Method for evaluating performance of explosion-proof sheet for current transformer based on discharge amount monitoring

Abstract

The invention relates to a method for evaluating the performance of an anti-explosion sheet for a current transformer based on discharge quantity monitoring. The method comprises the following steps: calculating the optimal discharge value of the anti-explosion sheet for the current transformer through a standard discharge quantity formula; the dynamic discharge area of the explosion-proof sheet for the current transformer during actual action is calculated through laser ranging; the actual release pressure of the explosion-proof sheet for the current transformer during actual action is monitored through the pressure sensor; calculating an actual discharge value of the explosion-proof sheet for the current transformer based on an actual discharge amount formula; and comparing the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof sheet. According to the method, the actual discharge area and the pressure discharge size of the explosion-proof sheet are obtained, so that the discharge amount is calculated to evaluate the performance of the explosion-proof sheet, and the blank of the method for evaluating the explosion-proof sheet for the current transformer is filled.

Description

Technical Field

[0001] The present invention relates to a method for evaluating the performance of an explosion-proof film for a current transformer based on discharge amount monitoring, belonging to the field of electrical equipment and involving equipment status evaluation technology. Background Art

[0002] As a key measurement device in the power system, the current transformer undertakes important functions such as current transformation, electrical isolation, and fault signal transmission. During long-term operation, a large amount of energy and gas may be generated inside the current transformer due to insulation aging, overload, or short-circuit faults, resulting in a sharp increase in the pressure of the sealed cavity. If the pressure cannot be released in time, it will cause deformation of the equipment housing at least, and explosion accidents at worst, seriously threatening the operation safety of the substation and the lives of personnel. As the last safety barrier of the current transformer, the performance of the explosion-proof film directly determines the safety margin of the equipment under extreme conditions.

[0003] However, the design and evaluation methods of explosion-proof films in the industrial field are difficult to meet the requirements of high-reliability power equipment. Although IEC61869 and IEEE C57.13 put forward requirements for static parameters such as the bursting pressure and sealing performance of explosion-proof films, there is a lack of systematic evaluation means for their dynamic discharge capacity and long-term performance degradation.

[0004] In the field of power equipment safety protection, the state evaluation method of explosion-proof films based on discharge amount monitoring has become the mainstream technical path. However, the cavity space of the current transformer is compact and contains multiple electromagnetic shielding components, which makes the installation of traditional contact flow meters face multiple obstacles such as limited physical space and signal interference shielding. Especially in special working conditions such as arc ignition and explosion, the instantaneously generated ultra-high temperature, high-pressure shock wave and strong electromagnetic interference constitute a complex extreme environment, resulting in a triple failure risk for conventional flow measurement devices. Therefore, it is necessary to design a method for evaluating the performance of an explosion-proof film for a current transformer based on discharge amount monitoring, obtain the actual discharge area and the magnitude of pressure release of the explosion-proof film, calculate the discharge amount for explosion-proof film performance evaluation, and make up for the blank of the evaluation method for explosion-proof films for current transformers. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the present invention designs a method for evaluating the performance of an explosion-proof film for current transformers based on the monitoring of the discharge amount, including: calculating the optimal discharge value of the explosion-proof film for current transformers through the standard discharge amount formula; calculating the dynamic discharge area when the explosion-proof film for current transformers actually acts through laser ranging; monitoring the actual discharge pressure when the explosion-proof film for current transformers actually acts through a pressure sensor; calculating the actual discharge value of the explosion-proof film for current transformers based on the actual discharge amount formula; comparing the size relationship between the actual discharge value and the optimal discharge value to evaluate the performance of the explosion-proof film. The present invention obtains the actual discharge area and the magnitude of the pressure discharge of the explosion-proof film, thereby calculating the discharge amount to evaluate the performance of the explosion-proof film, filling the blank in the evaluation method of the explosion-proof film for current transformers.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for evaluating the performance of an explosion-proof film for current transformers based on the monitoring of the discharge amount, comprising the following steps:

[0008] Step 1: Calculating the optimal discharge value of the explosion-proof film for current transformers through the standard discharge amount formula;

[0009] Step 2: Calculating the dynamic discharge area when the explosion-proof film for current transformers actually acts through laser ranging;

[0010] Step 3: Monitoring the actual discharge pressure when the explosion-proof film for current transformers actually acts through a pressure sensor;

[0011] Step 4: Calculating the actual discharge value of the explosion-proof film for current transformers based on the actual discharge amount formula;

[0012] Step 5: Comparing the size relationship between the actual discharge value and the optimal discharge value to evaluate the performance of the explosion-proof film.

[0013] Further, according to the standard discharge amount formula, the optimal discharge value is calculated, and the formula is expressed as:

[0014]

[0015] In the formula, A0 is the standard discharge area, with the unit of m 2 ; P0 is the opening pressure of the explosion-proof film, with the unit of Pa; α is the flow coefficient; v0 is the standard gas flow velocity, with the unit of m / s; v1 is the critical flow velocity, with the unit of m / s; M is the molar mass of air, with the unit of kg / kmol; Z is the compression coefficient of the gas at the discharge pressure and temperature; T f is the discharge temperature, with the unit of K.

[0016] Furthermore, install a high-precision laser ranging device directly above the current transformer to ensure that it can scan the surface of the rupture disc vertically downward, scan the surface of the rupture disc at a high frequency, generate a series of 3D point cloud data maps containing timestamps, extract the geometric features of the rupture disc surface, and calculate the dynamic relief area at each time point in combination with the time variable.

[0017] Furthermore, install an embedded pressure sensor at the relief channel of the current transformer to monitor the pressure value below the rupture disc during the combustion explosion process of the current transformer, which is equivalent to the actual relief pressure.

[0018] Furthermore, substitute the obtained relief area and relief pressure into the actual relief volume formula to calculate the actual relief value of the rupture disc for the current transformer, which is expressed by the formula:

[0019]

[0020] In the formula, A(t) is the dynamic relief area, with the unit of m 2 ; P(t) is the actual relief pressure, with the unit of Pa; is a function of the gas characteristic γ, τ is the adiabatic index; t, t1, and t2 are the pressure relief time, the rupture disc opening moment, and the moment when the relief pressure is less than the opening threshold, respectively, with the unit of s.

[0021] Furthermore, obtain the correlation index δ through the magnitude relationship between the actual relief value and the optimal relief value. The greater the correlation, the more ideal the actual relief value, and the better the performance of the rupture disc, which is 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 characteristics and beneficial effects:

[0025] 1. The present invention obtains the dynamic relief area and pressure when the rupture disc acts, constructs a mathematical model in combination with the time variable, realizes the accurate quantitative analysis of the dynamic relief process, and solves the defect that the traditional method cannot evaluate the dynamic performance.

[0026] 2. The present invention adopts non-contact laser ranging technology, avoiding the measurement errors caused by limited physical space or electromagnetic interference of traditional flow meters; directly monitors the pressure at the bottom of the rupture disc through an embedded pressure sensor, with high data reliability, and significantly improves the accuracy of relief volume calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the flowchart of the present invention;

[0028] Figure 2 This is a schematic diagram of the arrangement of the laser ranging device and the pressure sensor. DETAILED DESCRIPTION

[0029] In order to overcome the problems existing in the prior art, the present invention designs a method for evaluating the performance of explosion-proof discs for current transformers based on discharge monitoring, including: calculating the optimal discharge value of explosion-proof discs for current transformers through a standard discharge formula; calculating the dynamic discharge area of ​​explosion-proof discs for current transformers when they are actually in action through laser ranging; monitoring the actual discharge pressure of explosion-proof discs for current transformers when they are actually in action through a pressure sensor; calculating the actual discharge value of explosion-proof discs for current transformers based on the actual discharge formula; and comparing the actual discharge value with the optimal discharge value to evaluate the performance of explosion-proof discs. The present invention obtains the actual discharge area of ​​explosion-proof discs and the magnitude of pressure discharge, thereby calculating the discharge amount to evaluate the performance of explosion-proof discs, filling the gap in the evaluation method of explosion-proof discs for current transformers.

[0030] In order to achieve the above object, the present invention adopts the following technical solution:

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

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

[0033] Step 2: Calculate the dynamic discharge area of ​​the explosion-proof disk for current transformer when it is actually in action through laser ranging;

[0034] Step 3: Monitor the actual discharge pressure of the explosion-proof disk for the current transformer when it actually operates through the pressure sensor;

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

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

[0037] Furthermore, according to the standard discharge volume formula, the optimal discharge value is calculated, which can be expressed as:

[0038]

[0039] Where A0 is the standard discharge area, in m 2 ; P0 is the opening pressure of the explosion-proof disk, in Pa; α is the flow coefficient; v0 is the standard gas flow rate, in m / s; v1 is the critical flow rate, 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 is the discharge temperature in 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 plate vertically downward, scan the surface of the explosion-proof plate at a high frequency, generate a series of three-dimensional point cloud data maps containing timestamps, extract the geometric features of the surface of the explosion-proof plate, and calculate the dynamic discharge area at each time point in combination with the time variable.

[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, the obtained discharge area and discharge pressure are substituted into the actual discharge amount formula to calculate the actual discharge value of the explosion-proof disk for the current transformer, which is expressed as follows:

[0043]

[0044] Where A(t) is the dynamic discharge area, in m 2 ; P(t) is the actual discharge pressure, unit: Pa; is a function of the gas characteristic γ, τ is the adiabatic index; t, t1, and t2 are the pressure release time, the explosion-proof disk opening time, and the time when the release pressure is less than the opening threshold, respectively, and the unit is s.

[0045] Furthermore, the correlation index δ is obtained through the relationship between the actual discharge value and the optimal discharge value. The greater the correlation, the more ideal the actual discharge value is and the better the performance of the explosion-proof disk is. It can be expressed as:

[0046]

[0047] Where σ is the sensitivity control parameter and n is the nonlinear parameter.

Claims

1. A method for evaluating the performance of explosion-proof disks for current transformers based on discharge monitoring, characterized in that: The following steps are involved: Step 1: Calculate the optimal discharge value of the explosion-proof disk for current transformer using the standard discharge formula; Step 2: Calculate the dynamic discharge area of ​​the explosion-proof disk for current transformer when it is actually in action through laser ranging; Step 3: Monitor the actual discharge pressure of the explosion-proof disk for the current transformer when it actually operates through the pressure sensor; Step 4: Calculate the actual discharge value of the explosion-proof disk for the current transformer based on the actual discharge amount formula; Step 5: Compare the actual discharge value with the optimal discharge value to evaluate the performance of the explosion-proof disk.

2. A method for evaluating the performance of explosion-proof disks for current transformers based on discharge monitoring according to claim 1, characterized in that: According to the standard discharge formula, the optimal discharge value is calculated, which can be expressed as: Where A0 is the standard discharge area, in m 2 ; P0 is the opening pressure of the explosion-proof disk, in Pa; α is the flow coefficient; v0 is the standard gas flow rate, in m / s; v1 is the critical flow rate, 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 is the discharge temperature in K.

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

4. The method for evaluating the performance of explosion-proof disks 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 disk 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 disks for current transformers based on discharge monitoring according to claim 1, characterized in that: Substitute the obtained discharge area and discharge pressure into the actual discharge amount formula to calculate the actual discharge value of the explosion-proof disk for the current transformer, which is expressed as follows: Where A(t) is the dynamic discharge area in m 2 ; P(t) is the actual discharge pressure, unit: Pa; is a function of the gas characteristic γ, τ is the adiabatic index; t, t1, and t2 are the pressure release time, the explosion-proof disk opening time, and the time when the release pressure is less than the opening threshold, respectively, and the unit is s.

6. The method for evaluating the performance of explosion-proof disks for current transformers based on discharge monitoring according to claim 1, characterized in that: Through the relationship between the actual discharge value and the optimal discharge value, the correlation index δ is obtained. The greater the correlation, the more ideal the actual discharge value is and the better the performance of the explosion-proof disk is. It can be expressed as: Where σ is the sensitivity control parameter and n is the nonlinear parameter.

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