, detect potential failures earlier, and provide a basis for maintenance planning, thereby extending equipment life and reducing downtime. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a schematic diagram of the improved transformer partial discharge rapid detection system of the utility model;
[0020] Figure 2 This is a circuit diagram of the ultrasonic detection module in the present utility model;
[0021] Figure 3 This is a circuit diagram of the UHF detection module in the present utility model;
[0022] 1-Ultrasonic sensor, 2-Amplifier, 3-Filter I, 4-Two-way switch, 5-UHF sensor, 6-Filter II, 7-Analog-to-digital converter, 8-Rectifier, 9-Logarithmic detector, 10-Data processing module, 11-PC host computer, 12-Alarm device, 13-Display device, 14-Infrared imaging camera. DETAILED DESCRIPTION
[0023] In order to better explain the present invention and facilitate understanding, the technical solutions and effects of the present invention are described in detail below with reference to the accompanying drawings through specific implementation methods.
[0024] like Figure 1As shown, an improved transformer partial discharge rapid detection system includes an ultrasonic detection module, a UHF detection module, and an infrared detection module. The ultrasonic detection module and the UHF detection module are respectively connected to the input of an analog-to-digital converter 7 via a two-way switch 4. The analog-to-digital converter 7 and the infrared detection module are connected to the input of a data processing module 10. The data processing module 10 is wirelessly connected to a PC host computer 11. As the core processor, the data processing module 10 receives signals collected and converted by the ultrasonic detection module, receives signals collected and converted by the UHF detection module, and receives information from the infrared detection module. By further analyzing the ultrasonic signals, UHF signals, and thermal electrical signals, it determines whether there is any discharge abnormality within the transformer.
[0025] Described data processing module 10 is connected with PC host computer 11 by communication circuit, adopts wifi communication mode to realize the communication between PC end host computer and MCU slave computer, and discharge information is uploaded to computer terminal.In the present embodiment, data processing module 10 adopts STM32F103VCT6, to ultrasonic signal after processing and UHF signal, heat signal are processed and transmitted to PC host computer 11 by wifi communication, analyze and judge in conjunction with PSCAD discharge analysis software, generate partial discharge characteristic spectrum (PRPD spectrum), PRPD spectrum is shown according to phase by each partial discharge pulse with phase mark, and it describes amplitude (Y axis) and phase angle (X axis) of each discharge event.By identifying the key information and discharge feature including discharge repeatability, discharge polarity, discharge dispersion in PRPD spectrum, as, determine discharge type.
[0026] The ultrasonic detection module is used to collect ultrasonic signals generated by partial discharge of the transformer and transmit the processed signals to the data processing module 10. It includes an ultrasonic sensor 1 installed on the transformer housing. The output end of the ultrasonic sensor 1 is connected to the input end of the amplifier 2, the output end of the amplifier 2 is connected to the input end of the filter, and the output end of the filter is connected to the two-way switch 4 to transmit the signal to the analog-to-digital converter 7 for conversion.
[0027] Preferably, the ultrasonic detection module described in this embodiment adopts a piezoelectric ultrasonic sensor SR150N. The piezoelectric ultrasonic sensor SR150N collects the ultrasonic signal generated during partial discharge of the transformer, amplifies the collected ultrasonic signal through the INA128 amplifier circuit, and then uses a 70-140kHz bandpass filter to filter out interference and useless signals in the signal. The high-frequency AC signal is changed into a DC signal through the AD8620BR rectifier circuit, and finally the signal is sent to the analog-to-digital converter AD9251 by the multi-way switch for analog-to-digital conversion and then sent to the data processing module STM32F103VCT6.
[0028] Ultrasonic detection module circuit diagram Figure 2 As shown, the ultrasonic sensor 1 transmits the ultrasonic signal to the data processing module 10 via the signal processing circuit. The signal processing circuit converts the collected ultrasonic waves into valid signals that can be received by the microcontroller through amplification, filtering, rectification, and A / D conversion circuits. The data processing module STM32F103VCT6 acts as a signal processor to process the collected signals.
[0029] The signal transmission and conversion process of the ultrasonic detection module is as follows:
[0030] a: The SR150N sensor sends the collected weak signal to the INA128 amplifier circuit to reduce signal distortion and external noise interference.
[0031] b: Because the ultrasonic energy generated during transformer partial discharge is primarily distributed within the frequency range of 50kHz to 300kHz, while the peak frequency of the discharge signal is concentrated between 70kHz and 140kHz, the ultrasonic detection module uses filter I3, a 70-140kHz Butterworth bandpass filter consisting of a cascade of a second-order active low-pass filter and a second-order active high-pass filter, to effectively eliminate interference from noise and unwanted signals and ensure accurate detection results. The circuit topology is SallenKey. Low-pass filtering is used at the input, allowing signals below 140kHz to pass, while high-pass filtering is used at the output, allowing signals above 70kHz to pass.
[0032] The filtered signal is fed into a rectifier circuit, which converts a high-frequency AC signal ranging from thousands to several megahertz into a DC signal. In this circuit, the AC signal flows through D1 in half a cycle and through D2 in the second half cycle. D1 and D2 enable the AC signal to flow through the load in the same direction, fully utilizing both half cycles. This improves the efficiency of the rectifier 8 and makes the rectified signal smoother.
[0033] c) The rectified signal passes through a single-ended to differential converter and two switches 4 into the AD9251 for analog-to-digital conversion, resulting in a signal that the STM32F103VCT6 can receive.
[0034] Preferably, the number of ultrasonic sensors 1 in this embodiment is four, arranged in a rhombus on the surface of the transformer tank, with each sensor installed at a vertex of the rhombus, and the vertex angle of the rhombus is 45 degrees. The four ultrasonic sensors 1 use a hyperbolic positioning technology, i.e., acoustic-acoustic signal positioning, to determine the sensor position. Specifically: the propagation speed of the sound wave in the transformer is V e, the ultrasonic sensor 1 corresponding to the first acoustic signal received by the data processing module 10 is the first ultrasonic sensor, and the ultrasonic sensor is used as the reference sensor. Similarly, the ultrasonic sensor 1 corresponding to the i-th acoustic signal received by the data processing module 10 is the i-th ultrasonic sensor. The time difference between the signal received by the i-th sensor and the signal received by the reference sensor can be measured as t i ; A coordinate system is established on the transformer. The three-dimensional coordinates of the first ultrasonic sensor are (x1, y1, z1). The relative sound wave propagation time of each sensor satisfies the hyperbolic surface equation (1):
[0035]
[0036] Where i = 2, 3, 4;
[0037] (x i ,y i ,z i ) is the three-dimensional coordinate of the position of the i-th sensor;
[0038] (x, y, z) is the three-dimensional coordinate of the corresponding discharge point.
[0039] The t is measured by the three-dimensional coordinates (x1, y1, z1) of the first ultrasonic sensor and the time difference of the sound wave propagation of the i-th sensor relative to the reference sensor. i (i=2, 3, 4) Solving the above nonlinear equation, the position coordinates of the discharge point can be obtained.
[0040] The UHF detection module is used to collect the UHF electromagnetic waves generated by partial discharge of the transformer and transmit the converted signals to the data processing module 10. It includes a UHF sensor 5, which is arranged in the area where the transformer can emit electromagnetic waves. The output end of the UHF sensor 5 is connected to the input end of the amplifier 2, the output end of the amplifier 2 is connected to the input end of the filter, and the output end of the filter is connected to the two-way switch 4 to transmit the signal to the analog-to-digital converter 7 for conversion.
[0041] Preferably, the UHF sensor 5 described in this embodiment adopts a UHF sensor PDU-T2 to collect UHF electromagnetic waves, amplify the collected signal through the ADL5611 amplifier module, and filter out interference and useless signals through a 300-1500MHz bandpass filter and a band-stop filter with a center frequency of 900MHz and a stop band of 100MHz. The PD signal is converted into a 40MHz low-frequency signal through the ADL5513 logarithmic detector 9, and finally, the signal is sent to the analog-to-digital converter AD9251 using a multiplexer for analog-to-digital conversion and then sent to the data processing module STM32F103VCT6.
[0042] UHF detection module circuit diagram Figure 3 As shown, the UHF sensor 5 transmits the UHF signal to the data processing module 10 via the signal processing circuit. The signal processing circuit converts the collected UHF electromagnetic waves into valid signals that can be received by the microcontroller through amplification, filtering, rectification, and A / D conversion circuits. The data processing module STM32F103VCT6 acts as a signal processor to process the collected signals.
[0043] The signal transmission and conversion process of the UHF detection module is as follows:
[0044] a: The UHF sensor PDU-T2 feeds the collected UHF electromagnetic wave signal into the ADL5611 RF gain module. Preamplifier 2, a key component in analog signal amplification, adjusts the signal amplitude to ensure it meets the input requirements of subsequent circuits. The ADL5611 offers broadband operation in the 30MHz to 6GHz range and boasts 22dB of gain. Within the UHF-PD operating frequency range of 300MHz to 1500MHz, the gain is extremely flat, with a gain ripple of less than 0.4dB.
[0045] b: In today's complex electromagnetic environment, numerous unrestricted interference signals operating in the 300-1500 MHz frequency range exist at test sites. According to statistical analysis, the Global System for Mobile Communications (GSM) wireless signal operating at approximately 900 MHz is the primary source of interference in actual testing. To address this issue, the filter II 6 used in the UHF detection module is configured as a cascade of a second-order Butterworth bandpass filter with a frequency band of 300-1500 MHz and a second-order Butterworth bandstop filter with a center frequency of 900 MHz and a stopband of 100 MHz. This filter suppresses interference signals in the 800-1000 MHz frequency range.
[0046] The filtered signal is fed into the ADL5513 logarithmic detector 9. With a response time as low as 20 ns and a dynamic range as high as 80 dB, the ADL5513 is well-suited for PD detection applications. It converts the ultra-high frequency electromagnetic wave signal generated by transformer partial discharge into a low-frequency signal of 40 MHz. In this embodiment, an analog-to-digital converter 7 with a sampling rate of 40 MSPS or 60 MSPS can be used to convert the analog PD signal into a digital signal.
[0047] c: Finally, the signal is sent to the AD9251 through a single-ended to differential circuit via two switches 4 for analog-to-digital conversion, obtaining a signal that can be received by the STM32F103VCT6.
[0048] The infrared detection module is used to monitor and observe the transformer to be detected, collect thermal signals, record heating points, and transmit the information to the data processing module 10.
[0049] Preferably, the infrared detection module includes an infrared imaging camera 14, specifically using the IRay Optoelectronics Tiny1-c micro infrared thermal imaging camera core, which directly transmits the collected and converted output digital signals to the data processing module STM32F103VCT6.
[0050] The improved transformer partial discharge rapid detection system also includes an alarm device 12, which is electrically connected to the data processing module 10 through an alarm circuit. When partial discharge information is detected, the data processing module 10 is electrically connected to the alarm circuit of the alarm device 12 to light an alarm light and trigger a buzzer to remind the user of the occurrence of partial discharge.
[0051] The data processing module 10 is externally connected to a display device 13 , including a display screen, for displaying images captured by the infrared thermal imaging camera.
[0052] During discharge detection, the infrared thermal imaging camera's infrared imaging function is first used to monitor and observe the transformer under inspection, recording hot spots. Ultrasonic and ultra-high frequency (UHF) signals are then collected and further analyzed to determine whether there are any abnormal discharges within the transformer. Specifically, if the infrared thermal imaging camera directly detects a high surface temperature outside the normal operating temperature range, it can be directly determined that the transformer is experiencing discharge or other faults. The ultrasonic and UHF signals are then used to analyze the location and type of the discharge. If the detected temperature is normal, it does not necessarily mean that there is no partial discharge. The remaining ultrasonic sensor 1 and ultra-high frequency sensor 5 need to be activated to further utilize the ultrasonic and UHF signals for accurate determination. First, ultrasonic sensor 1 is activated to begin collecting ultrasonic signals around the transformer, monitoring and recording ultrasonic signals in the 70-140 kHz range, which may be acoustic waves generated by partial discharges. The signals are then transmitted to the data processing module 10, where they are analyzed using PSCAD software to determine the frequency, amplitude, and duration characteristics of the signals. The ultrasonic characteristics of known discharge types are then compared to determine the type and intensity of the discharge. The waveform of a needle-plate discharge is a sharp pulse; the waveform of an air-gap discharge is a wide pulse with a long duration; the waveform of a surface discharge is a continuous oscillation; and the waveform of a suspended discharge may be irregular, with frequency and amplitude varying over time. The coordinates of the discharge points are calculated based on the time difference in acoustic wave propagation between multiple ultrasonic sensors 1 and a reference sensor.
[0053] The UHF sensor 5 is then activated to begin collecting UHF signals around the transformer. UHF signals in the 300-800 MHz and 1000-1500 MHz range are recorded. These signals are likely electromagnetic waves generated by partial discharges. The signals are then transmitted to the data processing module 10, where PSCAD software analyzes the collected UHF signals to generate a PRPD characteristic spectrum, determining the signal's frequency, amplitude, and phase characteristics. The PRPD characteristic spectrum is combined with the UHF characteristics of known discharge types to determine the type, location, and severity of the discharge, allowing appropriate repair and maintenance measures to be taken. Among these, corona discharge has a small discharge amplitude and widely distributed discharge points; internal gap discharge has a large discharge amplitude; poor contact discharge has a regular discharge amplitude and phase angle; and floating metal part discharge has a stable discharge amplitude and a periodic phase angle.
[0054] Based on this information, it is determined whether there is a discharge anomaly inside the transformer. If multiple sensors detect abnormal signals and these signals have similar characteristics, it can be assumed that there is a discharge anomaly inside the transformer.
Claims
1. An improved transformer partial discharge rapid detection system, characterized by: The ultrasonic detection module is used to collect the ultrasonic signals generated by partial discharge of the transformer, and transmit the signals to the data processing module after signal processing; during the processing process, a bandpass filter is used for filtering; The UHF detection module is used to collect the UHF electromagnetic waves generated by partial discharge of the transformer, and transmit the signals to the data processing module after signal conversion; during the processing, a bandpass filter is used for filtering; Infrared detection module, used to monitor and observe the transformer to be inspected and collect thermal signals, and transmit the information to the data processing module for display; The data processing module determines whether there is abnormal discharge inside the transformer and determines the discharge location based on the analysis of ultrasonic signals, ultra-high frequency signals and thermal signals; the data processing module is connected to the PC host computer through wireless communication.
2. The improved transformer partial discharge rapid detection system according to claim 1, characterized in that: The ultrasonic detection module includes a plurality of piezoelectric ultrasonic sensors installed on the transformer housing.
3. The improved transformer partial discharge rapid detection system according to claim 1, characterized in that: The signal processing of the ultrasonic detection module includes amplification, filtering, and rectification, and is transmitted to the data processing module after conversion by an analog-to-digital converter; the bandpass filter used in the filtering process is a 70-140kHz Butterworth bandpass filter composed of a cascade of a second-order active low-pass filter and a second-order active high-pass filter, and the circuit topology is a SallenKey type.
4. The improved transformer partial discharge rapid detection system according to claim 3, characterized in that: A low-pass filter is used at the input to allow signals within 140kHz to pass through, and a high-pass filter is used at the output to allow signals above 70kHz to pass through.
5. The improved transformer partial discharge rapid detection system according to claim 3, characterized in that: In the rectifier circuit, the AC signal flows through D1 in half a cycle and flows through D2 in the second half cycle. D1 and D2 can make the AC signal flow through the load in the same direction.
6. The improved transformer partial discharge rapid detection system according to claim 1, characterized in that: The UHF detection module includes a UHF sensor, which is arranged in an area where the transformer can emit electromagnetic waves.
7. The improved transformer partial discharge rapid detection system according to claim 1, characterized in that: The signal processing of the UHF detection module includes amplification, filtering, and digital detector conversion output, which is then converted by an analog-to-digital converter and transmitted to the data processing module; the bandpass filter used in the filtering process is a cascade of a second-order Butterworth bandpass filter with a frequency band of 300 to 1500 MHz and a second-order Butterworth bandstop filter with a center frequency of 900 MHz and a stop band of 100 MHz.
8. The improved transformer partial discharge rapid detection system according to claim 1, characterized in that: The improved transformer partial discharge rapid detection system further comprises an alarm device electrically connected to the data processing module via an alarm circuit.
9. The improved transformer partial discharge rapid detection system according to claim 1, characterized in that: The data processing module is externally connected to a display device, including a display screen, for displaying the image captured by the infrared detection module.