Insulation margin distribution calculation method, device, equipment, medium and product

Abstract

The invention discloses an insulation margin distribution calculation method and device, equipment, a medium and a product, and relates to the technical field of converter transformers, and the method comprises the steps: determining the moisture content distribution of solid insulation in a target converter transformer under a temperature distribution field based on an oil-paper moisture balance curve; based on the moisture content distribution, determining distribution rule fitting formulas of the relative dielectric constant and the conductivity, and then calculating a field domain electric field intensity distribution result of the target converter transformer based on the two fitting formulas; forming discretization based on a conductor of the target converter transformer to obtain a plurality of grid units; drawing a power line corresponding to each conductor based on the electric field intensity direction; each power line comprises a plurality of power line segments; two end points of each power line segment are located on boundary lines of the grid units; and calculating the insulation margin corresponding to the power line according to the electric field intensity and distance of all the power line segments in the power line, thereby improving the evaluation accuracy of the insulation margin distribution of the converter transformer.

Description

Technical Field

[0001] The present application relates to the technical field of converter transformers, and in particular to a method, device, equipment, medium and product for calculating insulation margin distribution taking into account the influence of temperature-moisture coupling. Background Art

[0002] With the vigorous development of ultra-high voltage direct current transmission, converter transformers play an important role in the operation of power grids. In actual operation, the insulation performance of the oil-paper insulation structure of the converter transformer will be affected by environmental factors such as temperature, moisture and impurities, showing dynamic characteristics. However, in the design process, the properties of each material are usually regarded as constant values, which makes the design of the oil-paper insulation structure often leave a large safety margin. Usually, long-term and complex operating conditions will cause the insulation performance of various parts of the transformer to deteriorate during service, resulting in a possible deviation between the insulation safety margin and the design state. Therefore, a more accurate insulation margin distribution calculation method is urgently needed. Summary of the invention

[0003] The purpose of this application is to provide an insulation margin distribution calculation method, device, equipment, medium and product, which can improve the evaluation accuracy of the insulation margin distribution of a converter transformer.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a method for calculating insulation margin distribution, comprising:

[0006] Based on the oil-paper moisture balance curve and the moisture content monitoring value in the insulating oil, the moisture content distribution of the internal solid insulation of the target converter transformer under the temperature distribution field is determined; the internal solid insulation includes insulating oil and insulating paper;

[0007] Based on the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field, the relative dielectric constant and conductivity of the insulating oil and insulating paper under the influence of temperature-moisture are fitted, and the fitting formulas for the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and insulating paper under the temperature-moisture coupling effect are determined;

[0008] According to the relative permittivity distribution law fitting formula and the conductivity distribution law fitting formula, the electric field distribution calculation is performed to obtain the field electric field intensity distribution result of the target converter transformer;

[0009] Based on the conductor composition of the target converter transformer, the field of the target converter transformer is discretized into a plurality of grid units; each conductor is composed of a plurality of grid units;

[0010] Based on the electric field intensity direction in the field electric field intensity distribution result, draw the electric field line corresponding to each conductor; each electric field line includes a plurality of electric field segments; and the two end points of each electric field segment are located on the boundary line of the grid unit;

[0011] For each power line, the insulation margin corresponding to the power line is calculated according to the electric field strength and distance of all power line segments in the power line; the insulation margins corresponding to all the power lines constitute the insulation margin distribution result of the target converter transformer.

[0012] Optionally, calculating the insulation margin corresponding to the power line according to the electric field strength and distance of all power line segments in the power line specifically includes:

[0013] Taking the electric field strength at the end point of each power line segment as the electric field strength of the power line segment, taking the length of each power line segment as the distance of the power line segment, and calculating the voltage value and distance value of the power line according to the electric field strength and distance of all power line segments in the power line;

[0014] Calculating the average electric field strength of the oil gap corresponding to the power line according to the voltage value and the distance value of the power line;

[0015] Calculate the electric field non-uniformity coefficient according to the average electric field strength of the oil gap corresponding to the electric line and the maximum electric field strength between two points; the maximum electric field strength between two points is the maximum electric field strength between the starting point and the end point of the electric line;

[0016] Determining the allowable value of the electric field of the oil gap according to the electric field non-uniformity coefficient;

[0017] The insulation margin corresponding to the power line is calculated according to the allowable electric field value of the oil gap and the average electric field strength of the oil gap corresponding to the power line.

[0018] Optionally, determining the allowable value of the electric field of the oil gap according to the electric field non-uniformity coefficient specifically includes:

[0019] When the electric field non-uniformity coefficient is not less than the set value, the calculation formula of the allowable value of the electric field of the oil gap is as follows:

[0020] E cp =C·d -0.39 ;

[0021] When the electric field non-uniformity coefficient is less than the set value, the calculation formula of the allowable value of the electric field of the oil gap is as follows:

[0022] E cp =0.9×C·d -0.39 ;

[0023] Among them, E cpIt represents the allowable value of the electric field in the oil gap, C is a constant, and d is the distance value of the electric line.

[0024] Optionally, the calculation formula of the electric field non-uniformity coefficient is as follows:

[0025]

[0026] Where f is the electric field inhomogeneity coefficient, E AB is the average electric field strength of the oil gap corresponding to the electric line, E MAX is the maximum electric field strength between two points.

[0027] Optionally, the grid unit is in the shape of a triangle.

[0028] Optionally, based on the electric field intensity direction in the field electric field intensity distribution result, drawing the electric field lines corresponding to each conductor specifically includes:

[0029] For each conductor, the midpoint on the boundary of the target grid cell is used as the starting point of the electric line; the target grid cell is any grid cell among all grid cells corresponding to the conductor;

[0030] The direction of the electric field intensity corresponding to the starting point of the electric line is taken as the direction of the electric line, and a straight line is drawn to intersect with the opposite side of the grid unit at one point, and the intersection point is recorded as the first field point;

[0031] The first field point is used to replace the starting point of the power line, and the value and direction of the electric field strength at the first field point are obtained. The step of "taking the direction of the electric field strength corresponding to the starting point of the power line as the direction of the power line, drawing a straight line and intersecting the opposite side of the grid unit at one point" is repeated until the next field point reaches the boundary of the conductor or another conductor. The starting point of the power line and the power line segments between all continuous field points constitute the power line corresponding to the conductor.

[0032] In a second aspect, the present application provides an insulation margin distribution calculation device, comprising:

[0033] The internal solid insulation moisture content distribution determination module is used to: determine the moisture content distribution of the internal solid insulation of the target converter transformer under the temperature distribution field based on the oil-paper moisture balance curve and the moisture content monitoring value in the insulating oil; the internal solid insulation includes insulating oil and insulating paper;

[0034] The relative dielectric constant and conductivity fitting module is used to: fit the relative dielectric constant and conductivity of the insulating oil and insulating paper under the influence of temperature-moisture based on the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field, and determine the fitting formula for the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and insulating paper under the temperature-moisture coupling effect;

[0035] An electric field distribution calculation module is used to: perform electric field distribution calculation according to the relative dielectric constant distribution law fitting formula and the conductivity distribution law fitting formula to obtain the field electric field intensity distribution result of the target converter transformer;

[0036] A grid discretization module is used to: discretize the field of the target converter transformer into a plurality of grid units based on the conductor composition of the target converter transformer; each conductor is composed of a plurality of grid units;

[0037] A power line drawing module is used to: draw the power line corresponding to each conductor based on the electric field intensity direction in the field electric field intensity distribution result; each power line includes a plurality of power line segments; and the two endpoints of each power line segment are located on the boundary line of the grid unit;

[0038] The insulation margin calculation module is used to: for each power line, calculate the insulation margin corresponding to the power line according to the electric field strength and distance of all power line segments in the power line; the insulation margins corresponding to all the power lines constitute the insulation margin distribution result of the target converter transformer.

[0039] In a third aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned insulation margin distribution calculation method.

[0040] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which implements the above-mentioned insulation margin distribution calculation method when executed by a processor.

[0041] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements any of the above-mentioned insulation margin distribution calculation methods.

[0042] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0043] The present application provides a method, device, equipment, medium and product for calculating insulation margin distribution. The electric field distribution is calculated by fitting formulas for the relative dielectric constant distribution law and the conductivity distribution law of insulating oil and insulating paper under the action of temperature-moisture coupling, and the field electric field strength distribution result of the target converter transformer is obtained. The power lines are drawn by the field electric field strength distribution result. For each power line, the insulation margin of each power line is calculated according to the electric field strength of the power line itself. When calculating the insulation margin distribution, the present application fully considers the influence of electric field non-uniformity on the calculation results, solves the inaccuracy of traditional calculation methods, improves the evaluation accuracy of the insulation margin distribution of the converter transformer, and can provide data support for the on-site design and operation and maintenance of the converter transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 This is an application environment diagram of an insulation margin distribution calculation method in one embodiment of the present application;

[0046] Figure 2 A schematic flow chart of a method for calculating insulation margin distribution provided in one embodiment of the present application;

[0047] Figure 3 A schematic diagram of the overall process of an insulation margin distribution calculation method provided in one embodiment of the present application;

[0048] Figure 4 A schematic diagram of relative dielectric constant distribution under the influence of temperature and moisture provided in one embodiment of the present application;

[0049] Figure 5 A schematic diagram of conductivity distribution under the influence of temperature and moisture provided in one embodiment of the present application;

[0050] Figure 6 A schematic diagram of power line drawing provided in an embodiment of the present application;

[0051] Figure 7 A schematic diagram of the insulation margin distribution result provided in one embodiment of the present application;

[0052] Figure 8 Schematic diagram of functional modules of an insulation margin distribution calculation device provided in one embodiment of the present application

[0053] Fig. 9A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0056] The insulation margin distribution calculation method provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown, the terminal 102 communicates with the server 104 through a network. The data storage system can store data that the server 104 needs to process. The data storage system can be set up separately, integrated on the server 104, or placed on the cloud or other servers. The terminal 102 can send the oil-paper moisture balance curve to the server 104. After the server 104 receives the oil-paper moisture balance curve, for the oil-paper moisture balance curve, the server 104 determines the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field based on the oil-paper moisture balance curve; based on the above moisture content distribution, determine the distribution law fitting formula of the relative dielectric constant and the conductivity, and then calculate the field electric field strength distribution result of the target converter transformer based on the two fitting formulas; based on the conductor structure of the target converter transformer, a number of grid units are obtained; based on the direction of the electric field strength, the power line corresponding to each conductor is drawn; each power line includes a number of power line segments; the two endpoints of each power line segment are located on the boundary line of the grid unit; according to the electric field strength and distance of all power line segments in the power line, the insulation margin corresponding to the power line is calculated, and the insulation margin corresponding to all power lines constitutes the insulation margin distribution result of the target converter transformer. The server 104 can feed back the insulation margin distribution result obtained for the target converter transformer to the terminal 102. In addition, in some embodiments, the insulation margin distribution calculation method can also be implemented independently by the server 104 or the terminal 102. For example, the terminal 102 can directly perform the insulation margin distribution calculation on the oil-paper moisture balance curve, or the server 104 can obtain the oil-paper moisture balance curve from the data storage system and perform the insulation margin distribution calculation on the oil-paper moisture balance curve.

[0057] The terminal 102 may be, but is not limited to, various desktop computers and laptop computers. The server 104 may be implemented as an independent server or a server cluster consisting of multiple servers, or may be a cloud server.

[0058] In an exemplary embodiment, Figure 2 As shown, a method for calculating insulation margin distribution is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or by a terminal and a server together. In the embodiment of the present application, the method is applied to Figure 1 The server 104 in the example is used as an example to illustrate the method, which includes the following steps 201 to 206. Among them:

[0059] Step 201: Based on the oil-paper moisture balance curve and the moisture content monitoring value in the insulating oil, determine the moisture content distribution of the internal solid insulation of the target converter transformer under the temperature distribution field; the internal solid insulation includes insulating oil and insulating paper.

[0060] Step 202: Based on the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field, the relative dielectric constant and conductivity of the insulating oil and the insulating paper under the influence of temperature-moisture are fitted to determine the fitting formula for the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and the insulating paper under the temperature-moisture coupling effect.

[0061] Step 203: Calculate the electric field distribution according to the relative permittivity distribution law fitting formula and the conductivity distribution law fitting formula to obtain the field electric field intensity distribution result of the target converter transformer.

[0062] Step 204: Based on the conductor composition of the target converter transformer, discretize the field of the target converter transformer into a plurality of grid units; each conductor is composed of a plurality of grid units.

[0063] Step 205: based on the electric field intensity direction in the field electric field intensity distribution result, draw the electric field lines corresponding to each conductor; each electric field line includes a plurality of electric field line segments; and the two endpoints of each electric field line segment are located on the boundary line of the grid unit.

[0064] Step 206: For each power line, the insulation margin corresponding to the power line is calculated according to the electric field strength and distance of all power line segments in the power line; the insulation margins corresponding to all the power lines constitute the insulation margin distribution result of the target converter transformer.

[0065] Implement the above-mentioned steps 201 to 206, perform electric field distribution calculation through the fitting formula of the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and insulating paper under the temperature-moisture coupling effect, and obtain the field electric field strength distribution result of the target converter transformer. Draw the power lines through the field electric field strength distribution result. For each power line, calculate the insulation margin of each power line according to the electric field strength of the power line itself. When calculating the insulation margin distribution, the present application fully considers the influence of electric field non-uniformity on the calculation results, solves the inaccuracy of traditional calculation methods, improves the evaluation accuracy of the insulation margin distribution of the converter transformer, and further guides the design and operation and maintenance of the target converter transformer.

[0066] like Figure 3 As shown in the figure, the calculation process of insulation margin distribution is as follows:

[0067] 1. Temperature-moisture distribution calculation: Based on the oil-paper moisture balance curve taking into account the influence of temperature, the moisture monitoring value in the insulating oil, combined with the key parameters of the target converter transformer of the evaluation object (applicable to target converter transformers of different models), the moisture distribution law of the insulating paper boundary inside the target converter transformer under the temperature distribution field is obtained.

[0068] 2. Calculation of relative dielectric constant and conductivity: Fit the relative dielectric constant and conductivity of insulating oil and insulating paper materials under the influence of temperature and moisture, and obtain the fitting formula for the distribution law of relative dielectric constant and conductivity of oil and paper materials under the coupling effect of temperature and moisture.

[0069] 3. Dynamic calculation of insulation margin distribution: Based on the target converter transformer temperature and moisture distribution results obtained through simulation, the target converter transformer electric field simulation iterative analysis is performed, and finally the dynamic change law of insulation margin distribution affected by temperature-moisture coupling is deduced.

[0070] Uneven temperature distribution will lead to changes in water solubility and water migration, which will lead to uneven water distribution. The temperature distribution can be quickly obtained through finite element simulation to obtain the uneven temperature field distribution. The water distribution can be obtained through the water balance equation to obtain the saturated water content of the insulation paper boundary, and the diffusion law can be used to determine its distribution in the steady state. According to the oil-paper water balance curve, the relevant parameters are calculated as follows:

[0071]

[0072] Where C1 is the moisture content under saturated conditions (10 -4 %); C2 is the partial pressure of water vapor under saturated conditions, MPa; C3 is the standard atmospheric pressure under this condition; P0 is 1 standard atmospheric pressure, MPa; P v is the water vapor partial pressure under current conditions; C oilis the moisture content in the oil under current conditions (10 -4 %); C paper It is the saturated moisture content (%) in the paper at each local location corresponding to the temperature T (℃).

[0073] Subsequently, through the statistical data of frequency domain dielectric spectroscopy (FDS) measurement, an empirical expression of the operating life of the on-site target converter transformer and the moisture content of the solid insulation is established to achieve the moisture content and distribution of the internal solid insulation of the target converter transformer at different times under different loads. The internal solid insulation is oil-immersed paperboard. The empirical formula of the operating life of the on-site target converter transformer and the moisture content of the solid insulation is shown as follows:

[0074] C t =0.7×e 0.0295×(t-3) (2);

[0075] Where t represents the operating year of the target converter transformer, C t represents the total moisture content of the solid insulation inside the target converter transformer in year t. Based on this, the moisture distribution of the solid insulation inside the target converter transformer under different operating years can be calculated.

[0076] During the operation of the target converter transformer, the accumulation of moisture and uneven temperature distribution lead to changes in the relative dielectric constant and conductivity of local oil and paper materials, thus affecting the insulation performance and electric field distribution. At a frequency of 50Hz, the relative dielectric constant of oil-impregnated paperboard with different moisture contents and different temperatures was tested. The test temperature was 280K~380K, and the moisture content of the paper was 0~6%. The test results are as follows: Figure 4 shown.

[0077] Depend on Figure 4 It can be seen that the relative dielectric constant of oil-impregnated paperboard increases with increasing temperature. When the moisture content of the oil-impregnated paperboard is low, the relative dielectric constant growth rate slows down with increasing temperature and tends to be saturated within the measurement temperature range; when the moisture content is high, the relative dielectric constant growth rate gradually accelerates with increasing temperature, which is significantly different from the relative dielectric constant change trend of oil-impregnated paperboard at low moisture content. Based on the above rules, the Poly2D model can be used to fit the test results to obtain the general distribution law of the relative dielectric constant, that is, the fitting formula for the relative dielectric constant distribution law of insulating paper is expressed as follows:

[0078] Z=Z0+a1x+b1y+c1x 2 +d1y 2 +f1xy (3);

[0079] Among them, Z represents the relative dielectric constant, x is the temperature, y is the moisture content in the insulating paper, and Z0, a1, b1, c1, d1, f1 are constants. Similarly, the relationship between the relative dielectric constant and temperature-moisture content in the insulating oil can be obtained, that is, the fitting formula for the relative dielectric constant distribution law of the insulating oil.

[0080] To verify the relationship between conductivity and temperature-moisture content, the test conditions are the same as above. The test results are as follows: Figure 5 shown.

[0081] Depend on Figure 5 It can be seen that when the temperature is between 300 and 340K and the moisture content of the paperboard is less than 3%, the conductivity of the oil-impregnated paperboard does not change significantly; however, as the temperature and moisture content of the paperboard further increase, the conductivity increases exponentially and reaches its highest point when both reach their peak values. Based on the above rules, the LogisticCum model can be used to fit the test results and calculate the general distribution law of conductivity, that is, the fitting formula for the conductivity distribution law of insulating paper is expressed as follows:

[0082]

[0083] Among them, Z e represents conductivity, x is temperature, y is the moisture content in the insulating paper, and Z1, B2, C2, D2, E2, and F2 are constants. Similarly, the relationship between the conductivity of the insulating oil and the temperature-moisture content can be obtained, that is, the fitting formula for the conductivity distribution law of the insulating oil.

[0084] The electric field distribution is calculated based on the temperature-moisture distribution results inside the target converter transformer (the fitting formula for the relative dielectric constant distribution law and the conductivity distribution law fitting formula of the insulating oil and insulating paper under the temperature-moisture coupling effect are considered), and the calculation method suitable for the insulation margin distribution of the target converter transformer is derived. This process includes power line drawing and dynamic calculation of the insulation margin distribution.

[0085] In an inhomogeneous electric field, charged particles near the electrode move in a directional manner, forming a charge accumulation zone, which in turn increases the electric field strength in the non-ionized area, resulting in a decrease in the breakdown voltage. Therefore, this embodiment fully considers the impact of electric field inhomogeneity on the calculation results when calculating the insulation margin distribution.

[0086] Step 203 specifically includes: calculating the field electric field strength according to finite element analysis, specifically, inputting the relative dielectric constant distribution law fitting formula and the conductivity distribution law fitting formula of the insulating oil and the insulating paper under the temperature-moisture coupling into the COMSOL finite element analysis software, performing electric field distribution calculation, obtaining the field electric field strength distribution result of the target converter transformer, and obtaining the field strength E of each grid unit in the field, and drawing the power lines according to the electric field strength calculation result.

[0087] The electric field distribution depicted by the power lines provides a key field strength parameter for calculating the insulation margin distribution. In this embodiment, the power lines are drawn using the tangent method. Based on the principle that the tangent direction of any point on the power line is consistent with the direction of the electric field strength at that point, the discrete points on the power line are gradually determined by integrating the ordinary differential equations satisfied by the power lines.

[0088] The shape of the grid unit in step 204 is a triangle. In another exemplary embodiment of the present application, the above step 205 may include the following steps 301 to 303:

[0089] Step 301: For each conductor, a midpoint on the boundary of a target grid cell is used as a starting point of the electric line; the target grid cell is any grid cell among all grid cells corresponding to the conductor.

[0090] Step 302: Taking the electric field intensity direction corresponding to the starting point of the electric line as the direction of the electric line, draw a straight line and intersect the opposite side of the grid unit at a point, and record the intersection point as the first field point.

[0091] Step 303: Replace the starting point of the power line with the first field point, obtain the value and direction of the electric field strength at the first field point, repeat the step of "taking the direction of the electric field strength corresponding to the starting point of the power line as the direction of the power line, drawing a straight line and intersecting the opposite side of the grid unit at one point", until the next field point reaches the boundary of the conductor or another conductor, and the power line segments between the starting point of the power line and all continuous field points constitute the power line corresponding to the conductor.

[0092] 1) Choose any boundary line on the conductor boundary and divide it equally, and select a point as the starting point A. Take the direction of the electric field strength E at this point as the direction of the electric line, and draw a straight line that intersects the opposite side of the triangular unit (other shapes can be used) at point A1.

[0093] 2) Taking A1 as the new starting point, use the interpolation method to calculate the value and direction of the electric field strength at A1, and then determine the position of the next point A2.

[0094] 3) Repeat the above step 302 until the next point reaches the boundary or another conductor, and the end point is recorded as B. The denser the unit division in the field, the higher the approximate accuracy of the obtained electric line. The schematic diagram of this process is as follows Figure 6 shown.

[0095] Based on the above process, complete electric power lines are drawn in the field.

[0096] In another exemplary embodiment of the present application, the above step 206 is replaced by the following steps 401 to 405:

[0097] Step 401: Taking the electric field strength at the end point of each power line segment as the electric field strength of the power line segment, taking the length of each power line segment as the distance of the power line segment, and calculating the voltage value and distance value of the power line according to the electric field strength and distance of all power line segments in the power line.

[0098] Along the path of each power line, integrate the electric field strength E and the distance l on each power line segment between the oil gaps, and obtain the voltage value U of the power line. AB And the distance value d, as shown below:

[0099]

[0100] For the sake of simplicity, the voltage value of the power line can also be calculated using formula (6):

[0101]

[0102] Where U i represents the voltage value of the power line segment with the i-th field point as the end point, i refers to the field point number on the grid unit boundary, l i Refers to the distance between two field points, for example, l2 is Figure 6 The distance from A1 to A2 in n e All points on the power line except the starting point.

[0103] Step 402: Calculate the average electric field strength of the oil gap corresponding to the power line. The average electric field strength between the oil gaps is the voltage value and distance value of the power line. The calculation formula of the average electric field strength is as follows:

[0104] E AB =U AB / d (8);

[0105] In the formula, E AB It is the average electric field strength between two points, that is, the average electric field strength of the oil gap corresponding to the electric lines.

[0106] Step 403: Calculate the electric field non-uniformity coefficient according to the average electric field strength of the oil gap corresponding to the electric line and the maximum electric field strength between two points; the maximum electric field strength between two points is the maximum electric field strength between the starting point and the end point of the electric line.

[0107] The non-uniformity coefficient is introduced to obtain the allowable value of the electric field of the insulation margin, as follows: In order to describe the non-uniformity of various electric fields, this embodiment introduces an electric field non-uniformity coefficient f, which is expressed as:

[0108]

[0109] Where f is the electric field inhomogeneity coefficient, EAB is the average electric field strength of the oil gap corresponding to the electric line; E MAX It is the maximum electric field strength between two points, that is, the maximum electric field strength between the starting point and the end point of the electric field line.

[0110] Step 404: Determine the allowable value of the electric field of the oil gap according to the electric field non-uniformity coefficient. Specifically including:

[0111] This embodiment provides a set value, the set value is 0.75, when the electric field non-uniformity coefficient is not less than the set value, the calculation formula of the allowable value of the electric field of the oil gap is as follows:

[0112] E cp =C·d -0.39 (10);

[0113] When the electric field non-uniformity coefficient is less than the set value, that is, f<0.75, the allowable electric field value of each oil gap is reduced by 10%. In this case, the calculation formula for the allowable electric field value of the oil gap is as follows:

[0114] E cp =0.9×C·d -0.39 (11);

[0115] Among them, E cp It represents the allowable value of the electric field of the oil gap; C is a constant, which is determined by factors such as the gas content and oil gap position of the target converter transformer, and is taken as 21.4 here; d is the distance value of the power line.

[0116] Step 405: Calculate the insulation margin corresponding to the power line according to the allowable electric field value of the oil gap and the average electric field strength of the oil gap corresponding to the power line.

[0117] Using the ratio of the allowable value of the electric field under the oil gap size to the average field strength value of the oil gap, the calculation formula for determining the insulation margin q is:

[0118] q=E cp / E AB (12).

[0119] Finally, when the insulation margin calculation on each power line is completed, the insulation margin distribution can be obtained. And with the change of operating years, the insulation margin will also change under the change of temperature field and moisture distribution. It is no longer a fixed value, which is more conducive to the operation and maintenance personnel to evaluate the insulation status of the converter transformer. In order to verify the dynamic evaluation result of the insulation margin of the insulation margin distribution calculation method proposed in this application, taking the top measurement point of the low-voltage winding as an example, the insulation margin result is as follows: Figure 7 As shown, C1, C25, and C48 represent different operating years of the target converter transformer.

[0120] Depend on Figure 7It can be seen that the insulation margin of the converter transformer decreases with the increase of operating years, which proves that the insulation material inside the converter transformer will gradually age with the operating years. At the local location with the smallest margin, the insulation margin after 48 years of operation decreases by about 10.95% compared with the first year.

[0121] This embodiment proposes a dynamic calculation method for insulation margin distribution based on temperature-moisture distribution coupling for converter transformers, and realizes dynamic evaluation of insulation margin distribution at different times during operation. According to the insulation margin distribution results, at the local position with the smallest margin, the insulation margin after 48 years of operation decays by about 10.95% compared with the first year. Compared with the traditional calculation method that the insulation margin remains unchanged, the evaluation is closer to the actual situation and more accurate.

[0122] The present application also provides an application scenario, which applies the above-mentioned insulation margin distribution calculation method. Specifically: the insulation margin distribution calculation method provided in this embodiment can be applied in the converter transformer design and maintenance scenario. The converter transformer design and maintenance scenario includes a curve relationship acquisition link, an insulation margin distribution calculation link, and a design and maintenance link; the oil-paper moisture balance curve enters the insulation margin distribution calculation link from the curve relationship acquisition link, obtains the insulation margin distribution result of the target converter transformer, and enters the downstream design and maintenance link. The insulation margin distribution calculation method provided in this embodiment belongs to the insulation margin distribution calculation link. Specifically, in the insulation margin distribution calculation link process for the target converter transformer, the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field can be determined based on the oil-paper moisture balance curve; based on the above moisture content distribution, the distribution law fitting formula of the relative dielectric constant and the conductivity is determined, and then the field electric field strength distribution result of the target converter transformer is calculated based on the two fitting formulas; a number of grid units are obtained based on the conductor structure of the target converter transformer; based on the direction of the electric field strength, the power lines corresponding to each conductor are drawn; each power line includes a number of power line segments; the two endpoints of each power line segment are located on the boundary line of the grid unit; according to the electric field strength and distance of all power line segments in the power line, the insulation margin corresponding to the power line is calculated, and the insulation margin corresponding to all power lines constitutes the insulation margin distribution result of the target converter transformer.

[0123] Based on the same inventive concept, the embodiment of the present application also provides an insulation margin distribution calculation device for implementing the insulation margin distribution calculation method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more insulation margin distribution calculation device embodiments provided below can refer to the limitations on the insulation margin distribution calculation method above, and will not be repeated here.

[0124] In an exemplary embodiment, Figure 8 As shown, an insulation margin distribution calculation device is provided, comprising:

[0125] The internal solid insulation moisture content distribution determination module T1 is used to: determine the moisture content distribution of the internal solid insulation of the target converter transformer under the temperature distribution field based on the oil-paper moisture balance curve and the moisture content monitoring value in the insulating oil; the internal solid insulation includes insulating oil and insulating paper;

[0126] The relative dielectric constant and conductivity fitting module T2 is used to fit the relative dielectric constant and conductivity of the insulating oil and insulating paper under the influence of temperature-moisture based on the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field, and determine the fitting formula for the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and insulating paper under the temperature-moisture coupling effect;

[0127] The electric field distribution calculation module T3 is used to: perform electric field distribution calculation according to the relative dielectric constant distribution law fitting formula and the conductivity distribution law fitting formula to obtain the field electric field intensity distribution result of the target converter transformer;

[0128] A grid discretization module T4 is used to discretize the field of the target converter transformer into a plurality of grid units based on the conductor composition of the target converter transformer; each conductor is composed of a plurality of grid units;

[0129] The power line drawing module T5 is used to: draw the power line corresponding to each conductor based on the electric field intensity direction in the field electric field intensity distribution result; each power line includes a plurality of power line segments; and the two end points of each power line segment are located on the boundary line of the grid unit;

[0130] The insulation margin calculation module T6 is used to: for each power line, calculate the insulation margin corresponding to the power line according to the electric field strength and distance of all power line segments in the power line; the insulation margins corresponding to all the power lines constitute the insulation margin distribution result of the target converter transformer.

[0131] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Fig. 9As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Wherein, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Wherein, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store insulation margin distribution calculation data. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for calculating insulation margin distribution is implemented.

[0132] Those skilled in the art will understand that Fig. 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0133] In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0134] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0135] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0136] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0137] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0138] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0139] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0140] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for calculating insulation margin distribution, characterized in that: The insulation margin distribution calculation method comprises: Based on the oil-paper moisture balance curve and the moisture content monitoring value in the insulating oil, the moisture content distribution of the internal solid insulation of the target converter transformer under the temperature distribution field is determined; the internal solid insulation includes insulating oil and insulating paper; Based on the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field, the relative dielectric constant and conductivity of the insulating oil and insulating paper under the influence of temperature-moisture are fitted, and the fitting formulas for the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and insulating paper under the temperature-moisture coupling effect are determined; According to the relative permittivity distribution law fitting formula and the conductivity distribution law fitting formula, the electric field distribution calculation is performed to obtain the field electric field intensity distribution result of the target converter transformer; Based on the conductor composition of the target converter transformer, the field of the target converter transformer is discretized into a plurality of grid units; each conductor is composed of a plurality of grid units; Based on the electric field intensity direction in the field electric field intensity distribution result, draw the electric field line corresponding to each conductor; each electric field line includes a plurality of electric field segments; and the two end points of each electric field segment are located on the boundary line of the grid unit; For each power line, the insulation margin corresponding to the power line is calculated according to the electric field strength and distance of all power line segments in the power line; the insulation margins corresponding to all the power lines constitute the insulation margin distribution result of the target converter transformer.

2. The insulation margin distribution calculation method according to claim 1, characterized in that: Calculating the insulation margin corresponding to the power line according to the electric field strength and distance of all power line segments in the power line, specifically including: Taking the electric field strength at the end point of each power line segment as the electric field strength of the power line segment, taking the length of each power line segment as the distance of the power line segment, and calculating the voltage value and distance value of the power line according to the electric field strength and distance of all power line segments in the power line; Calculating the average electric field strength of the oil gap corresponding to the power line according to the voltage value and the distance value of the power line; Calculate the electric field non-uniformity coefficient according to the average electric field strength of the oil gap corresponding to the electric line and the maximum electric field strength between two points; the maximum electric field strength between two points is the maximum electric field strength between the starting point and the end point of the electric line; Determining the allowable value of the electric field of the oil gap according to the electric field non-uniformity coefficient; The insulation margin corresponding to the power line is calculated according to the allowable electric field value of the oil gap and the average electric field strength of the oil gap corresponding to the power line.

3. The insulation margin distribution calculation method according to claim 2, characterized in that: According to the electric field non-uniformity coefficient, the allowable value of the electric field of the oil gap is determined, specifically including: When the electric field non-uniformity coefficient is not less than the set value, the calculation formula of the allowable value of the electric field of the oil gap is as follows: E cp =C·d -0.39 ; When the electric field non-uniformity coefficient is less than the set value, the calculation formula of the allowable value of the electric field of the oil gap is as follows: E cp =0.9×C·d -0.39 ; Among them, E cp It represents the allowable value of the electric field in the oil gap, C is a constant, and d is the distance value of the electric line.

4. The insulation margin distribution calculation method according to claim 2, characterized in that: The calculation formula of the electric field non-uniformity coefficient is as follows: Where f is the electric field inhomogeneity coefficient, E AB is the average electric field strength of the oil gap corresponding to the electric line, E MAX is the maximum electric field strength between two points.

5. The insulation margin distribution calculation method according to claim 1, characterized in that: The grid unit is in the shape of a triangle.

6. The insulation margin distribution calculation method according to claim 5, characterized in that: Based on the electric field intensity direction in the field electric field intensity distribution result, drawing the electric field lines corresponding to each conductor specifically includes: For each conductor, the midpoint on the boundary of the target grid cell is used as the starting point of the electric line; the target grid cell is any grid cell among all grid cells corresponding to the conductor; The direction of the electric field intensity corresponding to the starting point of the electric line is taken as the direction of the electric line, and a straight line is drawn to intersect with the opposite side of the grid unit at one point, and the intersection point is recorded as the first field point; The first field point is used to replace the starting point of the power line, and the value and direction of the electric field strength of the first field point are obtained. The step of "taking the direction of the electric field strength corresponding to the starting point of the power line as the direction of the power line, drawing a straight line and intersecting the opposite side of the grid unit at one point" is repeated until the next field point reaches the boundary of the conductor or another conductor, and the power line segments between the starting point of the power line and all continuous field points constitute the power line corresponding to the conductor.

7. An insulation margin distribution calculation device, characterized in that: The insulation margin distribution calculation device comprises: The internal solid insulation moisture content distribution determination module is used to: determine the moisture content distribution of the internal solid insulation of the target converter transformer under the temperature distribution field based on the oil-paper moisture balance curve and the moisture content monitoring value in the insulating oil; the internal solid insulation includes insulating oil and insulating paper; The relative dielectric constant and conductivity fitting module is used to: fit the relative dielectric constant and conductivity of the insulating oil and insulating paper under the influence of temperature-moisture based on the moisture content distribution of the solid insulation inside the target converter transformer under the temperature distribution field, and determine the fitting formula for the relative dielectric constant distribution law and the conductivity distribution law of the insulating oil and insulating paper under the temperature-moisture coupling effect; An electric field distribution calculation module is used to: perform electric field distribution calculation according to the relative dielectric constant distribution law fitting formula and the conductivity distribution law fitting formula to obtain the field electric field intensity distribution result of the target converter transformer; A grid discretization module is used to: discretize the field of the target converter transformer into a plurality of grid units based on the conductor composition of the target converter transformer; each conductor is composed of a plurality of grid units; A power line drawing module is used to: draw the power line corresponding to each conductor based on the electric field intensity direction in the field electric field intensity distribution result; each power line includes a plurality of power line segments; and the two endpoints of each power line segment are located on the boundary line of the grid unit; The insulation margin calculation module is used to: for each power line, calculate the insulation margin corresponding to the power line according to the electric field strength and distance of all power line segments in the power line; the insulation margins corresponding to all the power lines constitute the insulation margin distribution result of the target converter transformer.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the insulation margin distribution calculation method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the insulation margin distribution calculation method described in any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the insulation margin distribution calculation method described in any one of claims 1 to 6 is implemented.

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