CN116429834A - Transformer insulation performance testing method, circuit and device - Google Patents

Abstract

The application relates to a transformer insulation performance testing method, a circuit and a device. The method comprises the steps of obtaining the cut-off frequency of a filter circuit in insulation performance test; when the cut-off frequency is a preset multiple of a test preset frequency, determining a capacitance value of a target capacitor in the filter circuit according to a resistance value of the target resistor in the filter circuit and the test preset frequency; and obtaining a target filter circuit according to the target resistor and the target capacitor, and testing the insulation performance of the transformer according to the target filter circuit. The method can improve the accuracy of the insulation performance detection of the transformer of the sample to be detected.

Description

Transformer insulation performance test method, circuit and device

technical field

The present application relates to the technical field of electrical equipment insulation diagnosis, in particular to a transformer insulation performance testing method, circuit and device.

Background technique

As the core of energy conversion in the process of power transmission and distribution, the transformer is the key equipment to ensure the safe operation of the power grid. During the long-term use of the transformer, the moisture content of the oil-paper insulation in the transformer may be too high due to climate effects such as moisture, thereby reducing the insulation performance of the transformer.

In order to test the insulation performance of transformers and take timely measures to prolong the life of transformers and improve operational reliability, it is necessary to accurately evaluate the moisture content of oil-paper insulation in transformers. The dielectric response method is a common method to detect the moisture content of oil-paper insulation through the response characteristics of the insulating medium under the external test signal. Since the oil-paper insulation resistance in the transformer is large and the response current signal is small, in the actual test process, the response is usually The current signal is amplified by the current amplification unit, and then the current signal is converted into a voltage signal by a filter circuit including a sampling resistor and a filter capacitor, and the actual response current signal is obtained through conversion.

However, when the response current is amplified by the current amplification module, the current amplitude may be too large or too small, resulting in low accuracy of the transformer insulation performance test results.

Contents of the invention

Based on this, it is necessary to provide a transformer insulation performance testing method, circuit and device capable of improving the accuracy of the insulation performance test in view of the above technical problems.

In a first aspect, the present application provides a method for testing insulation performance of a transformer. The method includes:

Obtain the cut-off frequency of the filter circuit in the insulation performance test;

When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency;

The target filter circuit is obtained according to the target resistance and target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit.

In one of the embodiments, obtaining the cut-off frequency of the filter circuit in the insulation performance test includes:

The AC test voltage signal is input to the filter circuit, and the cut-off frequency of the filter circuit in response to the AC test voltage signal is obtained.

In one of the embodiments, when the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency, including:

Obtain the capacitive reactance of the target capacitor according to the resistance value of the target resistor in the filter circuit;

The capacitance value of the target capacitor is obtained according to the capacitive reactance and the test preset frequency.

In one of the embodiments, the resistance value of the target resistor in the filter circuit is obtained in the following manner:

A DC test voltage signal is input to the filter circuit, and the resistance value of the target resistor is obtained according to the DC test voltage signal.

In one embodiment, the method further includes: when the cutoff frequency is not a preset multiple of the test preset frequency, updating the target resistance in the filter circuit until the cutoff frequency is a preset multiple of the test preset frequency.

In one of the embodiments, the transformer insulation performance test is performed according to the target filter circuit, including:

The response current signal of the target transformer is obtained according to the target filter circuit, and the insulation performance of the target transformer is tested according to the response current signal.

In one embodiment, the preset multiple is 18-22 times.

In the second aspect, the present application also provides a transformer insulation performance testing circuit. The circuit includes a current amplification circuit, a target filter circuit and a data analysis circuit connected in sequence;

The current amplification circuit is used to amplify the response current in the transformer insulation performance test;

The target filter circuit is used to collect and filter the current output by the current amplification circuit, and output it to the data analysis circuit for analysis;

The data analysis circuit is used to test the insulation performance of the transformer according to the target filter circuit;

Among them, the target filter circuit is obtained by the following methods:

Obtain the cutoff frequency of the filter circuit in the insulation performance test; when the cutoff frequency is a preset multiple of the test preset frequency, determine the capacitance value of the target capacitor in the filter circuit according to the resistance value of the target resistor in the filter circuit and the test preset frequency; The target resistance and the target capacitance obtain the target filter circuit.

In one embodiment, the target filter circuit includes a target capacitor and a target resistor, and the target capacitor and the target resistor are connected in parallel; the parallel-connected target capacitor or target resistor is connected in parallel with the current amplification circuit.

In a third aspect, the present application also provides a transformer insulation performance testing device. The transformer insulation performance testing device is used to realize the following steps:

Obtain the cut-off frequency of the filter circuit in the insulation performance test;

When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency;

The target filter circuit is obtained according to the target resistance and target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit.

In the fourth aspect, the present application also provides a computer device, including a memory and a processor, a computer program is stored in the memory, and the processor implements the following steps when executing the computer program:

Obtain the cut-off frequency of the filter circuit in the insulation performance test;

When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency;

The target filter circuit is obtained according to the target resistance and target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit.

In the fifth aspect, the present application also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the following steps are implemented:

Obtain the cut-off frequency of the filter circuit in the insulation performance test;

When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency;

The target filter circuit is obtained according to the target resistance and target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit.

In a sixth aspect, the present application also provides a computer program product, including a computer program, and when the computer program is executed by a processor, the following steps are implemented:

Obtain the cut-off frequency of the filter circuit in the insulation performance test;

When the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency;

The target filter circuit is obtained according to the target resistance and target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit.

The above transformer insulation performance testing method, circuit and device obtain the cut-off frequency of the filter circuit in the insulation performance test, and when the cut-off frequency is a preset multiple of the test preset frequency, according to the resistance value of the target resistance in the filter circuit and the test preset frequency The capacitance value of the target capacitor in the filter circuit is determined, the target filter circuit is obtained according to the target resistance and the target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit. At present, in the dielectric response insulation performance test, the response current signal of the transformer under test is amplified to evaluate the moisture content of the oil-paper insulation. However, during the amplification process of the response current, the current amplitude may be too large. So much so that it exceeds the range of signal acquisition; it is also possible that the current amplitude is too small, resulting in waveform distortion, and finally the system cannot obtain accurate test results. In the embodiment of the present application, the amplified response current signal is collected and filtered by a filter circuit. The target resistance in the filter circuit is used to convert the amplified response current signal into a voltage signal, and the actual response current waveform can be obtained through conversion. Select the appropriate target resistance to make the cut-off frequency of the filter circuit a preset multiple of the test preset frequency, so that the response current signal or waveform amplitude collected by the sampling resistor in the filter circuit is within a reasonable range. Acquisition in response to the current will affect the phase difference between the excitation voltage and the response current of the measured sample, that is, the transformer. Therefore, according to the resistance value of the target resistance, match the filter capacitor and compensate the circuit after adding the sampling resistance to restore the original waveform and have a good The signal-to-noise ratio improves the accuracy of the transformer insulation performance test of the tested sample.

Description of drawings

Fig. 1 is the schematic flow sheet of transformer insulation performance test method in an embodiment;

Fig. 2 is the filter circuit schematic diagram of tested sample transformer equivalent in an embodiment;

Fig. 3 is a schematic flow chart of the step of determining the capacitance value of the target capacitance in the filter circuit in one embodiment;

Fig. 4 is the schematic flow sheet of transformer insulation performance testing method in another embodiment;

Fig. 5 is the response current waveform diagram of the measured sample transformer when the target resistance is relatively large in one embodiment;

Fig. 6 is the response current waveform diagram of the tested sample transformer when the target resistance is small in another embodiment;

Fig. 7 is the response current waveform diagram of the tested sample transformer when the target resistance is suitable in one embodiment;

Fig. 8 is a transformer insulation performance test circuit in an embodiment;

Figure 9 is an internal block diagram of a computer device in one embodiment.

Detailed ways

In order to make the purpose, technical solution and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application, and are not intended to limit the present application.

In one embodiment, as shown in FIG. 1 , a method for testing insulation performance of a transformer is provided. In this embodiment, the method is applied to a power grid system server as an example. It can be understood that the method can be applied to a server, or It can be applied to a system including a terminal and a server, and is realized through interaction between the terminal and the server. In the embodiment of this application, the method includes the following steps:

Step 102, obtaining the cut-off frequency of the filter circuit in the insulation performance test.

Among them, the insulation performance test refers to testing the insulation performance of the transformer through the dielectric response method. During the operation of the transformer, the insulating material gradually ages due to long-term exposure to temperature, moisture, electric field and oxygen. Under the action of the electric field, the insulating material causes energy loss inside it due to the hysteresis effect of the dielectric conductance and dielectric polarization.

The dielectric response method refers to measuring the dielectric relaxation characteristics of the insulating medium under DC or sinusoidal AC voltage, obtaining its insulation aging, moisture, etc., and then predicting the insulation life. At present, widely used dielectric response measurement methods include time-domain-based polarization-depolarization current method (Polarization depolarization current, PDC), return voltage method (Return voltage method, RVM) and frequency-domain-based frequency-domain dielectric spectrum Method (Frequency domain spectroscopy, FDS). The dielectric response method is one of the most promising non-destructive testing methods in transformer insulation state assessment due to its advantages of convenient on-site measurement, less environmental interference, rich insulation information, and good interpretability.

Due to the high impedance of the insulating sample, the response current signal is very small, which cannot be directly recognized by the acquisition circuit. Therefore, in the traditional technology, it is considered to connect the response current signal to the current amplification module to amplify the response current through the oil-paper insulation, which is convenient for evaluating the oil-paper insulation. moisture content. However, during the amplification process of the response current, the current amplitude may be too large, so that it exceeds the range of signal acquisition; the current amplitude may also be too small, resulting in waveform distortion, and finally the system cannot obtain accurate data. Test Results.

Based on this, the embodiment of the present application adjusts the resistance value of the sampling resistor in the filter circuit so that after the response current signal is amplified, the response current signal or waveform amplitude collected by the sampling resistor in the filter circuit is within a reasonable range and has Good signal-to-noise ratio.

Wherein, the filter circuit may include a reactance element, for example, a capacitor connected in parallel at both ends of the load resistor. Exemplarily, the filter circuit includes a sampling resistor and a filter capacitor connected in parallel. The sampling resistor is used to convert the amplified response current signal into a voltage signal, and the actual response current waveform can be obtained through conversion. Since the sampling resistor is added to collect the response current, it will affect the phase difference between the excitation voltage and the response current of the measured sample, that is, the transformer. Therefore, it is necessary to match the filter capacitor according to the resistance value of the sampling resistor and compensate the circuit after adding the sampling resistor. The waveform is restored.

In order to select an appropriate target resistance, it can be judged by the cut-off frequency of the filter circuit. The target resistance in the embodiment of the present application is the sampling resistor that needs to be adjusted or selected with an appropriate resistance in the filter circuit. The cut-off frequency refers to the index describing the performance of the filter, which indicates the boundary frequency at which the output signal energy of a system begins to drop sharply or rises sharply in the band-stop filter (generally, the limit is -3dB). In order to make the collected response current signal or waveform amplitude within a reasonable range and have a good signal-to-noise ratio, it is necessary to select different amplification factors and filter circuits for test signals of different amplitudes or frequencies. On the basis of amplifying the response current, select the appropriate sampling resistor and filter capacitor as the target resistor and target capacitor to realize the switching of the current amplification factor and the filter cut-off frequency.

Step 104, when the cutoff frequency is a preset multiple of the test preset frequency, determine the capacitance value of the target capacitor in the filter circuit according to the resistance value of the target resistor in the filter circuit and the test preset frequency.

Wherein, the test preset frequency refers to the frequency of a preset test signal, and the test signal refers to various electrical signals input into the circuit for observing the characteristics of a circuit system. For example, a signal generator can be used to send a test signal to the tested sample transformer.

In the case of test signals with different amplitudes and frequencies, the cut-off frequency of the filter circuit is different. In the embodiment of the present application, the amplitude and frequency of the test signal are preset, and the sample transformer under test is input according to the preset amplitude and frequency to obtain the cutoff frequency of the filter circuit under the test signal.

Exemplarily, after obtaining the cut-off frequency of the filter circuit in the insulation performance test, it is judged whether the cut-off frequency is a preset multiple of the test preset frequency. When the cut-off frequency is a preset multiple of the test preset frequency, it is determined that the response current signal or waveform amplitude collected by the target resistance of the current resistance value is within a reasonable range and has a good signal-to-noise ratio.

After the selected target resistance is determined, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistance and the test preset frequency. Since the sampling resistor is added to collect the response current, it will affect the phase difference between the excitation voltage and the response current of the measured sample, that is, the transformer. Therefore, it is necessary to match the filter capacitor according to the resistance value of the sampling resistor and compensate the circuit after adding the sampling resistor. The waveform is restored.

Step 106, obtaining a target filter circuit according to the target resistance and target capacitance, and performing a transformer insulation performance test according to the target filter circuit.

Among them, according to the test preset frequency, by adjusting or selecting the target resistance with different resistance values as the sampling resistor, and then according to the test preset frequency and target resistance, a suitable target capacitance can be obtained, and the target filter circuit can be obtained through the target resistance and target capacitance. Make sure that the cutoff frequency of the target filter circuit is within the appropriate range.

Exemplarily, after the target filter circuit is determined, the amplified response current is collected by the target filter circuit, converted into a voltage signal, and the actual response current signal can be obtained through conversion. Then according to the actual response current signal and test signal, test the insulation performance of the tested sample transformer. For example, the phase difference between the actual response current signal and the test signal can be obtained to judge the dielectric loss of the oil-paper insulation in the tested sample transformer. Then determine the moisture content of the grease insulation through the dielectric loss, and then test the insulation performance of the tested sample transformer.

In the above transformer insulation performance test method, the cut-off frequency of the filter circuit in the insulation performance test is obtained, and when the cut-off frequency is a preset multiple of the test preset frequency, the filter circuit is determined according to the resistance value of the target resistance in the filter circuit and the test preset frequency According to the capacitance value of the target capacitor, the target filter circuit is obtained according to the target resistance and target capacitance, and the insulation performance test of the transformer is carried out according to the target filter circuit. At present, in the dielectric response insulation performance test, the response current signal of the transformer under test is amplified to evaluate the moisture content of the oil-paper insulation. However, during the amplification process of the response current, the current amplitude may be too large. So much so that it exceeds the range of signal acquisition; it is also possible that the current amplitude is too small, resulting in waveform distortion, and finally the system cannot obtain accurate test results. In the embodiment of the present application, the amplified response current signal is collected and filtered by a filter circuit. The target resistance in the filter circuit is used to convert the amplified response current signal into a voltage signal, and the actual response current waveform can be obtained through conversion. Select the appropriate target resistance to make the cut-off frequency of the filter circuit a preset multiple of the test preset frequency, so that the response current signal or waveform amplitude collected by the sampling resistor in the filter circuit is within a reasonable range. Acquisition in response to the current will affect the phase difference between the excitation voltage and the response current of the measured sample, that is, the transformer. Therefore, according to the resistance value of the sampling resistor, match the filter capacitor and compensate the circuit after adding the sampling resistor to restore the original waveform and have a good The signal-to-noise ratio improves the accuracy of the transformer insulation performance test of the tested sample.

In one embodiment, when the cutoff frequency is a preset multiple of the test preset frequency, in the process of determining the capacitance value of the target capacitor in the filter circuit according to the resistance value of the target resistor in the filter circuit and the test preset frequency, the preset multiple 18-22 times can be selected. Preferably, when the cut-off frequency is 20 times the test preset frequency, a relatively smooth sinusoidal current waveform can be obtained.

In this embodiment, the range of preset multiples is set, that is, when the cut-off frequency is 18 to 22 times the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency , so that the acquired response signal of the transformer under test is a relatively smooth sinusoidal current waveform, thereby having a good signal-to-noise ratio and improving the accuracy of the insulation performance detection of the transformer under test.

In one embodiment, the step of obtaining the cutoff frequency of the filter circuit in the insulation performance test includes: inputting an AC test voltage signal to the filter circuit, and obtaining the cutoff frequency of the filter circuit in response to the AC test voltage signal.

Referring to FIG. 2, FIG. 2 is a schematic diagram of a filter circuit equivalent to a transformer of the tested sample in an embodiment, and the filter circuit can be equivalent to a parallel model of a target resistance R and a target capacitance C.

In one implementation, the parallel connection of the target resistance R and the target capacitance C can form the first node and the second node, and applying an AC test voltage signal to the filter circuit can apply a test between the first node and the second node. AC voltage with preset frequency f.

In this embodiment, by inputting an AC test voltage signal to the filter circuit, the cutoff frequency of the filter circuit when responding to the AC test voltage signal is obtained, and an appropriate target resistance can be selected through the cutoff frequency.

In one embodiment, as shown in Figure 3, when the cutoff frequency is a preset multiple of the test preset frequency, the capacitance value of the target capacitor in the filter circuit is determined according to the resistance value of the target resistor in the filter circuit and the test preset frequency, include:

Step 302, obtain the capacitive reactance of the target capacitor according to the resistance value of the target resistor in the filter circuit.

Exemplarily, when the AC test voltage signal is applied to the filter circuit, as shown in FIG. 2, the capacitive reactance at the test preset frequency can be calculated according to the resistance value of the target resistor R, and the capacitance of the target capacitor C can be calculated from the capacitive reactance. Effective capacitance value.

Step 304, obtain the capacitance value of the target capacitor according to the capacitive reactance and the test preset frequency.

Among them, the capacitance value of the target capacitor C can be calculated by the following formula:

Among them, Z represents the impedance, ω represents the angular frequency, f represents the test preset frequency, and C represents the capacitance value of the target capacitor.

In this embodiment, when the cut-off frequency is a preset multiple of the test preset frequency, the capacitive reactance of the target capacitor is obtained according to the resistance value of the target resistor in the filter circuit, and the capacitance value of the target capacitor is obtained according to the capacitive reactance and the test preset frequency. After the cut-off frequency of the filter circuit determines the selection of the target resistance, since the sampling resistor is added to collect the response current, it will affect the phase difference between the excitation voltage and the response current of the measured sample, that is, the transformer. Therefore, according to the resistance value of the sampling resistor, match the filter capacitor , Compensate the circuit after adding the sampling resistor, restore the original waveform and have a good signal-to-noise ratio, and improve the accuracy of the transformer insulation performance test of the tested sample.

In one embodiment, the resistance value of the target resistor in the filter circuit is acquired in the following manner: a DC test voltage signal is input to the filter circuit, and the resistance value of the target resistor is obtained according to the DC test voltage signal.

Referring to Figure 2, when a DC voltage is applied to the filter circuit, for example, the voltage in Figure 2 is set as a DC voltage, at this time the target capacitor is equivalent to a short circuit, and the resistance value of the target resistor R can be calculated from Ohm's law, where the target The resistance value of the resistor R is its actual resistance value in the insulation performance test circuit.

In an implementation manner, the target capacitor C and the target resistor R are connected in parallel to form a first node and a second node, and applying a DC voltage to the filter circuit may be applying a DC voltage between the first node and the second node.

In this embodiment, by inputting a DC test voltage signal to the filter circuit, the resistance value of the target resistance is obtained according to the DC test voltage signal, and after the target resistance is selected, the actual resistance value of the target resistance in the insulation performance test circuit can be obtained, thereby further passing The resistance value of the target resistor determines the capacitance value of the target capacitor.

In one embodiment, the transformer insulation performance testing method further includes: when the cutoff frequency is not a preset multiple of the test preset frequency, updating the target resistance in the filter circuit until the cutoff frequency is a preset multiple of the test preset frequency .

Wherein, if the cut-off frequency is not a preset multiple of the test preset frequency, adjust the resistance value of the sampling resistor until the cut-off frequency is a preset multiple of the test frequency, determine the sampling resistor of the current resistance value as the target resistance, and Recalculate the capacitance value according to the resistance value of the current target resistance, so as to select the target capacitance corresponding to the capacitance value.

In this embodiment, when the cutoff frequency is not a preset multiple of the test preset frequency, the target resistance in the filter circuit is updated until the cutoff frequency is a preset multiple of the test preset frequency, by adjusting the gear of the target resistance in the filter circuit To obtain a suitable target resistance to make the cut-off frequency of the filter circuit a preset multiple of the test preset frequency, so that the filter circuit can obtain a response current with a reasonable amplitude and a good signal-to-noise ratio.

In one embodiment, testing the insulation performance of the transformer according to the target filter circuit includes: obtaining a response current signal of the target transformer according to the target filter circuit, and testing the insulation performance of the target transformer according to the response current signal.

Exemplarily, the response current signal whose waveform amplitude is within a reasonable range and has a good signal-to-noise ratio can be obtained through the target filter circuit. According to the response current signal and the test signal, the insulation performance of the tested sample transformer is tested, for example , can obtain the phase difference between the actual response current signal and the test signal, judge the dielectric loss of the oil-paper insulation in the tested sample transformer, and then determine the moisture content of the grease insulation through the dielectric loss, and then test the insulation performance of the tested sample transformer.

In this embodiment, the response current signal of the target transformer is obtained through the target filter circuit, and the insulation performance of the target transformer is tested according to the response current signal, so that the cut-off frequency output by the filter circuit of the tested sample transformer can be controlled within the preset frequency of the test. Set the range of multiples, so that when testing the response current of the tested sample voltage transformer based on the dielectric response method, it will not exceed the acquisition range of signal acquisition due to too large response current waveform, nor will it be caused by too small response current waveform The output shows waveform distortion, thereby improving the accuracy of the insulation performance test of the tested sample voltage device.

In one embodiment, as shown in Figure 4, the transformer insulation performance testing method includes:

Step 402, obtaining the cut-off frequency of the filter circuit in response to the AC test voltage in the insulation performance test.

Step 404, judging whether the cutoff frequency is a preset multiple of the test preset frequency.

Step 406, if the cutoff frequency is a preset multiple of the test preset frequency, obtain the resistance value of the target resistor, and determine the capacitance value of the target capacitor in the filter circuit according to the resistance value of the target resistor and the preset frequency.

Wherein, the resistance value of the target resistance is acquired by inputting a DC test voltage signal to the filter circuit, and the resistance value of the target resistance is obtained according to the DC test voltage signal.

Step 408, if the cutoff frequency is not a preset multiple of the test preset frequency, adjust the target resistance and reacquire the cutoff frequency until the cutoff frequency is a preset multiple of the test preset frequency.

After adjusting the target resistance so that the cutoff frequency is a preset multiple of the test preset frequency, refer to step 406, by inputting a DC test voltage signal to the filter circuit, the resistance value of the target resistance is obtained according to the DC test voltage signal, and then according to the target resistance. The resistance value and the preset frequency determine the capacitance value of the target capacitor in the filter circuit.

Step 410, obtain a target filter circuit according to the target resistance and target capacitance, obtain a response current signal of the target transformer according to the target filter circuit, and test the insulation performance of the target transformer through the response current signal.

In this embodiment, by selecting a target resistance with a suitable resistance value and a suitable target capacitance in the dielectric response test, the cut-off frequency output by the filter circuit can be controlled within a preset multiple range of the test frequency, so that based on the dielectric When the response method tests the response current of the tested sample transformer, it will not exceed the signal acquisition range due to the large response current waveform, and will not cause waveform distortion due to the small response current waveform, which can improve the dielectric strength. The test accuracy of the responding device.

Fig. 5 is the response current waveform of the tested sample transformer when the target resistance is relatively large in one embodiment, when the resistance value of the selected target resistance is relatively large, the response current waveform of the tested sample transformer is as shown in Fig. 5, as can be seen, The sinusoidal response current waveform presents a jagged shape, indicating that the current waveform contains a lot of high-frequency clutter, and high-frequency clutter will reduce the accuracy of the insulation performance test.

Fig. 6 is the response current waveform of the tested sample transformer when the target resistance is small in another embodiment, when the resistance value of the selected target resistance is small, the response current waveform of the tested sample transformer is as shown in Figure 6, as can be seen, the response The current waveform is distorted, and the positive and negative high-amplitude segments of the sinusoidal current waveform are cut off. This is because the resistance value of the target resistor is too small to measure higher currents.

In the embodiment of the present application, according to the determined target resistance value and the test preset frequency, an appropriate filter capacitor is selected so that the cut-off frequency of the filter circuit is 20 times the test preset frequency, which can achieve a good filtering effect. Figure 7 is a The response current waveform diagram of the tested sample transformer when the target resistance is suitable in the embodiment, when the cut-off frequency is 20 times of the test frequency, the response current waveform of the tested sample transformer is as shown in Figure 7, it can be seen that the response current satisfies the sinusoidal waveform, The entire waveform is relatively smooth in the time domain, indicating that the gear of the target resistance is very reasonable, and the waveform value of the actual response current can be read with high precision.

It should be understood that although the steps in the flow charts involved in the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed sequentially 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 some of the steps in the flow charts involved in the above-mentioned embodiments may include multiple steps or stages, and these steps or stages are not necessarily executed at the same time, but may be performed at different times For execution, the execution order of these steps or stages is not necessarily performed sequentially, but may be executed in turn or alternately with other steps or at least a part of steps or stages in other steps.

Based on the same inventive concept, the embodiment of the present application also provides a transformer insulation performance testing circuit. The solution to the problem provided by this circuit is similar to the implementation described in the above method, so the specific limitations in one or more transformer insulation performance test circuit embodiments provided below can be referred to above for the transformer insulation performance test The limitation of the method will not be repeated here.

In one embodiment, as shown in FIG. 8 , a transformer insulation performance test circuit is provided, including a current amplification circuit 804 and a target filter circuit 802 connected in sequence, and the current amplification circuit 804 is used to test the insulation performance of the transformer. To amplify the response current, the target filter circuit 802 is used to collect and filter the current output by the current amplifier circuit 804, and output it to the data analysis circuit 806 for analysis; the data analysis circuit 806 is used to perform transformer insulation performance testing according to the target filter circuit .

The transformer insulation performance testing circuit also includes a signal generating circuit 808 and a voltage amplifying circuit 810. The signal generating circuit 808 and the voltage amplifying circuit 810 are used to apply a test signal with a preset frequency to the tested sample transformer.

Wherein, the target filtering circuit 802 includes a target capacitor and a target resistor, and the target capacitor and the target resistor are connected in parallel; the parallel-connected target capacitor or target resistor is connected in parallel with the current amplification circuit.

Among them, the target filter circuit 802 is obtained in the following manner: obtain the cut-off frequency of the filter circuit in the insulation performance test; when the cut-off frequency is a preset multiple of the test preset frequency, according to the resistance value of the target resistance in the filter circuit and the test preset frequency The capacitance value of the target capacitor in the filter circuit is determined; and the target filter circuit is obtained according to the target resistance and the target capacitor.

For the manner of obtaining the above-mentioned target filter circuit, reference may be made to the steps in the embodiment of the above-mentioned transformer insulation performance testing method.

Based on the same inventive concept, an embodiment of the present application further provides a transformer insulation performance test device, which is used to implement the steps in the above-mentioned transformer insulation performance test method embodiment.

Each module in the above-mentioned transformer insulation performance testing device can be fully or partially realized by software, hardware and combinations thereof. The above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, and can also be stored in the memory of the computer device in the form of software, so that the processor can invoke and execute the corresponding operations of the above-mentioned modules.

In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure may be as shown in FIG. 9 . The computer device includes a processor, a memory, an input/output interface, a communication interface, a display unit and an input device. Wherein, the processor, the memory and the input/output interface are connected through the system bus, and the communication interface, the display unit and the input device are connected to the system bus through the input/output interface. Wherein, the processor of the computer device is used to provide calculation and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The input/output interface of the computer device is used for exchanging information between the processor and external devices. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be realized through WIFI, mobile cellular network, NFC (Near Field Communication) or other technologies. When the computer program is executed by the processor, a transformer insulation performance testing method is realized.

Those skilled in the art can understand that the structure shown in FIG. 9 is only a block diagram of a part of the structure related to the solution of this application, and does not constitute a limitation on the computer equipment on which the solution of this application is applied. The specific computer equipment can be More or fewer components than shown in the figures may be included, or some components may be combined, or have a different arrangement of components.

In one embodiment, a computer device is provided, including a memory and a processor, where a computer program is stored in the memory, and the processor implements the steps in the foregoing method embodiments when executing the computer program.

In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the steps in the foregoing method embodiments are implemented.

In one embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the foregoing method embodiments are implemented.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above-mentioned embodiments can be completed by instructing related hardware through computer programs, and the computer programs can be stored in a non-volatile computer-readable memory In the medium, when the computer program is executed, it may include the processes of the embodiments of the above-mentioned methods. Wherein, any reference to storage, database or other media used in the various embodiments provided in the present application may include at least one of non-volatile and volatile storage. Non-volatile memory can include read-only memory (Read-Only Memory, ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive variable memory (ReRAM), magnetic variable memory (Magnetoresistive Random Access Memory, MRAM), Ferroelectric Random Access Memory (FRAM), Phase Change Memory (Phase Change Memory, PCM), graphene memory, etc. The volatile memory may include random access memory (Random Access Memory, RAM) or external cache memory. As an illustration and not a limitation, RAM can be in various forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (Dynamic Random Access Memory, DRAM). The databases involved in the various embodiments provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a blockchain-based distributed database, etc., but is not limited thereto. The processors involved in the various embodiments provided by this application can be general-purpose processors, central processing units, graphics processors, digital signal processors, programmable logic devices, data processing logic devices based on quantum computing, etc., and are not limited to this.

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

The above-mentioned embodiments only express several implementation modes of the present application, and the description thereof is relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be determined by the appended claims.

Claims (10)

1. A method for testing insulation performance of a transformer, the method comprising:

acquiring the cut-off frequency of a filter circuit in an insulation performance test;

when the cut-off frequency is a preset multiple of a test preset frequency, determining a capacitance value of a target capacitor in the filter circuit according to a resistance value of the target resistor in the filter circuit and the test preset frequency;

and obtaining a target filter circuit according to the target resistor and the target capacitor, and testing the insulation performance of the transformer according to the target filter circuit.

2. The method of claim 1, wherein the obtaining the cut-off frequency of the filter circuit in the insulation performance test comprises:

and inputting an alternating current test voltage signal to the filter circuit, and acquiring the cut-off frequency of the filter circuit when responding to the alternating current test voltage signal.

3. The method of claim 1, wherein determining the capacitance value of the target capacitor in the filter circuit based on the resistance value of the target resistor in the filter circuit and the test preset frequency when the cutoff frequency is a preset multiple of the test preset frequency comprises:

acquiring the capacitance of the target capacitor according to the resistance value of the target resistor in the filter circuit;

and obtaining the capacitance value of the target capacitor according to the capacitive reactance and the test preset frequency.

4. A method according to claim 3, wherein the resistance of the target resistor in the filter circuit is obtained by:

and inputting a direct-current test voltage signal to the filter circuit, and obtaining the resistance value of the target resistor according to the direct-current test voltage signal.

5. A method according to claim 3, characterized in that the method further comprises:

and when the cut-off frequency is not a preset multiple of the test preset frequency, updating the target resistance in the filter circuit until the cut-off frequency is a preset multiple of the test preset frequency.

6. The method of claim 5, wherein said performing a transformer insulation performance test according to said target filter circuit comprises:

and obtaining a response current signal of the target transformer according to the target filter circuit, and testing the insulation performance of the target transformer according to the response current signal.

7. The method of claim 1, wherein the predetermined multiple is 18-22 times.

8. The transformer insulation performance testing circuit is characterized by comprising a current amplifying circuit, a target filtering circuit and a data analysis circuit which are connected in sequence;

the current amplifying circuit is used for amplifying the response current in the insulation performance test of the transformer;

the target filter circuit is used for collecting and filtering the current output by the current amplifying circuit and outputting the current to the data analysis circuit for analysis;

the data analysis circuit is used for testing the insulation performance of the transformer according to the target filter circuit;

wherein the target filter circuit is obtained by:

acquiring the cut-off frequency of a filter circuit in an insulation performance test; when the cut-off frequency is a preset multiple of a test preset frequency, determining a capacitance value of a target capacitor in the filter circuit according to a resistance value of the target resistor in the filter circuit and the test preset frequency; and obtaining the target filter circuit according to the target resistance and the target capacitance.

9. The circuit of claim 8, wherein the target filter circuit comprises a target capacitance and a target resistance, the target capacitance and the target resistance being in parallel; and the target capacitor or the target resistor after being connected in parallel is connected in parallel with the current amplifying circuit.

10. A transformer insulation performance testing apparatus, characterized in that the apparatus uses the transformer insulation performance testing method according to any one of claims 1 to 7.

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