A method for evaluating performance of a very high frequency sensor based on threshold attenuation coefficient contrast

Abstract

This invention provides a method for evaluating the performance of ultra-high frequency (UHF) sensors based on threshold attenuation coefficient comparison. The method includes: determining the placement positions of a first UHF sensor and a UHF sensor under test; acquiring partial discharge (PD) UHF signals using the UHF sensor under test; performing simulation modeling of a transformer device and detecting the electric field strength using an ideal probe; calculating the attenuation coefficient A1 of the PD UHF signal in the dielectric window based on the physical parameters of the transformer device; calculating the attenuation coefficient A2 of the PD UHF signal propagating in the transformer; and calculating the threshold attenuation coefficient A of the PD UHF signal based on the above attenuation coefficients. 总 The performance status of the UHF sensor under test is determined by comparing the threshold attenuation coefficient with the actual attenuation coefficient. This invention proposes a verification method for UHF sensors embedded in transformers, improving the accuracy and reliability of on-site verification of UHF sensors.

Description

Technical Field

[0001] This invention relates to the field of ultra-high frequency sensor calibration, and more specifically to a method for evaluating the performance of ultra-high frequency sensors based on threshold attenuation coefficient comparison. Background Technology

[0002] Ultra-high frequency (UHF) partial discharge detection technology has become an important means of assessing the insulation condition of transformers due to its advantages such as high sensitivity and strong anti-interference ability. Built-in UHF sensors are directly installed inside the transformer tank, avoiding external environmental interference and effectively capturing UHF electromagnetic wave signals generated by insulation defects inside the equipment.

[0003] In actual operating conditions, the built-in sensors are installed inside the transformer, and their performance parameters are difficult to test directly using conventional methods. Furthermore, with long-term transformer operation, the built-in sensors are constantly immersed in high-temperature transformer oil, enduring thermal aging, electrical aging, and long-term corrosion from chemicals in the oil. This can lead to performance degradation of their internal sensitive elements, feeder connectors, and sealing structures. Failure to detect sensor degradation in a timely manner will result in distorted partial discharge monitoring data, causing false alarms or missed alarms, posing a significant threat to the safe operation of the transformer. Therefore, it is necessary to perform regular calibration of the sensors. By establishing a signal propagation attenuation model and combining the attenuation characteristics of the propagation path with the sensor's own performance, an accurate assessment of the actual detection capability of the built-in UHF sensor can be achieved, providing technical assurance for the reliability of the UHF partial discharge monitoring system for transformers. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the issue that existing verification technologies have poor applicability to built-in UHF sensors installed in transformer equipment in field environments, which affects the accuracy and reliability of sensor verification results.

[0005] This invention solves the above-mentioned technical problems by employing the following technical solution: a performance evaluation method for ultra-high frequency sensors based on threshold attenuation coefficient comparison includes:

[0006] S1. Arrange a first UHF sensor and a UHF sensor under test at the medium window on the outer wall of the transformer equipment box. Inject a verification pulse signal peak value U1 into the first UHF sensor to excite the first UHF sensor to emit a partial discharge verification signal, and control the UHF sensor under test to detect and save the partial discharge UHF signal peak value U2.

[0007] S2. The transformer equipment is simulated and modeled in CST simulation software. A first ideal probe and a second ideal probe are arranged on the outer wall of the transformer simulation model. A local discharge power supply is set in the transformer simulation model using discrete ports. The electric field strength E1 detected by the first ideal probe and the electric field strength E2 detected by the second ideal probe are obtained through simulation.

[0008] S3. Obtain the physical parameters of the transformer equipment, including the dielectric window radius and dielectric window height. Based on the above physical parameters, calculate the attenuation coefficient A1 of the partial discharge ultra-high frequency signal in the dielectric window.

[0009] Based on the peak electric field strength E1 detected by the first ideal probe and the peak electric field strength E2 detected by the second ideal probe, the attenuation coefficient A2 of the partial discharge UHF signal propagating in the transformer is calculated.

[0010] S4. Based on the attenuation coefficient A1 of the partial discharge UHF signal in the dielectric window and the attenuation coefficient A2 of the partial discharge UHF signal propagating in the transformer, calculate the threshold attenuation coefficient A of the partial discharge UHF signal. 总 ;

[0011] Based on the verification pulse signal U1 injected by the first UHF sensor and the partial discharge UHF signal U2 detected by the UHF sensor under test, the true attenuation coefficient A between the two sensors is calculated. 真实 ;

[0012] S5. By comparing the threshold attenuation coefficient and the actual attenuation coefficient, the performance status of the UHF sensor under test is determined.

[0013] In a more specific technical solution, in S1, the first UHF sensor and the UHF sensor to be tested are arranged at the medium window on the outer wall of the transformer tank according to the preset layout position, and the first UHF sensor is set on the opposite side tank wall and is on the same horizontal line.

[0014] In a more specific technical solution, in S2, according to the preset deployment position, the first ideal probe and the second ideal probe are arranged on the outer wall of the transformer simulation model, the first ideal probe and the second ideal probe are set on the same horizontal line, and the preset deployment position of the first ideal probe and the second ideal probe is the same as that of the first UHF sensor and the UHF sensor under test in S1.

[0015] According to the preset deployment location and deployment distance, a partial discharge power source is set on the inner wall of the transformer simulation model tank. The partial discharge power source and the first ideal probe are set on the same vertical line. The deployment distance is the distance l from the first ideal probe where the partial discharge power source is arranged, where l is 1 cm.

[0016] In a more specific technical solution, the formula for calculating the attenuation coefficient A1 of the partial discharge UHF signal in the dielectric window in S3 is as follows:

[0017] ;

[0018] ;

[0019] In the formula, λ is the wavelength of the partial discharge ultra-high frequency signal, and c is the speed of light in vacuum, taken as 3 × 10⁻⁶. 8 m / s, f is the maximum sweep frequency of the first ultra-high frequency sensor, taken as 1.5 GHz, ε r Let r be the relative permittivity of the transformer oil, r be the radius of the dielectric window, and h be the height of the dielectric window.

[0020] The formula for calculating the attenuation coefficient A2 of the partial discharge ultra-high frequency signal propagating in the transformer is as follows:

[0021] ;

[0022] In the formula, E1 is the peak value of the electric field intensity detected by the first ideal probe, E2 is the peak value of the electric field intensity detected by the second ideal probe, V is the voltage level of the transformer, and k is the voltage correction coefficient. If the voltage level of the transformer is ≥500kV, then k is 5, and otherwise k is 1.3.

[0023] In a more specific technical solution, in S4, the threshold attenuation coefficient A of the partial discharge UHF signal 总 The calculation formula is as follows:

[0024] ;

[0025] The true attenuation coefficient A between the two sensors 真实 The calculation formula is as follows:

[0026] .

[0027] In a more specific technical solution, in S5, the threshold attenuation coefficient and the actual attenuation coefficient are compared. If the threshold attenuation coefficient is greater than or equal to the actual attenuation coefficient, the performance of the UHF sensor under test is qualified; if the threshold attenuation coefficient is less than the actual attenuation coefficient, the performance of the UHF sensor under test is abnormal. Attached Figure Description

[0028] Figure 1 A flowchart of the UHF sensor performance evaluation method based on threshold attenuation coefficient comparison provided by the present invention;

[0029] Figure 2A schematic diagram of the built-in ultra-high frequency sensor provided by the present invention;

[0030] Figure 3 This is a schematic diagram of the location of the local discharge power source provided by the present invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, the UHF sensor performance evaluation method based on threshold attenuation coefficient comparison provided by this invention includes the following basic steps:

[0034] Step S1, as follows Figure 2 As shown, a first UHF sensor and a UHF sensor under test are arranged at the medium window on the outer wall of the transformer equipment box. A verification pulse signal peak value U1 is injected into the first UHF sensor to excite the first UHF sensor to emit a partial discharge verification signal, and the UHF sensor under test is controlled to detect and save the partial discharge UHF signal peak value U2.

[0035] In this embodiment, according to the preset layout position, the first UHF sensor and the UHF sensor to be tested are arranged at the medium window on the outer wall of the transformer tank, and the first UHF sensor is set on the opposite side tank wall and is on the same horizontal line.

[0036] Step S2, as follows Figure 3 As shown, the transformer equipment is simulated and modeled in CST simulation software. A first ideal probe and a second ideal probe are arranged on the outer wall of the transformer simulation model. A local discharge power supply is set in the transformer simulation model using discrete ports. The electric field strength E1 detected by the first ideal probe and the electric field strength E2 detected by the second ideal probe are obtained by simulation.

[0037] In this embodiment, according to the preset deployment position, the first ideal probe and the second ideal probe are arranged on the outer wall of the transformer simulation model, the first ideal probe and the second ideal probe are set on the same horizontal line, and the preset deployment position of the first ideal probe and the second ideal probe is the same as that of the first UHF sensor and the UHF sensor under test in S1.

[0038] According to the preset deployment location and deployment distance, a partial discharge power source is set in the transformer simulation model, and the partial discharge power source and the first ideal probe are set on the same vertical line. The deployment distance is the distance l from the first ideal probe where the partial discharge power source is arranged, where l is 1 cm.

[0039] Step S3: Obtain the physical parameters of the transformer equipment, including: the radius of the dielectric window and the height of the dielectric window. Based on the above physical parameters, calculate the attenuation coefficient A1 of the partial discharge ultra-high frequency signal in the dielectric window.

[0040] Based on the peak electric field strength E1 detected by the first ideal probe and the peak electric field strength E2 detected by the second ideal probe, the attenuation coefficient A2 of the partial discharge UHF signal propagating in the transformer is calculated.

[0041] In this embodiment, the formula for calculating the attenuation coefficient A1 of the partial discharge ultra-high frequency signal in the dielectric window is as follows:

[0042] ;

[0043] ;

[0044] In the formula, λ is the wavelength of the partial discharge ultra-high frequency signal, and c is the speed of light in vacuum, typically taken as 3 × 10⁻⁶. 8 m / s, f is the maximum sweep frequency of the first ultra-high frequency sensor, typically taken as 1.5 GHz, ε r Let r be the relative permittivity of the transformer oil, r be the radius of the dielectric window, and h be the height of the dielectric window.

[0045] The formula for calculating the attenuation coefficient A2 of the partial discharge ultra-high frequency signal propagating in the transformer is as follows:

[0046] ;

[0047] In the formula, E1 is the peak value of the electric field intensity detected by the first ideal probe, E2 is the peak value of the electric field intensity detected by the second ideal probe, V is the voltage level of the transformer, and k is the voltage correction coefficient. If the voltage level of the transformer is ≥500kV, then k is 5, and otherwise k is 1.3.

[0048] Step S4: Calculate the threshold attenuation coefficient A of the partial discharge UHF signal based on the attenuation coefficient A1 of the partial discharge UHF signal in the dielectric window and the attenuation coefficient A2 of the partial discharge UHF signal propagating in the transformer. 总 ;

[0049] Based on the verification pulse signal U1 injected by the first UHF sensor and the partial discharge UHF signal U2 detected by the UHF sensor under test, the true attenuation coefficient A between the two sensors is calculated. 真实 ;

[0050] In this embodiment, the threshold attenuation coefficient A of the partial discharge ultra-high frequency signal is... 总 The calculation formula is as follows:

[0051] ;

[0052] The true attenuation coefficient A between the two sensors 真实 The calculation formula is as follows:

[0053] .

[0054] Step S5: By comparing the threshold attenuation coefficient and the actual attenuation coefficient, determine the performance status of the UHF sensor under test.

[0055] In this embodiment, the threshold attenuation coefficient and the actual attenuation coefficient are compared. If the threshold attenuation coefficient is greater than or equal to the actual attenuation coefficient, the performance of the UHF sensor under test is qualified. If the threshold attenuation coefficient is less than the actual attenuation coefficient, the performance of the UHF sensor under test is abnormal.

Claims

1. A method for evaluating the performance of ultra-high frequency sensors based on threshold attenuation coefficient comparison, characterized in that, Includes the following steps: S1. Arrange a first UHF sensor and a UHF sensor under test at the medium window on the outer wall of the transformer equipment box. Inject a verification pulse signal peak value U1 into the first UHF sensor to excite the first UHF sensor to emit a partial discharge verification signal, and control the UHF sensor under test to detect and save the partial discharge UHF signal peak value U2. S2. The transformer equipment is simulated and modeled in CST simulation software. A first ideal probe and a second ideal probe are arranged on the outer wall of the transformer simulation model. A local discharge power supply is set in the transformer simulation model using discrete ports. The electric field strength E1 detected by the first ideal probe and the electric field strength E2 detected by the second ideal probe are obtained through simulation. S3. Obtain the physical parameters of the transformer equipment, including the dielectric window radius and dielectric window height. Based on the above physical parameters, calculate the attenuation coefficient A1 of the partial discharge ultra-high frequency signal in the dielectric window. Based on the peak electric field strength E1 detected by the first ideal probe and the peak electric field strength E2 detected by the second ideal probe, the attenuation coefficient A2 of the partial discharge UHF signal propagating in the transformer is calculated. S4. Based on the attenuation coefficient A1 of the partial discharge UHF signal in the dielectric window and the attenuation coefficient A2 of the partial discharge UHF signal propagating in the transformer, calculate the threshold attenuation coefficient A of the partial discharge UHF signal. 总 ; Based on the verification pulse signal U1 injected by the first UHF sensor and the partial discharge UHF signal U2 detected by the UHF sensor under test, the true attenuation coefficient A between the two sensors is calculated. 真实 ; S5. By comparing the threshold attenuation coefficient and the actual attenuation coefficient, the performance status of the UHF sensor under test is determined.

2. The method according to claim 1, characterized in that, In step S1, the first UHF sensor and the UHF sensor to be tested are arranged at the medium window on the outer wall of the transformer tank according to the preset layout position. The first UHF sensor is set on the opposite side of the tank wall and is on the same horizontal line.

3. The method according to claim 1, characterized in that, In step S2, the first ideal probe and the second ideal probe are arranged on the outer wall of the transformer simulation model according to the preset arrangement position. The first ideal probe and the second ideal probe are set on the same horizontal line, and the preset arrangement position of the first ideal probe and the second ideal probe is the same as that of the first UHF sensor and the UHF sensor under test in step S1. According to the preset deployment location and deployment distance, a partial discharge power source is set in the transformer simulation model, and the partial discharge power source and the first ideal probe are set on the same vertical line. The deployment distance is that the partial discharge power source is arranged at a distance l from the first ideal probe, where l is 1 cm.

4. The method according to claim 1, characterized in that, The formula for calculating the attenuation coefficient A1 of the partial discharge UHF signal in the dielectric window in S3 is as follows: ； ； In the formula, λ is the wavelength of the partial discharge ultra-high frequency signal, and c is the speed of light in vacuum, taken as 3 × 10⁻⁶. 8 m / s, f is the maximum sweep frequency of the first ultra-high frequency sensor, taken as 1.5 GHz, ε r Let r be the relative permittivity of the transformer oil, r be the radius of the dielectric window, and h be the height of the dielectric window. The formula for calculating the attenuation coefficient A2 of the partial discharge ultra-high frequency signal propagating in the transformer is as follows: ； In the formula, E1 is the peak value of the electric field intensity detected by the first ideal probe, E2 is the peak value of the electric field intensity detected by the second ideal probe, V is the voltage level of the transformer, and k is the voltage correction coefficient. If the voltage level of the transformer is ≥500kV, then k is 5, and otherwise k is 1.

3.

5. The method according to claim 1, characterized in that, In S4, the threshold attenuation coefficient A of the partial discharge ultra-high frequency signal 总 The calculation formula is as follows: ； The true attenuation coefficient A between the two sensors 真实 The calculation formula is as follows: 。 6. The method according to claim 1, characterized in that, In step S5, the threshold attenuation coefficient and the actual attenuation coefficient are compared. If the threshold attenuation coefficient is greater than or equal to the actual attenuation coefficient, the performance of the UHF sensor under test is qualified. If the threshold attenuation coefficient is less than the actual attenuation coefficient, the performance of the UHF sensor under test is abnormal.

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