Frequency domain diagnosis method, system and equipment for insulation aging of distribution transformer and medium

Abstract

The invention relates to the related technical field of distribution transformer insulation aging, in particular to a frequency domain diagnosis method, system and device for distribution transformer insulation aging and a medium, and the method comprises the steps: carrying out the frequency response test of a to-be-tested transformer, and obtaining a first frequency response curve; performing a frequency response simulation test on a transformer equivalent circuit model pre-constructed based on the to-be-tested transformer to obtain a second frequency response curve; constructing a target function based on the deviation of the first frequency response curve and the second frequency response curve; taking element parameters in the equivalent circuit model of the transformer as position vectors, taking the objective function as a fitness function, and adopting a multi-objective particle swarm algorithm to solve the element parameters to obtain optimal values of the element parameters; respectively comparing the optimal values of the element parameters with corresponding normal values to obtain insulation aging degrees; according to the method, the insulation aging degree can be obtained by comparing the element parameters obtained through optimization with the normal unaged element parameters.

Description

Technical Field

[0001] The present invention relates to the technical field related to insulation aging of distribution transformers, and in particular to a frequency domain diagnosis method, system, equipment and medium for insulation aging of distribution transformers. Background Art

[0002] The power system is a critical network platform connecting electricity production and consumption and a core component of energy transformation. Its operation must ensure the provision of high-quality and reliable electricity to users. However, due to technical and economic constraints, power supply cannot always meet demand. Failures in the distribution system, which directly serves users, are the primary cause of most power outages. Furthermore, with the integration of a large number of distributed photovoltaic power generation systems and charging stations, the structure of the distribution system will undergo significant changes. Systemic risks caused by frequent equipment failures and insufficient network carrying capacity will increase significantly, significantly impacting the reliability and quality of the distribution system.

[0003] In the distribution network, the distribution transformer is one of the most important equipment. At present, the research on transformer insulation node feature extraction and insulation status assessment methods at home and abroad mainly focuses on physical and chemical tests and electrical tests. Among them, physical and chemical tests include moisture content analysis, dissolved gas analysis and cellulose polymerization degree measurement; electrical tests include resistance measurement method, recovery voltage method, polarization / depolarization current method and frequency domain dielectric spectroscopy method. At present, the transformer insulation aging detection methods studied at home and abroad have their limitations, which are mainly reflected in the following three aspects:

[0004] 1. High testing costs. Physical and chemical tests, such as moisture content analysis, dissolved gas analysis, and cellulose polymerization degree measurement, require expensive equipment and are highly dependent on expert experience and labor costs. These tests are primarily applicable to expensive, high-voltage transformers in the main grid, while distribution transformers are relatively inexpensive. Therefore, these methods are not applicable.

[0005] 2. The detection equipment needs to be laid out on a large scale. The distribution network has a large area and many internal devices. The above method requires the detection equipment to be laid out on a large scale. In addition to the high cost, it also brings great inconvenience to the staff in detection and recording.

[0006] 3. Current methods focus more on timely detection and maintenance plan formulation after transformer faults occur, but lack condition assessment strategies before faults occur. Summary of the Invention

[0007] In order to solve the problem that the existing technology cannot predict transformer insulation aging in advance, the first aspect of the present invention proposes a frequency domain diagnosis method for distribution transformer insulation aging, comprising:

[0008] Performing a frequency response test on the transformer to be tested to obtain a first frequency response curve; performing a frequency response simulation test on a transformer equivalent circuit model pre-built based on the transformer to be tested to obtain a second frequency response curve;

[0009] constructing an objective function based on a deviation between the first frequency response curve and the second frequency response curve;

[0010] Taking the component parameters in the transformer equivalent circuit model as position vectors and the objective function as the fitness function, a multi-objective particle swarm algorithm is used to solve the component parameters to obtain the optimal values ​​of the component parameters;

[0011] The optimal values ​​of the component parameters are compared with the corresponding normal values ​​to obtain the degree of insulation aging.

[0012] Preferably, constructing the objective function based on the deviation between the first frequency response curve and the second frequency response curve is specifically as follows:

[0013] Obtaining an amplitude deviation, a number of resonance points, and a frequency deviation of a first frequency response curve and a second frequency response curve;

[0014] A weighted sum is performed on the amplitude deviation, the number of resonance points, and the frequency deviation, and an objective function is constructed with the minimum weighted sum as the goal.

[0015] Preferably, the component parameters include capacitance, resistance and inductance.

[0016] Preferably, the objective function is:

[0017] Minimize Func

[0018]

[0019] Among them, Minimize is minimized, Func = α·F1+β·F2+γ·F3, α, β, and γ are three weight coefficients, F1 is the sum of the amplitude deviations at all positions between the first frequency response curve and the second frequency response curve, F2 is the inverse of the number of resonance points between the first frequency response curve and the second frequency response curve, F3 is the weighted sum of the frequency deviations at all resonance points between the first frequency response curve and the second frequency response curve, st is the constraint condition, and R i is the resistance value of the i-th resistor, R i is the lower limit of the i-th resistance value, is the upper limit of the i-th resistance value, L i is the inductance of the i-th inductor, L i is the lower limit of the i-th inductance value, is the upper limit of the i-th inductance value, C iis the capacitance value of the i-th capacitor, C i is the lower limit of the ith capacitance value, is the upper limit of the i-th capacitance value.

[0020] Preferably, R i The value of resistance is 45% to 55% of the normal resistance value. The value of L is 145% to 155% of the normal resistance value. i The value of is 45% to 55% of the normal inductance value. The value of is 145% to 155% of the normal inductance value. C i The value of is 45% to 55% of the normal capacitance value. The value is 145% to 155% of the normal capacitance value.

[0021] Preferably, the calculation formula for the sum F1 of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve is:

[0022]

[0023] Where j is the jth position, n is the total number of positions, H(s) test is the transfer function of the transformer equivalent circuit model, H(s) compare is the transfer function of the transformer under test.

[0024] Preferably, the expression of the inverse number F2 of the number of resonance points of the first frequency response curve and the second frequency response curve is:

[0025] F2=-η re

[0026] Among them, η re is the number of resonance points that are the same between the first frequency response curve and the second frequency response curve.

[0027] Preferably, the weighted sum F3 of the frequency deviations of the first frequency response curve and the second frequency response curve at all resonance points is expressed as:

[0028]

[0029] Wherein, λ and τ are weight coefficients, m is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is less than the preset value, k is the kth resonance point, p is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is greater than the preset value, f test | k is the frequency of the transformer equivalent circuit model at the kth resonance point, f compare | kis the frequency of the transformer under test at the kth resonance point.

[0030] Preferably, the preset value is (a+b) / 2, wherein a is the minimum value of the tested spectrum and b is the maximum value of the tested spectrum.

[0031] Preferably, the normal value is obtained by the following steps:

[0032] Construct a normal transformer equivalent circuit model based on a new, non-aging transformer;

[0033] The component parameters in the normal transformer equivalent circuit model are tested to obtain corresponding normal values.

[0034] Preferably, the step of comparing the optimal values ​​of the component parameters with corresponding normal values ​​to obtain the degree of insulation aging specifically includes:

[0035] Compare the error between the optimal value of each component parameter and the corresponding normal value;

[0036] Determine whether at least one of the errors is greater than or equal to 20%. If so, the corresponding transformer to be tested is judged to have severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, the corresponding transformer is judged to have general insulation aging. If not, the corresponding transformer is judged to have not aged.

[0037] Preferably, the transformer equivalent circuit model includes multiple circuit modules and multiple transition capacitor and resistor units. The high-voltage side and low-voltage side of the transformer to be tested are simulated by multiple circuit modules, and the circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor units.

[0038] Preferably, the circuit module includes a resistor-inductor unit and a capacitor-resistor unit, the resistor-inductor unit includes a capacitor and an inductor connected in series, and the capacitor-resistor unit includes a capacitor and a resistor connected in parallel, wherein the two ends of the resistor-inductor unit are each connected to a capacitor-resistor unit, and the two ends of the resistor-inductor unit are respectively connected to the two ends of another capacitor-resistor unit.

[0039] Preferably, the multiple circuit modules on the high-voltage side are connected in sequence through the resistance and inductance units therein; and the multiple circuit modules on the low-voltage side are connected in sequence through the resistance and inductance units therein.

[0040] Preferably, the circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor unit, specifically:

[0041] One end of each transition capacitor and resistor unit is connected to one end of a resistor and inductor unit on the high voltage side, and the other end of each transition capacitor and resistor unit is connected to one end of a corresponding resistor and inductor unit on the low voltage side.

[0042] Preferably, the number of the circuit modules on the high-voltage side is the same as the number of the circuit modules on the low-voltage side.

[0043] A second aspect of the present invention provides a frequency domain diagnosis system for insulation aging of a distribution transformer, comprising:

[0044] The test module is configured to perform a frequency response test on the transformer to be tested to obtain a first frequency response curve; and perform a frequency response simulation test on a transformer equivalent circuit model pre-built based on the transformer to be tested to obtain a second frequency response curve;

[0045] A construction module, configured to construct an objective function based on a deviation between the first frequency response curve and the second frequency response curve;

[0046] A solution module, configured to use the component parameters in the transformer equivalent circuit model as position vectors and the objective function as a fitness function, and adopt a multi-objective particle swarm algorithm to solve the component parameters to obtain optimal values ​​of the component parameters;

[0047] The comparison module is used to compare the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the insulation aging degree.

[0048] Preferably, the construction module constructs an objective function based on the deviation between the first frequency response curve and the second frequency response curve, specifically:

[0049] Obtaining an amplitude deviation, a number of resonance points, and a frequency deviation of a first frequency response curve and a second frequency response curve;

[0050] A weighted sum is performed on the amplitude deviation, the number of resonance points, and the frequency deviation, and an objective function is constructed with the minimum weighted sum as the goal.

[0051] Preferably, the component parameters in the solution module include capacitance, resistance and inductance.

[0052] Preferably, the objective function in the building block is:

[0053] Minimize Func

[0054]

[0055] Among them, Minimize is minimized, Func = α·F1+β·F2+γ·F3, α, β, and γ are three weight coefficients, F1 is the sum of the amplitude deviations at all positions between the first frequency response curve and the second frequency response curve, F2 is the inverse of the number of resonance points between the first frequency response curve and the second frequency response curve, F3 is the weighted sum of the frequency deviations at all resonance points between the first frequency response curve and the second frequency response curve, st is the constraint condition, and R i is the resistance value of the i-th resistor, R i is the lower limit of the i-th resistance value, is the upper limit of the i-th resistance value, L i is the inductance of the i-th inductor, L i is the lower limit of the i-th inductance value, is the upper limit of the i-th inductance value, C i is the capacitance value of the i-th capacitor, C i is the lower limit of the ith capacitance value, is the upper limit of the i-th capacitance value.

[0056] Preferably, R in the building block i The value of resistance is 45% to 55% of the normal resistance value. The value of L is 145% to 155% of the normal resistance value. i The value of is 45% to 55% of the normal inductance value. The value of the inductance is 145% to 155% of the normal inductance value, C i The value of is 45% to 55% of the normal capacitance value. The value is 145% to 155% of the normal capacitance value.

[0057] Preferably, the calculation formula for the sum F1 of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve in the building module is:

[0058]

[0059] Where j is the jth position, n is the total number of positions, H(s) test is the transfer function of the transformer equivalent circuit model, H(s) compare is the transfer function of the transformer under test.

[0060] Preferably, the expression of the inverse number F2 of the number of resonance points of the first frequency response curve and the second frequency response curve in the building module is:

[0061] F2=-η re

[0062] Among them, η reis the number of resonance points that are the same between the first frequency response curve and the second frequency response curve.

[0063] Preferably, the expression of the weighted sum F3 of the frequency deviations of the first frequency response curve and the second frequency response curve at all resonance points in the building module is:

[0064]

[0065] Wherein, λ and τ are weight coefficients, m is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is less than the preset value, k is the kth resonance point, p is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is greater than the preset value, f test | k is the frequency of the transformer equivalent circuit model at the kth resonance point, f compare | k is the frequency of the transformer under test at the kth resonance point.

[0066] Preferably, the preset value in the building module is (a+b) / 2, wherein a is the minimum value of the tested spectrum and b is the maximum value of the tested spectrum.

[0067] Preferably, the normal value in the comparison module is obtained by the following steps:

[0068] Construct a normal transformer equivalent circuit model based on a new, non-aging transformer;

[0069] The component parameters in the normal transformer equivalent circuit model are tested to obtain corresponding normal values.

[0070] Preferably, the comparison module compares the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the insulation aging degree, specifically including:

[0071] Compare the error between the optimal value of each component parameter and the corresponding normal value;

[0072] Determine whether at least one of the errors is greater than or equal to 20%. If so, the corresponding transformer to be tested is judged to have severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, the corresponding transformer is judged to have general insulation aging. If not, the corresponding transformer is judged to have not aged.

[0073] Preferably, the transformer equivalent circuit model in the test module includes multiple circuit modules and multiple transition capacitor and resistor units. The high-voltage side and low-voltage side of the transformer to be tested are simulated by multiple circuit modules, and the circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor units.

[0074] Preferably, the circuit module in the test module includes a resistor-inductor unit and a capacitor-resistor unit, the resistor-inductor unit includes a capacitor and an inductor connected in series, and the capacitor-resistor unit includes a capacitor and a resistor connected in parallel, wherein the two ends of the resistor-inductor unit are each connected to a capacitor-resistor unit, and the two ends of the resistor-inductor unit are respectively connected to the two ends of another capacitor-resistor unit.

[0075] Preferably, the multiple circuit modules on the high-voltage side of the test module are connected in sequence through the resistance and inductance units therein; and the multiple circuit modules on the low-voltage side are connected in sequence through the resistance and inductance units therein.

[0076] Preferably, the circuit module on the high-voltage side of the test module is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor unit, specifically:

[0077] One end of each transition capacitor and resistor unit is connected to one end of a resistor and inductor unit on the high voltage side, and the other end of each transition capacitor and resistor unit is connected to one end of a corresponding resistor and inductor unit on the low voltage side.

[0078] Preferably, the number of circuit modules on the high-voltage side and circuit modules on the low-voltage side in the test module is the same.

[0079] A third aspect of the present invention provides a computer device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0080] The memory is used to store one or more programs;

[0081] When the one or more programs are executed by the at least one processor, the frequency domain diagnosis method for insulation aging of a distribution transformer as described above is implemented.

[0082] A fourth aspect of the present invention provides a computer-readable storage medium having an execution program stored thereon, which, when executed, implements the frequency domain diagnosis method for insulation aging of a distribution transformer as described above.

[0083] Compared with the prior art, the present invention has the following beneficial effects:

[0084] The present invention provides a frequency domain diagnosis method, system, equipment and medium for insulation aging of a distribution transformer, comprising the following steps: performing a frequency response test on a transformer to be tested to obtain a first frequency response curve; performing a frequency response simulation test on a transformer equivalent circuit model pre-constructed based on the transformer to be tested to obtain a second frequency response curve; constructing an objective function based on the deviation between the first frequency response curve and the second frequency response curve; using component parameters in the transformer equivalent circuit model as position vectors and the objective function as a fitness function, solving the component parameters using a multi-objective particle swarm algorithm to obtain optimal values ​​of the component parameters; comparing the optimal values ​​of the component parameters with corresponding normal values ​​to obtain the degree of insulation aging; and optimizing the component parameters in the model using a multi-objective particle swarm algorithm so that the frequency response curve of the transformer equivalent circuit model and the frequency response curve of the transformer to be tested are close to overlapping, so that the transformer equivalent circuit model can represent the transformer to be tested, and comparing the component parameters obtained by optimization with normal, non-aged component parameters to obtain the degree of insulation aging. BRIEF DESCRIPTION OF THE DRAWINGS

[0085] Figure 1 This is a flow chart of the frequency domain diagnosis method for insulation aging of distribution transformers proposed by the present invention;

[0086] Figure 2 This is a schematic diagram of the structure of the transformer equivalent circuit model proposed in the present invention;

[0087] Figure 3 This is a schematic diagram of the frequency response test of the transformer to be tested proposed by the present invention;

[0088] Figure 4 The present invention proposes Figure 2 Schematic diagram of frequency response simulation test of the transformer equivalent circuit model in FIG;

[0089] Figure 5 The present invention proposes Figure 1 Detailed step diagram of step S2;

[0090] Figure 6 A comparison diagram of the second frequency response curve and the first frequency response curve before optimization proposed by the present invention;

[0091] Figure 7 A comparison diagram of the optimized second frequency response curve and the first frequency response curve proposed by the present invention;

[0092] Figure 8 This is a schematic structural diagram of the frequency domain diagnosis system for insulation aging of distribution transformers proposed by the present invention;

[0093] Figure 9 This is a schematic structural diagram of the electronic device proposed by the present invention. DETAILED DESCRIPTION

[0094] The present invention proposes a frequency-domain diagnostic method, system, device, and medium for distribution transformer insulation aging. This method conducts in-depth analysis of the transformer's spectral data from a frequency-domain perspective, thereby identifying the transformer's internal aging condition and improving the distribution network's ability to resist operational risks, effectively handle faults, and quickly restore power supply, both now and in the future.

[0095] Example 1:

[0096] A frequency domain diagnosis method for insulation aging of distribution transformers, such as Figure 1 As shown, the process includes the following steps S1 to S4.

[0097] S1: Perform a frequency response test on the transformer to be tested to obtain a first frequency response curve; perform a frequency response simulation test on a transformer equivalent circuit model pre-built based on the transformer to be tested to obtain a second frequency response curve.

[0098] When it is necessary to detect the insulation status of a transformer, the transformer must first be modeled. In the field of transformer modeling, a hybrid multi-conductor transmission line model consisting of a series of distributed resistors, inductors, and capacitors is usually used to simulate the transformer and establish a transformer equivalent circuit model. The topology of this model corresponds to the geometric shape of the transformer and can describe the insulation status of different parts of the transformer in detail, as shown below: Figure 2 As shown, where C HG Represents the high-voltage side series capacitor, R HG Represents the high-voltage side series resistance, L HW Represents the high-voltage side inductance, C HS Represents the high-voltage side parallel capacitor, R HS Represents the high-voltage side parallel resistance, R HW Represents the high-voltage side resistance, C LG Represents the low-voltage side series capacitor, R LG Represents the low-voltage side series resistance, L LW Represents the low-voltage side inductance, C LS Represents the low-voltage side parallel capacitor, R LS Represents the low-voltage side parallel resistance, R LW Represents the low-voltage side resistance, C HL is the transition capacitance, R HL The transformer equivalent circuit model includes multiple circuit modules and multiple transition capacitor and resistor units. The high-voltage side and the low-voltage side are simulated by multiple circuit modules. The circuit module on the high-voltage side is sequentially connected to the circuit module on the low-voltage side through the transition capacitor and resistor units.

[0099] In a further preferred embodiment, the circuit module includes a resistor-inductor unit and a capacitor-resistor unit, wherein the resistor-inductor unit includes a capacitor and an inductor connected in series, and the capacitor-resistor unit includes a capacitor and a resistor connected in parallel, wherein the two ends of the resistor-inductor unit are each connected to a capacitor-resistor unit, and the two ends of the resistor-inductor unit are respectively connected to the two ends of another capacitor-resistor unit.

[0100] In a further preferred solution, the high-voltage side includes multiple circuit modules, and the resistance and inductance units of the multiple circuit modules are connected in sequence; the low-voltage side includes multiple circuit modules, and the resistance and inductance units of the multiple circuit modules are connected in sequence.

[0101] In a further preferred solution, the circuit module on the high-voltage side is sequentially connected to the circuit module on the low-voltage side through the transition capacitor and resistor unit, specifically:

[0102] One end of the transition capacitor and resistor unit is connected to one end of the resistance and inductance unit on the high voltage side, and the other end of the transition capacitor and resistor unit is connected to one end of the corresponding resistance and inductance unit on the low voltage side.

[0103] In a further preferred solution, the number of the circuit modules on the high voltage side is the same as that of the circuit modules on the low voltage side. Therefore, the circuit modules on the high voltage side are connected to the circuit modules on the low voltage side in a one-to-one correspondence through the transition capacitor and resistor units.

[0104] like Figure 3 As shown, a frequency response analyzer can be used to perform a frequency response test on the transformer to be tested to obtain a first frequency response curve as a comparison curve. Figure 4 As shown, a frequency response simulation test (Frequency Response Analysis, FRA) is performed on the transformer equivalent circuit model constructed above to obtain a second frequency response curve.

[0105] S2: Constructing an objective function based on the deviation between the first frequency response curve and the second frequency response curve.

[0106] The component parameters of the transformer equivalent circuit model are closely related to the insulation state of the transformer itself, as shown in Table 1 below. Changes in the transformer insulation state will cause changes in the corresponding equivalent circuit component parameters. The changes in the transformer equivalent circuit model component parameters due to transformer insulation aging are gradual and continuous. When the parameters reach a certain critical value, related faults may occur. Therefore, the degree of insulation aging can be evaluated by analyzing the component parameters. The purpose of evaluating the transformer insulation aging and preventing potential risks can be achieved by calculating the component parameters in the transformer equivalent circuit model of the current transformer.

[0107] Table 1

[0108]

[0109] Performing frequency-domain response simulation on the constructed transformer equivalent circuit model yields the frequency response curve for the current parameter configuration, also known as the second frequency response curve. Different component configuration parameters correspond to different frequency response curves. Therefore, it is necessary to find a suitable set of component parameters that ensures that the second frequency response curve matches the control curve, effectively simulating the transformer under test.

[0110] Since there are many components in constructing the transformer equivalent circuit model, the present invention adopts a multi-objective particle swarm algorithm to optimize it, and firstly, it is necessary to construct an objective function.

[0111] Therefore, if Figure 5 As shown, step S2 specifically includes the following steps S21 and S22.

[0112] S21: Obtaining the amplitude deviation, the number of resonance points, and the frequency deviation of the first frequency response curve and the second frequency response curve.

[0113] S22: performing weighted summation on the amplitude deviation, the number of resonance points, and the frequency deviation, and constructing an objective function with the goal of minimizing the weighted sum.

[0114] In a further preferred embodiment, the objective function is:

[0115] Minimize Func

[0116]

[0117] Among them, Minimize is minimized, Func = α·F1+β·F2+γ·F3, α, β, and γ are three weight coefficients used to balance the weights of the three parts, F1 is the sum of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve, F2 is the inverse of the number of resonance points of the first frequency response curve and the second frequency response curve, F3 is the weighted sum of the frequency deviations at all resonance points of the first frequency response curve and the second frequency response curve, st is the constraint condition, and R i is the resistance value of the i-th resistor, R i is the lower limit of the i-th resistance value, is the upper limit of the i-th resistance value, L i is the inductance of the i-th inductor, L i is the lower limit of the i-th inductance value, is the upper limit of the i-th inductance value, C i is the capacitance value of the i-th capacitor, C i is the lower limit of the ith capacitance value, is the upper limit of the i-th capacitance value.

[0118] In a further preferred embodiment, R i The value of is 45% to 55% of the normal resistance value, preferably 50%; The value of L is 145% to 155% of the normal resistance value, preferably 150%; i The value of is 45% to 55% of the normal inductance value, preferably 50%; The value of is 145% to 155% of the normal inductance value, preferably 150%; C i The value of is 45% to 55% of the normal capacitance value, preferably 50%; The value of is 145% to 155% of the normal capacitance value, preferably 150%, which can ensure comprehensive coverage while narrowing the search range of the particle swarm.

[0119] In a further preferred solution, the calculation formula for the sum F1 of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve is:

[0120]

[0121] Where j is the jth position, n is the total number of positions, H(s) test is the transfer function of the transformer equivalent circuit model, H(s) compare is the transfer function of the transformer under test.

[0122] F1 refers to the sum of the amplitude deviations of the two curves at all positions. The smaller F1 is, the closer the two curves are.

[0123] In a further preferred solution, the expression for the inverse number F2 of the number of resonance points of the first frequency response curve and the second frequency response curve is:

[0124] F2=-η re

[0125] Among them, η re is the number of resonance points that are the same between the first frequency response curve and the second frequency response curve.

[0126] F2 refers to the inverse of the number of identical resonance points of the two curves. Since the more identical resonance points there are, the closer the two curves are, F2 is introduced as a reward factor.

[0127] In a further preferred solution, the weighted sum F3 of the frequency deviations of the first frequency response curve and the second frequency response curve at all resonance points is expressed as:

[0128]

[0129] Wherein, λ and τ are weight coefficients, m is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is less than the preset value, k is the kth resonance point, p is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is greater than the preset value, f test | k is the frequency of the transformer equivalent circuit model at the kth resonance point, f compare | k is the frequency of the transformer under test at the kth resonance point.

[0130] F3 refers to the weighted sum of the frequency deviations of the two curves at all resonant points. The purpose of introducing F3 is to prevent the curves from shifting in the frequency direction.

[0131] In a further preferred solution, since the value of F3 is affected by the frequency magnitude, the frequency segment is divided into two parts based on a preset value, and the preset value is (a+b) / 2, where a is the minimum value of the tested spectrum and b is the maximum value of the tested spectrum. For example, in the present invention, the preset value is 5*10 6 Hz, the frequency segment is divided into less than 5*10 6 The partial sum of Hz is greater than 5*10 6 For the Hz part, the frequency deviation of the two parts is calculated separately, and the coefficients λ and τ are used to correct the weights, so that the program can take into account and balance the two frequency bands at the same time.

[0132] S3: Taking the component parameters in the transformer equivalent circuit model as the position vector and the objective function as the fitness function, a multi-objective particle swarm algorithm is used to solve the component parameters to obtain the optimal values ​​of the component parameters.

[0133] Taking the resistance, capacitance and inductance of the transformer equivalent circuit model as the optimization targets and the above objective function as the fitness function, a multi-objective particle swarm algorithm is used to iteratively optimize the resistance, capacitance and inductance under the above constraints, so that the simulation frequency response curve (the second frequency response curve) gradually approaches the control curve (the first frequency response curve). When the two curves are very close, it means that the component parameters in the transformer equivalent circuit model can represent the insulation state of the actual transformer.

[0134] like Figure 6 The figure shows the comparison between the second frequency response curve and the first frequency response curve before optimization. It can be seen that when the optimization just started, the obtained test curve and the control curve are very different, not only in amplitude but also in frequency. Figure 7This is the comparison chart after optimization. It can be seen that after optimization, the test curve and the control curve are highly consistent, indicating that the parameters of the component can be adjusted to achieve the fitting of the two curves.

[0135] S4: Compare the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the degree of insulation aging.

[0136] The normal value is obtained by the following steps:

[0137] Construct a normal transformer equivalent circuit model based on a new, non-aging transformer;

[0138] The component parameters in the normal transformer equivalent circuit model are tested to obtain corresponding normal values.

[0139] In a further preferred solution, the step of comparing the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the degree of insulation aging specifically includes:

[0140] Compare the error between the optimal value of each component parameter and the corresponding normal value;

[0141] Determine whether at least one of the errors is greater than or equal to 20%. If so, the corresponding transformer to be tested is judged to have severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, the corresponding transformer is judged to have general insulation aging. If not, the corresponding transformer is judged to have not aged.

[0142] In this embodiment, the resistance error is obtained by comparing the error between the optimal resistance value and the normal resistance value, the capacitance error is obtained by comparing the error between the optimal capacitance value and the normal capacitance value, and the inductance error is obtained by comparing the error between the optimal inductance value and the normal inductance value;

[0143] Determine whether at least one of the resistance error, capacitance error, and inductance error is greater than or equal to 20%. If so, determine that the corresponding transformer has severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, determine that the corresponding transformer has general insulation aging. If not, determine that the corresponding transformer has not aged.

[0144] In order to better evaluate the similarity between the two curves, the goodness of fit R between the optimized test curve and the control curve was calculated. 2 , the calculation formula is as follows:

[0145]

[0146] Among them, l is the lth position, Q is the total number of positions, The average value of the amplitude of the frequency response curve of the transformer to be tested.

[0147] All the initial parameters, optimized parameters, actual parameters and calculated errors are shown in Table 2 below. Compared with the initial errors, the errors of all parameters after optimization and actual parameters are significantly reduced, making the two curves close enough. The inductance value L on the high-voltage side is HW , and the parallel capacitor C on the high voltage side HS The optimization errors of the two parameters are particularly low, and the errors of other parameters are basically around 10%, which is also at a low level. 2 The value is 0.99473, which means that the model can simulate about 99.47% of the total variation in the curve, which is a good effect.

[0148] Table 2

[0149]

[0150] In summary, the transformer equivalent circuit model and optimization method proposed in the present invention can accurately approximate the model's frequency response curve to the frequency response curve of the transformer under test by adjusting the model's parameters. In practical applications, when it is necessary to evaluate the insulation condition of a transformer, a frequency response test can be performed on it, and the obtained curve can be used as the control curve in the model. Then, by building a transformer equivalent circuit model and adjusting the component parameters in the model using a particle swarm optimization algorithm, the model's frequency curve is made close to the actual curve, and the insulation performance of the transformer under test can be evaluated based on the component parameters.

[0151] The present invention analyzes the frequency domain data of the transformer through streamlined steps, which greatly reduces the detection cost. It only needs to collect the frequency domain data of the transformer without the need for a large number of experiments. Secondly, the present invention uses a frequency response analyzer for data acquisition, and there is no need to lay additional detection equipment on a large scale, thereby saving a lot of resources and installation time. Finally, by extracting the insulation characteristics of equivalent circuit parameters and evaluating the insulation status, the pre-fault monitoring and maintenance level of the distribution transformer is effectively improved, so that the overall operating status and risk resistance can be accurately grasped.

[0152] Example 2:

[0153] The present invention based on the same inventive concept also provides a frequency domain diagnosis system for insulation aging of distribution transformers, such as Figure 8 Shown, including:

[0154] The test module is configured to perform a frequency response test on the transformer to be tested to obtain a first frequency response curve; and perform a frequency response simulation test on a transformer equivalent circuit model pre-built based on the transformer to be tested to obtain a second frequency response curve;

[0155] A construction module, configured to construct an objective function based on a deviation between the first frequency response curve and the second frequency response curve;

[0156] A solution module, configured to use the component parameters in the transformer equivalent circuit model as position vectors and the objective function as a fitness function, and adopt a multi-objective particle swarm algorithm to solve the component parameters to obtain optimal values ​​of the component parameters;

[0157] The comparison module is used to compare the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the insulation aging degree.

[0158] In a further preferred solution, the construction module constructs an objective function based on the deviation between the first frequency response curve and the second frequency response curve, specifically:

[0159] Obtaining an amplitude deviation, a number of resonance points, and a frequency deviation of a first frequency response curve and a second frequency response curve;

[0160] A weighted sum is performed on the amplitude deviation, the number of resonance points, and the frequency deviation, and an objective function is constructed with the minimum weighted sum as the goal.

[0161] In a further preferred solution, the component parameters in the solution module include capacitance, resistance and inductance.

[0162] In a further preferred embodiment, the objective function in the building block is:

[0163] Minimize Func

[0164]

[0165] Among them, Minimize is minimized, Func = α·F1+β·F2+γ·F3, α, β, and γ are three weight coefficients, F1 is the sum of the amplitude deviations at all positions between the first frequency response curve and the second frequency response curve, F2 is the inverse of the number of resonance points between the first frequency response curve and the second frequency response curve, F3 is the weighted sum of the frequency deviations at all resonance points between the first frequency response curve and the second frequency response curve, st is the constraint condition, and R i is the resistance value of the i-th resistor, R i is the lower limit of the i-th resistance value, is the upper limit of the i-th resistance value, L i is the inductance of the i-th inductor, L i is the lower limit of the i-th inductance value, is the upper limit of the i-th inductance value, C i is the capacitance value of the i-th capacitor, C i is the lower limit of the ith capacitance value, is the upper limit of the i-th capacitance value.

[0166] In a further preferred embodiment, the building blocks R i The value of resistance is 45% to 55% of the normal resistance value. The value of L is 145% to 155% of the normal resistance value. i The value of is 45% to 55% of the normal inductance value. The value of the inductance is 145% to 155% of the normal inductance value, C i The value of is 45% to 55% of the normal capacitance value. The value is 145% to 155% of the normal capacitance value.

[0167] In a further preferred embodiment, the calculation formula for the sum F1 of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve in the building module is:

[0168]

[0169] Where j is the jth position, n is the total number of positions, H(s) test is the transfer function of the transformer equivalent circuit model, H(s) compare is the transfer function of the transformer under test.

[0170] In a further preferred solution, the expression of the inverse number F2 of the number of resonance points of the first frequency response curve and the second frequency response curve in the building module is:

[0171] F2=-η re

[0172] Among them, η re is the number of resonance points that are the same between the first frequency response curve and the second frequency response curve.

[0173] In a further preferred embodiment, the weighted sum F3 of the frequency deviations of the first frequency response curve and the second frequency response curve at all resonance points in the building module is expressed as follows:

[0174]

[0175] Wherein, λ and τ are weight coefficients, m is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is less than the preset value, k is the kth resonance point, p is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is greater than the preset value, f test | k is the frequency of the transformer equivalent circuit model at the kth resonance point, f compare | k is the frequency of the transformer under test at the kth resonance point.

[0176] In a further preferred solution, the preset value in the building module is (a+b) / 2, wherein a is the minimum value of the tested spectrum and b is the maximum value of the tested spectrum.

[0177] In a further preferred embodiment, the normal value in the comparison module is obtained by the following steps:

[0178] Construct a normal transformer equivalent circuit model based on a new, non-aging transformer;

[0179] The component parameters in the normal transformer equivalent circuit model are tested to obtain corresponding normal values.

[0180] In a further preferred solution, the comparison module compares the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the degree of insulation aging, specifically including:

[0181] Compare the error between the optimal value of each component parameter and the corresponding normal value;

[0182] Determine whether at least one of the errors is greater than or equal to 20%. If so, the corresponding transformer to be tested is judged to have severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, the corresponding transformer is judged to have general insulation aging. If not, the corresponding transformer is judged to have not aged.

[0183] In a further preferred scheme, the transformer equivalent circuit model in the test module includes multiple circuit modules and multiple transition capacitor and resistor units. The high-voltage side and the low-voltage side of the transformer to be tested are simulated by multiple circuit modules, and the circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor units.

[0184] In a further preferred solution, the circuit module in the test module includes a resistor-inductor unit and a capacitor-resistor unit, the resistor-inductor unit includes a capacitor and an inductor connected in series, and the capacitor-resistor unit includes a capacitor and a resistor connected in parallel, wherein the two ends of the resistor-inductor unit are each connected to a capacitor-resistor unit, and the two ends of the resistor-inductor unit are respectively connected to the two ends of another capacitor-resistor unit.

[0185] In a further preferred solution, the multiple circuit modules on the high-voltage side of the test module are connected in sequence through the resistance and inductance units therein; and the multiple circuit modules on the low-voltage side are connected in sequence through the resistance and inductance units therein.

[0186] In a further preferred solution, the circuit module on the high-voltage side of the test module is sequentially connected to the circuit module on the low-voltage side through the transition capacitor and resistor unit, specifically:

[0187] One end of each transition capacitor and resistor unit is connected to one end of a resistor and inductor unit on the high voltage side, and the other end of each transition capacitor and resistor unit is connected to one end of a corresponding resistor and inductor unit on the low voltage side.

[0188] In a further preferred solution, the number of circuit modules on the high-voltage side and the number of circuit modules on the low-voltage side in the test module are the same.

[0189] Example 3

[0190] like Figure 9 As shown, the present invention also provides an electronic device, which may be a computer, a single-chip microcomputer, a smart mobile device, or the like. The electronic device in this embodiment may include a processor, a memory, a transceiver component, and the like. The memory, processor, and transceiver component are connected via a bus; the memory may be used to store an execution program, which may include instructions; and the processor may be used to execute the instructions stored in the memory. The memory may also be used to store data, which may be accessed and / or modified during the execution of the instructions.

[0191] The processor may be a central processing unit (CPU), or it may be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in the storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a frequency domain diagnosis method for insulation aging of a distribution transformer in the above embodiment.

[0192] Example 4

[0193] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in the electronic device for storing programs and data. It can be understood that the storage medium here can include both the built-in storage medium in the electronic device and the extended storage medium supported by the electronic device. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space. These instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of the frequency domain diagnosis method for insulation aging of a distribution transformer in the above embodiment.

[0194] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0195] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0196] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0197] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0198] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A frequency domain diagnosis method for insulation aging of distribution transformers, characterized in that: include: Performing a frequency response test on the transformer to be tested to obtain a first frequency response curve; performing a frequency response simulation test on a transformer equivalent circuit model pre-built based on the transformer to be tested to obtain a second frequency response curve; constructing an objective function based on a deviation between the first frequency response curve and the second frequency response curve; Taking the component parameters in the transformer equivalent circuit model as position vectors and the objective function as the fitness function, a multi-objective particle swarm algorithm is used to solve the component parameters to obtain the optimal values ​​of the component parameters; The optimal values ​​of the component parameters are compared with the corresponding normal values ​​to obtain the degree of insulation aging.

2. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 1, characterized in that: The objective function is constructed based on the deviation between the first frequency response curve and the second frequency response curve, specifically: Obtaining an amplitude deviation, a number of resonance points, and a frequency deviation of a first frequency response curve and a second frequency response curve; A weighted sum is performed on the amplitude deviation, the number of resonance points, and the frequency deviation, and an objective function is constructed with the minimum weighted sum as the goal.

3. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 1, characterized in that: The component parameters include capacitance, resistance and inductance.

4. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 3, characterized in that: The objective function is: Minimize Func Among them, Minimize is minimized, Func = α·F1+β·F2+γ·F3, α, β, and γ are three weight coefficients, F1 is the sum of the amplitude deviations at all positions between the first frequency response curve and the second frequency response curve, F2 is the inverse of the number of resonance points between the first frequency response curve and the second frequency response curve, F3 is the weighted sum of the frequency deviations at all resonance points between the first frequency response curve and the second frequency response curve, st is the constraint condition, and R i is the resistance value of the i-th resistor, R i is the lower limit of the i-th resistance value, is the upper limit of the i-th resistance value, L i is the inductance of the i-th inductor, L i is the lower limit of the i-th inductance value, is the upper limit of the i-th inductance value, C i is the capacitance value of the i-th capacitor, C i is the lower limit of the ith capacitance value, is the upper limit of the ith capacitance value.

5. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 4, characterized in that: R i The value of resistance is 45% to 55% of the normal resistance value. The value of L is 145% to 155% of the normal resistance value. i The value of is 45% to 55% of the normal inductance value. The value of is 145% to 155% of the normal inductance value. The value of is 45% to 55% of the normal capacitance value. The value is 145% to 155% of the normal capacitance value.

6. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 4, characterized in that: The calculation formula for the sum F1 of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve is: Where j is the jth position, n is the total number of positions, H(s) test is the transfer function of the transformer equivalent circuit model, H(s) compare is the transfer function of the transformer under test.

7. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 4, characterized in that: The expression of the inverse number F2 of the number of resonance points of the first frequency response curve and the second frequency response curve is: F2=-η re Among them, η re is the number of resonance points that are the same between the first frequency response curve and the second frequency response curve.

8. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 4, characterized in that: The expression of the weighted sum F3 of the frequency deviations of the first frequency response curve and the second frequency response curve at all resonance points is: Wherein, λ and τ are weight coefficients, m is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is less than the preset value, k is the kth resonance point, p is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is greater than the preset value, f test | k is the frequency of the transformer equivalent circuit model at the kth resonance point, f compare | k is the frequency of the transformer under test at the kth resonance point.

9. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 8, characterized in that: The preset value is (a+b) / 2, where a is the minimum value of the tested spectrum and b is the maximum value of the tested spectrum.

10. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 1, characterized in that: The normal value is obtained by the following steps: Construct a normal transformer equivalent circuit model based on a new, non-aging transformer; The component parameters in the normal transformer equivalent circuit model are tested to obtain corresponding normal values.

11. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 10, characterized in that: The step of comparing the optimal values ​​of the component parameters with corresponding normal values ​​to obtain the insulation aging degree specifically includes: Compare the error between the optimal value of each component parameter and the corresponding normal value; Determine whether at least one of the errors is greater than or equal to 20%. If so, the corresponding transformer to be tested is judged to have severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, the corresponding transformer is judged to have general insulation aging. If not, the corresponding transformer is judged to have not aged.

12. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 1, characterized in that: The transformer equivalent circuit model includes multiple circuit modules and multiple transition capacitor and resistor units. The high-voltage side and the low-voltage side of the transformer to be tested are simulated by multiple circuit modules. The circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor units.

13. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 12, characterized in that: The circuit module includes a resistor-inductor unit and a capacitor-resistor unit, wherein the resistor-inductor unit includes a capacitor and an inductor connected in series, and the capacitor-resistor unit includes a capacitor and a resistor connected in parallel, wherein the two ends of the resistor-inductor unit are each connected to a capacitor-resistor unit, and the two ends of the resistor-inductor unit are respectively connected to the two ends of another capacitor-resistor unit.

14. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 13, characterized in that: The multiple circuit modules on the high-voltage side are connected in sequence through the resistance and inductance units therein; and the multiple circuit modules on the low-voltage side are connected in sequence through the resistance and inductance units therein.

15. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 14, characterized in that: The circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor unit, specifically: One end of each transition capacitor and resistor unit is connected to one end of a resistor and inductor unit on the high voltage side, and the other end of each transition capacitor and resistor unit is connected to one end of a corresponding resistor and inductor unit on the low voltage side.

16. The frequency domain diagnosis method for insulation aging of distribution transformers according to claim 12, characterized in that: The number of the circuit modules on the high-voltage side is the same as the number of the circuit modules on the low-voltage side.

17. A frequency domain diagnosis system for insulation aging of distribution transformers, characterized in that: include: A testing module, configured to perform a frequency response test on the transformer to be tested to obtain a first frequency response curve; Performing a frequency response simulation test on a transformer equivalent circuit model pre-built based on the transformer to be tested to obtain a second frequency response curve; A construction module, configured to construct an objective function based on a deviation between the first frequency response curve and the second frequency response curve; A solution module, configured to use the component parameters in the transformer equivalent circuit model as position vectors and the objective function as a fitness function, and adopt a multi-objective particle swarm algorithm to solve the component parameters to obtain optimal values ​​of the component parameters; The comparison module is used to compare the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the insulation aging degree.

18. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 17, characterized in that: The construction module constructs an objective function based on the deviation between the first frequency response curve and the second frequency response curve, specifically: Obtaining an amplitude deviation, a number of resonance points, and a frequency deviation of a first frequency response curve and a second frequency response curve; A weighted sum is performed on the amplitude deviation, the number of resonance points, and the frequency deviation, and an objective function is constructed with the minimum weighted sum as the goal.

19. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 17, characterized in that: The component parameters in the solution module include capacitance, resistance and inductance.

20. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 19, characterized in that: The objective function in the building block is: Minimize Func Among them, Minimize is minimized, Func = α·F1+β·F2+γ·F3, α, β, and γ are three weight coefficients, F1 is the sum of the amplitude deviations at all positions between the first frequency response curve and the second frequency response curve, F2 is the inverse of the number of resonance points between the first frequency response curve and the second frequency response curve, F3 is the weighted sum of the frequency deviations at all resonance points between the first frequency response curve and the second frequency response curve, st is the constraint condition, and R i is the resistance value of the i-th resistor, R i is the lower limit of the i-th resistance value, is the upper limit of the i-th resistance value, L i is the inductance of the i-th inductor, L i is the lower limit of the i-th inductance value, is the upper limit of the i-th inductance value, C i is the capacitance value of the i-th capacitor, C i is the lower limit of the ith capacitance value, is the upper limit of the ith capacitance value.

21. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 20, characterized in that: The building blocks in R i The value of resistance is 45% to 55% of the normal resistance value. The value of L is 145% to 155% of the normal resistance value. i The value of is 45% to 55% of the normal inductance value. The value of the inductance is 145% to 155% of the normal inductance value, C i The value of is 45% to 55% of the normal capacitance value. The value is 145% to 155% of the normal capacitance value.

22. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 20, characterized in that: The calculation formula for the sum F1 of the amplitude deviations at all positions of the first frequency response curve and the second frequency response curve in the building module is: Where j is the jth position, n is the total number of positions, H(s) test is the transfer function of the transformer equivalent circuit model, H(s) compare is the transfer function of the transformer under test.

23. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 20, characterized in that: The expression of the inverse number F2 of the number of resonance points of the first frequency response curve and the second frequency response curve in the building module is: F2=-η re Among them, η re is the number of resonance points that are the same between the first frequency response curve and the second frequency response curve.

24. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 20, characterized in that: The expression of the weighted sum F3 of the frequency deviations of the first frequency response curve and the second frequency response curve at all resonance points in the building module is: Wherein, λ and τ are weight coefficients, m is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is less than the preset value, k is the kth resonance point, p is the total number of resonance points of the first frequency response curve and the second frequency response curve when the frequency is greater than the preset value, f test | k is the frequency of the transformer equivalent circuit model at the kth resonance point, f compare | k is the frequency of the transformer under test at the kth resonance point.

25. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 24, characterized in that: The preset value in the building module is (a+b) / 2, where a is the minimum value of the tested spectrum and b is the maximum value of the tested spectrum.

26. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 17, characterized in that: The normal value in the comparison module is obtained by the following steps: Construct a normal transformer equivalent circuit model based on a new, non-aging transformer; The component parameters in the normal transformer equivalent circuit model are tested to obtain corresponding normal values.

27. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 26, characterized in that: The comparison module compares the optimal values ​​of the component parameters with the corresponding normal values ​​to obtain the insulation aging degree, specifically including: Compare the error between the optimal value of each component parameter and the corresponding normal value; Determine whether at least one of the errors is greater than or equal to 20%. If so, the corresponding transformer to be tested is judged to have severe insulation aging. If all are less than 20%, further determine whether at least one is between 10% and 20%. If so, the corresponding transformer is judged to have general insulation aging. If not, the corresponding transformer is judged to have not aged.

28. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 17, characterized in that: The transformer equivalent circuit model in the test module includes multiple circuit modules and multiple transition capacitor and resistor units. The high-voltage side and low-voltage side of the transformer to be tested are simulated by multiple circuit modules, and the circuit module on the high-voltage side is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor units.

29. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 28, characterized in that: The circuit module in the test module includes a resistance and inductance unit and a capacitance and resistance unit, wherein the resistance and inductance unit includes a capacitor and an inductor connected in series, and the capacitance and resistance unit includes a capacitor and a resistor connected in parallel, wherein the two ends of the resistance and inductance unit are each connected to a capacitance and resistance unit, and the two ends of the resistance and inductance unit are respectively connected to the two ends of another capacitance and resistance unit.

30. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 29, characterized in that: The multiple circuit modules on the high-voltage side of the test module are connected in sequence through the resistance and inductance units therein; and the multiple circuit modules on the low-voltage side are connected in sequence through the resistance and inductance units therein.

31. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 30, characterized in that: The circuit module on the high-voltage side of the test module is connected to the circuit module on the low-voltage side in sequence through the transition capacitor and resistor unit, specifically: One end of each transition capacitor and resistor unit is connected to one end of a resistor and inductor unit on the high voltage side, and the other end of each transition capacitor and resistor unit is connected to one end of a corresponding resistor and inductor unit on the low voltage side.

32. The frequency domain diagnosis system for insulation aging of distribution transformers according to claim 28, characterized in that: The number of the circuit modules on the high-voltage side of the test module is the same as the number of the circuit modules on the low-voltage side.

33. A computer device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, the frequency domain diagnosis method for insulation aging of a distribution transformer according to any one of claims 1 to 16 is implemented.

34. A computer-readable storage medium, characterized in that An execution program is stored thereon, and when the execution program is executed, the frequency domain diagnosis method for insulation aging of a distribution transformer according to any one of claims 1 to 16 is implemented.

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