Wide temperature range compensation method for resistive current of lightning arrester

Abstract

The application discloses a wide-temperature-range compensation method for resistive current of a lightning arrester, and belongs to the technical field of online monitoring of power equipment. The method comprises the following steps: collecting waveform data under a reference low-temperature working condition, and establishing an initial capacitive harmonic base; collecting working condition data under an arbitrary temperature in real time, and performing harmonic decomposition, and analyzing and generating a nonlinear distortion characteristic vector; dynamically correcting the initial base by using the characteristic vector, and performing subtraction operation on the total current harmonic to obtain a final resistive current harmonic vector; and reconstructing an instantaneous resistive current waveform by inverse transformation, and calculating an eigenvalue. The method adopts the technical scheme of establishing the initial capacitive harmonic base, quantifying the harmonic distortion of the nonlinear coupling between the temperature and the valve piece based on the real-time working condition, generating the nonlinear distortion characteristic vector for dynamically feedback correction of the base, can accurately separate and reconstruct the real resistive current waveform under the wide-temperature range, and improves the accuracy and reliability of the state evaluation of the lightning arrester.

Description

Technical Field

[0001] This invention relates to the field of online monitoring technology for power equipment, and in particular to a wide-temperature-range compensation method for resistive current in surge arresters. Background Technology

[0002] Metal oxide surge arresters are key components used to protect electrical equipment from overvoltage damage. During long-term operation, their core component, the metal oxide varistor, gradually deteriorates due to factors such as moisture absorption or material aging. This deterioration process is directly reflected in changes in the leakage current. The leakage current mainly consists of two parts: capacitive current and resistive current, with capacitive current dominating. Changes in the resistive current component can sensitively reflect the health of the varistor. Therefore, accurate measurement of the resistive current is a core method for assessing the operating status of surge arresters.

[0003] In existing technologies, various methods are typically employed to separate the weak resistive current from the total leakage current. One method is the compensation method, which compensates for the capacitive current component through hardware or software. Another method is harmonic analysis, which utilizes the nonlinearity of the valve plate's volt-ampere characteristics to estimate the resistive current by analyzing the high-order harmonic content in the leakage current. Furthermore, some methods attempt to incorporate temperature sensors to correct the measurement results for temperature variations, aiming to reduce the impact of ambient temperature changes.

[0004] However, the aforementioned existing technical solutions have significant drawbacks. Methods based on fixed compensation values ​​cannot adapt to the actual changes in arrester capacitance characteristics with temperature and aging, leading to incomplete compensation. Traditional harmonic analysis methods often neglect the harmonic distortion of the grid voltage itself and the complex changes in valve plate harmonic characteristics with temperature, resulting in limited separation accuracy. Existing temperature correction methods mostly use simplified empirical formulas for post-correction; this open-loop correction method struggles to accurately describe the complex coupling relationship between temperature, valve plate nonlinearity, and harmonic distortion. In wide temperature range environments, its compensation effect is often unsatisfactory, leading to significant errors in resistive current measurement results. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a wide-temperature-range compensation method for the resistive current of surge arresters. This method employs a technique of establishing an initial capacitive harmonic substrate and generating a nonlinear distortion feature vector based on the real-time operating conditions and the nonlinear coupling of temperature and valve plates to dynamically correct the substrate. This approach can accurately separate and reconstruct the true resistive current waveform over a wide temperature range, improving the accuracy and reliability of surge arrester condition assessment.

[0006] The above objectives can be achieved through the following approach:

[0007] A wide-temperature-range compensation method for resistive current in surge arresters includes: simultaneously acquiring reference waveform data of leakage current and operating voltage under a reference low-temperature stable operating condition for the target surge arrester; extracting and storing an initial capacitive harmonic substrate based on inherent capacitance characteristics through harmonic analysis; simultaneously acquiring the full leakage current waveform, operating voltage waveform, and ambient temperature data of the target surge arrester under arbitrary ambient temperatures in real time; performing harmonic decomposition on the full leakage current waveform; and using the initial capacitive harmonic substrate for preliminary separation to obtain a preliminary resistive harmonic spectrum; analyzing the amplitude and phase relationship of each harmonic component in the preliminary resistive harmonic spectrum to quantify the relationship between temperature change and valve nonlinearity. Harmonic distortion caused by coupling is used to generate a nonlinear distortion feature vector that deviates from the reference low-temperature operating condition under the current operating condition. The nonlinear distortion feature vector is used as a correction operator to dynamically correct the initial capacitive harmonic substrate, generating a dynamically compensated capacitive harmonic spectrum that matches the current real-time operating condition. The dynamic compensated capacitive harmonic spectrum is then used to perform harmonic domain subtraction on the full leakage current waveform to obtain the final resistive current harmonic vector after feedback correction. Inverse harmonic transformation is performed on the final resistive current harmonic vector to reconstruct the instantaneous resistive current waveform after wide-temperature-range compensation, and the target resistive current characteristic value is calculated based on the instantaneous resistive current waveform.

[0008] Optionally, the extraction and storage of the initial capacitive harmonic substrate of inherent capacitance characteristics includes: monitoring the ambient temperature and operating voltage waveform of the target surge arrester, determining whether the ambient temperature is lower than a preset first temperature reference value and whether the fluctuation rate of the operating voltage waveform is less than a preset first stability reference value, and confirming that the target surge arrester has entered a reference low temperature stable operating condition; under the reference low temperature stable operating condition, continuously collecting leakage current and operating voltage for multiple cycles to form reference waveform data; performing harmonic analysis on the reference waveform data to calculate the harmonic admittance under each harmonic; separating the imaginary part of the harmonic admittance to obtain the harmonic susceptance value of the capacitance characteristics at each harmonic frequency, and constructing and storing an initial capacitive harmonic substrate composed of capacitive current harmonic vectors based on the harmonic susceptance value and the voltage harmonic vector in the reference waveform data.

[0009] Optionally, obtaining the preliminary resistive harmonic spectrum includes: activating a high-frequency current sensor and a voltage sensor at any ambient temperature to continuously acquire and digitize the full leakage current waveform and operating voltage waveform of the target surge arrester, forming a real-time data stream; segmenting the real-time data stream using a sliding time window, and synchronizing the full leakage current waveform, the operating voltage waveform, and the ambient temperature with the fundamental zero-crossing point of the operating voltage waveform as a reference, generating a synchronous data frame in units of the voltage fundamental period; performing harmonic analysis on the full leakage current waveform in each synchronous data frame to analyze the full current harmonic vector of each harmonic amplitude and phase; and subtracting the corresponding capacitive current harmonic vector in the initial capacitive harmonic base from the full current harmonic vector in the harmonic domain to obtain the preliminary resistive harmonic spectrum.

[0010] Optionally, the step of analyzing the amplitude and phase of each harmonic to obtain the full current harmonic vector includes: preprocessing the full leakage current waveform within the synchronous data frame to suppress spectral leakage and form a windowed current data sequence; performing a discrete frequency domain transformation on the current data sequence to calculate the discrete spectral data of the corresponding fundamental frequency and integer multiple harmonic frequencies; extracting the amplitude and phase information corresponding to each harmonic from the discrete spectral data, and combining the amplitude and phase information to construct the full current harmonic vector.

[0011] Optionally, generating the nonlinear distortion feature vector of the current operating condition deviating from the reference low-temperature operating condition includes: extracting the fundamental resistive current component and the higher harmonic resistive current component from the preliminary resistive harmonic spectrum, calculating the amplitude ratio and phase difference of the higher harmonic resistive current component relative to the fundamental resistive current component, and forming an initial distortion parameter set; calculating the temperature rise difference of the current operating condition based on the ambient temperature data and the temperature under the reference low-temperature stable operating condition; calculating the temperature drift sensitivity coefficient for each parameter in the initial distortion parameter set by combining the initial distortion parameter set and the temperature rise difference; and combining each parameter in the initial distortion parameter set with the corresponding temperature drift sensitivity coefficient to construct a nonlinear distortion feature vector.

[0012] Optionally, the initial distortion parameter set includes: a harmonic amplitude ratio parameter and a harmonic phase difference parameter, wherein: the harmonic amplitude ratio parameter is used to characterize the proportion of each higher harmonic energy in the total resistive current, reflecting the curvature of the valve plate's volt-ampere characteristic; the harmonic phase difference parameter is used to characterize the lead of each higher harmonic component on the time axis, reflecting the hysteresis response characteristics of the valve plate material under an alternating electric field.

[0013] Optionally, the method further includes: combining the preliminary resistive harmonic spectrum and the nonlinear distortion feature vector to calculate and generate a dynamic degradation assessment factor for the current valve plate health status; comparing the dynamic degradation assessment factor with multiple state reference values ​​derived from the baseline low-temperature stable operating condition, and determining and outputting an adaptive compensation mode identifier.

[0014] Optionally, obtaining the feedback-corrected final resistive current harmonic vector includes: applying the nonlinear distortion eigenvector as a correction operator to the initial capacitive harmonic substrate to generate a preliminary dynamically compensated capacitive harmonic spectrum; adjusting each harmonic component in the preliminary dynamically compensated capacitive harmonic spectrum by applying differentiated correction weights according to the adaptive compensation mode identifier to obtain a dynamically compensated capacitive harmonic spectrum that matches the current real-time operating condition; and subtracting the dynamically compensated capacitive harmonic spectrum from the harmonic vector of the full leakage current waveform in the harmonic domain to generate the feedback-corrected final resistive current harmonic vector.

[0015] Optionally, calculating the target resistive current characteristic value based on the instantaneous resistive current waveform includes: performing an inverse discrete frequency domain transformation on each harmonic component in the final resistive current harmonic vector and performing time domain superposition to synthesize an instantaneous resistive current waveform; extracting the resistive current peak value from the waveform sequence based on the instantaneous resistive current waveform and calculating the effective value of the resistive current in the waveform sequence; and outputting the resistive current peak value and the effective value of the resistive current together as the target resistive current characteristic value.

[0016] Based on the same inventive concept, this invention also provides a wide-temperature-range compensation system for resistive current of a surge arrester. The system includes: an initial harmonic substrate generation module, used to simultaneously acquire reference waveform data of leakage current and operating voltage under reference low-temperature stable operating conditions of the target surge arrester, and extract and store the initial capacitive harmonic substrate with inherent capacitance characteristics through harmonic analysis; a data acquisition and preliminary separation module, used to synchronously acquire the full leakage current waveform, operating voltage waveform, and ambient temperature data of the target surge arrester at any ambient temperature in real time, perform harmonic decomposition on the full leakage current waveform, and perform preliminary separation using the initial capacitive harmonic substrate to obtain a preliminary resistive harmonic spectrum; and a thermal distortion calculation module, used to analyze the amplitude and phase of each harmonic component in the preliminary resistive harmonic spectrum. The system identifies the positional relationship, quantifies the harmonic distortion caused by the coupling of temperature changes and valve plate nonlinear characteristics, and generates a nonlinear distortion feature vector that deviates from the reference low-temperature operating condition. A dynamic feedback correction module uses this nonlinear distortion feature vector as a correction operator to dynamically correct the initial capacitive harmonic substrate, generating a dynamically compensated capacitive harmonic spectrum that matches the current real-time operating condition. This spectrum is then used to perform harmonic domain subtraction on the full leakage current waveform to obtain the final resistive current harmonic vector after feedback correction. A waveform reconstruction and eigenvalue calculation module performs inverse harmonic transformation on the final resistive current harmonic vector to reconstruct the instantaneous resistive current waveform after wide-temperature-range compensation, and calculates the target resistive current eigenvalue based on the instantaneous resistive current waveform.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. By constructing an initial capacitive harmonic substrate and combining it with real-time operating condition analysis, a nonlinear distortion feature vector is generated to dynamically correct the substrate, achieving high-precision compensation for the resistive current of the surge arrester. This method can effectively overcome the influence of ambient temperature changes on the capacitance characteristics of the surge arrester. Even under conditions of drastic temperature fluctuations, it can separate weak resistive current components, improving the accuracy and stability of the measurement.

[0019] 2. By introducing dynamic degradation assessment factors and adaptive compensation modes, the condition diagnosis and compensation process are deeply integrated. This method can not only compensate for measurement deviations caused by temperature, but also adaptively adjust the compensation strategy according to the evolution of the valve plate's own health condition. This synergistic effect enables the compensation model to adapt to the entire life cycle of the surge arrester from health to degradation, enhancing the long-term effectiveness and reliability of the method and avoiding the failure of the compensation model due to valve plate aging;

[0020] 3. A complete closed-loop processing flow from data acquisition to feature output is proposed, which has strong engineering applicability. This method is based on harmonic domain computation, has high processing efficiency, and can meet the real-time requirements of online monitoring of power systems. By reconstructing the instantaneous resistive current waveform and outputting key features such as peak and RMS values, it provides intuitive and reliable data support for subsequent condition assessment, fault early warning, and predictive maintenance, thereby improving the intelligence level of power grid equipment management.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic flowchart of a wide-temperature-range compensation method for resistive current of a surge arrester according to an embodiment of the present invention.

[0024] Figure 2 This is a waveform diagram of voltage and leakage current under the reference operating conditions of an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the leakage current phasor relationship in an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of a wide-temperature-range compensation system for resistive current of a surge arrester according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Reference Figure 1One embodiment of the present invention proposes a wide-temperature-range compensation method for the resistive current of a surge arrester. The method adopts a technical solution of establishing an initial capacitive harmonic substrate and generating a nonlinear distortion feature vector based on the real-time operating condition quantification of temperature and nonlinear coupling of the valve plate to perform dynamic feedback correction on the substrate. This method can accurately separate and reconstruct the real resistive current waveform under a wide temperature range, thereby improving the accuracy and reliability of surge arrester condition assessment.

[0029] The method described in this embodiment specifically includes:

[0030] Under the reference low temperature stable operating condition of the target surge arrester, the reference waveform data of leakage current and operating voltage are collected synchronously, and the initial capacitive harmonic basis of inherent capacitance characteristics is extracted and stored through harmonic analysis.

[0031] Optionally, the initial capacitive harmonic substrate for extracting and storing inherent capacitance characteristics includes:

[0032] Monitor the ambient temperature and operating voltage waveform of the target surge arrester, determine whether the ambient temperature is lower than the preset first temperature reference value and whether the fluctuation rate of the operating voltage waveform is less than the preset first stability reference value, and confirm that the target surge arrester has entered the reference low temperature stable operating condition.

[0033] Under the aforementioned baseline low-temperature stable operating conditions, leakage current and operating voltage are continuously collected for multiple cycles to form baseline waveform data;

[0034] Harmonic analysis is performed on the reference waveform data to calculate the harmonic admittance for each harmonic.

[0035] The imaginary part of the harmonic admittance is separated to obtain the harmonic susceptance value of the capacitance characteristic at each harmonic frequency. Based on the harmonic susceptance value and the voltage harmonic vector in the reference waveform data, an initial capacitive harmonic substrate composed of capacitive current harmonic vectors is constructed and stored.

[0036] Specifically, during execution, the ambient temperature is continuously monitored by a temperature sensor, while the data acquisition equipment monitors the root mean square (RMS) value of the operating voltage waveform. The first temperature reference value is determined based on the physical characteristic that the resistive current of the zinc oxide varistor is negligible at low temperatures, for example, a value of 5°C. The first stability reference value is used to ensure stable grid operation; it can be determined according to grid operation procedures, for example, requiring the voltage RMS value fluctuation rate to be less than 0.5% over one minute. When both the ambient temperature and the operating voltage fluctuation rate meet these two reference value conditions, the processing equipment confirms that the target surge arrester has entered the baseline low-temperature stable operating condition and triggers subsequent data acquisition, such as... Figure 2As shown, in this state, the leakage current is mainly composed of capacitive components, whose phase ideally leads the operating voltage by 90 degrees, while the resistive component is negligible. Once the reference low-temperature stable operating condition is confirmed, the data acquisition equipment simultaneously activates high-frequency current and voltage sensors at a high sampling rate, such as 25.6kHz, to continuously acquire, for example, the instantaneous values ​​of the total leakage current and operating voltage for 10 power frequency cycles. These high-density sampling point sequences are digitized and stored, collectively forming the reference waveform data required for subsequent harmonic analysis. The processing equipment performs harmonic analysis algorithms, such as Fast Fourier Transform, on the leakage current and operating voltage in the reference waveform data, decomposing them into current harmonic components and voltage harmonic components up to, for example, the 21st harmonic. Each harmonic component contains amplitude and phase information. Subsequently, for each harmonic order, the harmonic admittance at that harmonic frequency is obtained by calculating the complex quotient of the current harmonic component and the voltage harmonic component. Since the resistive component of the surge arrester is extremely small under the reference low-temperature operating condition, the harmonic admittance is mainly contributed by the capacitive component. The processing device decomposes the calculated harmonic admittance into real and imaginary parts, and extracts the imaginary part as the harmonic susceptance value characterizing the capacitance. Then, it multiplies the harmonic susceptance value at each harmonic frequency with the corresponding voltage harmonic vector to calculate a set of pure capacitive current harmonic vectors. This set of capacitive current harmonic vectors, covering the fundamental frequency to higher harmonics, is stored as a whole, forming the initial capacitive harmonic basis for subsequent compensation calculations.

[0037] For example, suppose that in the early morning of a winter day, the ambient temperature is monitored to be 4 degrees Celsius, and the grid voltage fluctuation rate is only 0.1%, indicating that the system has entered a baseline low-temperature stable operating condition. At this time, leakage current and operating voltage waveform data for 10 power frequency cycles are simultaneously acquired at a sampling rate of 25.6 kHz. Harmonic analysis is performed on these two sets of data, obtaining the 1st, 3rd, 5th, and up to the 21st harmonic components of current and voltage. The analysis yields the 3rd harmonic: the voltage component is 1.5 kV, and the leakage current component is 2.12 mA. The 3rd harmonic admittance is then calculated by dividing the current component by the voltage component, resulting in 1.413 microsiemens. Decomposing this admittance value into real and imaginary parts, it is found that the real part is close to zero, while the imaginary part is 1.413 microsiemens. This is consistent with the characteristic that resistive current is negligible at low temperatures. The susceptance value is then extracted and multiplied by the third voltage harmonic component to calculate a pure third capacitive current harmonic component, which is 2.12 mA. This process is repeated for all target harmonics, and the resulting set of capacitive current harmonic components is stored as a complete base in the database.

[0038] The full leakage current waveform, operating voltage waveform and ambient temperature data of the target surge arrester are collected in real time at any ambient temperature. The full leakage current waveform is decomposed into harmonics, and the initial capacitive harmonic substrate is used for preliminary separation to obtain the preliminary resistive harmonic spectrum.

[0039] Optionally, obtaining the preliminary resistive harmonic spectrum includes:

[0040] At any ambient temperature, the high-frequency current sensor and voltage sensor are activated to continuously collect and digitize the full leakage current waveform and operating voltage waveform of the target surge arrester, forming a real-time data stream.

[0041] The real-time data stream is segmented using a sliding time window, and the full leakage current waveform, the operating voltage waveform, and the ambient temperature are synchronized and aligned based on the fundamental zero-crossing point of the operating voltage waveform to generate a synchronized data frame in units of the fundamental voltage period.

[0042] Harmonic analysis is performed on the full leakage current waveform in each of the aforementioned synchronous data frames to analyze the full current harmonic vectors of each harmonic amplitude and phase.

[0043] Within the harmonic domain, the corresponding capacitive current harmonic vector in the initial capacitive harmonic substrate is successively subtracted from the total current harmonic vector to obtain the preliminary resistive harmonic spectrum.

[0044] Specifically, this step is used to acquire electrical and environmental information of the surge arrester in real time under any operating state. The processing equipment activates a high-frequency current sensor connected in series with the target surge arrester and a voltage sensor connected in parallel, while simultaneously activating an ambient temperature sensor. These sensors continuously acquire analog signals of the total leakage current, operating voltage, and ambient temperature readings at a high sampling frequency, and digitize these analog signals through an analog-to-digital converter to form a real-time data stream containing multi-dimensional information, providing raw data for subsequent synchronization and analysis. To achieve effective processing of continuous data, this method uses a sliding time window technique to segment the real-time data stream. The processing equipment identifies the fundamental component in the operating voltage waveform and captures its zero-crossing point as a time reference. Using this reference point as an anchor, the total leakage current waveform data, operating voltage waveform data, and corresponding ambient temperature readings within a complete voltage fundamental cycle are precisely time-aligned and correlated, encapsulated into a data packet, thus generating a synchronization data frame with accurate phase relationship. For each generated synchronization data frame, the processing equipment performs harmonic analysis on the total leakage current waveform data within it. The time-domain current waveform is transformed to the frequency domain, decomposing the fundamental wave and a series of higher harmonic components. The processing device parses the amplitude and phase information of each harmonic component from the transformation result and combines this information into a set of complex vectors, which constitute the total current harmonic vector. In the harmonic domain, the processing device aligns the total current harmonic vector parsed in the previous step with the previously stored initial capacitive harmonic substrate. For each harmonic order, the processing device subtracts the corresponding order of capacitive current harmonic vector stored in the initial capacitive harmonic substrate from the component of that order in the total current harmonic vector. The result of this vector subtraction operation is a new set of harmonic vectors, which theoretically only contain resistive components and temperature-induced distortion. This new set of harmonic vectors constitutes the preliminary resistive harmonic spectrum, such as... Figure 3 As shown, the total leakage current is a vector synthesis of a resistive component that is in phase with the voltage and a capacitive component that leads the voltage by 90 degrees.

[0045] For example, the current ambient temperature is detected to be 35 degrees Celsius. At this time, the high-frequency current sensor, voltage sensor, and temperature sensor are all operating continuously, collecting the total leakage current, operating voltage, and temperature readings to form a real-time data stream. The processing device monitors the fundamental waveform of the operating voltage in the real-time data stream, and when a fundamental zero-crossing point is detected, it immediately captures all sensor data within a complete power frequency cycle, i.e., 20 milliseconds, including the total leakage current waveform, operating voltage waveform, and the 35-degree Celsius temperature value. This data is packaged into a synchronous data frame. Next, the processing device performs harmonic analysis only on the total leakage current waveform in this data frame, resolving the total current harmonic vector. For example, the analysis yields a 3rd total current harmonic component of 2.5 mA with a phase of 105 degrees. The processing device retrieves the initial capacitive harmonic substrate previously established under reference low-temperature conditions from memory. Assume that the 3rd capacitive current harmonic component stored in the substrate is 2.12 mA with a phase of 100 degrees. Subsequently, the processing equipment performs a subtraction operation in the harmonic domain, subtracting the third capacitive current harmonic component in the substrate (2.12 mA, 100 degrees phase) from the currently acquired third full current harmonic component (2.5 mA, 105 degrees phase). The result of this vector subtraction operation is a new harmonic component, which is considered the third preliminary resistive harmonic component. This operation is performed on all target harmonics, including the fundamental, fifth, and seventh harmonics. Combining the results of all subtraction operations forms the preliminary resistive harmonic spectrum under the current 35-degree Celsius operating condition.

[0046] Optionally, the total current harmonic vector for analyzing the amplitude and phase of each harmonic includes:

[0047] The full leakage current waveform within the synchronous data frame is preprocessed to suppress spectral leakage and form a windowed current data sequence.

[0048] Perform a discrete frequency domain transformation on the current data sequence to calculate the discrete spectrum data of the corresponding fundamental frequency and integer multiple harmonic frequencies;

[0049] The amplitude and phase information corresponding to each harmonic are extracted from the discrete spectrum data, and the amplitude and phase information are combined to construct the full current harmonic vector.

[0050] Specifically, this step aims to improve the accuracy of subsequent frequency domain transformation. Since the truncation of the synchronous data frame may cause discontinuities in the waveform data at the start and end points of the time window, direct transformation can lead to spectral leakage, affecting the accuracy of harmonic analysis. To suppress this phenomenon, the processing device performs point-by-point multiplication preprocessing on the full leakage current waveform within the synchronous data frame. This processing smooths the amplitude at both ends of the data sequence, reducing the truncation effect, thus forming a windowed current data sequence. The processing device then performs a discrete frequency domain transformation algorithm, such as the Fast Fourier Transform, on the windowed current data sequence. This transformation converts the time-domain current data sequence into a frequency-domain representation, outputting a set of complex sequences, which is the discrete spectrum data. This discrete spectrum data reflects the energy distribution of the original current signal at multiple discrete frequency points, including the signal components of the fundamental frequency and its integer multiples of harmonic frequencies. The processing device locates the frequency points corresponding to the fundamental frequency and its integer multiples of harmonic frequencies within the calculated discrete spectrum data. For each located frequency point, the processing device calculates the magnitude and argument from its corresponding complex values ​​and performs amplitude correction based on the characteristics, thereby obtaining the precise amplitude and phase information of that harmonic. Finally, the amplitude and phase information corresponding to all target harmonic orders are systematically combined to construct a full current harmonic vector that can completely describe the characteristics of the current leakage current harmonics.

[0051] For example, the processing device acquires a synchronous data frame containing 20 milliseconds of full leakage current waveform data. Since this data frame is extracted from a continuous signal, the values ​​at the beginning and end may not be the same, leading to errors in direct analysis. To address this, the processing device first applies a smoothing process, such as a Hanning window function, to the current data sequence in this data frame. This operation slightly adjusts the data at both ends of the sequence, smoothly transitioning it to zero, thus forming a windowed current data sequence. Subsequently, the processing device performs a Fast Fourier Transform (FFT) on this windowed current data sequence. This transform converts the time-domain current waveform into discrete frequency spectrum data. This spectrum data shows the components of the current signal at different frequencies. The processing device then precisely locates positions such as the fundamental frequency of 50 Hz, the third harmonic frequency of 150 Hz, and the fifth harmonic frequency of 250 Hz from this spectrum data. For example, at the 150 Hz position, the processing device calculates a complex value and resolves the corresponding amplitude of 2.5 mA and phase of 105 degrees. At 250 Hz, the amplitude might be resolved to be 0.8 mA and the phase to be 130 degrees. The processing equipment extracts the amplitude and phase information of all target harmonics and combines them to construct a complete dataset, which is the total current harmonic vector, used for subsequent subtraction operations.

[0052] The amplitude and phase relationship of each harmonic component in the preliminary resistive harmonic spectrum are analyzed, the harmonic distortion caused by the coupling of temperature change and valve plate nonlinearity is quantified, and the nonlinear distortion feature vector of the current working condition deviating from the reference low temperature working condition is generated.

[0053] Optionally, generating the nonlinear distortion feature vector of the current operating condition deviating from the baseline low-temperature operating condition includes:

[0054] From the preliminary resistive harmonic spectrum, the fundamental resistive current component and the higher harmonic resistive current component are extracted, and the amplitude ratio and phase difference of the higher harmonic resistive current component relative to the fundamental resistive current component are calculated to form an initial distortion parameter set.

[0055] Based on the ambient temperature data and the temperature under the benchmark low-temperature stable operating condition, the temperature rise difference under the current operating condition is calculated.

[0056] By combining the initial distortion parameter set with the temperature rise difference, a temperature drift sensitivity coefficient is calculated for each parameter in the initial distortion parameter set;

[0057] The parameters in the initial distortion parameter set are combined with the corresponding temperature drift sensitivity coefficients to construct a nonlinear distortion feature vector.

[0058] Specifically, this step aims to extract core features reflecting the nonlinear characteristics of the valve plate from the initially separated resistive current harmonics. The processing equipment first identifies and extracts the fundamental resistive current component and several higher-order harmonic resistive current components sensitive to the valve plate state, such as the 3rd, 5th, and 7th harmonic components, from the initial resistive harmonic spectrum. Then, using the fundamental resistive current component as a reference, the amplitude ratio and phase difference between each higher-order harmonic component and the fundamental component are calculated. All calculated amplitude ratios and phase difference parameters are compiled into a set, forming the initial distortion parameter set characterizing the basic form of harmonic distortion under the current operating condition. To quantify the impact of temperature changes on the valve plate characteristics, the processing equipment reads the ambient temperature data contained in the current synchronization data frame and retrieves the temperature value recorded during the establishment of the initial capacitive harmonic substrate under the reference low-temperature stable operating condition. By subtracting the current ambient temperature data from the temperature value under the reference low-temperature stable operating condition, the temperature rise difference between the current operating condition and the reference operating condition is calculated. The processing equipment combines the temperature rise difference calculated in the previous step with the initial distortion parameter set, and calculates the temperature drift sensitivity coefficient for each parameter in the parameter set, such as the amplitude ratio or phase difference of the nth harmonic, using the following formula:

[0059] ,

[0060] in, The temperature drift sensitivity coefficient for a specific distortion parameter; These are the parameter values ​​obtained from the initial distortion parameter set under the current operating conditions; This is the theoretical reference value of the parameter under the reference low temperature stable operating condition. This reference value can be determined according to the design characteristics of the valve plate or taken as zero when there is no obvious distortion. This represents the temperature rise difference under the current operating conditions. The processing equipment systematically pairs and combines the parameters in the initial distortion parameter set, such as the amplitude ratio and phase difference of each harmonic, with their corresponding temperature drift sensitivity coefficients. All these parameter pairs are integrated into a multi-dimensional vector, thereby constructing a nonlinear distortion feature vector. Each dimension of this vector represents a temperature-quantified harmonic distortion feature, fully describing the nonlinear state of the arrester's resistive current under the current operating conditions and its response characteristics to temperature changes.

[0061] For example, the processing device extracts the fundamental resistive component and the third harmonic resistive component from the obtained preliminary resistive harmonic spectrum. The amplitude ratio of the third harmonic component relative to the fundamental component is calculated, for example, to be 0.8, and the phase difference is calculated, for example, to be 10 degrees. These parameters constitute the initial distortion parameter set. Simultaneously, the current ambient temperature of 35 degrees Celsius is read, and a reference temperature of 4 degrees Celsius is retrieved, calculating a temperature rise difference of 31 degrees Celsius. Next, a temperature drift sensitivity coefficient is calculated for the amplitude ratio of 0.8. This calculation uses the current value of 0.8, the theoretical reference value, and the temperature rise difference of 31. Finally, the amplitude ratio of 0.8 and its corresponding temperature drift sensitivity coefficient are combined as a data pair, along with all other parameter pairs, to form a multidimensional nonlinear distortion feature vector.

[0062] Optionally, the initial distortion parameter set includes: harmonic amplitude ratio parameter and harmonic phase difference parameter, wherein:

[0063] The harmonic amplitude ratio parameter is used to characterize the proportion of each higher harmonic energy in the total resistive current, reflecting the degree of bending of the valve plate's volt-ampere characteristic.

[0064] The harmonic phase difference parameter is used to characterize the lead of each higher harmonic component on the time axis, reflecting the hysteresis response characteristics of the valve plate material under an alternating electric field.

[0065] Specifically, the harmonic amplitude ratio parameter quantifies the degree of nonlinearity of the valve plate. The processing equipment extracts the amplitude of the fundamental resistive current component and the amplitudes of each higher-order harmonic resistive current component from the preliminary resistive harmonic spectrum. By dividing the amplitude of each higher-order harmonic component by the amplitude of the fundamental component, a dimensionless relative ratio is obtained, which is the harmonic amplitude ratio parameter. This parameter directly reflects the relative intensity of the higher-order harmonic energy generated by the nonlinear volt-ampere characteristics of the valve plate in the total resistive current; the more significant the curvature of the volt-ampere characteristics, the larger the value of this parameter. The harmonic phase difference parameter aims to quantify the dynamic response characteristics of the valve plate material. The processing equipment extracts the phase of the fundamental resistive current component and the phases of each higher-order harmonic resistive current component from the preliminary resistive harmonic spectrum. By calculating the phase difference between the phase of each higher-order harmonic component and the phase of the fundamental component, the harmonic phase difference parameter is obtained. This parameter characterizes the time lead of each higher-order harmonic component relative to the fundamental wave. Because actual valve plate materials exhibit hysteresis response characteristics under alternating electric fields, meaning that the polarization state of the material cannot instantaneously follow changes in the electric field, the current waveform is time-shifted. This parameter is a precise quantification of this dynamic effect.

[0066] For example, suppose the processing device extracts the fundamental resistive component with an amplitude of 100 microamps and a phase of 5 degrees from the preliminary resistive harmonic spectrum. Simultaneously, it extracts the third harmonic resistive component with an amplitude of 30 microamps and a phase of 15 degrees. The amplitude ratio parameter of the third harmonic is then calculated by dividing 30 microamps by 100 microamps, resulting in 0.3. This value of 0.3 reflects the degree of curvature in the valve plate's volt-ampere characteristic. Next, the phase difference parameter of the third harmonic is calculated by subtracting 5 degrees from 15 degrees, resulting in 10 degrees. This 10-degree difference reflects the hysteresis response characteristics of the valve plate material.

[0067] Optionally, the method further includes:

[0068] By combining the preliminary resistive harmonic spectrum and the nonlinear distortion eigenvector, a dynamic degradation assessment factor for the current valve plate health status is calculated and generated.

[0069] The dynamic degradation assessment factor is compared with multiple state reference values ​​derived from the baseline low temperature stable operating condition to determine and output the adaptive compensation mode identifier.

[0070] Specifically, this step aims to transform multi-dimensional harmonic characteristics into a single quantitative indicator of valve health. The processing equipment comprehensively utilizes the obtained preliminary resistive harmonic spectrum and nonlinear distortion eigenvector. Each component in the nonlinear distortion eigenvector, such as the amplitude ratio and phase difference parameters of each harmonic, is considered as a multi-dimensional indicator characterizing the valve plate's health status. Through weighted fusion calculations of these indicators, a single quantitative indicator is generated, namely, the dynamic degradation assessment factor of the current valve plate health status. The weight coefficients of each indicator can be determined through experimental data analysis based on the sensitivity of different harmonic components to the valve plate's degradation status. To provide a decision-making basis for subsequent adaptive compensation, the processing equipment requires a set of benchmarks for comparison, namely multiple state reference values. These state reference values ​​are derived and divided into multiple threshold intervals based on the dynamic degradation assessment factor calculated for the target surge arrester under baseline low-temperature stable operating conditions at the initial stage of method establishment, combined with industry standards and the equipment's design aging margin. These intervals define different health states of the valve plate, such as "healthy," "concerned," or "degraded." The processing device compares the dynamically deteriorated assessment factors calculated in real time with the threshold ranges of these state reference values, determines the range to which it belongs, and thus identifies and outputs a corresponding adaptive compensation mode identifier, which is used to guide the adjustment of subsequent compensation strategies.

[0071] For example, using the obtained nonlinear distortion feature vector, such as the third harmonic amplitude ratio of 0.3 and the third harmonic phase difference of 10 degrees, these indicators are fused to calculate a dynamic degradation assessment factor, assuming a value of 2.6. Simultaneously, multiple state reference values ​​are pre-stored internally; for example, a factor less than 2.0 is defined as "healthy," a factor between 2.0 and 4.0 is defined as "concerned," and a factor greater than 4.0 is defined as "deteriorated." Since the currently calculated factor of 2.6 falls within the "concerned" range, the processing device determines and outputs an adaptive compensation mode identifier for the "concerned" state to guide the next compensation step.

[0072] The nonlinear distortion feature vector is used as a correction operator to dynamically correct the initial capacitive harmonic substrate, generating a dynamically compensated capacitive harmonic spectrum that matches the current real-time operating conditions. The dynamic compensated capacitive harmonic spectrum is then used to perform harmonic domain subtraction on the full leakage current waveform to obtain the final resistive current harmonic vector after feedback correction.

[0073] Optionally, obtaining the feedback-corrected final resistive current harmonic vector includes:

[0074] The nonlinear distortion eigenvector is used as a correction operator and applied to the initial capacitive harmonic substrate to generate a preliminary dynamic compensation capacitive harmonic spectrum.

[0075] Based on the adaptive compensation mode identifier, the harmonic components in the preliminary dynamic compensation capacitive harmonic spectrum are adjusted by applying differentiated correction weights to obtain a dynamic compensation capacitive harmonic spectrum that matches the current real-time operating conditions.

[0076] Within the harmonic domain, the dynamically compensated capacitive harmonic spectrum is subtracted from the harmonic vector of the full leakage current waveform to generate the final resistive current harmonic vector after feedback correction.

[0077] Specifically, the processing device uses the previously generated nonlinear distortion eigenvector as the core correction operator, applying it to the stored initial capacitive harmonic substrate. The temperature and nonlinear coupling information contained in the nonlinear distortion eigenvector is used to adjust the amplitude and phase of each capacitive current harmonic vector in the initial capacitive harmonic substrate. The output of this process is a preliminary dynamically compensated capacitive harmonic spectrum, which initially reflects the impact of real-time ambient temperature on the surge arrester's capacitance characteristics. Based on the adaptive compensation mode identifier output from the previous step, the processing device calls upon a set of corresponding differentiated correction weights. These weights are applied to each harmonic component in the preliminary dynamically compensated capacitive harmonic spectrum for secondary correction. For example, when identified as a "deterioration" mode, the processing device may increase the correction intensity for certain aging-sensitive high-order harmonic components. After weighted adjustment, a dynamic compensated capacitive harmonic spectrum that highly matches the current real-time operating conditions, including temperature and valve plate health status, is finally obtained. The final step is to achieve precise separation within the harmonic domain. The processing equipment aligns the harmonic vector of the real-time acquired full leakage current waveform with the dynamically compensated capacitive harmonic spectrum obtained after two-step correction. By subtracting the corresponding component from the dynamically compensated capacitive harmonic spectrum from the harmonic components of the full current for each harmonic order, a set of pure resistive current harmonic components is obtained. The collection of these components constitutes the final resistive current harmonic vector after feedback correction.

[0078] For example, the nonlinear distortion eigenvector generated in the previous step is first used as a correction operator to correct the stored initial capacitive harmonic substrate. Assume the third capacitive harmonic in the substrate is 2.12 mA with a phase of 100 degrees. The information in the eigenvector adjusts it to 2.15 mA with a phase of 100.5 degrees, which is the preliminary dynamic compensation capacitive harmonic spectrum. Next, the adaptive compensation mode marker generated in the previous step is read as "focused". The correction weight corresponding to the "focused" mode is called to perform a second correction on the preliminary spectrum. For example, this weight multiplies the amplitude of the third harmonic by 1.01 and increases the phase by 0.5 degrees. Thus, the final dynamic compensation capacitive harmonic spectrum is determined to be 2.17 mA with a phase of 101 degrees. Finally, this final dynamic compensation spectrum is subtracted from the harmonic vector of the real-time total leakage current. The result of this vector subtraction is the clean, feedback-corrected third final resistive current harmonic component. This operation is performed on all harmonics to obtain the final resistive current harmonic vector.

[0079] Perform inverse harmonic transformation on the final resistive current harmonic vector to reconstruct the instantaneous resistive current waveform after wide-temperature-range compensation, and calculate the target resistive current characteristic value based on the instantaneous resistive current waveform.

[0080] Optionally, calculating the target resistive current characteristic value based on the instantaneous resistive current waveform includes:

[0081] The inverse discrete frequency domain transformation is performed on each harmonic component in the final resistive current harmonic vector, and then time domain superposition is performed to synthesize the instantaneous resistive current waveform.

[0082] Based on the instantaneous resistive current waveform, the peak value of the resistive current in the waveform sequence is extracted, and the effective value of the resistive current in the waveform sequence is calculated.

[0083] The peak value of the resistive current and the effective value of the resistive current are used together as the target resistive current characteristic value for output.

[0084] Specifically, the processing device performs an inverse discrete frequency domain transform, such as an inverse fast Fourier transform, on each harmonic component in the final resistive current harmonic vector. This operation converts each harmonic component from its amplitude and phase representation in the frequency domain back to its corresponding sinusoidal waveform in the time domain. Subsequently, the processing device superimposes the time-domain sinusoidal waveforms corresponding to all harmonic components point-by-point, combining them into a complete instantaneous resistive current waveform that reflects the actual change of resistive current over time. The processing device first iterates through all sampling points in the instantaneous resistive current waveform, finding the maximum absolute value and using this maximum value as the peak value of the compensated resistive current. Simultaneously, the processing device performs a root mean square operation on the values ​​of all sampling points in the instantaneous resistive current waveform; that is, it first calculates the sum of the squares of the values ​​at each sampling point and then takes the average, and finally takes the square root of this average to calculate the effective value of the compensated resistive current. The processing device combines the peak value of the compensated resistive current calculated in the previous step with the effective value of the compensated resistive current to form a dataset containing two core indicators. This dataset represents the final target resistive current characteristic value and is output to the monitoring interface or upper-level evaluation for the condition assessment and diagnosis of the surge arrester.

[0085] For example, the final resistive current harmonic vector generated in the previous step is obtained, which is a set containing fundamental, 3rd, 5th, and other harmonic components. An inverse fast Fourier transform is performed on this set to combine the frequency-domain harmonic components into a time-domain instantaneous resistive current waveform. This waveform is a sequence of current sampling points arranged in chronological order. The processing device then analyzes this waveform sequence. It iterates through all sampling points, finding the point with the largest absolute value, for example, 150 microamps, and records it as the peak resistive current. A root mean square operation is performed on the values ​​of all sampling points in the waveform sequence to calculate the effective value of the resistive current, for example, 80 microamps. Finally, the processing device packages the two calculation results, 150 microamps and 80 microamps, into a dataset and outputs it as the target resistive current characteristic value to the monitoring system for assessing the health status of the surge arrester.

[0086] Based on the same inventive concept, this invention also provides a wide-temperature-range compensation system for the resistive current of a surge arrester, such as... Figure 4 As shown, the system includes:

[0087] The initial harmonic substrate generation module is used to simultaneously collect reference waveform data of leakage current and operating voltage when the target surge arrester is under reference low temperature stable operating conditions, and extract and store the initial capacitive harmonic substrate with inherent capacitance characteristics through harmonic analysis.

[0088] The data acquisition and preliminary separation module is used to synchronously acquire the full leakage current waveform, operating voltage waveform and ambient temperature data of the target surge arrester under any ambient temperature in real time, perform harmonic decomposition on the full leakage current waveform, and perform preliminary separation using the initial capacitive harmonic substrate to obtain the preliminary resistive harmonic spectrum.

[0089] The thermal distortion calculation module is used to analyze the amplitude and phase relationship of each harmonic component in the preliminary resistive harmonic spectrum, quantify the harmonic distortion caused by the coupling of temperature change and valve plate nonlinear characteristics, and generate the nonlinear distortion feature vector of the current working condition deviating from the reference low temperature working condition.

[0090] The dynamic feedback correction module is used to use the nonlinear distortion feature vector as a correction operator to dynamically correct the initial capacitive harmonic substrate, generate a dynamic compensation capacitive harmonic spectrum that matches the current real-time operating conditions, and use the dynamic compensation capacitive harmonic spectrum to perform harmonic domain subtraction on the full leakage current waveform to obtain the final resistive current harmonic vector after feedback correction.

[0091] The waveform reconstruction and eigenvalue calculation module is used to perform inverse harmonic transformation on the final resistive current harmonic vector, reconstruct the instantaneous resistive current waveform after wide temperature range compensation, and calculate the target resistive current eigenvalue based on the instantaneous resistive current waveform.

[0092] To verify the feasibility and effectiveness of this invention in practice, it was applied to the online monitoring of zinc oxide surge arresters in a 500kV substation. This substation is located inland, experiencing significant seasonal temperature variations, with nighttime temperatures reaching -2°C in winter and daytime temperatures reaching 38°C in summer. Traditional resistive current measurement methods cannot effectively compensate for temperature effects, resulting in significant seasonal fluctuations in monitoring data and making it difficult to accurately assess the true health status of the surge arrester varistors. This embodiment aims to apply the method of this invention to perform wide-temperature-range compensation for the resistive current of the surge arrester, thereby achieving high-precision condition assessment.

[0093] In this embodiment, the monitoring device integrates a high-frequency current sensor, a high-precision voltage sensor, and an ambient temperature sensor to perform long-term monitoring of a 500kV surge arrester in operation. The processing equipment within the device automatically executes a series of steps, including data acquisition, harmonic basis construction, dynamic compensation, and eigenvalue calculation, according to the method of this invention.

[0094] To verify the beneficial effects of the present invention, monitoring data at two typical time points, February 2025 and August 2025, were recorded and compared with the results obtained by the traditional harmonic analysis method without wide temperature range compensation.

[0095] In the early morning of February 2025, the processing equipment detected that the ambient temperature remained consistently below the first temperature reference value, stabilizing at -2°C. Simultaneously, the fluctuation rate of the operating voltage waveform was less than the first stability reference value, confirming that the target surge arrester had entered the baseline low-temperature stable operating condition. Under this condition, the processing equipment collected multiple cycles of total leakage current and operating voltage waveforms to form baseline waveform data. By performing harmonic analysis on the baseline waveform data, the harmonic admittance under each harmonic was calculated, and its imaginary part was separated to obtain the harmonic susceptance value. Based on this, the processing equipment constructed a capacitive current harmonic vector containing the fundamental, 3rd, 5th, and 7th harmonics, and stored it as the personalized initial capacitive harmonic base for the surge arrester.

[0096] On an afternoon in August 2025, with an ambient temperature of 38°C, the processing equipment collected real-time data on total leakage current, operating voltage, and temperature, forming a real-time data stream. The equipment generated synchronous data frames based on the zero-crossing point of the fundamental voltage. For the total leakage current waveform in each data frame, harmonic analysis was performed to obtain the total current harmonic vector. Within the harmonic domain, this vector was subtracted from the initial capacitive harmonic basis stored in step one to obtain the preliminary resistive harmonic spectrum.

[0097] The processing equipment analyzes the preliminary resistive harmonic spectrum obtained in the previous step, calculating the amplitude ratio and phase difference of the 3rd and 5th harmonics relative to the fundamental wave, thus forming an initial distortion parameter set. At this point, the temperature rise difference is 40℃. Combining the distortion parameters under reference operating conditions, the temperature drift sensitivity coefficient of each parameter is calculated. Finally, by combining the amplitude ratio, phase difference, and their corresponding temperature drift sensitivity coefficients, a nonlinear distortion characteristic vector capable of quantifying the nonlinear coupling effect between temperature and the valve plate is constructed.

[0098] The processing equipment first integrates the preliminary resistive harmonic spectrum and the nonlinear distortion eigenvector to calculate a dynamic degradation assessment factor. This factor is compared with a state reference value derived from the baseline low-temperature stable operating condition, and the corresponding adaptive compensation mode identifier is output. Next, the generated nonlinear distortion eigenvector is used as a correction operator to dynamically correct the initial capacitive harmonic substrate, generating a preliminary dynamically compensated capacitive harmonic spectrum. Then, based on the adaptive compensation mode identifier, a set of differentiated correction weights for the "focused" state are invoked to perform a secondary correction on the preliminary spectrum, obtaining the final dynamically compensated capacitive harmonic spectrum. Finally, this dynamic spectrum is subtracted from the total current harmonic vector to obtain the final resistive current harmonic vector after feedback correction.

[0099] The processing device performs an inverse discrete frequency domain transform on the final resistive current harmonic vector and then performs time-domain superposition to reconstruct a clean instantaneous resistive current waveform. Based on this waveform, the peak value and effective value of the resistive current are calculated as the final evaluation indicators, i.e., the target resistive current characteristic value, and then output.

[0100] It should be noted that the functional division and information interaction between the various modules described above are logical, but in terms of physical implementation, they can be integrated on the same software platform or deployed in a distributed manner. The connections between them represent data flow and control flow, aiming to collaboratively achieve the objectives of this invention. The above descriptions are merely exemplary embodiments of this invention and should not be construed as limiting the scope of protection of this invention.

Claims

1. A wide-temperature-range compensation method for resistive current in a surge arrester, characterized in that, The method includes: Under the reference low temperature stable operating condition of the target surge arrester, the reference waveform data of leakage current and operating voltage are collected synchronously, and the initial capacitive harmonic basis of inherent capacitance characteristics is extracted and stored through harmonic analysis. The full leakage current waveform, operating voltage waveform and ambient temperature data of the target surge arrester are collected in real time at any ambient temperature. The full leakage current waveform is decomposed into harmonics, and the initial capacitive harmonic substrate is used for preliminary separation to obtain the preliminary resistive harmonic spectrum. The amplitude and phase relationship of each harmonic component in the preliminary resistive harmonic spectrum are analyzed, the harmonic distortion caused by the coupling of temperature change and valve plate nonlinearity is quantified, and the nonlinear distortion feature vector of the current working condition deviating from the reference low temperature working condition is generated. The nonlinear distortion feature vector is used as a correction operator to dynamically correct the initial capacitive harmonic substrate, generating a dynamically compensated capacitive harmonic spectrum that matches the current real-time operating conditions. The dynamic compensated capacitive harmonic spectrum is then used to perform harmonic domain subtraction on the full leakage current waveform to obtain the final resistive current harmonic vector after feedback correction. Perform inverse harmonic transformation on the final resistive current harmonic vector to reconstruct the instantaneous resistive current waveform after wide-temperature-range compensation, and calculate the target resistive current characteristic value based on the instantaneous resistive current waveform.

2. The wide-temperature-range compensation method for resistive current in a surge arrester according to claim 1, characterized in that, The initial capacitive harmonic substrate for extracting and storing inherent capacitance characteristics includes: Monitor the ambient temperature and operating voltage waveform of the target surge arrester, determine whether the ambient temperature is lower than the preset first temperature reference value and whether the fluctuation rate of the operating voltage waveform is less than the preset first stability reference value, and confirm that the target surge arrester has entered the reference low temperature stable operating condition. Under the aforementioned baseline low-temperature stable operating conditions, leakage current and operating voltage are continuously collected for multiple cycles to form baseline waveform data; Harmonic analysis is performed on the reference waveform data to calculate the harmonic admittance for each harmonic. The imaginary part of the harmonic admittance is separated to obtain the harmonic susceptance value of the capacitance characteristic at each harmonic frequency. Based on the harmonic susceptance value and the voltage harmonic vector in the reference waveform data, an initial capacitive harmonic substrate composed of capacitive current harmonic vectors is constructed and stored.

3. The wide-temperature-range compensation method for resistive current in a surge arrester according to claim 1, characterized in that, The preliminary resistive harmonic spectrum obtained includes: At any ambient temperature, the high-frequency current sensor and voltage sensor are activated to continuously collect and digitize the full leakage current waveform and operating voltage waveform of the target surge arrester, forming a real-time data stream. The real-time data stream is segmented using a sliding time window, and the full leakage current waveform, the operating voltage waveform, and the ambient temperature are synchronized and aligned based on the fundamental zero-crossing point of the operating voltage waveform to generate a synchronized data frame in units of the fundamental voltage period. Harmonic analysis is performed on the full leakage current waveform in each of the aforementioned synchronous data frames to analyze the full current harmonic vectors of each harmonic amplitude and phase. Within the harmonic domain, the corresponding capacitive current harmonic vector in the initial capacitive harmonic substrate is successively subtracted from the total current harmonic vector to obtain the preliminary resistive harmonic spectrum.

4. The wide-temperature-range compensation method for resistive current in a surge arrester according to claim 3, characterized in that, The total current harmonic vectors for analyzing the amplitude and phase of each harmonic include: The full leakage current waveform within the synchronous data frame is preprocessed to suppress spectral leakage and form a windowed current data sequence. Perform a discrete frequency domain transformation on the current data sequence to calculate the discrete spectrum data of the corresponding fundamental frequency and integer multiple harmonic frequencies; The amplitude and phase information corresponding to each harmonic are extracted from the discrete spectrum data, and the amplitude and phase information are combined to construct the full current harmonic vector.

5. The wide-temperature-range compensation method for resistive current in a surge arrester according to claim 1, characterized in that, The generation of the nonlinear distortion feature vector that deviates from the baseline low-temperature operating condition under the current operating condition includes: From the preliminary resistive harmonic spectrum, the fundamental resistive current component and the higher harmonic resistive current component are extracted, and the amplitude ratio and phase difference of the higher harmonic resistive current component relative to the fundamental resistive current component are calculated to form an initial distortion parameter set. Based on the ambient temperature data and the temperature under the benchmark low-temperature stable operating condition, the temperature rise difference under the current operating condition is calculated. By combining the initial distortion parameter set with the temperature rise difference, a temperature drift sensitivity coefficient is calculated for each parameter in the initial distortion parameter set; The parameters in the initial distortion parameter set are combined with the corresponding temperature drift sensitivity coefficients to construct a nonlinear distortion feature vector.

6. A wide-temperature-range compensation method for resistive current in a surge arrester according to claim 5, characterized in that, The initial distortion parameter set includes: harmonic amplitude ratio parameter and harmonic phase difference parameter, wherein: The harmonic amplitude ratio parameter is used to characterize the proportion of each higher harmonic energy in the total resistive current, reflecting the degree of bending of the valve plate's volt-ampere characteristic. The harmonic phase difference parameter is used to characterize the lead of each higher harmonic component on the time axis, reflecting the hysteresis response characteristics of the valve plate material under an alternating electric field.

7. The wide-temperature-range compensation method for resistive current in a surge arrester according to claim 1, characterized in that, The method further includes: By combining the preliminary resistive harmonic spectrum and the nonlinear distortion eigenvector, a dynamic degradation assessment factor for the current valve plate health status is calculated and generated. The dynamic degradation assessment factor is compared with multiple state reference values ​​derived from the baseline low temperature stable operating condition to determine and output the adaptive compensation mode identifier.

8. A wide-temperature-range compensation method for resistive current in a surge arrester according to claim 7, characterized in that, The process of obtaining the final resistive current harmonic vector after feedback correction includes: The nonlinear distortion eigenvector is used as a correction operator and applied to the initial capacitive harmonic substrate to generate a preliminary dynamic compensation capacitive harmonic spectrum. Based on the adaptive compensation mode identifier, the harmonic components in the preliminary dynamic compensation capacitive harmonic spectrum are adjusted by applying differentiated correction weights to obtain a dynamic compensation capacitive harmonic spectrum that matches the current real-time operating conditions. Within the harmonic domain, the dynamically compensated capacitive harmonic spectrum is subtracted from the harmonic vector of the full leakage current waveform to generate the final resistive current harmonic vector after feedback correction.

9. A wide-temperature-range compensation method for resistive current in a surge arrester according to claim 1, characterized in that, The calculation of the target resistive current characteristic value based on the instantaneous resistive current waveform includes: The inverse discrete frequency domain transformation is performed on each harmonic component in the final resistive current harmonic vector, and then time domain superposition is performed to synthesize the instantaneous resistive current waveform. Based on the instantaneous resistive current waveform, the peak value of the resistive current in the waveform sequence is extracted, and the effective value of the resistive current in the waveform sequence is calculated. The peak value of the resistive current and the effective value of the resistive current are used together as the target resistive current characteristic value for output.

10. A wide-temperature-range compensation system for the resistive current of a surge arrester, applied to the wide-temperature-range compensation method for the resistive current of a surge arrester as described in any one of claims 1-9, characterized in that, The system includes: The initial harmonic substrate generation module is used to simultaneously collect reference waveform data of leakage current and operating voltage when the target surge arrester is under reference low temperature stable operating conditions, and extract and store the initial capacitive harmonic substrate with inherent capacitance characteristics through harmonic analysis. The data acquisition and preliminary separation module is used to synchronously acquire the full leakage current waveform, operating voltage waveform and ambient temperature data of the target surge arrester under any ambient temperature in real time, perform harmonic decomposition on the full leakage current waveform, and perform preliminary separation using the initial capacitive harmonic substrate to obtain the preliminary resistive harmonic spectrum. The thermal distortion calculation module is used to analyze the amplitude and phase relationship of each harmonic component in the preliminary resistive harmonic spectrum, quantify the harmonic distortion caused by the coupling of temperature change and valve plate nonlinear characteristics, and generate the nonlinear distortion feature vector of the current working condition deviating from the reference low temperature working condition. The dynamic feedback correction module is used to use the nonlinear distortion feature vector as a correction operator to dynamically correct the initial capacitive harmonic substrate, generate a dynamic compensation capacitive harmonic spectrum that matches the current real-time operating conditions, and use the dynamic compensation capacitive harmonic spectrum to perform harmonic domain subtraction on the full leakage current waveform to obtain the final resistive current harmonic vector after feedback correction. The waveform reconstruction and eigenvalue calculation module is used to perform inverse harmonic transformation on the final resistive current harmonic vector, reconstruct the instantaneous resistive current waveform after wide temperature range compensation, and calculate the target resistive current eigenvalue based on the instantaneous resistive current waveform.

Images