A performance evaluation method for explosion-proof sheets for current transformers based on discharge amount monitoring

Abstract

The present application relates to a kind of based on the performance evaluation method of explosion-proof sheet for current transformer based on discharge amount monitoring, comprising: the best discharge value of explosion-proof sheet for current transformer is calculated by standard discharge amount formula;The dynamic discharge area of explosion-proof sheet for current transformer when actually operating is calculated by laser ranging;Actual discharge pressure of explosion-proof sheet for current transformer when actually operating is monitored by pressure sensor;The actual discharge value of explosion-proof sheet for current transformer is calculated based on actual discharge amount formula;The size relationship of actual discharge value and best discharge value is compared to carry out the performance evaluation of explosion-proof sheet.The actual discharge area and pressure discharge size of explosion-proof sheet are obtained, so as to calculate discharge amount to carry out the performance evaluation of explosion-proof sheet, make up the blank of the evaluation method of explosion-proof sheet for current transformer.

Description

Technical Field

[0001] This invention relates to a method for evaluating the performance of explosion-proof sheets for current transformers based on leakage monitoring, belonging to the field of electrical equipment, and relating to equipment condition assessment technology. Background Technology

[0002] Current transformers, as critical measuring devices in power systems, perform vital functions such as current transformation, electrical isolation, and fault signal transmission. During long-term operation, current transformers may generate significant amounts of energy and gas due to insulation aging, overload, or short-circuit faults, leading to a rapid increase in pressure within the sealed cavity. If this pressure cannot be released in time, it can cause deformation of the equipment casing, or even an explosion, seriously threatening the operational safety of substations and the lives of personnel. Explosion-proof diaphragms, as the last line of defense for current transformers, directly determine the safety margin of the equipment under extreme operating conditions.

[0003] However, the design and evaluation methods for explosion-proof discs in the industrial field are no longer sufficient to meet the needs of high-reliability electrical equipment. Although IEC61869 and IEEEC57.13 specify requirements for static parameters such as burst pressure and sealing performance of explosion-proof discs, they lack systematic evaluation methods for their dynamic venting capacity and long-term performance degradation.

[0004] In the field of power equipment safety protection, the explosion-proof diaphragm condition assessment method based on leakage monitoring has become the mainstream technical approach. However, the compact cavity space of current transformers and the inclusion of multiple layers of electromagnetic shielding components pose multiple obstacles to the installation of traditional contact flowmeters, including limited physical space and signal interference shielding. Especially under special operating conditions such as arc explosions, the instantaneously generated ultra-high temperature, high pressure shock waves, and strong electromagnetic interference constitute a complex extreme environment, leading to a triple failure risk for conventional flow measurement devices. Therefore, it is necessary to design a performance assessment method for explosion-proof diaphragms of current transformers based on leakage monitoring, obtain the actual leakage area and pressure leakage magnitude of the explosion-proof diaphragm, calculate the leakage amount to assess the performance of the explosion-proof diaphragm, and fill the gap in the assessment methods for explosion-proof diaphragms of current transformers. Summary of the Invention

[0005] To overcome the problems existing in the prior art, this invention designs a performance evaluation method for explosion-proof discs used in current transformers based on discharge capacity monitoring. The method includes: calculating the optimal discharge value of the explosion-proof disc using a standard discharge capacity formula; calculating the dynamic discharge area of ​​the explosion-proof disc during actual operation using laser ranging; monitoring the actual discharge pressure of the explosion-proof disc during actual operation using a pressure sensor; calculating the actual discharge value of the explosion-proof disc based on the actual discharge capacity formula; and comparing the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof disc. This invention obtains the actual discharge area and pressure discharge magnitude of the explosion-proof disc, thereby calculating the discharge capacity for performance evaluation, filling a gap in the evaluation methods for explosion-proof discs used in current transformers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring includes the following steps:

[0008] Step 1: Calculate the optimal discharge value for the explosion-proof diaphragm of the current transformer using the standard discharge formula;

[0009] Step 2: Calculate the dynamic discharge area of ​​the explosion-proof sheet of the current transformer when it is actually activated by laser ranging;

[0010] Step 3: Monitor the actual discharge pressure when the explosion-proof disc of the current transformer actually operates using a pressure sensor;

[0011] Step 4: Calculate the actual discharge value of the explosion-proof sheet for the current transformer based on the actual discharge formula;

[0012] Step 5: Compare the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof sheet.

[0013] Furthermore, based on the standard discharge formula, the optimal discharge value is calculated, expressed by the formula:

[0014]

[0015] In the formula, A0 is the standard discharge area, in m². 2 P0 is the opening pressure of the explosion-proof diaphragm, in Pa; α is the flow coefficient; v0 is the standard gas velocity, in m / s; v1 is the critical velocity, in m / s; M is the molar mass of air, in kg / kmol; Z is the compressibility coefficient of the gas at the release pressure and temperature; T f The discharge temperature is expressed in Kelvin (K).

[0016] Furthermore, a high-precision laser ranging device is installed directly above the current transformer to ensure that it can scan the surface of the explosion-proof sheet vertically downwards. The surface of the explosion-proof sheet is scanned at a high frequency to generate a series of three-dimensional point cloud data maps containing timestamps. The geometric features of the explosion-proof sheet surface are extracted, and the dynamic discharge area at each time point is calculated in combination with time variables.

[0017] Furthermore, an embedded pressure sensor is installed at the discharge channel of the current transformer to monitor the pressure value below the explosion-proof plate during the explosion of the current transformer, which is equivalent to the actual discharge pressure.

[0018] Furthermore, by substituting the obtained discharge area and discharge pressure into the formula for actual discharge volume, the actual discharge value of the explosion-proof diaphragm used in the current transformer is calculated, expressed by the formula:

[0019]

[0020] In the formula, A(t) represents the dynamic discharge area, with units of m². 2 P(t) is the actual pressure released, in Pa. τ is a function of the gas property γ, and τ is the adiabatic index; t, t1, and t2 are the pressure relief time, the opening time of the explosion-proof diaphragm, and the time when the relief pressure is less than the opening threshold, respectively, in seconds.

[0021] Furthermore, by analyzing the relationship between the actual discharge value and the optimal discharge value, a correlation index δ is obtained. A higher correlation indicates a more ideal actual discharge value and better performance of the explosion-proof sheet. This can be expressed by the formula:

[0022]

[0023] In the formula, σ is the sensitivity control parameter; n is the nonlinear parameter.

[0024] Compared with the prior art, the present invention has the following features and beneficial effects:

[0025] 1. This invention obtains the dynamic release area and pressure when the explosion-proof disc is activated, and constructs a mathematical model by combining it with time variables, thereby realizing accurate quantitative analysis of the dynamic release process and solving the defect of traditional methods that cannot evaluate dynamic performance.

[0026] 2. This invention uses non-contact laser ranging technology, which avoids the measurement errors caused by physical space limitations or electromagnetic interference in traditional flow meters; it directly monitors the pressure at the bottom of the explosion-proof sheet through an embedded pressure sensor, resulting in high data reliability and significantly improving the accuracy of the discharge volume calculation. Attached Figure Description

[0027] Figure 1 This is a flowchart of the invention;

[0028] Figure 2 This is a schematic diagram of the arrangement of the laser rangefinder and pressure sensor. Detailed Implementation

[0029] To overcome the problems existing in the prior art, this invention designs a performance evaluation method for explosion-proof discs used in current transformers based on discharge capacity monitoring. The method includes: calculating the optimal discharge value of the explosion-proof disc using a standard discharge capacity formula; calculating the dynamic discharge area of ​​the explosion-proof disc during actual operation using laser ranging; monitoring the actual discharge pressure of the explosion-proof disc during actual operation using a pressure sensor; calculating the actual discharge value of the explosion-proof disc based on the actual discharge capacity formula; and comparing the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof disc. This invention obtains the actual discharge area and pressure discharge magnitude of the explosion-proof disc, thereby calculating the discharge capacity for performance evaluation, filling a gap in the evaluation methods for explosion-proof discs used in current transformers.

[0030] To achieve the above objectives, the present invention adopts the following technical solution:

[0031] A method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring includes the following steps:

[0032] Step 1: Calculate the optimal discharge value for the explosion-proof diaphragm of the current transformer using the standard discharge formula;

[0033] Step 2: Calculate the dynamic discharge area of ​​the explosion-proof sheet of the current transformer when it is actually activated by laser ranging;

[0034] Step 3: Monitor the actual discharge pressure when the explosion-proof disc of the current transformer actually operates using a pressure sensor;

[0035] Step 4: Calculate the actual discharge value of the explosion-proof sheet for the current transformer based on the actual discharge formula;

[0036] Step 5: Compare the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof sheet.

[0037] Furthermore, based on the standard discharge formula, the optimal discharge value is calculated, expressed by the formula:

[0038]

[0039] In the formula, A0 is the standard discharge area, in m². 2 P0 is the opening pressure of the explosion-proof diaphragm, in Pa; α is the flow coefficient; v0 is the standard gas velocity, in m / s; v1 is the critical velocity, in m / s; M is the molar mass of air, in kg / kmol; Z is the compressibility coefficient of the gas at the release pressure and temperature; Tf The discharge temperature is expressed in Kelvin (K).

[0040] Furthermore, a high-precision laser ranging device is installed directly above the current transformer to ensure that it can scan the surface of the explosion-proof sheet vertically downwards. The surface of the explosion-proof sheet is scanned at a high frequency to generate a series of three-dimensional point cloud data maps containing timestamps. The geometric features of the explosion-proof sheet surface are extracted, and the dynamic discharge area at each time point is calculated in combination with time variables.

[0041] Furthermore, an embedded pressure sensor is installed at the discharge channel of the current transformer to monitor the pressure value below the explosion-proof plate during the explosion of the current transformer, which is equivalent to the actual discharge pressure.

[0042] Furthermore, by substituting the obtained discharge area and discharge pressure into the formula for actual discharge volume, the actual discharge value of the explosion-proof diaphragm used in the current transformer is calculated, expressed by the formula:

[0043]

[0044] In the formula, A(t) represents the dynamic discharge area, with units of m². 2 P(t) is the actual pressure released, in Pa. τ is a function of the gas property γ, and τ is the adiabatic index; t, t1, and t2 are the pressure relief time, the opening time of the explosion-proof diaphragm, and the time when the relief pressure is less than the opening threshold, respectively, in seconds.

[0045] Furthermore, by analyzing the relationship between the actual discharge value and the optimal discharge value, a correlation index δ is obtained. A higher correlation indicates a more ideal actual discharge value and better performance of the explosion-proof sheet. This can be expressed by the formula:

[0046]

[0047] In the formula, σ is the sensitivity control parameter; n is the nonlinear parameter.

Claims

1. A method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring, characterized in that, Includes the following steps: Step 1: Calculate the optimal discharge value for the explosion-proof diaphragm of the current transformer using the standard discharge formula; Step 2: Calculate the dynamic discharge area of ​​the explosion-proof sheet of the current transformer when it is actually activated by laser ranging; Step 3: Monitor the actual discharge pressure when the explosion-proof disc of the current transformer actually operates using a pressure sensor; Step 4: Calculate the actual discharge value of the explosion-proof diaphragm for the current transformer based on the actual discharge capacity formula. Substitute the obtained discharge area and discharge pressure into the actual discharge capacity formula to calculate the actual discharge value of the explosion-proof diaphragm for the current transformer, expressed by the formula: In the formula, The dynamic discharge area is expressed in square meters. 2 ; The actual pressure released is expressed in Pa. τ is a function of the gas property γ, and τ is the adiabatic index; t, t1, and t2 are the pressure relief time, the opening time of the explosion-proof diaphragm, and the time when the relief pressure is less than the opening threshold, respectively, in seconds; Step 5: Compare the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof sheet.

2. The method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring according to claim 1, characterized in that, The optimal discharge value is calculated based on the standard discharge capacity formula, expressed as follows: In the formula, A0 is the standard discharge area, in m². 2 ; P0 is the opening pressure of the explosion-proof diaphragm, in Pa; α is the flow coefficient; v0 is the standard gas flow velocity, in m / s; v1 is the critical flow velocity, in m / s; M is the molar mass of air, in kg / kmol; Z is the compressibility coefficient of the gas at the release pressure and temperature. T f The discharge temperature is expressed in Kelvin (K).

3. The method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring according to claim 1, characterized in that, Install a non-contact ranging device directly above the current transformer to obtain cloud images at different times, and calculate the dynamic discharge area when the explosion-proof sheet of the current transformer actually operates.

4. The method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring according to claim 1, characterized in that, An embedded pressure sensor is installed at the discharge channel of the current transformer to monitor the pressure value below the explosion-proof plate during the explosion of the current transformer, which is equivalent to the actual discharge pressure.

5. The method for evaluating the performance of explosion-proof diaphragms for current transformers based on discharge monitoring according to claim 1, characterized in that, By comparing the actual discharge value with the optimal discharge value, a correlation index δ is obtained. The higher the correlation, the more ideal the actual discharge value and the better the performance of the explosion-proof sheet. This can be expressed by the formula: In the formula, σ is the sensitivity control parameter; n is the nonlinear parameter.

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