Transformer insulation performance test methods, devices, equipment, media and products

Abstract

The application relates to a transformer insulation performance test method, device, equipment, medium and product. The method comprises the following steps: obtaining an initial voltage frequency domain signal and an initial current frequency domain signal of a transformer in response to a preset excitation signal; filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal; and judging the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal. The method can perform necessary filtering processing on the initial voltage frequency domain signal and the initial current frequency domain signal after the initial voltage frequency domain signal and the initial current frequency domain signal are obtained, so that the required response signal is restored, the insulation performance of the transformer is more accurately predicted, the anti-interference capability is high, and the method is suitable for on-site testing.

Description

Technical Field

[0001] The present application relates to the technical field of transformer performance testing, and in particular to a transformer insulation performance testing method, device, equipment, medium and product. Background Art

[0002] Transformers, the core of energy conversion during power transmission and distribution, are crucial for ensuring the safe operation of power grids. Their internal insulation materials are susceptible to aging due to electrical, thermal, mechanical, and chemical factors during operation, resulting in a degradation of insulation performance. Therefore, to extend transformer life and improve grid reliability, transformer insulation performance testing is essential.

[0003] At present, the extraction method combined with Karl Fischer titration and the dew point method combined with the oil-water balance curve method are commonly used to detect the aging degree of the internal insulation material of the transformer. The extraction method combined with Karl Fischer titration is a method for directly measuring the moisture content of the insulation cardboard sample.

[0004] However, it is difficult to directly remove insulating paper samples from the inside of the transformer in the project, which is not suitable for on-site application; on the one hand, the dew point method combined with the oil-water balance curve method requires a long time to ensure the balance of moisture in the insulating paperboard, oil and gas, and is greatly affected by temperature, and the test accuracy of the transformer insulation performance is not high. Summary of the Invention

[0005] Based on this, it is necessary to provide a transformer insulation performance testing method, device, equipment, medium and product that can be applied on-site and accurately test the insulation performance of the transformer to address the above technical problems.

[0006] In a first aspect, the present application provides a method for testing the insulation performance of a transformer. The method comprises:

[0007] Acquire an initial voltage frequency domain signal and an initial current frequency domain signal when the transformer responds to a preset excitation signal;

[0008] Filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal;

[0009] The insulation performance of the transformer is judged according to the target current frequency domain signal and the target voltage frequency domain signal.

[0010] In one embodiment, filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain the target voltage frequency domain signal and the target current frequency domain signal includes:

[0011] Extracting a voltage fundamental component from an initial voltage frequency domain signal based on a frequency of a preset excitation signal;

[0012] Extracting a current fundamental component from the initial current frequency domain signal based on the frequency of the preset excitation signal;

[0013] According to the voltage fundamental component, the target voltage frequency domain signal is obtained;

[0014] According to the current fundamental component, the target current frequency domain signal is obtained.

[0015] In one embodiment, determining the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal includes:

[0016] Obtaining a phase difference between a target voltage frequency domain signal and a target current frequency domain signal;

[0017] The insulation performance of the transformer is determined based on the phase difference.

[0018] In one embodiment, obtaining the phase difference between the target voltage frequency domain signal and the target current frequency domain signal includes:

[0019] The target voltage frequency domain signal is expressed by a sinusoidal voltage analytical expression to obtain the initial phase of the target voltage frequency domain signal;

[0020] The target current frequency domain signal is expressed by the sinusoidal current analytical expression to obtain the initial phase of the target current frequency domain signal;

[0021] The initial phase of the target voltage frequency domain signal and the initial phase of the target current frequency domain signal are subtracted to obtain a phase difference between the target voltage frequency domain signal and the target current frequency domain signal.

[0022] In one embodiment, determining the insulation performance of the transformer based on the phase difference includes:

[0023] Determine the dielectric loss of the transformer based on the phase difference;

[0024] The insulation performance of the transformer is judged based on the dielectric loss of the transformer.

[0025] In one embodiment, obtaining an initial voltage frequency domain signal and an initial current frequency domain signal of a transformer in response to a preset excitation signal includes:

[0026] Acquire an initial voltage time domain signal and an initial current time domain signal of the transformer, where the initial voltage time domain signal and the initial current time domain signal are data of the transformer in response to a preset excitation signal;

[0027] Transforming the initial voltage time domain signal into frequency domain to obtain the initial voltage frequency domain signal;

[0028] The initial current time domain signal is transformed into the frequency domain to obtain the initial current frequency domain signal.

[0029] In a second aspect, the present application also provides a transformer insulation performance testing device. The device comprises:

[0030] An acquisition module, configured to acquire an initial voltage frequency domain signal and an initial current frequency domain signal of the transformer when the transformer responds to a preset excitation signal;

[0031] A filtering module, configured to filter the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal;

[0032] The judgment module is used to judge the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal.

[0033] In a third aspect, the present application further provides a computer device. The computer device includes a memory and a processor. The memory stores a computer program. When the processor executes the computer program, the following steps are performed:

[0034] Acquire an initial voltage frequency domain signal and an initial current frequency domain signal when the transformer responds to a preset excitation signal;

[0035] Filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal;

[0036] The insulation performance of the transformer is judged according to the target current frequency domain signal and the target voltage frequency domain signal.

[0037] In a fourth aspect, the present application further provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0038] Acquire an initial voltage frequency domain signal and an initial current frequency domain signal when the transformer responds to a preset excitation signal;

[0039] Filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal;

[0040] The insulation performance of the transformer is judged according to the target current frequency domain signal and the target voltage frequency domain signal.

[0041] In a fifth aspect, the present application further provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the following steps:

[0042] Acquire an initial voltage frequency domain signal and an initial current frequency domain signal when the transformer responds to a preset excitation signal;

[0043] Filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal;

[0044] The insulation performance of the transformer is judged according to the target current frequency domain signal and the target voltage frequency domain signal.

[0045] The above-mentioned transformer insulation performance testing method, device, equipment, medium and product obtain the initial voltage frequency domain signal and initial current frequency domain signal when the transformer responds to a preset excitation signal, filter the initial voltage frequency domain signal and initial current frequency domain signal to obtain the target voltage frequency domain signal and target current frequency domain signal, and judge the insulation performance of the transformer based on the target current frequency domain signal and target voltage frequency domain signal. In the traditional dielectric response test process, the insulation material inside the transformer may be affected by high-order harmonics, unreasonable selection of sampling resistor gears, and some environmental noise, causing harmonic interference or waveform distortion in the response signal. After obtaining the initial voltage frequency domain signal and initial current frequency domain signal, the embodiment of the present application performs necessary filtering processing on them to obtain target voltage frequency domain data and target current frequency domain data, and then restores the required response signal based on the target voltage data and target current frequency domain data, thereby more accurately predicting the insulation performance of the transformer, having strong anti-interference ability, and testing the transformer insulation performance with high accuracy, and being suitable for on-site testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 1 is a flow chart of a method for testing transformer insulation performance in one embodiment;

[0047] Figure 2 Schematic diagram showing a comparison of current waveforms of an initial current time-domain signal and a target current time-domain signal in one embodiment;

[0048] Figure 3 is a schematic diagram comparing current waveforms of an initial current time-domain signal and a target current time-domain signal in another embodiment;

[0049] Figure 4 is an equivalent schematic diagram of a transformer insulation material in one embodiment;

[0050] Figure 5 Schematic diagram of a flow chart of a method for testing transformer insulation performance in another embodiment;

[0051] Figure 6 is a structural block diagram of a transformer insulation performance device in one embodiment;

[0052] Figure 7 FIG. 1 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0054] In one embodiment, Figure 1 As shown, a method for testing the insulation performance of a transformer is provided. This embodiment uses the method applied to a power grid system server as an example for illustration. It is understandable that the method can be applied to a server or to a system including a terminal and a server, and implemented through the interaction between the terminal and the server. In this embodiment of the application, the method includes the following steps:

[0055] Step 102 : Acquire an initial voltage frequency domain signal and an initial current frequency domain signal of the transformer when the transformer responds to a preset excitation signal.

[0056] The term "excitation signal" refers to any electrical signal input into a circuit to observe the characteristics of a circuit system. The voltage of the excitation signal is the excitation voltage. In this embodiment, the transformer excitation signal amplitude and frequency are set, and input to the transformer based on the excitation signal amplitude and frequency to obtain the transformer's initial voltage frequency domain signal and initial current frequency domain signal in response to the preset excitation signal.

[0057] In one implementation, the excitation signal of the transformer can be set using existing commercial dielectric equipment or a self-built platform, and based on the preset excitation signal amplitude and excitation signal frequency, the initial voltage frequency domain signal and initial current frequency domain signal of the transformer in response to the preset excitation signal can be obtained.

[0058] It should be noted that since the original waveform of the excitation signal may contain high-order harmonics or the sampling resistor value is inappropriate, the voltage waveform and current waveform may be distorted. The initial voltage frequency domain signal and the initial current frequency domain signal may contain DC signal data and sinusoidal signal data of different frequencies.

[0059] Step 104 : Filter the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal.

[0060] Among them, when a single-frequency fundamental wave is incident on a nonlinear medium, due to the coupling effect of the high-order nonlinear electric polarization coefficient, light wave radiation with a frequency three, four, or even higher than that of the incident light wave (fundamental wave) may be generated. In addition, to obtain the current data flowing through the transformer, a sampling resistor is usually connected in series with the transformer under test, and the sampling resistor is used to convert the current signal into a voltage signal for acquisition. Therefore, the response data of the transformer may be affected by high-order harmonics or inappropriate sampling resistor values, resulting in the initial voltage frequency domain signal and the initial current frequency domain signal containing DC signal data and sinusoidal signal data of different frequencies.

[0061] The embodiment of the present application obtains the target voltage frequency domain signal and the target current frequency domain signal by filtering out the specific band frequency in the initial voltage frequency domain signal and the initial current frequency domain signal, thereby suppressing and preventing the interference of the specific band frequency on the prediction of the transformer insulation performance.

[0062] In one implementation, different weights may be given to different signal components in the initial voltage frequency domain signal and the initial current frequency domain signal. For example, the weight of the low-frequency signal is 1, and the weight of the high-frequency signal is 0, thereby achieving filtering.

[0063] Step 106 : Determine the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal.

[0064] The insulation material used in power transformers typically utilizes an oil-paper structure. The presence of mineral oil not only effectively improves the transformer's electrical insulation strength, reduces equipment size, and reduces manufacturing costs, but also enhances the transformer's effective heat transfer and dissipation through oil circulation, while also preventing oxygen from coming into contact with transformer components and the insulation paper. Due to its excellent oil absorption properties, the insulation paper is fully impregnated with insulating oil, dividing the oil channels into multiple oil gaps, significantly enhancing insulation strength. Furthermore, the insulation paper provides support for the transformer windings and improves the internal electric field distribution.

[0065] During transformer operation, the insulation material gradually ages due to long-term exposure to temperature, moisture, electric fields, and oxygen. Under the influence of the electric field, the insulation material experiences internal energy loss due to the hysteresis effects of dielectric conductivity and dielectric polarization. The transformer's insulation performance is determined based on the target current and voltage frequency domain signals in response to a preset excitation signal.

[0066] In the above-mentioned transformer insulation performance test method, by obtaining the initial voltage frequency domain signal and the initial current frequency domain signal when the transformer responds to a preset excitation signal, the initial voltage frequency domain signal and the initial current frequency domain signal are filtered to obtain the target voltage frequency domain signal and the target current frequency domain signal, and the insulation performance of the transformer is judged based on the target current frequency domain signal and the target voltage frequency domain signal. During the dielectric response test process, the insulating material inside the transformer will inevitably be affected by high-order harmonics, unreasonable selection of the sampling resistor position, and some environmental noise, causing harmonic interference or waveform distortion in the response signal. After obtaining the initial voltage frequency domain signal and the initial current frequency domain signal, the embodiment of the present application performs necessary filtering processing on them to restore the required response signal, more accurately predict the insulation performance of the transformer, have strong anti-interference ability, and are suitable for on-site testing.

[0067] In one embodiment, obtaining an initial voltage frequency domain signal and an initial current frequency domain signal of the transformer in response to a preset excitation signal includes:

[0068] Step A1: Acquire the initial voltage time domain signal and the initial current time domain signal of the transformer.

[0069] The initial voltage time-domain signal and the initial current time-domain signal are time-domain signals of the transformer in response to a preset excitation signal.

[0070] Step A2: performing frequency domain transformation on the initial voltage time domain signal to obtain an initial voltage frequency domain signal, and performing frequency domain transformation on the initial current time domain signal to obtain an initial current frequency domain signal.

[0071] Frequency domain transformation refers to converting complex time or space signals into a structure represented by frequency components. The time domain signal generated by the transformer in response to a preset excitation signal may be distorted by the presence of higher harmonics in the original waveform, improper sampling resistor values, or environmental noise, leading to distortion of the voltage and current waveforms. Therefore, after acquiring the time domain signal, the present embodiment performs frequency domain transformation to facilitate subsequent filtering in the frequency domain.

[0072] In one implementation, a fast discrete Fourier transform (FFT) algorithm is used to perform frequency domain transformation on the initial voltage time-domain signal and the initial current time-domain signal, respectively. It is understandable that the initial voltage time-domain signal and the initial current time-domain signal should be processed in the same manner, and both are converted using the fast FFT discrete Fourier transform algorithm. The difference is that when the initial voltage time-domain signal is processed using the fast FFT discrete Fourier transform algorithm, voltage data is input to obtain an initial voltage frequency-domain signal. When the initial current time-domain signal is processed using the fast FFT discrete Fourier transform algorithm, current data is input to obtain an initial current frequency-domain signal.

[0073] The fast Fourier transform (FFT) algorithm of discrete Fourier transform is used to perform frequency domain transformation on the initial voltage time domain signal and the initial current time domain signal, which can be expressed by the following formula:

[0074]

[0075] Where n represents the current or voltage sampling data point, j represents the imaginary unit, k represents the frequency domain signal point, N represents the number of sampling data points, x(n) represents the initial voltage time domain signal or the initial current time domain signal, and X(k) represents the initial voltage frequency domain signal or the initial current frequency domain signal.

[0076] In an embodiment of the present application, by setting the excitation signal amplitude and excitation signal frequency of the transformer, the initial voltage time domain signal and the initial current time domain signal of the transformer in response to the excitation signal are obtained. Since the transformer insulation material is inevitably affected by high-order harmonics, unreasonable selection of the sampling resistor gear, and some environmental noise during the dielectric response test, the response time domain signal may have harmonic interference or waveform distortion. The time domain signal of the transformer in response to the excitation signal is transformed into the frequency domain to facilitate the necessary filtering processing of the time domain waveform, thereby facilitating the restoration of the required response signal.

[0077] In one embodiment, filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain the target voltage frequency domain signal and the target current frequency domain signal includes:

[0078] Step B1: extracting a voltage fundamental component from an initial voltage frequency domain signal and a current fundamental component from an initial current frequency domain signal based on a preset frequency of an excitation signal.

[0079] The fundamental component refers to a sinusoidal signal with the same frequency and period as the preset excitation signal. Other sinusoidal signals with different frequency and period are called harmonic components. To accurately calculate the parameters used to test transformer insulation performance, when the resulting response current waveform is distorted, it is necessary to filter and analyze the original waveform. The measured time domain signal is mapped to the frequency domain through frequency domain transformation, and then the fundamental component is extracted.

[0080] The initial voltage and current frequency domain signals, after frequency domain transformation, include a linear superposition of DC signal data and sinusoidal signal data of varying frequencies. Based on the frequency of a preset excitation signal, the voltage fundamental component is extracted from the initial voltage frequency domain signal, and the current fundamental component is extracted from the initial current frequency domain signal. The fundamental components extracted from the initial voltage and current frequency domain signals can provide a basis for testing transformer insulation performance. For example, dielectric loss parameters used in insulation performance testing can be calculated based on the voltage and current fundamental components.

[0081] Step B2: obtaining a target voltage frequency domain signal according to the voltage fundamental wave component, and obtaining a target current frequency domain signal according to the current fundamental wave component.

[0082] After extracting the voltage fundamental wave component and the current fundamental wave component from the initial voltage frequency domain signal and the initial current frequency domain signal, the target voltage frequency domain signal and the target current frequency domain signal are obtained.

[0083] The embodiment of the present application extracts the voltage fundamental component from the initial voltage frequency domain signal and the current fundamental component from the initial current frequency domain signal based on the frequency of the preset excitation signal, thereby providing a basis for subsequent accurate testing of the insulation performance of the transformer.

[0084] In one embodiment, determining the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal includes:

[0085] Step C1: Acquire the phase difference between the target voltage frequency domain signal and the target current frequency domain signal.

[0086] The phase difference represents the phase difference between two sinusoidal quantities of the same frequency. When determining the phase difference between the target voltage frequency-domain signal and the target current frequency-domain signal, the extracted fundamental component can be transformed in the time domain to obtain the fundamental wave of the time-domain excitation and response. That is, the target voltage frequency-domain signal and the target current frequency-domain signal are transformed in the time domain to obtain a filtered voltage time-domain signal and a filtered current time-domain signal. The phase difference is then determined based on the filtered voltage time-domain signal and the filtered current time-domain signal.

[0087] Step C2: judging the insulation performance of the transformer according to the phase difference.

[0088] Among them, when the insulating material is subjected to the action of the electric field, the hysteresis effect of the dielectric conductivity and dielectric polarization will cause a phase difference between the voltage and current, thereby judging the insulation performance of the transformer.

[0089] In an embodiment of the present application, the insulation performance of the transformer is judged by the phase difference between the target voltage frequency domain signal and the target current frequency domain signal. Since the target voltage frequency domain signal and the target current frequency domain signal are filtered data, they can more accurately determine the phase of the voltage and current, so that the calculated phase difference can more accurately judge the insulation performance of the transformer.

[0090] In one embodiment, determining the phase difference between the target voltage frequency domain signal and the target current frequency domain signal includes: determining the initial phase of the target voltage frequency domain signal and the initial phase of the target current frequency domain signal; and determining the phase difference between the target voltage frequency domain signal and the target current frequency domain signal based on the initial phase of the target voltage frequency domain signal and the initial phase of the target current frequency domain signal.

[0091] The phase difference between two sinusoidal quantities of the same frequency is equal to their initial phase difference, which is independent of time t and reflects the relative position of the two sinusoidal quantities of the same frequency.

[0092] In one implementation, the target voltage frequency domain signal and the target current frequency domain signal are transformed in the time domain to obtain the target voltage time domain signal and the target current time domain signal. For example, the frequency domain spectrum of the extracted fundamental component is subjected to an inverse Fourier transform to obtain the fundamental wave of the time domain excitation and response. The inverse Fourier transform can use the following formula:

[0093]

[0094] Where n represents the current sampling data point, j represents the imaginary unit, k represents the frequency domain signal point, N represents the number of sampling data points, F represents the inverse Fourier transform sequence, X F (k) represents the target voltage frequency domain signal or the target current time domain signal, that is, the frequency domain signal containing only the fundamental component, x F (n) represents the target voltage time domain signal or the target current time domain signal.

[0095] After the initial voltage time domain signal and the initial current time domain signal are frequency-domain transformed, filtering is performed to extract the voltage fundamental component and the current fundamental component to obtain the target voltage frequency domain signal and the target current frequency domain signal. The target voltage frequency domain signal and the target current frequency domain signal are then time-domain transformed to obtain the target voltage time domain signal and the target current time domain signal. The required response waveform is restored through time-frequency domain conversion and filtering, and the influence of high-order harmonics, inappropriate sampling resistor selection and environmental noise on the accuracy of the calculated phase difference is reduced, thereby more accurately testing the insulation performance of the transformer.

[0096] In one implementation, after obtaining the target voltage time-domain signal and the target current time-domain signal, the phase difference may be calculated using an analytical expression of the sinusoidal alternating current and an analytical expression of the voltage.

[0097] For example, the known voltage effective value U=220V, the initial phase ψ u =60°, effective current value I=22A, initial phase ψ i = -30°, the phase difference between voltage and current can be solved as follows:

[0098] The analytical expression for voltage is:

[0099]

[0100] The analytical expression for the current is:

[0101]

[0102] Then the phase difference between voltage and current is:

[0103]

[0104] It should be noted that when calculating the phase difference between two sinusoidal quantities, the two sinusoidal quantities need to be quantized into standard functions of the same name, that is, they are both sinusoidal quantities or cosine quantities, and the amplitudes are both preceded by a positive sign.

[0105] Figure 2 FIG. 1 is a schematic diagram showing a comparison of current waveforms of an initial current time domain signal and a target current time domain signal in an embodiment. Figure 2 As shown in the figure, the sawtooth waveform represents the initial current time domain signal, which is a distorted current waveform. The distortion is caused by the high-order harmonics in the original waveform. The current time domain signal included in the distorted waveform is subjected to frequency domain transformation and filtering, which can filter out the high-order harmonics in the original waveform and obtain the current fundamental component. The target current frequency domain signal including the current fundamental component is then subjected to time domain transformation to obtain Figure 2 The smoothed current waveform is obtained by performing the same processing on the voltage time-domain signal to obtain a smoothed voltage waveform. As can be understood, the positions of the two curves representing the distorted current waveform and the smoothed current waveform on the X-axis remain unchanged. Therefore, when calculating the phase difference between the filtered current and voltage waveforms, the filtering process does not affect the calculation results. On the contrary, because the voltage and current phases can be accurately determined, the calculated voltage and current phase difference reflects the insulation performance more accurately.

[0106] Figure 3 In another embodiment, a schematic diagram showing a comparison of the current waveforms of the initial current time domain signal and the target current time domain signal is shown. Figure 3As shown, the distorted waveform is trapezoidal due to the sine waveform being truncated, and the reason for this phenomenon is that the sampling resistance is too small, so that the too high waveform position is truncated. After the time domain signal of the current included in the distorted waveform is transformed into the frequency domain and filtered, the current fundamental component is obtained, and then the target current frequency domain signal including the current fundamental component is transformed into the time domain, so that the Figure 3 smooth current waveform is obtained, and the same processing is performed on the voltage time domain signal to obtain a smooth voltage waveform. Understandably, the positions of the two curves on the X axis do not change, so that the filtered current waveform and the voltage waveform do not affect the calculation result when the phase difference is calculated, but make the calculated phase difference between the voltage and the current more accurately reflect the insulation performance.

[0107] In the embodiments of the present application, the initial phase of the target voltage frequency domain signal and the initial phase of the target current frequency domain signal are determined, and the phase difference between the target voltage frequency domain signal and the target current frequency domain signal is determined according to the initial phase of the target voltage frequency domain signal and the initial phase of the target current frequency domain signal. The initial phase of the filtered current waveform and the voltage waveform is used to calculate the phase difference, which does not affect the calculation result due to the filtering process, but makes the calculated phase difference between the voltage and the current more accurately reflect the insulation performance.

[0108] In one embodiment, the insulation performance of the transformer is determined according to the phase difference, including: determining the dielectric loss of the transformer according to the phase difference; and determining the insulation performance of the transformer according to the dielectric loss of the transformer.

[0109] For example, the dielectric loss is calculated, and the dielectric of the insulation material can be equivalent to an RC circuit, and the principle is as shown in Figure 4 . The resistance R and the capacitance C are connected in parallel, I R and I C represent the currents through the resistance R and the capacitance C, respectively, and I represents the total current through the main circuit, Figure 4 The arrow in the formula indicates the direction of the current from the positive electrode + to the negative electrode -.

[0110] As shown in Figure 4 , the current I flows through the resistance R and the capacitance C, respectively, to obtain I R and I C . When the insulation material is dry enough, i.e., the moisture content is very low, it is mainly capacitive, and the phase angle of the resistive current I R and the total current I is 90°. However, in the actual operation of the transformer, the insulation material will inevitably produce moisture due to dampness, aging, etc., which will cause the phase angle of the capacitive current I C and the total current I to be less than 90°, and the dielectric loss can be calculated using the resistive current and the capacitive current.

[0111] In one implementation, the following formula may be used to determine the dielectric loss of the transformer based on the phase difference:

[0112] S = tanδ;

[0113] Wherein, δ represents the phase difference and S represents the dielectric loss.

[0114] The insulation performance of the transformer's oil-paper insulation is evaluated based on the numerical value of the dielectric loss. It can be understood that when the phase difference is 0, it means that the transformer has no dielectric loss, and the larger the phase difference, the greater the dielectric loss of the transformer. Since the data involved in calculating the transformer's dielectric loss is pre-filtered after frequency domain transformation, even if the current or voltage passing through the transformer is distorted, the phase of the voltage and current can be determined more accurately, thereby enabling a more accurate evaluation of the insulation performance of the insulating material in the transformer.

[0115] The embodiment of the present application determines the dielectric loss of the transformer through the phase difference, and judges the insulation performance of the transformer based on the dielectric loss of the transformer. Due to the hysteresis effect of the dielectric conductivity and dielectric polarization of the insulating material under the action of the electric field, a phase difference will appear between the voltage and the current, and then the dielectric loss is calculated. The dielectric loss is used to more accurately test the insulation performance of the transformer.

[0116] In one embodiment, Figure 5 As shown, a method for testing transformer insulation performance is provided, the method comprising:

[0117] Step 502: Acquire the initial voltage time domain signal and the initial current time domain signal of the transformer.

[0118] The initial voltage time-domain signal and the initial current time-domain signal are data generated when the transformer responds to a preset excitation signal.

[0119] It should be noted that due to the influence of high-order harmonics, inappropriate sampling resistors and environmental noise, the voltage waveform and current waveform of the initial voltage time-domain signal and the initial current time-domain signal may be distorted.

[0120] Step 504 : Perform frequency domain transformation on the initial voltage time domain signal and the initial current time domain signal to obtain an initial voltage frequency domain signal and an initial current frequency domain signal.

[0121] In order to filter the initial voltage time domain signal and the initial current time domain signal and extract the fundamental component, the time domain signal needs to be mapped to the frequency domain through Fourier transform.

[0122] The fast algorithm of discrete Fourier transform (fast fourier transform, FFT) is used to respectively perform frequency domain transformation on the initial voltage time domain signal and the initial current time domain signal, and the following formula can be used to express:

[0123]

[0124] Wherein, n represents the current or voltage sampling data point, j represents the imaginary unit, k represents the frequency domain signal point, N represents the sampling number of data points, x(n) represents the initial voltage time domain signal or the initial current time domain signal, and X(k) represents the initial voltage frequency domain signal or the initial current frequency domain signal.

[0125] Step 506, based on the frequency of the preset excitation signal, the fundamental component is extracted from the initial voltage frequency domain signal and the initial current frequency domain signal to obtain the target voltage frequency domain signal and the target current frequency domain signal.

[0126] Wherein, the initial voltage frequency domain signal and the initial current frequency domain signal include linear superposition of direct current signal data and different frequency sine signal data. Based on the frequency of the preset excitation signal, the fundamental component is extracted from the initial voltage frequency domain signal and the initial current frequency domain signal to obtain the target voltage frequency domain signal and the target current frequency domain signal. The target voltage frequency domain signal only contains voltage fundamental component, and the target current frequency domain signal only contains current fundamental component.

[0127] Step 508, time domain transformation is performed on the target voltage frequency domain signal and the target current frequency domain signal, and the phase difference between the target voltage frequency domain signal and the target current frequency domain signal is determined.

[0128] Wherein, inverse Fourier transform can be used for time domain transformation, and the formula is as follows:

[0129]

[0130] Wherein, n represents the current sampling data point, j represents the imaginary unit, k represents the frequency domain signal point, N represents the sampling number of data points, F represents the inverse Fourier transform sequence, and X F (k) represents the target voltage frequency domain signal or the target current time domain signal, i.e. the frequency domain signal containing only the fundamental component, and x F (n) represents the target voltage time domain signal or the target current time domain signal.

[0131] Step 510, according to the phase difference, the dielectric loss of the transformer is calculated, and the insulation performance of the transformer is judged according to the dielectric loss of the transformer.

[0132] Before testing the insulation performance of the transformer, the embodiment of the present application performs necessary filtering processing on the time domain waveform of the transformer in response to the excitation signal, thereby restoring the required response waveform and providing a basis for calculating the parameter of dielectric loss. The target current frequency domain signal containing only the current fundamental component and the target voltage frequency domain signal containing only the voltage fundamental component are transformed in the time domain, and then the phase difference between the voltage and the current is calculated, and the insulation performance of the transformer insulation material is tested based on the phase difference. When the insulating material is under the action of the electric field, due to the hysteresis effect of the dielectric conductivity and dielectric polarization, a phase difference will appear between the voltage and the current, and then the dielectric loss is calculated, and the dielectric loss is used to test the insulation performance of the transformer. The embodiment of the present application can not only test the insulation performance of the transformer more accurately through filtering, but also has strong anti-interference ability and is suitable for on-site detection.

[0133] It should be understood that, although the various steps in the flowcharts involved in the various embodiments described above are displayed in sequence according to the instructions of the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the flowcharts involved in the various embodiments described above can include multiple steps or multiple stages, and these steps or stages are not necessarily executed and completed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a portion of steps or stages in other steps.

[0134] Based on the same inventive concept, embodiments of the present application also provide a transformer insulation performance testing device for implementing the aforementioned transformer insulation performance testing method. The solution provided by this device is similar to the solution described in the aforementioned method. Therefore, the specific limitations of one or more transformer insulation performance testing device embodiments provided below can be found in the aforementioned limitations of the transformer insulation performance testing method and will not be further elaborated here.

[0135] In one embodiment, Figure 6 As shown, a transformer insulation performance testing device is provided, including: an acquisition module 602, a filtering module 604 and a judgment module 606, wherein:

[0136] The acquisition module 602 is configured to acquire an initial voltage frequency domain signal and an initial current frequency domain signal of the transformer when the transformer responds to a preset excitation signal.

[0137] The filtering module 604 is configured to filter the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal.

[0138] The judging module 606 is configured to judge the insulation performance of the transformer according to the target voltage frequency domain signal and the target current frequency domain signal.

[0139] In one embodiment, the filtering module 604 is configured to extract a voltage fundamental wave component from the initial voltage frequency domain signal based on the frequency of the preset excitation signal, extract a current fundamental wave component from the initial current frequency domain signal based on the frequency of the preset excitation signal, obtain the target voltage frequency domain signal according to the voltage fundamental wave component, and obtain the target current frequency domain signal according to the current fundamental wave component.

[0140] In one embodiment, the judging module 606 is configured to determine a phase difference between the target voltage frequency domain signal and the target current frequency domain signal, and judge the insulation performance of the transformer according to the phase difference.

[0141] In one embodiment, the judging module 606 is configured to determine an initial phase of the target voltage frequency domain signal and an initial phase of the target current frequency domain signal, and determine a phase difference between the target voltage frequency domain signal and the target current frequency domain signal according to the initial phase of the target voltage frequency domain signal and the initial phase of the target current frequency domain signal.

[0142] In one embodiment, the judging module 606 is configured to determine a dielectric loss of the transformer according to the phase difference, and judge the insulation performance of the transformer according to the dielectric loss of the transformer.

[0143] In one embodiment, the obtaining module 602 is configured to obtain an initial voltage time domain signal and an initial current time domain signal of the transformer, the initial voltage time domain signal and the initial current time domain signal being data of the transformer in response to a preset excitation signal, perform frequency domain transformation on the initial voltage time domain signal to obtain an initial voltage frequency domain signal, and perform frequency domain transformation on the initial current time domain signal to obtain an initial current frequency domain signal.

[0144] The above modules in the transformer insulation performance testing device can be realized by software, hardware, or a combination thereof. The above modules can be embedded in or independent of a processor in a computer device in a hardware form, or stored in a memory in a computer device in a software form, so as to be called and executed by a processor to perform operations corresponding to the above modules.

[0145] In one embodiment, a computer device is provided, which can be a server, and an internal structure diagram of the computer device can be as shown in FIG. 8. Figure 7As shown in the figure. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through the system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capability. 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 input / output interface of the computer device is used to exchange information between the processor and the external device. The communication interface of the computer device is used to communicate with the terminal outside through the network connection. The computer program is executed by the processor to realize a transformer insulation performance test method.

[0146] Those skilled in the art can understand that, Figure 7 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application, and does not constitute a limitation on the computer device to which the scheme of the present application is applied. The specific computer device can include more or fewer components than those shown in the figure, or combine certain components, or have a different component arrangement.

[0147] In one embodiment, a computer device is provided, including a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps in the above method embodiments.

[0148] In one embodiment, a computer readable storage medium is provided, which stores a computer program, and the computer program is executed by the processor to implement the steps in the above method embodiments.

[0149] In one embodiment, a computer program product is provided, including a computer program, and the computer program is executed by the processor to implement the steps in the above method embodiments.

[0150] It should be noted that the user information (including but not limited to user equipment information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in the present application are all information and data authorized by the user or authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards of relevant countries and regions.

[0151] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented 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 memory, database or other media used in the embodiments provided in this application may include at least one of non-volatile and volatile memory. Non-volatile memory may include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory may include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in the various embodiments provided herein may include at least one of a relational database and a non-relational database. Non-relational databases may include, but are not limited to, distributed databases based on blockchains. The processor involved in the various embodiments provided herein may be, but are not limited to, a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic unit, a data processing logic unit based on quantum computing, and the like.

[0152] The technical features of the above embodiments can 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.

[0153] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for testing transformer insulation performance, characterized in that: The method comprises: Acquire an initial voltage frequency domain signal and an initial current frequency domain signal when the transformer responds to a preset excitation signal; Filtering the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal; determining the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal; The determining the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal includes: Acquiring a phase difference between the target voltage frequency domain signal and the target current frequency domain signal; determining the insulation performance of the transformer according to the phase difference; The determining the insulation performance of the transformer according to the phase difference includes: determining a dielectric loss of the transformer according to the phase difference; The insulation performance of the transformer is judged according to the dielectric loss of the transformer.

2. The method according to claim 1, characterized in that The filtering of the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal includes: extracting a voltage fundamental component from the initial voltage frequency domain signal based on the frequency of the preset excitation signal, and obtaining a target voltage frequency domain signal according to the voltage fundamental component; Based on the frequency of the preset excitation signal, a current fundamental component is extracted from the initial current frequency domain signal, and a target current frequency domain signal is obtained according to the current fundamental component.

3. The method according to claim 1, characterized in that The acquiring the phase difference between the target voltage frequency domain signal and the target current frequency domain signal includes: Determining an initial phase of the target voltage frequency domain signal and an initial phase of the target current frequency domain signal; A phase difference between the target voltage frequency domain signal and the target current frequency domain signal is determined according to an initial phase of the target voltage frequency domain signal and an initial phase of the target current frequency domain signal.

4. The method according to claim 1, wherein The acquiring the phase difference between the target voltage frequency domain signal and the target current frequency domain signal includes: Representing the target voltage frequency domain signal by a sinusoidal voltage analytical expression to obtain an initial phase of the target voltage frequency domain signal; Representing the target current frequency domain signal by a sinusoidal current analytical expression to obtain an initial phase of the target current frequency domain signal; A difference is made between an initial phase of the target voltage frequency domain signal and an initial phase of the target current frequency domain signal to obtain a phase difference between the target voltage frequency domain signal and the target current frequency domain signal.

5. The method according to claim 1, wherein The step of obtaining an initial voltage frequency domain signal and an initial current frequency domain signal of the transformer in response to a preset excitation signal includes: Acquire an initial voltage time domain signal and an initial current time domain signal of the transformer, wherein the initial voltage time domain signal and the initial current time domain signal are data of the transformer in response to a preset excitation signal; Performing frequency domain transformation on the initial voltage time domain signal to obtain the initial voltage frequency domain signal; The initial current time domain signal is transformed into a frequency domain to obtain the initial current frequency domain signal.

6. A transformer insulation performance testing device, characterized in that: The device comprises: An acquisition module, configured to acquire an initial voltage frequency domain signal and an initial current frequency domain signal of the transformer when the transformer responds to a preset excitation signal; a filtering module, configured to filter the initial voltage frequency domain signal and the initial current frequency domain signal to obtain a target voltage frequency domain signal and a target current frequency domain signal; a judgment module, configured to judge the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal; The determining the insulation performance of the transformer according to the target current frequency domain signal and the target voltage frequency domain signal includes: Acquiring a phase difference between the target voltage frequency domain signal and the target current frequency domain signal; determining the insulation performance of the transformer according to the phase difference; The determining the insulation performance of the transformer according to the phase difference includes: determining a dielectric loss of the transformer according to the phase difference; The insulation performance of the transformer is judged according to the dielectric loss of the transformer.

7. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 5 are implemented.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

9. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 5 are implemented.

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