Capacitor life monitoring method, system and device for reactive power compensation

Abstract

The application discloses a kind of capacitors oriented to reactive power compensation life monitoring method, system and device, it is related to capacitor test technical field;Method includes: periodically collecting original data set;Multiple frequency points are selected in power grid, obtain multiple multiple frequency points, and the complex impedance and admittance corresponding to each multiple frequency point are calculated;Based on the complex impedance corresponding to each multiple frequency point, the estimated value of equivalent series resistance, equivalent series inductance and capacitor capacity is calculated, and consistency check is carried out using admittance;Based on running time, the estimated value of equivalent series resistance, equivalent series inductance and capacitor capacity, the degradation degree of capacitor is judged;Based on original data set, the comprehensive life consumption rate is calculated;Based on the degradation degree of capacitor, the comprehensive life consumption rate is corrected, and the comprehensive life consumption rate after correction is obtained, and the capacitor health state is obtained;The application can judge capacitor degradation degree, so that life consumption rate is corrected more in line with actual aging process.

Description

Technical Field

[0001] This invention relates to the field of capacitor testing technology, and more specifically, to a method, system, and device for monitoring capacitor lifespan for reactive power compensation. Background Technology

[0002] In scenarios such as industrial power distribution systems, commercial complex power distribution substations, and new energy grid-connected equipment, the capacitors in reactive power compensation devices operate in a harmonic environment for a long time. Their capacity status, loss status, and remaining lifespan directly affect the reactive power compensation effect and power supply reliability. With the large-scale connection of nonlinear loads such as motors, frequency converters, and rectifiers, the grid voltage and current signals usually have significant higher-order harmonic components superimposed on the fundamental frequency, making the online status assessment of compensation capacitors face a more complex signal environment.

[0003] Chinese patent CN104007321B discloses an online parameter identification method for reactive power compensation capacitor banks. It extracts the fundamental phasor and harmonic phasors by measuring the three-phase voltage and three-phase current of the capacitor bank, and calculates the equivalent resistance, capacitance, and inductance of the reactor using the selected data. This method recognizes that online parameter identification can be performed in reactive power compensation capacitor banks using harmonic information, which is a further improvement over the detection method based solely on a single power frequency quantity.

[0004] However, the focus of this method is still on the online identification of parameters itself. Its purpose is to obtain the equivalent resistance, capacitance and inductance values ​​of the capacitor bank under non-stop operation conditions. It does not form a complete evaluation link around the health status and remaining life of the capacitor. In particular, although the technical solution obtains equivalent parameters, it does not further establish a hierarchical correction mechanism for the rate of life consumption. Therefore, it is difficult to solve the problem of the transmission from capacity estimation deviation to health status misjudgment and life assessment deviation.

[0005] Chinese patent CN102830310B discloses a method for evaluating the remaining life of a power capacitor based on operational data. It considers factors such as dielectric temperature, supply voltage, system background harmonics, operational defects, and years of operation to correct the life index of the power capacitor and thereby estimate the remaining operating life. This solution demonstrates that existing technology can already dynamically evaluate the life of a capacitor to a certain extent based on external operational data.

[0006] However, this method focuses on correcting the life index based on external stress and operating conditions, and does not solve the problem of insufficient accuracy in online estimation of capacitor capacity in reactive power compensation scenarios. Especially in complex power grid environments containing significant high-order harmonics, if the actual capacity, equivalent series resistance, and equivalent series inductance of the front-end capacitor cannot be accurately identified, the basic data for subsequent life assessment may be distorted, thus making it difficult to accurately reflect the true aging state of the capacitor.

[0007] Therefore, although existing technologies have disclosed technical solutions such as online identification of reactive power compensation capacitor bank parameters and life assessment based on operating data, they still have not solved the following technical problem: In reactive power compensation scenarios, facing complex power grid environments containing high-order harmonics, how to accurately obtain the true parameters and degradation degree of capacitors while considering the influence of equivalent series resistance and equivalent series inductance, and on this basis, make corrections to the life consumption rate that are more in line with the actual aging state, so as to more accurately determine the health status and remaining life of capacitors.

[0008] In view of this, the present invention proposes a capacitor life monitoring method, system and device for reactive power compensation to solve the above problems. Summary of the Invention

[0009] To overcome the aforementioned deficiencies of the prior art and achieve the above objectives, the present invention provides the following technical solution: a capacitor lifetime monitoring method for reactive power compensation, comprising:

[0010] The raw dataset is collected periodically; the raw dataset includes the time-domain signal of the grid voltage, the time-domain signal of the compensation branch current, the ambient temperature, the rated capacity of the capacitor, the rated life of the capacitor, and the operating time.

[0011] Multiple frequency points are selected in the power grid to obtain multiple frequency points, and the complex impedance and admittance corresponding to each frequency point are calculated.

[0012] Based on the complex impedance corresponding to each multi-frequency point, the estimated values ​​of equivalent series resistance, equivalent series inductance and capacitance are calculated, and the admittance is used for consistency verification.

[0013] Based on the estimated values ​​of running time, equivalent series resistance, equivalent series inductance, and capacitance, the degree of capacitor degradation is determined; based on the original dataset, the overall lifetime attrition rate is calculated; based on the degree of capacitor degradation, the overall lifetime attrition rate is corrected to obtain the corrected overall lifetime attrition rate.

[0014] The health status of the capacitor is determined based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the benchmark, the equivalent series resistance in the benchmark, the operating time, the corrected overall lifetime consumption rate, and the rated lifetime of the capacitor.

[0015] Furthermore, the selection of multiple frequency points in the power grid includes: determining the fundamental frequency of the power grid; selecting naturally occurring harmonic frequencies in the power grid as the multiple frequency points; and when the natural harmonic frequencies are insufficient to construct an overdetermined set of equations concerning the equivalent series resistance, the equivalent series inductance, and the capacitance, supplementing the selection with a signal frequency as the multiple frequency points.

[0016] Furthermore, before calculating the complex impedance and admittance corresponding to each multi-frequency point, the method includes: extracting the complex voltage component and complex current component at the corresponding frequency for each multi-frequency point, and adapting the window function to the time-domain signal of the grid voltage and the time-domain signal of the compensation branch current according to the type of the multi-frequency point.

[0017] Further, the extraction of complex voltage components and complex current components at the corresponding frequencies includes: constructing a signal-to-noise ratio based on the complex voltage components and the complex current components within a preset calculation period; retaining the spectrum data corresponding to the current multi-frequency point when the signal-to-noise ratio meets the requirements; and dividing the grid voltage time-domain signal and the compensation branch current time-domain signal into multiple data segments when the signal-to-noise ratio does not meet the requirements, and averaging the spectrum results of the effective data segments to obtain the spectrum data corresponding to the current multi-frequency point.

[0018] Furthermore, the calculation of the complex impedance and admittance corresponding to each multi-frequency point includes: decomposing the complex voltage component and complex current component corresponding to each multi-frequency point into real and imaginary parts respectively, obtaining the complex impedance corresponding to each multi-frequency point through complex division, and determining the reciprocal of the complex impedance as the corresponding admittance.

[0019] Furthermore, the step of calculating the estimated values ​​of the equivalent series resistance, equivalent series inductance, and capacitance based on the complex impedance corresponding to each multi-frequency point includes: decomposing the complex impedance corresponding to each multi-frequency point into the real part and the imaginary part of the complex impedance; performing least-squares fitting on the real part of the complex impedance to obtain the estimated value of the equivalent series resistance; substituting the imaginary part of the complex impedance and the angular frequency of the frequency corresponding to the multi-frequency point into the equivalent circuit model of the capacitor, constructing a system of linear equations, and solving them to obtain the estimated values ​​of the equivalent series inductance and capacitance.

[0020] Furthermore, the consistency verification using admittance includes: applying physical constraints to the estimated values ​​of the equivalent series resistance, the equivalent series inductance, and the capacitance; and when the reciprocal correspondence between the admittance and the complex impedance does not meet the preset consistency conditions, the current calculation result is discarded, recalculated, or marked.

[0021] Furthermore, the determination of the degree of degradation of the capacitor includes: obtaining the initial baseline parameters at the standard ambient temperature, or establishing a correspondence model between ambient temperature and baseline parameters based on the baseline parameters at different ambient temperatures; and determining the baseline parameters at the current ambient temperature in combination with the current ambient temperature, and using the baseline parameters at the current ambient temperature or the rated capacitance and rated equivalent series resistance of the capacitor to form the comparison benchmark.

[0022] The capacitance decay ratio is determined based on the capacitance value in the comparison benchmark and the estimated value of the capacitance value. The equivalent series resistance growth ratio is determined based on the equivalent series resistance in the comparison benchmark and the estimated value of the equivalent series resistance. The capacitor is then classified into a mildly degraded state, a moderately degraded state, or a severely degraded state according to the capacitance decay ratio and the equivalent series resistance growth ratio.

[0023] Furthermore, the step of calculating the overall lifetime consumption rate based on the original dataset includes: extracting the fundamental current component from the time-domain signal of the compensation branch current, and subtracting the fundamental current component from the time-domain signal of the compensation branch current to obtain the ripple current;

[0024] The baseline lifetime consumption rate is corrected based on ambient temperature, grid voltage, ripple current, and operating time to obtain the comprehensive lifetime consumption rate corresponding to the current calculation period. The lifetime consumption increment is determined based on the comprehensive lifetime consumption rate and the operating time corresponding to the current calculation period, and then accumulated in chronological order to obtain the cumulative lifetime consumption.

[0025] Furthermore, the correction of the overall lifetime consumption rate based on the degree of capacitor degradation includes: establishing a correspondence between the degree of capacitor degradation and the lifetime consumption rate correction coefficient; determining a first lifetime consumption rate correction coefficient based on the capacitance decay ratio; determining a second lifetime consumption rate correction coefficient based on the equivalent series resistance growth ratio; and selecting the larger of the first lifetime consumption rate correction coefficient and the second lifetime consumption rate correction coefficient to correct the overall lifetime consumption rate.

[0026] Furthermore, the determination of the capacitor's health status based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the benchmark, the equivalent series resistance in the benchmark, the operating time, the corrected overall lifetime consumption rate, and the rated lifetime of the capacitor includes: accumulating the cumulative lifetime consumption based on the corrected overall lifetime consumption rate and operating time corresponding to each calculation period, and converting it into the remaining lifetime by combining it with the current corrected overall lifetime consumption rate; and determining the health index based on the estimated capacitance and the estimated equivalent series resistance.

[0027] Furthermore, the determination of the health status of the capacitor includes: determining the health status of the capacitor based on the threshold ranges corresponding to the health index and the remaining lifespan; reviewing and adjusting the threshold ranges according to the aging observation sequence formed by multiple consecutive preset calculation cycles; and triggering an emergency review when the change in the health index or the remaining lifespan exceeds the corresponding threshold within the preset monitoring period.

[0028] A capacitor life monitoring system for reactive power compensation includes:

[0029] The data acquisition module is used to periodically acquire raw datasets; the raw datasets include the time-domain signal of the grid voltage, the time-domain signal of the compensation branch current, the ambient temperature, the rated capacity of the capacitor, the rated life of the capacitor, and the operating time.

[0030] The multi-frequency point selection module is used to select multiple frequency points in the power grid, obtain multiple frequency points, and calculate the complex impedance and admittance corresponding to each frequency point.

[0031] The estimation calculation module calculates the estimated values ​​of equivalent series resistance, equivalent series inductance and capacitance based on the complex impedance corresponding to each multi-frequency point, and uses admittance for consistency verification.

[0032] The lifetime calculation module determines the degree of capacitor degradation based on the estimated values ​​of running time, equivalent series resistance, equivalent series inductance, and capacitance; it calculates the overall lifetime consumption rate based on the original dataset; and it corrects the overall lifetime consumption rate based on the degree of capacitor degradation to obtain the corrected overall lifetime consumption rate.

[0033] The health assessment module determines the health status of the capacitor based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the comparison benchmark, the equivalent series resistance in the comparison benchmark, the running time, the corrected overall lifespan consumption rate, and the rated lifespan of the capacitor.

[0034] A capacitor life monitoring device for reactive power compensation includes a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements the capacitor life monitoring method for reactive power compensation.

[0035] Compared with existing technologies, this application does not only perform single capacitance value detection on reactive power compensation capacitors or estimate lifespan solely based on external operating stress. Instead, it addresses the problems of difficulty in accurately obtaining the true parameters of capacitors in complex power grid environments with high-order harmonics, difficulty in effectively incorporating degradation levels into lifespan assessments, and the tendency for discrepancies between health status and remaining lifespan determinations. It constructs a closed-loop processing chain consisting of raw data acquisition, multi-frequency parameter identification, degradation level judgment, lifespan consumption rate correction, and health status determination. This allows the parameter results obtained in the preceding steps to be continuously transmitted as inputs for subsequent lifespan assessments and status determinations, thereby improving the accuracy, consistency, and reliability of capacitor status monitoring results in reactive power compensation scenarios.

[0036] First, this application selects multiple frequency points in the power grid and calculates the estimated values ​​of equivalent series resistance, equivalent series inductance, and capacitance based on the complex impedance corresponding to each frequency point. This changes the existing technology's approach of mainly relying on a single frequency point for capacitance conversion. As a result, it can simultaneously consider the coupling effects between equivalent series resistance, equivalent series inductance, and capacitance in a harmonic operating environment. This makes capacitance parameter estimation no longer limited to a single capacitive reactance relationship, thereby reducing the impact of parameter distortion under complex operating conditions on subsequent life assessment and improving the accuracy of the capacitance's true state characterization.

[0037] Secondly, this application does not directly output state conclusions after obtaining parameter estimates. Instead, it judges the degree of capacitor degradation based on estimated values ​​of operating time, equivalent series resistance, equivalent series inductance, and capacitance, and calculates the overall lifespan consumption rate based on the original data. This combines the degradation information of the capacitor's internal parameters with the external operating stress information, so that the lifespan assessment no longer depends solely on external factors such as ambient temperature, grid voltage, and ripple current. Instead, it can further reflect the impact of the capacitor's current aging state on the lifespan consumption process, thereby making the lifespan assessment results more consistent with the actual aging process.

[0038] Furthermore, this application corrects the overall lifespan consumption rate based on the degree of capacitor degradation, and then combines the estimated value of capacitor capacity, the estimated value of equivalent series resistance, the comparison benchmark, the operating time, and the rated lifespan of the capacitor to determine the health status of the capacitor. In this way, the parameter identification results, degradation judgment results, and lifespan calculation results can be organized into a continuously transferable state assessment chain, avoiding the problem of the separation between online parameter identification, lifespan calculation, and health determination in the prior art. This results in better overall consistency of the final health status and remaining lifespan determination results, which is more conducive to online monitoring, operation and maintenance decision-making, and fault early warning of reactive power compensation equipment.

[0039] Therefore, this application not only improves the local defects of the prior art in obtaining inaccurate capacitor parameters and the distortion of the basis of lifetime assessment under complex harmonic environments, but also makes the determination of capacitor health status more suitable for stable generation and continuous use in reactive power compensation application scenarios by organizing parameter identification, degradation assessment, lifetime correction and health determination into a closed process. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a capacitor life monitoring system for reactive power compensation according to an embodiment of the present invention;

[0041] Figure 2 This is a flowchart of a capacitor lifetime monitoring method for reactive power compensation according to an embodiment of the present invention.

[0042] Figure 3 This is a flowchart of a method for determining the degree of degradation of a capacitor according to an embodiment of the present invention;

[0043] Figure 4 This is a flowchart of a method for determining the health status of a capacitor according to an embodiment of the present invention. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be described in detail, clearly and completely below with reference to the accompanying drawings. It should be noted that the specific embodiments described below are only used to better illustrate and explain the technical solutions of the present invention, and are intended to enable those skilled in the art to better understand and implement the present invention, and should not be construed as limiting the scope of protection of the present invention. Without departing from the spirit and substance of the present invention, those skilled in the art can modify, adjust or make equivalent substitutions based on the content disclosed in the present invention, and these should all be considered as within the scope of protection of the present invention.

[0045] Example 1:

[0046] Please see Figure 1 As shown in the figure, this embodiment discloses a capacitor life monitoring system for reactive power compensation, including a data acquisition module, a multi-frequency point selection module, an estimation calculation module, a life calculation module, and a health judgment module. Each module is connected by wired or wireless means to realize data transmission.

[0047] The data acquisition module is used to periodically acquire raw datasets, which include the time-domain signal of the grid voltage, the time-domain signal of the compensation branch current, the ambient temperature, the rated capacity of the capacitor, the rated life of the capacitor, and the operating time.

[0048] The grid voltage time-domain signal is the voltage waveform sampled by an on-site AC voltage sensor or power monitoring unit, used to calculate frequency domain harmonic components; the compensation branch current time-domain signal is the AC current of the capacitor branch measured using an existing current transformer or energy meter, used to calculate capacitor admittance; the ambient temperature is the temperature sampled in real time by a temperature sensor placed near the capacitor, used for thermal modeling and life assessment; the rated capacitance is the nominal capacitance obtained from the component specification manual, used as an initial reference value; the rated lifespan is the rated lifespan obtained from the component specification manual, used as a reference value; the operating time is the cumulative operating time or usage time of the corresponding capacitor, recorded by the controller or clock, used for lifespan consumption calculation.

[0049] Initiate periodic data acquisition, acquire the grid voltage time-domain signal from the grid side, acquire the compensation branch current time-domain signal from the compensation branch, and record the ambient temperature; read the rated capacitance and rated life of the capacitor from the hardware manual or database; read the running time from the system controller; perform basic filtering and noise reduction on the acquired data, such as low-pass filtering to remove measurement noise, to obtain the original dataset.

[0050] The multi-frequency point selection module is used to select multiple frequency points in the power grid, obtain multiple frequency points, and calculate the complex impedance and admittance corresponding to each frequency point.

[0051] The fundamental frequency of the power grid is determined using a synchronous rotating coordinate system phase-locked loop (PLL) technique, for example, a fundamental frequency of 50Hz or 60Hz. Subsequently, multiple frequency points are selected, which are specific frequency points used for capacitor equivalent parameter identification. By extracting the grid voltage and compensation branch current signals at these multiple specific frequency points and constructing parameter-solving equations based on the signals, the accuracy and robustness of capacitor equivalent parameter calculation can be effectively improved. Capacitor equivalent parameters include equivalent series resistance, equivalent series inductance, and capacitance. Priority is given to selecting high-order harmonic frequencies that naturally exist in the power grid and whose amplitude is not lower than a preset amplitude ratio of the signal corresponding to the fundamental frequency. The amplitude ratio is preset according to the nonlinear load characteristics of the power grid, and it must be ensured that the signal corresponding to the selected high-order harmonic frequency can be stably extracted. At least three frequency points are used to construct an overdetermined equation system to improve the robustness of parameter identification. For ease of description in this embodiment, only three frequency points are selected, including the fundamental frequency, the 3rd harmonic frequency, and the 5th harmonic frequency.

[0052] If the amplitude of natural high-order harmonic frequencies in the power grid is lower than a preset amplitude ratio corresponding to the fundamental frequency signal amplitude, a small-signal frequency is injected as a supplement. For example, the frequency range of the injected small-signal frequency is limited to 45Hz-47Hz or 53Hz-55Hz. The signal amplitude corresponding to the injected small-signal frequency does not exceed a preset injection amplitude of the grid's rated voltage. This preset injection amplitude does not exceed a safety threshold of the grid's rated voltage, which is preset according to the operating parameters of the power grid protection device. The duration of the injected small-signal frequency does not exceed a preset injection duration, which is preset according to the response time of the power grid protection device. The purpose of injecting small signal frequencies is to avoid triggering the power grid protection device. The purpose of injecting small signal frequencies is to supplement the acquisition of a sufficient number of effective frequency points. Since the identification of equivalent capacitor parameters requires at least three frequency points to construct an overdetermined equation system, the interference of a single frequency point signal can be eliminated through the equation solution, and the robustness of the parameter calculation results can be ensured. When the amplitude of the natural high-order harmonic frequencies in the power grid is insufficient, resulting in the number of effective frequency points not meeting the requirements for constructing the equation system, the injection of small signal frequencies can supplement the required effective frequency points, ensuring that the equation system for solving the equivalent series resistance, equivalent series inductance, and capacitance can be established normally and reliable results can be obtained.

[0053] For each selected multi-frequency point, the complex voltage component and complex current component at the corresponding frequency are extracted using Fast Fourier Transform or Digital Bandpass Filter. To improve the accuracy of signal extraction, window functions are adapted for the grid voltage time-domain signal and the compensation branch current time-domain signal according to the selected multi-frequency point type. Hanning window is used for the time-domain signal corresponding to the fundamental frequency, and Blackman window is used for the time-domain signals corresponding to the 3rd and 5th harmonic frequencies. The spectral leakage phenomenon is suppressed by the window function.

[0054] An adaptive noise suppression strategy is designed to filter random noise, impulse interference, and voltage sag interference signals in the power grid, ensuring the usability of the extracted spectrum data corresponding to multiple frequency points. Specifically, within each preset calculation cycle, the corresponding complex voltage and complex current components are calculated for each selected multiple frequency point, and the signal-to-noise ratio (SNR) is constructed based on these components. The SNR calculation method uses the target frequency component represented by the complex voltage and complex current components at the current multiple frequency point as the effective signal amplitude, and the remaining spectral fluctuation after deducting the target frequency component in the adjacent frequency band of the current multiple frequency point as the noise amplitude. The SNR is obtained from the correspondence between the effective signal amplitude and the noise amplitude. To ensure consistency in the judgment criteria across different preset calculation cycles, the adjacent frequency band range, the statistical method for the remaining spectral fluctuation, and the SNR threshold are all preset and maintained consistently within the same evaluation process.

[0055] When the calculated signal-to-noise ratio (SNR) is greater than or equal to the SNR threshold, the signal quality corresponding to the current multi-frequency point is deemed to meet the requirements, and the spectral data corresponding to the current multi-frequency point is retained. When the calculated SNR is lower than the SNR threshold, the signal quality corresponding to the current multi-frequency point is deemed not to meet the requirements, and segmented averaging filtering is initiated. During segmented averaging filtering, the grid voltage time-domain signal and the compensation branch current time-domain signal are divided into a data segment according to a preset number of grid cycles. A preset number of data segments are continuously collected, and the spectrum of each data segment is extracted separately. Then, the consistency of the spectral results of the same multi-frequency point corresponding to each data segment is compared, and the data segments identified as abnormal data segments are removed. The spectral results of the remaining valid data segments are arithmetically averaged to obtain the spectral data corresponding to the current multi-frequency point. The preset number of cycles is used to limit the time length of a single data segment; the preset number of collection segments is used to limit the number of data segments participating in the averaging process. Both are preset according to the grid operating conditions.

[0056] In the process of identifying data segments containing pulse interference, the amplitude change sequences of the grid voltage time-domain signal and the compensation branch current time-domain signal, as well as the change sequences of adjacent sampling points, are first extracted within each data segment. Then, pulse interference markers are determined based on the local baseline. If an abnormal waveform segment exists within a data segment with a duration not exceeding the preset pulse duration and an amplitude deviation exceeding the preset pulse amplitude threshold, then the data segment is identified as containing pulse interference. The preset pulse duration is in milliseconds or grid cycles, and the preset pulse amplitude threshold is in volts or amperes. Data segments identified as containing pulse interference are not included in the arithmetic average process. Data segments not identified as containing pulse interference are included as valid data segments in the subsequent spectral result averaging. Through this processing method, the data segment identification criteria for pulse interference can directly correspond to the duration and amplitude deviation of the time-domain waveform.

[0057] During the handling of voltage sags and short-term current anomalies, the instantaneous change amplitude of the current in the time-domain signal of the compensation branch and the voltage sag amplitude of the grid voltage in the time-domain signal are monitored in real time. If the instantaneous change amplitude of the current exceeds a preset current change ratio, or the voltage sag amplitude exceeds a preset voltage sag ratio, it is determined that the current single grid cycle is subject to instantaneous interference. For a single grid cycle subject to instantaneous interference, the spectrum data extracted from that single grid cycle is not directly used. Instead, it is first determined whether the spectrum data corresponding to the two adjacent grid cycles before and after the instantaneous interference meet the interpolation compensation conditions. The interpolation compensation conditions include that neither the previous grid cycle nor the next grid cycle is determined to be an instantaneous interference cycle, and the previous grid cycle and the next grid cycle are not determined to be instantaneous interference cycles. The spectral amplitude variation at the same multi-frequency point in the grid cycle is within a preset continuous variation range. When the interpolation compensation condition is met, linear interpolation is performed using the spectral data corresponding to the previous grid cycle and the next grid cycle to supplement the spectral data of the current single grid cycle. When the interpolation compensation condition is not met, interpolation compensation for the current single grid cycle is abandoned, and the current single grid cycle is marked as an invalid cycle, waiting for subsequent preset calculation cycles to be re-acquired. The preset current variation ratio is preset according to the load characteristics of the compensation branch, the preset voltage sag ratio is preset according to the grid voltage operating conditions, and the preset continuous variation range is used to limit the allowable spectral variation between adjacent effective cycles. The unit can be volt, ampere, or the corresponding spectral amplitude unit.

[0058] By clarifying the calculation criteria for signal-to-noise ratio, the rules for identifying data segments of impulse interference, and the interpolation compensation conditions, the adaptive noise suppression strategy can select the retention, averaging, elimination, or compensation processing path under different interference types, so that the spectrum data generation process corresponding to multiple frequency points has a consistent data judgment basis.

[0059] The complex impedance and admittance of each selected multi-frequency point are calculated based on the complex voltage and current components corresponding to those points. The complex impedance is calculated by decomposing the complex voltage component at each multi-frequency point into its real and imaginary parts, and the complex current component at each point into its real and imaginary parts. The complex impedance is then calculated using a complex division formula: Complex impedance = (real voltage + j × imaginary voltage) / (real current + j × imaginary current) = ((real voltage × real current + imaginary voltage × imaginary current) + j × (imaginary voltage × real current - real voltage × imaginary current)) / (square of real current + square of imaginary current), where j is the imaginary unit; admittance is the reciprocal of the complex impedance. Finally, the complex voltage component, complex current component, complex impedance, and admittance for each selected multi-frequency point are obtained.

[0060] The estimation calculation module calculates the estimated values ​​of equivalent series resistance, equivalent series inductance and capacitance based on the complex impedance corresponding to each multi-frequency point, and uses admittance for consistency verification.

[0061] Based on the capacitor equivalent circuit model Perform parameter solving, among which For equivalent series resistance, For equivalent series inductance, For capacitance, The angular frequency corresponding to the multiple frequency points, i.e. , For multiple frequency points, the corresponding frequencies are determined; methods for parameter solving include:

[0062] The complex impedance corresponding to each multi-frequency point is decomposed to obtain the real part and the imaginary part of the complex impedance. The real part of the complex impedance corresponds to the equivalent series resistance component in the capacitor equivalent circuit model, and the imaginary part corresponds to the component in the capacitor equivalent circuit model. Relevant components.

[0063] Since the value of R is relatively stable at different frequencies in the capacitor equivalent circuit model, the real part of the complex impedance corresponding to all multi-frequency points is fitted using the least squares method. The mean of the fitted real part is the estimated value of the equivalent series resistance. If the number of multi-frequency points is small, the arithmetic mean of the real part of the complex impedance can also be taken as the average. .

[0064] Will Substituting into the equivalent circuit model of the capacitor, the equation for the imaginary part of the complex impedance is now: For each multi-frequency point, determine the angular frequency of the corresponding frequency. Substituting the imaginary part of the complex impedance into the equation for the imaginary part of the complex impedance, a system of linear equations concerning the equivalent series inductance and capacitance C is constructed. Since there are at least three frequency points, the constructed system of linear equations is an overdetermined system. The least squares method is used to solve the overdetermined system to obtain an estimate of the equivalent series inductance. Estimated value of capacitance .

[0065] The solution obtained , and Apply physical constraints to ensure , Capacitance If there are parameters whose estimated values ​​do not meet the above physical constraints, the solution result is determined to be invalid, and the parameter solution steps are repeated until all parameter estimates meet the physical constraints.

[0066] Complex voltage and complex current components are the fundamental data for calculating complex impedance. Complex impedance is obtained by performing calculations on complex voltage and complex current components, and the data source of complex impedance can be mapped to the original sampled data and the calculation results of complex components. Based on this processing path, the generation process of complex impedance has a clear data transmission relationship, which facilitates the tracking and verification of the calculation process of complex impedance.

[0067] Since both admittance and complex impedance originate from the same set of complex voltage and current components, admittance is not used as an independent measurement to prove the correctness of complex impedance. Instead, it is used to check the consistency of the complex number calculation process. When abnormal fluctuations occur in the complex impedance calculation result, admittance is calculated simultaneously, and a consistency check is performed based on the reciprocal correspondence between admittance and complex impedance. The preset consistency conditions include amplitude consistency conditions and phase consistency conditions. The amplitude consistency condition is used to determine whether the deviation between the current admittance amplitude and the current complex impedance amplitude under the corresponding reciprocal correspondence is within the preset amplitude error range, which is expressed as a percentage. The phase consistency condition is used to determine whether the phase difference between the current admittance phase and the current complex impedance phase under the reciprocal correspondence is within the preset phase error range, which is expressed in degrees. The preset amplitude error range and preset phase error range are preset according to the accuracy requirements of complex number operations, sampling resolution, and signal quality requirements, and remain unchanged during the same evaluation process.

[0068] During the specific verification, the corresponding admittance reference value is first calculated based on the current complex impedance. Then, the admittance reference value is compared with the current admittance to obtain the amplitude deviation result and the phase deviation result. When the amplitude deviation result is within the preset amplitude error range and the phase deviation result is within the preset phase error range, it is determined that the reciprocal correspondence between admittance and complex impedance meets the preset consistency condition, indicating that the current complex number operation link is consistent. When the amplitude deviation result exceeds the preset amplitude error range or the phase deviation result exceeds the preset phase error range, it is determined that the reciprocal correspondence between admittance and complex impedance does not meet the preset consistency condition, indicating that there is an anomaly in the current complex number operation process, and the current calculation result is removed, recalculated, or marked.

[0069] After the reciprocal correspondence between admittance and complex impedance meets the preset consistency condition, the quality of the original sampled data is used to determine whether the current complex impedance should be included in the subsequent analysis process. The judgment of the quality of the original sampled data includes at least the judgment of the integrity of the sampling points, the judgment of the signal-to-noise ratio, and the judgment of abnormal interference. Only when the reciprocal correspondence between admittance and complex impedance meets the preset consistency condition and the quality of the original sampled data meets the preset data quality requirements will the current complex impedance be used for subsequent lifetime assessment.

[0070] The lifetime calculation module determines the degree of capacitor degradation based on estimated values ​​of running time, equivalent series resistance, equivalent series inductance, and capacitance. Based on the original dataset, it calculates the overall lifetime consumption rate. Based on the degree of capacitor degradation, it corrects the overall lifetime consumption rate to obtain the corrected overall lifetime consumption rate.

[0071] Determining the baseline parameters of a capacitor at the current ambient temperature involves several methods. These include: obtaining the initial baseline parameters of the capacitor at standard ambient temperatures from the capacitor manufacturer's specifications or technical documents. These initial baseline parameters include the initial capacitance, initial equivalent series resistance, and initial equivalent series inductance. If baseline parameters at non-standard ambient temperatures are required, offline calibration experiments can be performed. Specifically, this involves: simulating different ambient temperature conditions in a laboratory environment; performing multi-frequency parameter identification on capacitors of the same model; calculating the capacitance, equivalent series resistance, and equivalent series inductance at different ambient temperatures using estimated values ​​of equivalent series resistance, equivalent series inductance, and capacitance; and establishing a model relating ambient temperature to baseline parameters. Finally, using the current ambient temperature and the model relating ambient temperature to baseline parameters, interpolation is performed to obtain the baseline parameters of the capacitor at the current ambient temperature. These baseline parameters include the current baseline capacitance, current baseline equivalent series resistance, and current baseline equivalent series inductance.

[0072] Please see Figure 3 As shown, the degradation degree of the capacitor is determined by comparing real-time parameters with rated or initial values. The method includes: if the capacitor's operating time does not exceed a preset operating time threshold, the rated capacitance and rated equivalent series resistance are used as comparison benchmarks; the rated equivalent series resistance is obtained from the rated parameters; the rated parameters are preferably derived from the product parameter file, factory inspection report, or nameplate information provided by the capacitor manufacturer; when the rated equivalent series resistance is specified in the product parameter file, factory inspection report, or nameplate information, the corresponding value is directly used as the rated equivalent series resistance; if the capacitor's operating time exceeds the preset operating time threshold, the baseline parameters at the current ambient temperature are used as the comparison benchmark; the preset operating time threshold is set based on the capacitor manufacturer's recommendations or engineering experience; degradation assessment indicators include the capacitance decay ratio and the equivalent series resistance growth ratio, where the capacitance decay ratio = (capacitor capacitance in the comparison benchmark - ... ) ÷ the capacitance in the comparison benchmark, the equivalent series resistance growth ratio = ( - Equivalent series resistance in the comparison benchmark) ÷ Equivalent series resistance in the comparison benchmark; Set a threshold for capacitance decay ratio and a threshold for equivalent series resistance growth ratio. If the capacitance decay ratio is less than the threshold for capacitance decay ratio and the equivalent series resistance growth ratio is less than the threshold for equivalent series resistance growth ratio, the capacitor is determined to be in a slightly degraded state. If the capacitance decay ratio is greater than or equal to the threshold for capacitance decay ratio and less than the upper limit threshold for capacitance decay ratio, or the equivalent series resistance growth ratio is greater than or equal to the threshold for equivalent series resistance growth ratio and less than the upper limit threshold for equivalent series resistance growth ratio, the capacitor is determined to be in a moderately degraded state. If the capacitance decay ratio is greater than or equal to the upper limit threshold for capacitance decay ratio or the equivalent series resistance growth ratio is greater than or equal to the upper limit threshold for equivalent series resistance growth ratio, the capacitor is determined to be in a severely degraded state. The threshold for capacitance decay ratio, the upper limit threshold for capacitance decay ratio, the threshold for equivalent series resistance growth ratio, and the upper limit threshold for equivalent series resistance growth ratio are all set according to the capacitor reliability requirements and the manufacturer's recommendations.

[0073] The health index H is defined as follows: H = a × (estimated capacitance ÷ capacitance in the benchmark) + b × (equivalent series resistance in the benchmark ÷ ... ), where a is the capacitance weighting coefficient and b is the equivalent series resistance weighting coefficient. The values ​​of a and b are both in the range of 0 to 1, and a + b = 1. The capacitance weighting coefficient a and the equivalent series resistance weighting coefficient b are set according to the reliability requirements of the capacitor application scenario. If the scenario has higher requirements for capacitance stability, the value of a is increased; if the scenario has higher requirements for equivalent series resistance stability, the value of b is increased.

[0074] By incorporating factors such as ambient temperature, grid voltage, and ripple current into a pre-built empirical lifetime model, the cumulative lifetime consumption of capacitors is assessed. The impact of stress factors such as ambient temperature, grid voltage, and ripple current on the capacitor's lifetime consumption rate is quantified, correcting the bias in lifetime consumption calculations based solely on rated operating conditions. This provides a basis for accurate calculation of remaining lifetime. Specific assessment methods include:

[0075] The ripple current is extracted from the time-domain signal of the compensation branch current. Within each preset calculation cycle, the time-domain signal of the compensation branch current corresponding to the current preset calculation cycle is first extracted as a current analysis segment. The duration of the current analysis segment is consistent with the preset calculation cycle, and the time unit can be seconds, minutes, or hours. To ensure that the ripple current extraction result corresponds to the current operating condition, the grid voltage time-domain signal is acquired synchronously within the current analysis segment. Based on the grid voltage time-domain signal, the current grid fundamental frequency and fundamental phase are determined. Then, the fundamental current component corresponding to the current grid fundamental frequency is extracted from the compensation branch current time-domain signal. After subtracting the fundamental current component from the compensation branch current time-domain signal, the ripple current is obtained.

[0076] The empirical lifetime model adopts a multi-stress accelerated lifetime model. The input parameters include ambient temperature, grid voltage, ripple current, and operating time. The output parameter is the cumulative lifetime consumption of the capacitor. The empirical lifetime model uses the lifetime consumption rate corresponding to the standard ambient temperature as the baseline lifetime consumption rate. In each calculation period, the ambient temperature, grid voltage, and ripple current are corrected respectively. The corrected lifetime consumption rate is combined with the operating time of the corresponding calculation period to obtain the lifetime consumption increment of the current calculation period. Then, the lifetime consumption increments are accumulated in chronological order to obtain the cumulative lifetime consumption of the capacitor.

[0077] Regarding the influence of ambient temperature, the empirical lifespan model uses the Arrhenius relation to establish the correspondence between ambient temperature and lifespan attrition rate. In processing, the ambient temperature and standard ambient temperature are first converted to thermodynamic temperatures, with Kelvin as the unit. Then, combined with the capacitor dielectric activation energy and ideal gas constant provided by the manufacturer, a temperature correction coefficient for the lifespan attrition rate corresponding to the ambient temperature is constructed. The standard ambient temperature is taken as the capacitor's rated operating ambient temperature, in degrees Celsius. The lifespan attrition rate temperature correction coefficient is calculated with reference to the lifespan attrition rate under the standard ambient temperature. When the ambient temperature is higher than the standard ambient temperature, the lifespan attrition rate temperature correction coefficient increases accordingly, causing the lifespan attrition rate to rise; when the ambient temperature is lower than the standard ambient temperature, the lifespan attrition rate temperature correction coefficient decreases accordingly, causing the lifespan attrition rate to fall. Therefore, the accelerating or decelerating effect of ambient temperature on the capacitor aging process can be uniformly mapped to the lifespan attrition rate.

[0078] During the ambient temperature correction process, the ideal gas constant uses the same notation and the same numerical source, and the capacitor dielectric activation energy uses the same manufacturer's data source. Ambient temperature, standard ambient temperature, capacitor dielectric activation energy, and ideal gas constant are used together to generate the lifetime consumption rate temperature correction coefficient. After the lifetime consumption rate temperature correction coefficient is output, the lifetime consumption rate voltage correction coefficient corresponding to the grid voltage, the lifetime consumption rate ripple current correction coefficient corresponding to the ripple current, and the running time are input into the lifetime consumption calculation process to obtain the lifetime consumption increment for the current period, and further update the cumulative lifetime consumption of the capacitor.

[0079] To address the ripple current factor, a ripple current loss model is used to establish the relationship between ripple current and lifespan decay rate. The expression for the ripple current loss model is: Lifespan decay rate ripple current correction coefficient = exp(k × (ripple current - rated ripple current)), where exp(·) is an exponential function with the natural constant as the base, k is the ripple current influence coefficient, obtained from manufacturer data or fitted through offline experiments, and the rated ripple current is taken from the capacitor's rated parameters. To address the grid voltage factor, a voltage stress model is used to establish the relationship between grid voltage and lifespan decay rate. The lifespan decay rate voltage correction coefficient is obtained in two ways: first, it is extracted from the voltage-lifespan curve provided by the capacitor manufacturer. Manufacturers usually provide the lifespan change ratio corresponding to different grid voltages based on experimental data, and the lifespan decay rate voltage correction coefficient is calculated accordingly; second, it is obtained through offline experimental fitting. In the offline experiment, a capacitor sample of the same model as the capacitor to be evaluated is selected, and different grid voltage conditions are set in the laboratory environment to cover the voltage range that may occur in actual applications. Accelerated aging experiments are conducted on the capacitor samples under each condition, and the running time of the capacitor sample from the start of operation to reaching the end-of-life criterion is recorded for each grid voltage condition, such as when the capacity decays to... The capacitor lifetime corresponding to different grid voltages is obtained by increasing the initial value to 80% or the equivalent series resistance to twice the initial value. Based on the recorded grid voltage data and the corresponding lifetime data, a nonlinear fitting algorithm such as exponential fitting is used to establish the correspondence between grid voltage and lifetime consumption rate voltage correction coefficient. The expression is: lifetime consumption rate voltage correction coefficient = exp(m × (grid voltage - rated grid voltage)), where m is the voltage influence coefficient, taken from the manufacturer's data or the above offline experimental fitting results, and the rated grid voltage is taken from the rated parameters of the capacitor. The comprehensive lifetime consumption rate is obtained by combining the rated lifetime consumption rate, the lifetime consumption rate temperature correction coefficient, the lifetime consumption rate voltage correction coefficient, and the lifetime consumption rate ripple current correction coefficient. The calculation method is the product of the rated lifetime consumption rate and the lifetime consumption rate temperature correction coefficient, the lifetime consumption rate voltage correction coefficient, and the lifetime consumption rate ripple current correction coefficient. The rated lifetime consumption rate is determined according to the rated lifetime of the capacitor and is calculated by dividing 1 by the rated lifetime of the capacitor. The rated lifetime of the capacitor is taken from the rated parameters of the capacitor and the unit is hours. Therefore, the unit of the rated lifetime consumption rate is per hour. Thus, the rated lifetime consumption rate is used to characterize the baseline lifetime consumption process per unit time under rated operating conditions.

[0080] The lifespan consumption rate temperature correction factor is calculated according to the Arrhenius relation; first, the capacitor dielectric activation energy and ideal gas constant are obtained; the capacitor dielectric activation energy is taken from the manufacturer's data, in joules per mole; the ideal gas constant is a unified constant, in joules per mole per Kelvin; then, the ambient temperature and standard ambient temperature are obtained; the ambient temperature is the temperature corresponding to the current evaluation time, and the standard ambient temperature is the capacitor's rated operating ambient temperature, both in degrees Celsius; then, the ambient temperature and standard ambient temperature are converted to thermodynamic temperatures respectively; the thermodynamic temperature corresponding to the ambient temperature is calculated by adding 273 to the ambient temperature, and the thermodynamic temperature corresponding to the standard ambient temperature is calculated by adding 273 to the standard ambient temperature, both in Kelvin; after completing the thermal... After mechanical temperature conversion, the reciprocals of the thermodynamic temperatures corresponding to the standard ambient temperature and the ambient temperature are calculated separately to obtain two temperature reciprocals. Then, the reciprocal of the thermodynamic temperatures corresponding to the ambient temperature is subtracted from the reciprocal of the standard ambient temperature to obtain the temperature reciprocal difference. Next, the activation energy of the capacitor dielectric is divided by the ideal gas constant to obtain the activation energy ratio. Then, the activation energy ratio is multiplied by the temperature reciprocal difference to obtain the exponent term of the natural exponential function. Finally, the natural exponent is calculated on this exponent term to obtain the lifetime consumption rate temperature correction coefficient. When the ambient temperature is higher than the standard ambient temperature, the lifetime consumption rate temperature correction coefficient is greater than 1; when the ambient temperature is lower than the standard ambient temperature, the lifetime consumption rate temperature correction coefficient is less than 1.

[0081] Based on the above parameters, the comprehensive lifespan attrition rate is calculated as follows: first, the rated lifespan attrition rate is calculated; then, the lifespan attrition rate temperature correction factor, lifespan attrition rate voltage correction factor, and lifespan attrition rate ripple current correction factor are calculated separately; finally, these four factors are multiplied together to obtain the comprehensive lifespan attrition rate. The unit of the comprehensive lifespan attrition rate is still per hour, used to characterize the lifespan attrition process per unit time under the current ambient temperature, grid voltage, and ripple current conditions. If the ambient temperature at the current evaluation time is 40 degrees Celsius, the grid voltage is 400 volts, and the ripple current is 12 amperes, then 40 degrees Celsius is first converted to 313 Kelvin. Then, the lifespan attrition rate temperature correction factor, lifespan attrition rate voltage correction factor, and lifespan attrition rate ripple current correction factor are obtained by combining the standard ambient temperature, rated capacitor voltage, and rated ripple current, respectively. These are then multiplied by the rated lifespan attrition rate to obtain the comprehensive lifespan attrition rate corresponding to that evaluation time.

[0082] To ensure consistent parameter sources, the capacitor's rated life, rated voltage, and rated ripple current are all taken from the capacitor's rated parameters. The capacitor's dielectric activation energy, voltage acceleration index, and ripple current acceleration index are preferentially taken from the manufacturer's life data. When the manufacturer does not directly provide the voltage acceleration index or ripple current acceleration index, they are determined by fitting historical operating data with historical fault data.

[0083] To correct the impact of the current aging state of the capacitor on the calculated lifespan attrition rate, and to make the overall lifespan attrition rate more closely reflect the actual aging process of the capacitor, a lifespan attrition rate correction coefficient based on the degree of capacitor degradation is set. Since the degree of capacitor degradation directly reflects the actual state of its internal dielectric aging and electrode corrosion, even if the external operating conditions such as operating voltage and ambient temperature are normal, the lifespan attrition rate of a severely degraded capacitor will be significantly higher than that of a mildly degraded capacitor. The overall lifespan attrition rate calculated based solely on external operating conditions cannot reflect this internal aging difference. By using the correction coefficient corresponding to the degree of degradation, the impact of the current aging state of the capacitor can be quantified and incorporated into the lifespan assessment, resulting in a corrected overall lifespan attrition rate, further improving the accuracy of remaining lifespan prediction.

[0084] Methods for obtaining the corrected overall lifetime attrition rate include:

[0085] Establish a correlation between degradation degree and lifetime attrition rate correction coefficient. Refer to lifetime attrition characteristic data provided by capacitor manufacturers under different degradation states. For example, if the manufacturer specifies that the lifetime attrition rate is 1.2 times the rated rate when the capacitance decays to 90% of the initial value, the correlation can be obtained through offline experimental fitting. The offline experimental implementation method is as follows: Select capacitor samples of the same model as the capacitor to be evaluated, and simulate different degradation degrees through accelerated aging experiments. Specifically, control the aging time and environmental stress to make the capacitor samples reach the preset capacitance decay ratio and equivalent series resistance growth ratio. For example, mild degradation corresponds to a capacitance decay ratio of less than 5% and an equivalent series resistance growth ratio of less than 10%, while moderate degradation corresponds to a capacitance decay ratio between [5%, 15%) or an equivalent series resistance growth ratio between [10% and 15%]. Between 10% and 30%, severe degradation corresponds to a capacitance decay ratio greater than or equal to 15% or an equivalent series resistance increase ratio greater than or equal to 30%. Subsequently, the actual lifetime consumption rate of samples with each degradation level is tested, and the ratio of this rate to the lifetime consumption rate under rated conditions is calculated. This ratio is the lifetime consumption rate correction coefficient for the corresponding degradation level. Finally, a mapping table is obtained. In the mapping table, the correction coefficient corresponding to mild degradation is close to 1, for example, greater than 1.0 and less than 1.2. The correction coefficient corresponding to moderate degradation is greater than mild degradation, for example, greater than or equal to 1.2 and less than 1.8. The correction coefficient corresponding to severe degradation is greater than moderate degradation, for example, greater than or equal to 1.8 and less than 2.5. The specific values ​​are adjusted according to the capacitor type and manufacturer's recommendations.

[0086] Based on the capacitor's degradation level, capacitance decay ratio, and equivalent series resistance growth ratio, a mapping table is consulted to find the first lifetime consumption rate correction coefficient corresponding to the current capacitor's capacitance decay ratio interval. Similarly, the second lifetime consumption rate correction coefficient corresponding to the current capacitor's equivalent series resistance growth ratio interval is found in the same table. If the first and second lifetime consumption rate correction coefficients differ, the larger value is selected as the final lifetime consumption rate correction coefficient for the current capacitor. This ensures that degradation indicators with a more significant impact on lifetime consumption are prioritized in the lifetime consumption rate calculation, avoiding underestimation of high-impact degradation indicators that would fail to reflect the actual aging and loss of the capacitor.

[0087] The overall lifespan attrition rate is multiplied by the lifespan attrition rate correction factor matched with the current capacitor to obtain the corrected overall lifespan attrition rate. The corrected overall lifespan attrition rate fully reflects the impact of the capacitor's internal aging state on lifespan attrition. For example, even if a severely degraded capacitor is operating at rated voltage and normal temperature, its corrected overall lifespan attrition rate will increase accordingly due to the larger correction factor, which is more in line with the actual lifespan loss situation in the aging process.

[0088] When assessing lifespan based on operating time, ambient temperature, grid voltage, and ripple current, the lifespan consumption increment for the current calculation period is first calculated using the comprehensive lifespan consumption rate and operating time. The lifespan consumption increment represents the share of lifespan consumed within the current calculation period and is a dimensionless quantity. Then, the lifespan consumption increments for each calculation period are accumulated in chronological order to obtain the cumulative lifespan consumption. The cumulative lifespan consumption represents the total share of lifespan that the capacitor has consumed up to the current moment and is a dimensionless quantity.

[0089] The remaining lifetime is calculated based on the cumulative lifetime consumption and the current comprehensive lifetime consumption rate, in hours. Specifically, the remaining lifetime share is first determined based on the cumulative lifetime consumption, calculated as 1 minus the cumulative lifetime consumption. If the remaining lifetime share is greater than 0, it is divided by the current comprehensive lifetime consumption rate to obtain the remaining lifetime. The current comprehensive lifetime consumption rate is calculated based on the current ambient temperature, grid voltage, and ripple current, in hours; therefore, the remaining lifetime is calculated in hours. If the cumulative lifetime consumption is greater than or equal to 1, the remaining lifetime is set to 0, and the capacitor is considered to have reached the end of its lifespan.

[0090] After each preset calculation cycle, the ambient temperature, grid voltage, ripple current, and running time within the current preset calculation cycle are reacquired. Based on the data corresponding to the current preset calculation cycle, the comprehensive lifetime consumption rate and lifetime consumption increment for the current calculation period are calculated. The running time here corresponds to the duration within the current preset calculation cycle, and the unit can be seconds, minutes, or hours. The comprehensive lifetime consumption rate is only used to characterize the lifetime consumption process within the current calculation period and is not used to retrospectively replace the lifetime consumption process of historical calculation periods. After this processing, the changes in ambient temperature, grid voltage, and ripple current at different times can all be included in the lifetime assessment process of the corresponding calculation period.

[0091] The health assessment module determines the health status of the capacitor based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the comparison benchmark, the equivalent series resistance in the comparison benchmark, the running time, the corrected overall lifespan consumption rate, and the rated lifespan of the capacitor.

[0092] The system acquires information such as health index, remaining lifespan, and operating time. Optionally, maintenance cost parameters are used to determine capacitor health status and generate maintenance recommendations. These parameters include capacitor replacement costs, downtime loss costs, spare parts storage costs, and fault repair costs. These parameters are sourced from the operation and maintenance management system, the procurement management system, and manually entered information. Specifically, capacitor replacement costs and spare parts storage costs can be obtained from the procurement management system, while downtime loss costs and fault repair costs can be obtained from the operation and maintenance management system. When the corresponding data is missing from the operation and maintenance management system or the procurement management system, maintenance personnel manually enter the data according to a unified entry standard, recording the entry time, the person entering the data, and the applicable equipment scope. By clearly defining the data source for the maintenance cost parameters, the subsequent maintenance recommendation generation process has a clear data basis.

[0093] After obtaining the health index, remaining lifespan, operating time, and maintenance cost parameters, basic decisions are first made based on the health index, remaining lifespan, and operating time to clarify the current health status of the capacitor. After the basic decisions are completed, the current health status is reviewed and corrected by combining dynamic threshold verification and abnormal fluctuation handling to ensure that the health status judgment results correspond to the current operating data. On this basis, the maintenance cost parameters are introduced into the maintenance suggestion generation process. By combining the current health status, remaining lifespan, and operating time of the capacitor, the cost results corresponding to different maintenance time arrangements are compared to determine the maintenance plan corresponding to the current operating conditions.

[0094] During the maintenance plan generation process, capacitor replacement cost represents the expenditure required to perform the replacement operation, downtime loss cost represents the downtime loss caused during replacement or fault handling, spare parts storage cost represents the storage expenditure incurred from the time of spare parts arrival to the actual time of use, and fault repair cost represents the repair and recovery expenditure after a capacitor failure. Based on the above maintenance cost parameters, cost assessments can be performed on both planned replacement and post-fault repair methods, and the results of basic decisions can be combined to determine whether the current capacitor should continue to operate, schedule planned replacement, or perform early replacement. The final output maintenance plan is designed to balance power supply reliability and operation and maintenance costs, and to ensure that the timing of maintenance is consistent with the needs of power grid operation.

[0095] Please see Figure 4 As shown, the methods for determining capacitor health status and generating maintenance recommendations include:

[0096] The lifespan end-of-life criteria provided by capacitor manufacturers, industry reliability standards for reactive power compensation equipment, and historical fault data are referenced. The historical fault data comes from the operation and maintenance records, fault repair records, periodic inspection records, and replacement records of reactive power compensation equipment already in operation. The historical fault data includes at least the capacitor number, commissioning time, operating time, ambient temperature, grid voltage, ripple current, detection time, fault occurrence time, fault type, and replacement time. All types of records are matched with a unified equipment identifier and a unified time base to form a historical fault dataset that can be used for lifespan analysis.

[0097] Before using historical fault data, the data is first cleaned. The cleaning process includes removing records lacking key time information, removing duplicate records with inconsistent equipment identification, removing abnormal records with incorrect acquisition time sequences, and standardizing the units for ambient temperature, grid voltage, and ripple current. For the same type of fault records repeatedly reported by the same capacitor within adjacent time periods, they are merged as a single fault event. Missing segments caused by downtime maintenance, manual data entry, or communication interruptions are marked as missing and are not directly used as fault statistics samples. After the cleaning process is completed, a historical fault dataset with a unified format and consistent time sequence is obtained.

[0098] To ensure consistency in statistical results, historical fault data is compiled according to a unified statistical standard. The statistical standard uses individual capacitors as the basic statistical object, fault events that actually reach the end-of-life criteria as the fault inclusion condition, and the operating process from commissioning to the fault occurrence or replacement time as the lifespan statistical interval. For capacitors that have been replaced without experiencing a fault, the operating data before the replacement time is recorded and marked as non-fault samples. For capacitors that are continuously operating and have not experienced a fault, the operating data up to the current statistical time is recorded and marked as non-fault samples. Based on the historical fault data compiled according to the unified statistical standard, combined with the end-of-life criteria provided by the capacitor manufacturer and the industry's reliability standards for reactive power compensation equipment, the lifespan status division boundaries, replacement thresholds, and warning thresholds are determined. This processing provides clear evidence for the collection sources, cleaning methods, and statistical standards of historical fault data, facilitating subsequent lifespan assessments and status determinations.

[0099] Set health index threshold ranges and remaining lifespan threshold ranges, and divide both health index threshold ranges and remaining lifespan threshold ranges into three levels: the first level is the normal threshold range, the second level is the attention threshold range, and the third level is the replacement threshold range. The specific range of each threshold range is set according to the power supply reliability requirements of the capacitor application scenario. For example, in scenarios with high power supply continuity requirements, the remaining lifespan range corresponding to the replacement threshold range can be appropriately expanded.

[0100] The health index is compared with the three-level threshold range of the health index, and the remaining lifespan is also compared with the three-level threshold range of the remaining lifespan. If both the health index and the remaining lifespan are within the normal threshold range, the capacitor's health status is determined to be normal. If either the health index or the remaining lifespan is within the attention threshold range, the capacitor's health status is determined to be at attention. If either the health index or the remaining lifespan is within the replacement threshold range, the capacitor's health status is determined to be replacement-needed.

[0101] After each preset review cycle, the health index level 3 threshold range and the remaining lifespan level 3 threshold range are reviewed in combination with the latest running time, health index and remaining lifespan data. The preset review cycle is set according to the capacitor aging rate. The preset review cycle is shortened for capacitors with a fast aging rate and extended for capacitors with a slow aging rate.

[0102] To ensure that the threshold range aligns with the actual aging trend of the capacitor, an aging observation sequence is first formed based on multiple consecutive preset calculation cycles. The aging observation sequence includes at least the cumulative lifetime consumption, remaining lifetime, and state determination results for each preset calculation cycle. Then, the changes in the aging observation sequence between adjacent preset calculation cycles are calculated in chronological order to obtain the actual aging trend data. Simultaneously, based on the currently used threshold ranges at each level, the theoretical change positions and theoretical change rhythms corresponding to each threshold boundary are determined to generate threshold reference data.

[0103] The actual aging trend data is compared with the threshold reference data to calculate the deviation result. The deviation result includes the threshold boundary deviation and the threshold crossing time difference. The threshold boundary deviation is used to characterize the difference between the actual state transition position and the corresponding threshold boundary position, in hours. The threshold crossing time difference is used to characterize the difference between the actual state transition time and the threshold predicted transition time, in hours or days. When the threshold boundary deviation or the threshold crossing time difference exceeds the preset deviation range, it is determined that there is a deviation between the current threshold interval and the current actual aging trend of the capacitor, and the threshold interval adjustment needs to be performed.

[0104] The preset deviation range is set based on historical fault data, historical operating data, and the allowable error for current state determination. Specifically, based on historical fault data and historical operating data, the actual state transition location distribution and actual state transition time distribution of the same type of capacitor at different life stages are statistically analyzed to obtain the historical distribution range of threshold boundary deviation and the historical distribution range of threshold time difference. Then, based on the historical distribution range of threshold boundary deviation and the historical distribution range of threshold time difference, and combined with the allowable error for current state determination, the preset deviation range corresponding to the threshold boundary deviation and the preset deviation range corresponding to the threshold time difference are determined. The allowable error for current state determination is set according to maintenance lead time requirements, fault risk control requirements, and early warning timeliness requirements.

[0105] When readjusting the threshold intervals at each level based on the latest data, the current actual state transition position is used as the correction basis, and the corresponding threshold boundary is shifted in the same direction. The adjustment step size for each adjustment is determined according to the preset minimum adjustment unit. If the deviation result is in the same direction for multiple consecutive preset calculation cycles, the corresponding threshold boundary is moved step by step until the threshold boundary deviation and threshold crossing time difference return to the preset deviation range. If the deviation result is in the opposite direction in adjacent preset calculation cycles, the current threshold boundary remains unchanged, and data from subsequent preset calculation cycles is collected before the judgment is executed, so as to avoid the data of a single preset calculation cycle from having a direct impact on the threshold interval.

[0106] After adjusting the threshold intervals, the order and width of each threshold interval are re-verified to ensure that the threshold intervals are arranged in descending order of lifespan, that there is no overlap or inversion between adjacent threshold boundaries, and that the threshold intervals are connected end to end. The updated threshold intervals are then used in the subsequent state determination process. By calculating the deviation results according to the aging observation sequence and updating the threshold intervals according to the deviation results, adjustment step size, and interval order constraints, the state determination results can maintain a correspondence with the actual aging trend of the capacitor.

[0107] The system monitors the rate of change of the health index and remaining lifespan in real time. If the health index decreases by more than the preset decrease rate within a preset monitoring period, or the remaining lifespan shortens by more than the preset shortening rate within a preset monitoring period, it is determined to be an abnormal fluctuation. At this time, an emergency review process is triggered to rule out abnormalities caused by data acquisition errors or calculation errors. If abnormal fluctuations still exist after review, the capacitor's health status is determined to require replacement to avoid the risk of failure.

[0108] Example 2:

[0109] This embodiment discloses a capacitor life monitoring system for reactive power compensation, which also includes:

[0110] The decision-making module is optimized to generate capacitor health status reports and life assessment results.

[0111] A failure probability model is established based on remaining life and historical failure data. Historical failure data includes records of remaining life of historical capacitors at multiple assessment times, records of operational results after each assessment time, records of failure occurrence times, failure repair costs, and downtime loss costs. To ensure the failure probability model corresponds to the replacement time-point decision-making process, each assessment time in the historical failure data is used as a sample starting point. Subsequent operational segments after that assessment time are extracted, and a preset risk observation period is used to determine whether a capacitor failure occurs within that subsequent operational segment, thus forming a historical sample table. Each sample in the historical sample table records the remaining life corresponding to the sample starting point, the preset risk observation period, and a result marker indicating whether a capacitor failure occurred within that preset risk observation period. The preset risk observation period uses a clear time span, in hours or days, to define the statistical time range corresponding to the capacitor failure probability.

[0112] The failure probability model is constructed using a piecewise statistical fitting method. First, the historical sample table is grouped according to the remaining lifespan interval and the preset risk observation period interval. Then, the proportion of capacitor failures occurring in each group is statistically analyzed to establish the correspondence between remaining lifespan, preset risk observation period, and capacitor failure probability. The input to the failure probability model is the remaining lifespan and the preset risk observation period, and the output is the capacitor failure probability occurring within that preset risk observation period. The capacitor failure probability here corresponds to the interval failure probability within a fixed time range, not the cumulative failure probability without time boundaries. Based on this output, combined with the failure repair cost and downtime loss cost in the maintenance cost parameters, the expected failure loss is calculated. The calculation method for the expected failure loss is as follows: First, determine the preset risk observation period corresponding to the current candidate maintenance arrangement. Then, input the current remaining lifespan and the preset risk observation period into the failure probability model to obtain the capacitor failure probability under the current candidate maintenance arrangement. Next, read the failure repair cost and downtime loss cost corresponding to the current candidate maintenance arrangement, and add the failure repair cost and downtime loss cost to obtain the failure loss amount corresponding to a single capacitor failure event. Finally, multiply the capacitor failure probability by the failure loss amount to obtain the expected failure loss.

[0113] Based on remaining lifetime and maintenance cost parameters, the total maintenance cost corresponding to different replacement time points is calculated. Different replacement time points are set according to multiple candidate time positions after the current moment, in hours or days. For each replacement time point, the waiting time from the current moment to the replacement time point is first determined, and this waiting time is used as the corresponding preset risk observation period and input into the failure probability model. Then, based on the current remaining lifetime and the waiting time, the predicted remaining lifetime corresponding to the replacement time point is calculated. The predicted remaining lifetime is used to determine whether the replacement time point has the conditions for execution under lifetime constraints.

[0114] After determining the replacement time point, the total maintenance cost corresponding to that replacement time point is calculated by combining the capacitor replacement cost, spare parts storage cost, and downtime loss cost. The total maintenance cost is calculated by summing the capacitor replacement cost, spare parts storage cost, and downtime loss cost. If there are additional costs incurred due to expedited procurement, these additional costs are also included in the total maintenance cost. The capacitor replacement cost is directly taken from the maintenance cost parameter and is used to represent the expenditure incurred in carrying out the capacitor replacement operation at that replacement time point; the unit of amount is yuan. The spare parts storage cost is based on the arrival time of the spare parts and the replacement... The storage duration between replacement time points is calculated by multiplying the spare parts storage cost per unit time by the storage duration. The unit of spare parts storage cost per unit time is RMB per hour or RMB per day, and the unit of storage duration is hours or days. Therefore, the unit of spare parts storage cost is RMB. The downtime loss cost is calculated based on the planned downtime corresponding to the planned replacement. The specific calculation method is multiplying the downtime loss cost per unit time by the planned downtime. The unit of downtime loss cost per unit time is RMB per hour or RMB per day, and the unit of planned downtime is hours or days. Therefore, the unit of downtime loss cost is RMB.

[0115] When the spare parts arrive before the replacement time, the spare parts storage cost is greater than 0; when the spare parts arrive at the same time as the replacement time, the spare parts storage cost is 0; if the spare parts arrive after the replacement time, the replacement time is determined to be unfeasible under normal spare parts supply conditions; for unfeasible time points, the replacement time point can be directly marked as unfeasible and not included in the subsequent comparison of total expected costs; or the additional costs incurred by expedited procurement can be calculated according to the procurement plan, and the additional costs incurred by expedited procurement can be summed together with the capacitor replacement cost, spare parts storage cost, and downtime loss cost to obtain the total maintenance cost corresponding to the replacement time point; through this processing method, the total maintenance cost corresponding to different replacement time points can be obtained according to a unified calculation method.

[0116] When constructing the total expected cost model, the total maintenance cost corresponding to each replacement time point is superimposed with the expected failure loss to obtain the total expected cost corresponding to each replacement time point. After traversing all replacement time points, the replacement time point with the minimum total expected cost is selected as the optimal replacement time. If the optimal replacement time point is earlier than the time point corresponding to the remaining lifespan replacement threshold, the maintenance recommendation is adjusted to early replacement based on the state judgment result of the basic decision. If the optimal replacement time point is later than the time point corresponding to the remaining lifespan replacement threshold, the replacement judgment in the basic decision takes precedence. After this processing, the correspondence between the remaining lifespan, the preset risk observation period, the capacitor failure probability, the total maintenance cost, the expected failure loss, and the total expected cost remains consistent.

[0117] After each preset cost update cycle, maintenance cost parameter data is collected again, and new operation result records and new fault records in historical fault data are updated synchronously. Maintenance cost parameter data includes capacitor replacement cost, spare parts storage cost, fault repair cost, and downtime loss cost. Based on the updated maintenance cost parameter data and historical fault data, the fault probability model is refitted, and the total maintenance cost, expected fault loss, and total expected cost corresponding to each replacement time point are recalculated, thereby updating the optimal replacement time. The preset cost update cycle adopts a clear time span, and the unit can be days, weeks, or months. Through periodic updates, the optimal replacement time can be continuously adjusted according to changes in remaining life, accumulation of historical fault data, and changes in maintenance cost parameters.

[0118] The final results are a capacitor health status report and a life assessment. The capacitor health status report includes the capacitor health status, health index, remaining life, and the basis for the status determination. The life assessment results include the calculation process of the remaining life and the trend curve of the health index. The maintenance recommendations include maintenance recommendations based on basic decisions, such as continue operation, near-term replacement, and immediate replacement, as well as recommendations on the optimal replacement time based on cost optimization decisions.

[0119] Example 3:

[0120] Please see Figure 2 As shown, this embodiment provides a capacitor lifetime monitoring method for reactive power compensation, including:

[0121] The raw dataset is collected periodically; the raw dataset includes the time-domain signal of the grid voltage, the time-domain signal of the compensation branch current, the ambient temperature, the rated capacity of the capacitor, the rated life of the capacitor, and the operating time.

[0122] Multiple frequency points are selected in the power grid to obtain multiple frequency points, and the complex impedance and admittance corresponding to each frequency point are calculated.

[0123] Based on the complex impedance corresponding to each multi-frequency point, the estimated values ​​of equivalent series resistance, equivalent series inductance and capacitance are calculated, and the admittance is used for consistency verification.

[0124] The degree of capacitor degradation is determined based on the estimated values ​​of running time, equivalent series resistance, equivalent series inductance, and capacitance.

[0125] Based on the original dataset, the overall lifetime attrition rate is calculated; based on the degree of capacitor degradation, the overall lifetime attrition rate is corrected to obtain the corrected overall lifetime attrition rate.

[0126] The health status of the capacitor is determined based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the benchmark, the equivalent series resistance in the benchmark, the operating time, the corrected overall lifetime consumption rate, and the rated lifetime of the capacitor.

[0127] Example 4:

[0128] This embodiment provides a capacitor life monitoring device for reactive power compensation, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements a capacitor life monitoring method for reactive power compensation provided by the above methods.

[0129] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

Claims

1. A method for monitoring the life of a capacitor for reactive power compensation, characterized in that, include: Periodically collect raw datasets; The original dataset includes the grid voltage time-domain signal, the compensation branch current time-domain signal, ambient temperature, rated capacitor capacity, rated capacitor life, and operating time; Multiple frequency points are selected in the power grid to obtain multiple frequency points, and the complex impedance and admittance corresponding to each frequency point are calculated. Based on the complex impedance corresponding to each multi-frequency point, the estimated values ​​of equivalent series resistance, equivalent series inductance and capacitance are calculated, and the admittance is used for consistency verification. The degree of capacitor degradation is determined based on the estimated values ​​of running time, equivalent series resistance, equivalent series inductance, and capacitance. Based on the original dataset, the overall lifetime attrition rate is calculated; based on the degree of capacitor degradation, the overall lifetime attrition rate is corrected to obtain the corrected overall lifetime attrition rate. The health status of the capacitor is determined based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the benchmark, the equivalent series resistance in the benchmark, the operating time, the corrected overall lifetime consumption rate, and the rated lifetime of the capacitor.

2. The method for monitoring the life of a capacitor for reactive power compensation according to claim 1, characterized in that, The selection of multiple frequency points in the power grid includes: determining the fundamental frequency of the power grid; selecting naturally occurring harmonic frequencies in the power grid as the multiple frequency points; and when the natural harmonic frequencies are insufficient to construct an overdetermined set of equations concerning the equivalent series resistance, the equivalent series inductance, and the capacitance, supplementing the selection with a signal frequency as the multiple frequency points.

3. The method for monitoring the life of a capacitor for reactive power compensation according to claim 1, characterized in that, Before calculating the complex impedance and admittance corresponding to each multi-frequency point, the process includes: extracting the complex voltage component and complex current component at the corresponding frequency for each multi-frequency point, and extracting the grid voltage time-domain signal and the compensation branch current time-domain signal from the original dataset; and adapting a window function to the grid voltage time-domain signal and the compensation branch current time-domain signal according to the multi-frequency point type.

4. The method for monitoring the life of a capacitor for reactive power compensation according to claim 3, characterized in that, The extraction of complex voltage and complex current components at corresponding frequencies includes: constructing a signal-to-noise ratio (SNR) based on the complex voltage and complex current components within a preset calculation period; retaining the spectral data corresponding to the current multi-frequency point when the SNR meets the requirements; and dividing the grid voltage time-domain signal and the compensation branch current time-domain signal into multiple data segments when the SNR does not meet the requirements, and averaging the spectral results of the effective data segments to obtain the spectral data corresponding to the current multi-frequency point.

5. The method for monitoring the life of a capacitor for reactive power compensation according to claim 3, characterized in that, The calculation of the complex impedance and admittance corresponding to each multi-frequency point includes: decomposing the complex voltage component and complex current component corresponding to each multi-frequency point into real and imaginary parts respectively, obtaining the complex impedance corresponding to each multi-frequency point through complex division, and determining the reciprocal of the complex impedance as the corresponding admittance.

6. The method for monitoring the life of a capacitor for reactive power compensation according to claim 1, wherein, The step of calculating the estimated values ​​of equivalent series resistance, equivalent series inductance, and capacitance based on the complex impedance corresponding to each multi-frequency point includes: decomposing the complex impedance corresponding to each multi-frequency point into the real part and the imaginary part of the complex impedance; performing least-squares fitting on the real part of the complex impedance to obtain the estimated value of the equivalent series resistance; substituting the imaginary part of the complex impedance and the angular frequency of the frequency corresponding to the multi-frequency point into the equivalent circuit model of the capacitor, constructing a system of linear equations, and solving them to obtain the estimated values ​​of the equivalent series inductance and the estimated value of the capacitance.

7. The capacitor life monitoring method for reactive power compensation according to claim 6, characterized in that, The consistency verification using admittance includes: applying physical constraints to the estimated values ​​of the equivalent series resistance, the equivalent series inductance, and the capacitance; and when the reciprocal correspondence between the admittance and the complex impedance does not meet the preset consistency conditions, the current calculation result is discarded, recalculated, or marked.

8. The method for monitoring the life of a capacitor for reactive power compensation according to claim 1, wherein, The determination of the degree of degradation of the capacitor includes: obtaining the initial baseline parameters at the standard ambient temperature, or establishing a correspondence model between the ambient temperature and the baseline parameters based on the baseline parameters at different ambient temperatures; and determining the baseline parameters at the current ambient temperature in combination with the current ambient temperature, and using the baseline parameters at the current ambient temperature or the rated capacitance and rated equivalent series resistance of the capacitor as the comparison benchmark. The capacitance decay ratio is determined based on the capacitance value in the comparison benchmark and the estimated value of the capacitance value. The equivalent series resistance growth ratio is determined based on the equivalent series resistance in the comparison benchmark and the estimated value of the equivalent series resistance. The capacitor is then classified into a mildly degraded state, a moderately degraded state, or a severely degraded state according to the capacitance decay ratio and the equivalent series resistance growth ratio.

9. The method for monitoring the life of a capacitor for reactive power compensation according to claim 1, wherein, The step of calculating the overall lifetime consumption rate based on the original dataset includes: extracting the fundamental current component from the time-domain signal of the compensation branch current, and subtracting the fundamental current component from the time-domain signal of the compensation branch current to obtain the ripple current; The baseline lifetime consumption rate is corrected based on ambient temperature, grid voltage, ripple current, and operating time to obtain the comprehensive lifetime consumption rate corresponding to the current calculation period. The lifetime consumption increment is determined based on the comprehensive lifetime consumption rate and the operating time corresponding to the current calculation period, and then accumulated in chronological order to obtain the cumulative lifetime consumption.

10. The method of claim 8, wherein, The method of correcting the overall lifetime consumption rate based on the degree of capacitor degradation includes: establishing a correspondence between the degree of capacitor degradation and the lifetime consumption rate correction coefficient; determining a first lifetime consumption rate correction coefficient based on the capacitance decay ratio; determining a second lifetime consumption rate correction coefficient based on the equivalent series resistance growth ratio; and selecting the larger of the first lifetime consumption rate correction coefficient and the second lifetime consumption rate correction coefficient to correct the overall lifetime consumption rate.

11. The method for monitoring the life of a capacitor for reactive power compensation according to claim 1, characterized in that, The determination of the capacitor's health status based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the benchmark, the equivalent series resistance in the benchmark, the operating time, the corrected overall lifespan consumption rate, and the rated lifespan of the capacitor includes: accumulating the cumulative lifespan consumption based on the corrected overall lifespan consumption rate and operating time corresponding to each calculation period, and converting it into the remaining lifespan by combining it with the current corrected overall lifespan consumption rate; and determining the health index based on the estimated capacitance and the estimated equivalent series resistance.

12. The method of claim 11, wherein, The determination of the health status of the capacitor includes: determining the health status of the capacitor based on the threshold ranges corresponding to the health index and the remaining lifespan; reviewing and adjusting the threshold ranges according to the aging observation sequence formed by multiple consecutive preset calculation cycles; and triggering an emergency review when the change in the health index or the remaining lifespan exceeds the corresponding threshold within the preset monitoring period.

13. A reactive power compensation oriented capacitor life monitoring system for implementing a reactive power compensation oriented capacitor life monitoring method according to any one of claims 1 to 12, characterized by include: The data acquisition module is used to periodically collect raw datasets; The original dataset includes the grid voltage time-domain signal, the compensation branch current time-domain signal, ambient temperature, rated capacitor capacity, rated capacitor life, and operating time; The multi-frequency point selection module is used to select multiple frequency points in the power grid, obtain multiple frequency points, and calculate the complex impedance and admittance corresponding to each frequency point. The estimation calculation module calculates the estimated values ​​of equivalent series resistance, equivalent series inductance and capacitance based on the complex impedance corresponding to each multi-frequency point, and uses admittance for consistency verification. The lifespan calculation module determines the degree of capacitor degradation based on estimated values ​​of running time, equivalent series resistance, equivalent series inductance, and capacitance. Based on the original dataset, the overall lifetime attrition rate is calculated; based on the degree of capacitor degradation, the overall lifetime attrition rate is corrected to obtain the corrected overall lifetime attrition rate. The health assessment module determines the health status of the capacitor based on the estimated capacitance, the estimated equivalent series resistance, the capacitance in the comparison benchmark, the equivalent series resistance in the comparison benchmark, the running time, the corrected overall lifespan consumption rate, and the rated lifespan of the capacitor.

14. A device for reactive power compensation-oriented capacitor life monitoring for implementing a method for reactive power compensation-oriented capacitor life monitoring according to any one of claims 1 to 12, characterized by It includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the capacitor lifetime monitoring method for reactive power compensation when executing the computer program.

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