A method for calibrating an external ultra-high frequency sensor based on penetration depth optimization

Abstract

The application provides an external ultrahigh frequency sensor calibration method based on penetration depth optimization, and the method comprises the following steps: obtaining a target parameter of a transformer; determining the installation position of a first ultrahigh frequency sensor through an ideal penetration depth formula; installing a to-be-tested external ultrahigh frequency sensor at the joint of the transformer oil tank; determining a calibration pulse signal injected into the first ultrahigh frequency sensor through a formula; and controlling the to-be-tested external ultrahigh frequency sensor to receive the calibration signal. The application provides an external ultrahigh frequency sensor calibration method suitable for the transformer equipment in a field environment, and improves the accuracy and reliability of field calibration.

Description

Technical Field

[0001] This invention relates to the field of ultra-high frequency sensor verification, and more specifically to an external ultra-high frequency sensor verification method based on penetration depth optimization. Background Technology

[0002] Partial discharge is a major manifestation and early sign of transformer insulation degradation. Accurate detection and location of partial discharge are crucial for preventing transformer insulation faults and ensuring safe equipment operation. Ultra-high frequency (UHF) sensors are widely used due to their high sensitivity and strong anti-interference capabilities. Depending on the installation method, UHF sensors can be divided into two types: internal and external. Internal sensors are implanted inside the transformer through a medium window or drain valve, directly coupling internal electromagnetic wave signals. External sensors are installed at the joints of the transformer tank, using the gaps at the tank joints to couple internal electromagnetic wave signals.

[0003] In actual operating conditions, due to long-term operation, UHF sensors are highly likely to experience problems such as electrical aging, corrosion, or abnormal cable interfaces. These issues can lead to a decrease in sensor sensitivity during operation, making it impossible to effectively monitor partial discharge signals inside the transformer, thus creating monitoring blind spots and posing a threat to the safe operation of the equipment. Therefore, it is necessary to perform regular sensor calibration. Researching calibration methods for external UHF sensors in transformers can provide a foundation for calibrating UHF sensors in field environments. 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 external ultra-high frequency 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: an external UHF sensor calibration method based on penetration depth optimization includes:

[0006] S1. Obtain the target parameters of the transformer, including the transformer dielectric window radius and the transformer dielectric window height;

[0007] S2. Arrange a first UHF sensor at the dielectric window on the outer wall of the transformer tank. Based on the target parameters of the transformer, fit the ideal penetration depth formula to determine the ideal penetration depth of the first UHF sensor, and control the depth at which the first UHF sensor is installed in the dielectric window to be the ideal penetration depth.

[0008] S3. Obtain the structural parameters of the joint of the transformer tank. The joint is formed by a sealing gasket and a limiting square steel to create a gap that can leak electromagnetic waves. The structural parameters include the gap height and gap depth.

[0009] S4. An external UHF sensor to be tested is arranged at the joint of the transformer tank. The first UHF sensor is controlled to be a signal transmitting sensor. A verification pulse signal S0(t) is injected into the first UHF sensor to excite the first UHF sensor to emit a partial discharge verification signal.

[0010] S5. Construct a partial discharge signal detection system, which includes a UHF sensor under test, a signal acquisition module, and a host computer.

[0011] S6. Control the UHF sensor under test to receive the partial discharge verification signal emitted by the first UHF sensor, and transmit the result to the host computer through the signal acquisition module, and analyze the detection result through the host computer.

[0012] In a more specific technical solution, in S2, based on the target parameters of the transformer, an ideal penetration depth formula is fitted to obtain the ideal penetration depth δ, where the ideal penetration depth formula is as follows:

[0013]

[0014] In the formula, f c The cutoff frequency of the dielectric window cavity is given by μ, which is the vacuum permeability, taken as 4π × 10⁻⁶. -7 H / m; σ is the conductivity of the dielectric material; H is the height of the transformer dielectric window; R is the inner diameter of the transformer dielectric window; f0 is the cutoff frequency of the first UHF sensor;

[0015] Dielectric window cavity cutoff frequency f c The formula is shown below:

[0016]

[0017] In the formula, c is the propagation speed of electromagnetic waves in vacuum, taken as 3 × 10⁻⁶. 8 m / s.

[0018] In a more specific technical solution, in S4, a UHF sensor to be tested is arranged at the joint of the transformer tank, and the UHF sensor to be tested and the first UHF sensor are set on the same side of the transformer tank, and the UHF sensor to be tested and the first UHF sensor are on the same vertical line.

[0019] In a more specific technical solution, in S4, if only a sealing gasket exists at the joint of the transformer tank, a verification pulse signal S0(t) is injected into the first ultra-high frequency sensor, wherein the formula for the verification pulse signal S0(t) is as follows:

[0020]

[0021] In the formula, k is taken as 0.8; A is the signal amplitude, and the formula is shown below:

[0022]

[0023] In the formula, D is the transformer gap depth, S is the transformer gap height, and V is the transformer voltage level.

[0024] If both a sealing gasket and a limiting square steel are present at the joint of the transformer tank, a verification pulse signal S0(t) is injected into the first UHF sensor, wherein the formula for the verification pulse signal S0(t) is as follows:

[0025]

[0026] In the formula, k is taken as 0.2.

[0027] In a more specific technical solution, in S5, the signal acquisition module is used to receive the UHF partial discharge signal received by the UHF sensor under test, convert it into a data format that the host computer can process, and transmit the data to the host computer.

[0028] The host computer is used to process and analyze data and visualize the analysis results;

[0029] The UHF sensor under test, the signal acquisition module, and the host computer are connected sequentially via UHF cables.

[0030] This invention provides a verification method for external UHF sensors installed on transformer equipment in a field substation environment. It can effectively verify UHF sensors and improve the accuracy and reliability of verification results. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the basic steps of the external UHF sensor verification method based on penetration depth optimization in Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic diagram of the UHF sensor setup in the field environment according to Embodiment 1 of the present invention;

[0033] Figure 3 This is a schematic diagram of the transformer tank joint in Embodiment 1 of the present invention; Detailed Implementation

[0034] 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.

[0035] Example 1

[0036] like Figure 1 As shown, the external UHF sensor calibration method based on penetration depth optimization provided by this invention includes the following basic steps:

[0037] Step S1: Obtain the target parameters of the transformer, including the transformer dielectric window radius and the transformer dielectric window height;

[0038] Step S2: Arrange a first UHF sensor at the dielectric window on the outer wall of the transformer tank. Based on the target parameters of the transformer, fit the ideal penetration depth formula to determine the ideal penetration depth of the first UHF sensor, and control the depth at which the first UHF sensor is installed in the dielectric window to be the ideal penetration depth.

[0039] like Figure 2 As shown, in the substation environment of this embodiment, a first UHF sensor is arranged at the medium window on the outer wall of the transformer box. The penetration depth of the first UHF sensor installed in the medium window is controlled to be δ, which is obtained by calculation.

[0040] Based on the following logic, a first ultra-high frequency sensor is installed at the penetration depth δ of the transformer dielectric window, and δ is calculated using the following formula:

[0041]

[0042] In the formula, f c The cutoff frequency of the dielectric window cavity is given by μ, which is the vacuum permeability, typically taken as 4π × 10⁻⁶. -7 H / m; σ is the conductivity of the dielectric material; H is the height of the transformer dielectric window; R is the inner diameter of the transformer dielectric window; f0 is the cutoff frequency of the first UHF sensor;

[0043] Dielectric window cavity cutoff frequency f c The formula is shown below:

[0044]

[0045] In the formula, c is the propagation speed of electromagnetic waves in vacuum, taken as 3 × 10⁻⁶. 8 m / s.

[0046] Step S3, as follows Figure 3 As shown, the structural parameters of the transformer tank joint are obtained. The joint is formed by a sealing gasket and a limiting square steel to create a gap that can leak electromagnetic waves. The structural parameters include the gap height and gap depth.

[0047] Step S4: Arrange the external UHF sensor to be tested at the joint of the transformer tank, control the first UHF sensor as a signal transmitting sensor, inject the verification pulse signal S0(t) into the first UHF sensor, and excite the first UHF sensor to emit a partial discharge verification signal.

[0048] like Figure 2 As shown, in this embodiment, a UHF sensor to be tested is arranged at the joint of the transformer tank. The UHF sensor to be tested and the first UHF sensor are set on the same side of the transformer tank, and the UHF sensor to be tested and the first UHF sensor are on the same vertical line.

[0049] If only a sealing gasket exists at the joint of the transformer tank, a verification pulse signal S0(t) is injected into the first UHF sensor, wherein the formula for the verification pulse signal S0(t) is as follows:

[0050]

[0051] In the formula, k is taken as 0.8; A is the signal amplitude, and the formula is shown below:

[0052]

[0053] In the formula, D is the depth of the transformer tank gap, S is the height of the transformer tank gap, and V is the transformer voltage level.

[0054] If both a sealing gasket and a limiting square steel are present at the joint of the transformer tank, a verification pulse signal S0(t) is injected into the first UHF sensor, wherein the formula for the verification pulse signal S0(t) is as follows:

[0055]

[0056] In the formula, k is taken as 0.2.

[0057] Step S5: Construct a partial discharge signal detection system. The detection system includes a UHF sensor under test, a signal acquisition module, and a host computer. The signal acquisition module is used to receive the UHF partial discharge signal received by the UHF sensor under test, convert it into a data format that the host computer can process, and transmit the data to the host computer.

[0058] The host computer is used to process and analyze data and visualize the analysis results;

[0059] The UHF sensor under test, the signal acquisition module, and the host computer are connected sequentially via UHF cables.

[0060] Step S6: Control the UHF sensor under test to receive the partial discharge verification signal emitted by the first UHF sensor, and transmit the result to the host computer through the signal amplification module and the signal acquisition module. The host computer analyzes the detection result.

[0061] In summary, this invention provides a verification method for external UHF sensors installed on transformer equipment in a field substation environment. This method can effectively verify UHF sensors and improve the accuracy and reliability of the verification results.

Claims

1. A method for verifying an external ultra-high frequency sensor based on penetration depth optimization, characterized in that, Specifically, the following steps are included: S1. Obtain the target parameters of the transformer, including the transformer dielectric window radius and the transformer dielectric window height; S2. Arrange a first UHF sensor at the dielectric window on the outer wall of the transformer tank. Based on the target parameters of the transformer, fit the ideal penetration depth formula to determine the ideal penetration depth of the first UHF sensor, and control the depth at which the first UHF sensor is installed in the dielectric window to be the ideal penetration depth. S3. Obtain the structural parameters of the joint of the transformer tank. The joint is formed by a sealing gasket and a limiting square steel to create a gap that can leak electromagnetic waves. The structural parameters include the gap height and gap depth. S4. An external UHF sensor to be tested is arranged at the joint of the transformer tank. The first UHF sensor is controlled to be a signal transmitting sensor. A verification pulse signal S0(t) is injected into the first UHF sensor to excite the first UHF sensor to emit a partial discharge verification signal. S5. Construct a partial discharge signal detection system, which includes a UHF sensor under test, a signal acquisition module, and a host computer. S6. Control the UHF sensor under test to receive the partial discharge verification signal emitted by the first UHF sensor, and transmit the result to the host computer through the signal acquisition module, and analyze the detection result through the host computer.

2. The external UHF sensor calibration method based on penetration depth optimization according to claim 1, characterized in that, In step S2, based on the target parameters of the transformer, an ideal penetration depth formula is fitted to obtain the ideal penetration depth δ, where the ideal penetration depth formula is as follows: In the formula, f c The cutoff frequency of the dielectric window cavity is given by μ, which is the vacuum permeability, taken as 4π × 10⁻⁶. -7 H / m; σ is the conductivity of the dielectric material; H is the height of the transformer dielectric window; R is the inner diameter of the transformer dielectric window; f0 is the cutoff frequency of the first UHF sensor; Dielectric window cavity cutoff frequency f c The formula is shown below: In the formula, c is the propagation speed of electromagnetic waves in vacuum, taken as 3 × 10⁻⁶. 8 m / s.

3. The external UHF sensor calibration method based on penetration depth optimization according to claim 1, characterized in that, In step S4, a UHF sensor to be tested is arranged at the joint of the transformer tank. The UHF sensor to be tested and the first UHF sensor are set on the same side of the transformer tank, and the UHF sensor to be tested and the first UHF sensor are on the same vertical line.

4. The external UHF sensor calibration method based on penetration depth optimization according to claim 1, characterized in that, In step S4, if only a sealing gasket exists at the joint of the transformer tank, a verification pulse signal S0(t) is injected into the first UHF sensor, wherein the formula for the verification pulse signal S0(t) is as follows: In the formula, k is taken as 0.8; A is the signal amplitude, and the formula is shown below: In the formula, D is the gap depth at the joint of the transformer tank, S is the gap height at the joint of the transformer tank, and V is the voltage level of the transformer.

5. The external UHF sensor calibration method based on penetration depth optimization according to claim 1, characterized in that, In step S4, if both a sealing gasket and a limiting square steel are present at the joint of the transformer tank, a verification pulse signal S0(t) is injected into the first UHF sensor, wherein the formula for the verification pulse signal S0(t) is as follows: In the formula, k is taken as 0.

2.

6. The external UHF sensor calibration method based on penetration depth optimization according to claim 1, characterized in that, In step S5, the signal acquisition module is used to receive the UHF partial discharge signal received by the UHF sensor under test, convert it into a data format that the host computer can process, and transmit the data to the host computer. The host computer is used to process and analyze data and visualize the analysis results; The UHF sensor under test, the signal acquisition module, and the host computer are connected sequentially via UHF cables.

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