Online capacitance value detection and life calculation method, system and storage medium of capacitor

Abstract

The present invention provides an on-line capacitance value detection and life calculation method, system and storage medium for a capacitor, including a capacitor fault detection process, and the capacitor fault detection process includes: S101. Sampling the working information of the capacitor multiple times, and calculating the working conditions of the capacitor for n components, where the working conditions of the capacitor include at least modulus, phase, and effective value; S102. Using the maximum value of the modulus voltage of each component among the n components as the system fundamental wave, extracting the corresponding current and frequency, and calculating the actual capacitance value corresponding to the capacitor; S103. Comparing the capacitance value obtained in S102 with the nominal rated capacitance value of the capacitor, and if it exceeds the error range, sending a capacitor fault warning. The present invention uses the fast Fourier transform to extract the maximum value of the modulus of each voltage and current as the system fundamental wave, and calculates the capacitance value of the capacitor by using the voltage difference between the frequency and the series reactance; by detecting the output current, working voltage, core temperature and actual working duration of the capacitor, etc., the remaining life value is calculated.

Description

Technical Field

[0001] The invention relates to an online capacitance detection and life calculation method, system and storage medium of a capacitor, and belongs to the field of electrical appliance monitoring. Background Art

[0002] Mainstream reactive power compensation devices are equipped with intelligent monitoring systems that can monitor the reactive power compensation capacitor's output current, operating voltage, device temperature, etc. in real time. A few high-end monitoring systems can intervene in the control loop of capacitor input and output, and timely cut off and protect the capacitor by judging whether the capacitor's operating parameters are abnormal.

[0003] However, it is one-sided to use the parameters such as output current, working voltage, temperature, etc. of capacitors as the basis for judging the safety of capacitors. The traditional capacitor monitoring system cannot effectively protect capacitors and reactive power compensation devices. For users, it cannot clearly and intuitively reflect the performance loss of capacitors. Irregular commissioning makes it difficult to ensure that the capacitors are still within the factory-promised warranty period. At present, in the use of occasions, most users blindly replace capacitors with good performance, resulting in a waste of resources, or continue to use capacitors with excessive loss and expired warranty without knowing it, which may endanger the operation of the power system. Summary of the invention

[0004] In order to more effectively monitor and protect reactive compensation capacitors and enable users to more intuitively understand the performance loss of capacitors, this patent provides an online capacitance detection and life calculation technology based on reactive compensation capacitors to enhance the intelligent monitoring system's more comprehensive monitoring of capacitors and user experience.

[0005] The present invention provides a method for online capacitance detection and life calculation of a capacitor, wherein the calculation method includes a capacitor fault detection process, and the capacitor fault detection process includes:

[0006] S101. The working information of the capacitor is sampled multiple times, and the working condition of the capacitor of the n-th component is calculated, and the working condition of the capacitor includes at least the modulus, phase, and effective value;

[0007] S102. Take the maximum value of the modulus voltage of each subcomponent in the n-th subcomponent as the system fundamental wave, extract the corresponding current and frequency, and calculate the actual corresponding capacitance of the capacitor;

[0008] S103. Compare the capacitance value obtained in S102 with the nominal rated capacitance of the capacitor. If the capacitance value exceeds the error range, a capacitor fault alarm is sent.

[0009] Furthermore, the working information includes at least one of a current and a voltage of the capacitor.

[0010] Furthermore, the capacitance calculation formula is:

[0011] 。

[0012] Further, the S1 specifically refers to sampling the working information of the capacitor multiple times, and calculating the modulus value, phase, and effective value of the nth component through fast Fourier transform operation.

[0013] Further, if the number of samplings in S1 is between 50 and 150 times.

[0014] Furthermore, the number of samplings is 64 times.

[0015] Further, the calculation method also includes the capacitor life calculation process:

[0016] S201. Collect the working voltage U, ambient temperature T, and actual working duration t of the capacitor;

[0017] S202. According to the formula: , obtain the expected life value under specific conditions;

[0018] S203. Deduct the consumed life value of the capacitor from the expected duration under the normal working conditions of the capacitor to obtain the remaining life value of the capacitor. If the remaining life is lower than the specified value of the capacitor, issue a capacitor fault alarm and protection mechanism.

[0019] Furthermore, the S203 specifically is: According to the formula: , obtain the remaining life value of the capacitor, where t(T,U) is the expected duration that the capacitor can work normally under specific working voltage and ambient temperature, and the ti(T i ,U i ) is the expected life value of the capacitor obtained in S202 under the existing working voltage and ambient temperature, and t 实际 is the working duration of the capacitor under the existing working voltage and ambient temperature.

[0020] On the other hand, the present invention also discloses a detection system. The detection system applies the above-mentioned on-line capacitance value detection and life calculation method of the capacitor. If there is a series reactor in the device for detecting the capacitor in this system, it is necessary to add the voltage difference of the reactor based on the measured voltage value of the capacitor.

[0021] On the other hand, the present invention also discloses a computer-readable storage medium. The computer-readable storage medium contains computer program instructions. When the computer program instructions are called, they are used to execute the above-mentioned on-line capacitance value detection and life calculation method of the capacitor.

[0022] Compared with the prior art, the present invention collects the grid-side voltage and the capacitor output current through a hardware system, uses the Fast Fourier Transform (FFT) to extract the maximum value of each order modulus of the voltage and current, determines it as the system fundamental wave, and then finds the corresponding frequency and the voltage difference of the series reactance to calculate the capacitance value of the capacitor; in addition, by detecting the capacitor output current, working voltage, core temperature, and actual working duration, etc., the remaining life value is calculated using a formula similar to the experimental derivation to promise the expected life, and finally the intelligent monitoring system can online and real-time display the capacitance value and life parameters, which can also be used as the judgment conditions for the loss and safety of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a flowchart of capacitance value detection in an embodiment of the present invention;

[0024] Figure 2 It is a schematic structural diagram of a detection system in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0026] The present invention provides an on-line capacitance value detection and life calculation method for a capacitor. The calculation method includes a capacitor fault detection process, and the capacitor fault detection process includes:

[0027] S101. Sampling the working information of the capacitor multiple times, and calculating the working condition of the capacitor of the nth component, where the working condition of the capacitor at least includes modulus, phase, and effective value;

[0028] S102. Taking the maximum value of the modulus voltage of each component in the nth component as the system fundamental wave, extracting the corresponding current and frequency, and calculating the actual capacitance value corresponding to the capacitor;

[0029] S103. Comparing the capacitance value obtained in S102 with the nominal rated capacitance value of the capacitor. If it exceeds the error range, a capacitor fault alarm is sent.

[0030] Optionally, the working information at least includes one of the current and voltage of the capacitor.

[0031] Among them, in the embodiment of the present invention, the working information includes the current and voltage of the capacitor. In addition, if there is a series reactor on the device for detecting the capacitor, the voltage difference of the reactor needs to be added to the measured voltage of the capacitor as the actual voltage of the capacitor.

[0032] Optionally, the capacitance value calculation formula is:

[0033] 。

[0034] Optionally, S1 specifically involves performing multiple samplings on the operating information of the capacitor, and through fast Fourier transform operations, calculating the modulus value, phase, and effective value of the nth component.

[0035] Optionally, if the number of multiple samplings in S1 is between 50 and 150 times.

[0036] Specifically, the number of multiple samplings is 64 times.

[0037] Among them, the capacitance value detection process of the embodiment of the present invention is specifically as follows:

[0038] S101. As Figure 1 shown, the method of the embodiment of the present invention can collect 64 sampling points of the voltage and current of the capacitor through a detection device, perform fast Fourier transform (FFT) operations on them, and obtain the modulus value, phase, and effective value of the 1st to 25th components;

[0039] S102. Find the maximum value of the modulus of each voltage component, and use this maximum value as the system fundamental wave U 基波 , and then find its corresponding current I 基波 , frequency F 基波 , according to the formula , calculate the capacitance value C of the capacitor;

[0040] S13. Compare the calculated capacitance value C of the capacitor with the nominal rated capacitance value of the capacitor. If it continuously exceeds the error range, the system will issue a capacitor failure warning. Here, the error range is the nominal error range or the range of ±10% of the rated capacitance value when the capacitor leaves the factory.

[0041] Optionally, the calculation method further includes the capacitor life calculation process:

[0042] S201. Collect the operating voltage U, ambient temperature T, and actual operating duration t of the capacitor;

[0043] S202. According to the formula: , obtain the expected life value under specific conditions;

[0044] S203. Deduct the already consumed life value of the capacitor from the expected duration under the normal operating conditions of the capacitor to obtain the remaining life value of the capacitor. If the remaining life is lower than the specified value of the capacitor, a capacitor failure warning and protection mechanism will be issued.

[0045] Optionally, S203 is specifically: According to the formula: , obtain the remaining life value of the capacitor, where t(T,U) is the expected duration for the capacitor to operate normally under specific working voltage and ambient temperature, and the ti(T i ,U i ) is the expected life value of the capacitor obtained in S202 under the existing working voltage and ambient temperature, and t 实际 is the elapsed working duration of the capacitor under the existing working voltage and ambient temperature.

[0046] Among them, the expected life of the capacitor is clearly defined in the product specification, which is the expected duration for the capacitor to operate normally under specific working voltage and ambient temperature. The actual operating voltage and actual ambient temperature of the capacitor cannot be guaranteed to be consistent with the specification. The relationship between the expected life of the capacitor and the applied voltage and ambient temperature is as follows:

[0047]

[0048] In actual use, through the above formula, the expected service life under specified working conditions can be deduced using the test results under accelerated test conditions. After detecting and recording the working voltage, ambient temperature, and actual working duration under the actual working state, calculate the working duration equivalent to the specified working conditions, and then gradually subtract it from the expected life. The formula is . When the remaining life is as low as the specified value, the system issues a capacitor fault warning and protection mechanism.

[0049] Compared with the prior art, the present invention collects the grid-side voltage and capacitor output current through a hardware system, uses the Fast Fourier Transform (FFT) to extract the maximum values of the voltage and current modulus values of each order as the fundamental wave of the system, and then calculates the capacitance value by finding the pressure difference between the corresponding frequency and the series reactance; in addition, by detecting the capacitor output current, working voltage, core temperature, and actual working duration, etc., the remaining life value is calculated using a formula similar to the experimental derivation to promise the expected life. Finally, the intelligent monitoring system can display the capacitance value and life parameters online in real time, and can also be used as a judgment condition for the loss and safety of the capacitor.

[0050] Another aspect of the embodiment of the present invention also discloses a detection system, as Figure 2 shown. The detection system applies the above online capacitance value detection and life calculation method for the capacitor. If there is a series reactor in the detection device at the capacitor being detected in the system, the pressure difference of the reactor needs to be added to the measured voltage value of the capacitor.

[0051] Among them, the detection system includes a reactive power compensation device and a monitoring system. The reactive power compensation device collects the working information of the capacitor through the monitoring system, calculates the on-line capacitance value of the capacitor, and then judges whether the parameter continuously exceeds the range of ±10% of the nominal rated capacitance value. If the on-line capacitance value exceeds the rated capacitance value range, the monitoring system issues a capacitor fault alarm and notifies the user through the display screen or the upper computer device.

[0052] In addition, the reactive power compensation device calculates the remaining service life of the capacitor through the monitoring system. Regardless of the performance loss of the capacitor, when the service life is nearly exhausted, the monitoring unit issues a capacitor fault alarm and a protection mechanism to permanently cut off the capacitor and notify the user through the display screen or the upper computer device.

[0053] Another aspect of the embodiment of the present invention also discloses a computer-readable storage medium. The computer-readable storage medium contains computer program instructions, and when the computer program instructions are called, they are used to execute the above-mentioned on-line capacitance value detection and life calculation method of the capacitor.

[0054] Among them, the computer-readable storage medium is a medium such as a USB flash drive, a cloud disk, or an optical disc that can store computer program instructions.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that after reading the specification of this application, they can still modify the specific implementation manners of the present invention or make equivalent replacements, but these modifications or changes do not fall within the protection scope of the pending claims of the present invention application.

Claims

1. An on-line capacitance value detection and life calculation method for a capacitor, characterized in that, The calculation method includes a capacitor fault detection process, and the capacitor fault detection process includes: S101. Sample the working information of the capacitor multiple times, and calculate the working conditions of the capacitor for n components. The working conditions of the capacitor include at least the modulus, phase, and effective value. S102. Use the maximum value of the modulus voltage of each component among the n components as the system fundamental wave, extract the corresponding current and frequency, and calculate the actual capacitance value corresponding to the capacitor. S103. Compare the capacitance value obtained in S102 with the nominal rated capacitance value of the capacitor. If it exceeds the error range, send a capacitor fault alarm. The calculation method also includes a capacitor life calculation process: S201. Collect the working voltage U, ambient temperature T, and actual working duration t of the capacitor. S202. According to the formula: , obtain the life expectancy value under specific conditions; S203. Deduct the consumed life value of the capacitor from the expected duration under the normal working conditions of the capacitor to obtain the remaining life value of the capacitor. If the remaining life is lower than the specified value of the capacitor, issue a capacitor fault alarm and protection mechanism. The specific operation of S203 is as follows: According to the formula: , the remaining life value of the capacitor is obtained, where t(T,U) is the expected life value, and the ti(T i ,U i ) is the expected life value of the capacitor obtained in S202 under the existing working voltage and ambient temperature, t 实际 is the working duration of the capacitor under the existing working voltage and ambient temperature, is the equal-loss life value under specific conditions, and i is the number of times of calculating the loss life value.

2. The online capacitance value detection and life calculation method of the capacitor according to claim 1, characterized in that The working information includes at least one of the current and voltage of the capacitor.

3. The online capacitance value detection and life calculation method of the capacitor according to claim 1, characterized in that, The capacitance value calculation formula is: 。 4. The online capacitance value detection and life calculation method of the capacitor according to claim 1, characterized in that, Specifically, S101 is to sample the working information of the capacitor multiple times, and calculate the modulus, phase, and effective value of the n components through fast Fourier transform operation.

5. The online capacitance value detection and life calculation method of the capacitor according to claim 1, characterized in that, If the number of samplings in S101 is between 50 and 150 times.

6. The on-line capacitance value detection and life calculation method of the capacitor according to claim 5, characterized in that The number of samplings is 64 times.

7. A detection system, characterized in that, The detection system applies the online capacitance value detection and life calculation method of the capacitor described in any one of claims 1-6. If there is a series reactor in the device for detecting the capacitor in the system, the voltage difference of the reactor needs to be added to the measured voltage value of the capacitor.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains computer program instructions, which are used to execute the online capacitance value detection and life calculation method of the capacitor described in any one of claims 1-6 when the computer program instructions are called.

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