Intelligent monitoring method and system for resistive current of lightning arrester based on real-time analysis

Abstract

The present application relates to the technical field of lightning arrester resistive current monitoring, in particular to a lightning arrester resistive current intelligent monitoring method and system based on real-time analysis. The method comprises the following steps: real-time acquisition of analog signals and conversion into full current signals and PT voltage signals. According to the phase shift of the disturbed voltage fundamental wave phase and the full current fundamental wave phase, the amplitude deviation is calculated by obtaining the substation PT secondary voltage nominal value and the effective value of the disturbed PT voltage. According to the amplitude deviation and the substation PT secondary voltage nominal value, the amplitude deviation rate is calculated. Based on the phase shift of the disturbed PT voltage and the amplitude deviation rate, the disturbed PT voltage signal is corrected point by point, so as to obtain the compensated PT voltage signal, so that the measurement accuracy of the resistive current can quickly recover and stabilize at the designed high standard, thereby improving the measurement accuracy, avoiding the false judgment or missed judgment of the lightning arrester fault caused by signal deviation, and improving the fault diagnosis confidence.

Description

Technical Field

[0001] This invention relates to the field of resistive current monitoring technology for surge arresters, and more specifically, to a method and system for intelligent monitoring of resistive current for surge arresters based on real-time analysis. Background Technology

[0002] Metal oxide surge arresters are core and critical equipment for the safe and stable operation of power equipment. The resistive current of the surge arrester is a core indicator for measuring its insulation level. The intelligent monitoring method of resistive current for surge arresters based on real-time analysis is applied to the field of real-time monitoring of the insulation status of metal oxide surge arresters in power systems. This method collects the total leakage current of the surge arrester and the secondary voltage signal of the PT on the bus where the surge arrester is located in real time, while monitoring the operating data of the surge arrester. The collected electrical signals are analyzed and processed to complete the decomposition of the resistive and capacitive components of the surge arrester leakage current, and extract the key characteristic parameters of the fundamental and harmonic increments of the resistive current. This allows for the timely detection of potential insulation faults such as moisture and aging of the surge arrester, providing a scientific and reliable data basis for the operation and maintenance of the surge arrester.

[0003] Currently, in the field of intelligent monitoring of resistive current in surge arresters, electrical signal acquisition is mainly achieved by equipping the sampling end with conventional high-precision current / voltage sensors. Signal transmission and anti-interference are only achieved through hardware-level cast aluminum / metal shielded housings, power / signal isolation modules, and double-shielded twisted-pair cables. The existing technology uses the combination of external PT secondary voltage signal and surge arrester full current signal for calculation, and uniformly uses the PT secondary voltage signal output by the external bus voltage monitoring device as the sole reference signal. The resistive and capacitive components of the surge arrester leakage current are decomposed using the phasor decomposition method. The fundamental and harmonic increments of the resistive current are used as the core fault characteristics for judging internal moisture and aging of the resistor elements in the surge arrester.

[0004] In actual substation engineering applications, the aforementioned existing technologies inevitably produce significant defects under the requirements of high-precision monitoring of power systems due to the inherent limitations of the technology design specific to the industry.

[0005] First, the core operational logic of existing technologies all heavily rely on the secondary voltage signal of the PT output by the external bus voltage monitoring device, using it as the sole reference for decomposing the resistance and capacitance components of the surge arrester leakage current and calculating the resistive current. The technology design inherently has a strong dependence on external signals and lacks an independent signal calibration reference design.

[0006] Secondly, existing anti-interference measures are limited to basic hardware-level shielding and isolation protection, lacking real-time detection and self-compensation mechanisms for PT voltage signal amplitude deviation and phase shift at the algorithm level. This is an inherent design shortcoming of conventional technologies in the field of surge arrester resistive current monitoring. Thirdly, there are numerous sources of interference in substations, including power frequency harmonics, electromagnetic radiation, and electromagnetic coupling of equipment. Such interference directly affects the entire process of PT secondary voltage signal acquisition and transmission, inevitably causing amplitude deviation and phase shift in the reference signal, thus compromising the original accuracy of the signal.

[0007] Finally, since traditional surge arresters lack any real-time signal deviation self-compensation mechanism, they can only directly substitute the distorted secondary voltage signal of the PT after interference into the core calculation of resistive-capacitive component decomposition and resistive current calculation. This leads to a decrease in the measurement accuracy of the surge arrester's resistive current. Furthermore, because the characteristic parameters of the distorted resistive current fundamental and harmonic increments cannot truly reflect the actual insulation state of the surge arrester, it is very easy to cause misjudgments and omissions of surge arrester moisture and aging faults. Ultimately, it cannot meet the high-precision monitoring requirements of surge arrester insulation state in the current power system's development towards intelligence. Therefore, we provide a real-time analysis-based intelligent monitoring method and system for resistive current of surge arresters. Summary of the Invention

[0008] The purpose of this invention is to provide a method and system for intelligent monitoring of resistive current in surge arresters based on real-time analysis, so as to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, one objective of this invention is to provide a method for intelligent monitoring of resistive current in surge arresters based on real-time analysis, comprising the following method steps:

[0010] S1. Real-time acquisition of analog signals and input to AD converter to obtain digitized full current signal and PT voltage signal, and then recording sampling timestamps to calculate phase synchronization error;

[0011] S2. Input the full current signal and PT voltage signal into the digital notch filter to obtain the filtered full current signal and the disturbed PT voltage signal;

[0012] S3. Perform Fourier transform on the full current signal and the disturbed PT voltage signal, extract the effective value of the full current and calculate the phase offset of the disturbed PT voltage, and correct the disturbed PT voltage signal point by point based on the phase offset of the disturbed PT voltage to obtain the compensated PT voltage signal.

[0013] S4. Perform phase pre-correction on the PT voltage signal to obtain the corrected PT voltage signal and perform joint compensation to obtain the compensated corrected PT voltage signal.

[0014] S5. Perform Fourier transform on the compensated PT voltage signal or the compensated PT voltage signal and calculate the effective value of the fundamental wave of the resistive current. Calculate the harmonic increment and the fundamental wave increment according to the effective value of the fundamental wave of the resistive current. Use the harmonic increment and the fundamental wave increment to determine the state of the surge arrester.

[0015] As a further improvement to this technical solution, obtaining the digitized full current signal and PT voltage signal includes the following method steps:

[0016] The system acquires raw current and voltage analog signals, obtains the maximum time deviation preset in the database, and then filters out the maximum phase synchronization error that is less than or equal to the maximum time deviation.

[0017] The original analog current signal is converted into a continuous analog voltage signal, which is then synchronously input into the AD converter along with the original analog voltage signal. The instantaneous amplitude of the continuous analog voltage signal and the original analog voltage signal is automatically captured.

[0018] The instantaneous amplitude of the analog signal is mapped to a discrete binary digital quantity, thereby generating a set of current and voltage digital quantities corresponding to the time moment, which are defined as the digitized full current signal and PT voltage signal, respectively.

[0019] As a further improvement to this technical solution, the process of obtaining the filtered full current signal and the disturbed PT voltage signal includes the following steps:

[0020] The full current signal and PT voltage signal are input into a digital notch filter to construct an attenuation channel at a frequency of 50Hz and attenuate the harmonic components derived from the 50Hz power frequency fundamental wave in the two signals, and output intermediate current and voltage signals.

[0021] Using the db4 wavelet as the basis function, the intermediate current and voltage signals are decomposed into three levels of approximate and detail components. The absolute value wavelet coefficients are extracted, and the wavelet coefficients are processed by elimination and retention based on the absolute value wavelet coefficients to obtain the processed approximate and detail components.

[0022] The processed approximate components and detail components are subjected to inverse wavelet transform to automatically reconstruct the intermediate current and voltage signals that have been freed from high-frequency electromagnetic interference, and these signals are defined as the filtered full current signal and the interfered PT voltage signal, respectively.

[0023] As a further improvement to this technical solution, the extraction of the RMS value of the total current includes the following method steps:

[0024] Step 1: Sample points from arrive Iterate through the full current signal corresponding to each sampling point. and Multiply them, then sum all the products together. This refers to the total number of discrete sampling points of the full current signal;

[0025] Step 2: Sample points from arrive Traverse the total current signal corresponding to each sampling point. and Multiply them, then sum all the products together;

[0026] Step 3: Square the two sums above and add them together. Multiply the sum by [missing information]. Then, take the square root of the final result to obtain the RMS value of the fundamental component of the total current. The specific algorithm formula for the effective value of the total current fundamental component is as follows:

[0027] ;

[0028] It also includes the following method steps for phasing the fundamental frequency of the entire current:

[0029] Take the second accumulated term from step 2 above as the numerator and the first accumulated term as the denominator, and calculate the ratio between the two based on the numerator and the denominator.

[0030] The fundamental phase of the total current component is obtained by performing an arctangent function operation on the comparison value. The specific algorithm formula for the phase of the fundamental wave of the full current is as follows: .

[0031] As a further improvement to this technical solution, the compensated PT voltage signal includes the following method steps:

[0032] Based on the fact that the fundamental phase of the total current of the surge arrester leads the fundamental phase of the normal PT voltage under normal operating conditions. Based on the inherent electrical characteristics of the PT, the phase offset of the PT voltage is calculated according to the fundamental phase of the PT voltage and the fundamental phase of the full current.

[0033] Obtain the nominal value of the secondary voltage of the substation PT, calculate the amplitude deviation of the affected PT voltage with the effective value of the affected PT voltage, and calculate the amplitude deviation rate based on the amplitude deviation and the nominal value of the secondary voltage of the substation PT.

[0034] Phase shift based on the disturbed PT voltage and amplitude deviation rate For the disturbed PT voltage signal Point-by-point correction is performed to obtain the compensated PT voltage signal. Specific algorithm formula:

[0035] ;in, This refers to the power frequency angular frequency.

[0036] As a further improvement to this technical solution, the corrected PT voltage signal includes the following method steps:

[0037] The maximum phase synchronization error is used as the maximum phase synchronization error threshold. The maximum phase synchronization error threshold and the phase synchronization error are used to determine whether to perform phase pre-correction on the digitized PT voltage signal.

[0038] When the phase synchronization error exceeds the maximum phase synchronization error threshold, it is determined that phase pre-correction should be performed on the digitized PT voltage signal to obtain the corrected PT voltage signal. Specific algorithm formula:

[0039] ,in, This refers to the imaginary unit, which in electrical engineering and signal processing is defined as follows: , This refers to phase synchronization error.

[0040] As a further improvement to this technical solution, the compensated PT voltage signal includes the following method steps:

[0041] The corrected PT voltage signal is input into a digital notch filter, and the filtered corrected PT voltage signal is output. ;

[0042] Call the phase offset of the disturbed PT voltage and amplitude deviation rate The filtered corrected PT voltage signal is jointly compensated to obtain the compensated corrected PT voltage signal. Specific algorithm formula:

[0043] ,in, This is the amplitude deviation rate compensation coefficient. This is the phase offset compensation term.

[0044] As a further improvement to this technical solution, the calculation of the fundamental and effective values ​​of the resistive current and capacitive current, and the construction of the fundamental and capacitive current phasors, include the following method steps:

[0045] Perform a Fast Fourier Transform on the compensated PT voltage signal or the compensated PT voltage signal to extract parameters;

[0046] Based on parameters, the compensated PT voltage signal or the compensated PT voltage signal is converted into the fundamental phasor of the compensated PT voltage or the fundamental phasor of the compensated PT voltage. Based on the effective value of the total current and the fundamental phase of the total current, the total current signal is converted into the fundamental phasor of the total current.

[0047] The phase difference is calculated based on the fundamental phase of the full current and the fundamental phase of the corrected or compensated PT voltage, and the effective value of the fundamental resistive current is calculated based on the phase difference and the effective value of the full current.

[0048] Construct the fundamental phasor of the resistive current based on the effective value of the fundamental wave of the resistive current and the fundamental phase of the corrected or compensated PT voltage;

[0049] The effective value of capacitive current is calculated based on the phase difference and the effective value of the total current. The fundamental phase phasor of capacitive current is constructed based on the effective value of capacitive current and the fundamental phase of the corrected or compensated PT voltage.

[0050] As a further improvement to this technical solution, the calculation of the resistance-capacitance ratio, harmonic increment, and fundamental frequency increment includes the following steps:

[0051] The resistance-capacitance ratio is calculated based on the fundamental phasor of resistive current and the fundamental phasor of capacitive current.

[0052] Perform a fast Fourier transform on the full current signal again to obtain the fundamental phasor of the resistive current. After superimposing these phasors, the effective value of the harmonic components of the resistive current is obtained.

[0053] The fundamental frequency increment and harmonic frequency increment are calculated based on the effective value of the fundamental frequency of the resistive current and the effective value of the harmonic components of the resistive current, respectively.

[0054] By using the fundamental frequency increment, harmonic frequency increment, and resistance-capacitance ratio to set a dynamic early warning threshold, the surge arrester is determined to be in a normal state, an early warning state, or a fault state.

[0055] The second objective of this invention is to provide a system for operating the real-time analysis-based intelligent monitoring method for resistive current in surge arresters, including any of the above-mentioned methods. The system includes a digital signal unit that acquires analog signals in real time and inputs them to an AD converter to obtain digitized full current signals and PT voltage signals, and then records the sampling timestamps to calculate the phase synchronization error. The system further includes:

[0056] The filtering signal unit is used to receive the full current signal and PT voltage signal from the digital signal unit and input them into the digital notch filter to obtain the filtered full current signal and the disturbed PT voltage signal.

[0057] The extraction compensation unit is used to receive the full current signal and the disturbed PT voltage signal from the filter signal unit and perform Fourier transform to extract the effective value of the full current and calculate the phase offset of the disturbed PT voltage. Based on the phase offset of the disturbed PT voltage, the disturbed PT voltage signal is corrected point by point to obtain the compensated PT voltage signal.

[0058] The correction and compensation unit is used to receive the PT voltage signal in the digital signal unit and perform phase pre-correction to obtain the corrected PT voltage signal and perform joint compensation to obtain the compensated corrected PT voltage signal.

[0059] The monitoring status unit is used to receive the compensated PT voltage signal after compensation in the correction and compensation unit or extract the compensated PT voltage signal after compensation in the compensation unit, perform Fourier transform, calculate the effective value of the fundamental wave of the resistive current, calculate the harmonic increment and the fundamental wave increment based on the effective value of the fundamental wave of the resistive current, and use the harmonic increment and the fundamental wave increment to determine the status of the surge arrester.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] 1. In this intelligent resistive current monitoring method and system for surge arresters based on real-time analysis, the fundamental phase of the total current of the surge arrester under normal operating conditions leads the fundamental phase of the normal PT voltage. Based on the inherent electrical characteristics of the PT, the phase offset of the disturbed PT voltage is calculated according to the fundamental phase of the disturbed voltage and the fundamental phase of the total current. Then, the nominal value of the secondary voltage of the substation PT is obtained, and the amplitude deviation of the disturbed PT voltage is calculated with the effective value of the disturbed PT voltage. The amplitude deviation rate is calculated based on the amplitude deviation and the nominal value of the secondary voltage of the substation PT. Based on the phase offset and amplitude deviation rate of the disturbed PT voltage... The interfered PT voltage signal is corrected point by point to obtain the compensated PT voltage signal. Utilizing the inherent characteristics of the fundamental phase of the total current of the surge arrester as a reference source unaffected by the same electromagnetic interference, the amplitude deviation and phase shift of the interfered PT voltage signal are calculated and corrected point by point in real time. This makes the decomposed PT voltage signal infinitely close to a pure and unbiased ideal signal, enabling the measurement accuracy of resistive current to be quickly restored and stabilized, thereby improving measurement accuracy. At the same time, it avoids misjudgment or omission of surge arrester faults caused by signal deviation, thus improving the confidence of fault diagnosis.

[0062] 2. In this real-time analysis-based intelligent monitoring method and system for resistive current in surge arresters, the maximum phase synchronization error is used as the maximum phase synchronization error threshold. The maximum phase synchronization error threshold and the phase synchronization error are used to perform phase pre-correction on the digitized PT voltage signal, thereby obtaining the corrected PT voltage signal. The corrected PT voltage signal is then input into a digital notch filter, outputting a filtered corrected PT voltage signal. The phase offset and amplitude deviation rate of the disturbed PT voltage are used to jointly compensate the filtered corrected PT voltage signal, resulting in a compensated corrected PT voltage signal. Based on direct compensation using inherent characteristics, front-end phase pre-correction and digital notch filtering are added, forming a three-stage series correction and compensation effect. This significantly improves the amplitude accuracy and phase authenticity of the resistive current separated from the total current of the surge arrester, enhancing the decomposition accuracy and stability of the resistive current. Attached Figure Description

[0063] Figure 1 This is an overall block diagram of the present invention;

[0064] Figure 2 This is a flowchart of the present invention.

[0065] The meanings of the labels in the diagram are as follows:

[0066] 1. Digital signal processing unit; 2. Filtering signal processing unit; 3. Extraction and compensation unit;

[0067] 4. Calibration and compensation unit; 5. Monitoring status unit. Detailed Implementation

[0068] The technical solutions in 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, and 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.

[0069] Example 1

[0070] Please see Figures 1-2 As shown, one of the objectives of this embodiment is to provide a method for intelligent monitoring of resistive current in surge arresters based on real-time analysis, including the following method steps:

[0071] S1 includes the following method steps:

[0072] Through intelligent sensors (current sensors with a resolution of [missing information]) ))by Sampling period Real-time acquisition of raw current simulation signals of the total leakage current of surge arresters Simultaneously, the original analog voltage signal of the PT secondary voltage is acquired through a smart sensor (voltage sensor). Record current sampling timestamps and voltage sampling timestamp The time difference is calculated based on the current and voltage sampling timestamps. Then based on the time difference and sampling period Calculate phase synchronization error Phase synchronization error algorithm formula: Obtain the maximum time deviation preset in the database. The maximum phase synchronization error, which is less than or equal to the maximum time deviation, is selected by using the phase synchronization error and the maximum time deviation as the basis for subsequent phase correction.

[0073] A smart sensor (current sensor) is used to convert the original analog current signal into a continuous analog voltage signal that conforms to the input range of the A / D converter. This continuous analog voltage signal is then synchronously input into the A / D converter along with the original analog voltage signal. Conversion frequency (sampling period) The continuous analog voltage signal and the original analog voltage signal are synchronously triggered for instantaneous sampling. The sampling period corresponds to the number of sampling times. Next, sampling points Calculate the sampling time corresponding to the sampling point based on the sampling point and the sampling period. Simultaneously, the A / D converter automatically captures the instantaneous amplitude of the continuous analog voltage signal and the original analog voltage signal to obtain the instantaneous amplitude of the analog signal. The instantaneous amplitude of the analog signal is then processed by a 16-bit A / D converter—16 bits represent the quantization precision (total...). (each level), the AD converter maps the instantaneous amplitude of the analog signal to... The discrete binary digital quantities within the range are used to complete the conversion from analog to digital signals. Then, the binary digital quantities are converted into corresponding physical quantity values. Finally, according to the sampling timing sequence, a set of current and voltage digital quantities corresponding to each moment is automatically generated after each AD conversion. The digital current obtained from the second sampling conversion is defined as the digitized full current signal. At the same time, the digital voltage quantity is defined as the digitized PT voltage signal. .

[0074] S2 includes the following method steps:

[0075] The digitized full current signal and PT voltage signal are input into a digital notch filter. The digital notch filter constructs an attenuation channel at a 50Hz frequency point, automatically identifying and attenuating the harmonic components (2nd and 3rd harmonics) derived from the 50Hz power frequency fundamental wave in both signals. Then, targeted attenuation and suppression of these harmonic components are performed. During this targeted attenuation and suppression process, while retaining the effective electrical components of both signals, noise interference from the harmonic components derived from the 50Hz power frequency fundamental wave is eliminated. This completes the pre-filtering processing of the digitized full current signal and PT voltage signal, ultimately outputting a pre-purified intermediate current signal free of significant power frequency harmonic interference. and intermediate voltage signal Then, wavelet decomposition is automatically performed on the intermediate current and voltage signals. Using the db4 wavelet as the basis function, the intermediate current and voltage signals are decomposed into three levels of approximate components (low-frequency components, corresponding to the effective main body of the signal) and detail components (high-frequency components, corresponding to high-frequency electromagnetic interference), thus completing the frequency domain layering of the signal. After the intermediate current and voltage signals are decomposed into three levels of wavelet decomposition using the db4 wavelet as the basis function, each level of detail component will output a set of discrete wavelet coefficients. By traversing each wavelet coefficient in a certain level of detail component, and then performing an absolute value operation on each wavelet coefficient, the absolute value of the wavelet coefficients is obtained.

[0076] Based on the minimization risk criterion, the soft thresholds of each layer of detail components are automatically calculated, and soft threshold quantization is performed on the detail components: wavelet coefficients with absolute values ​​less than the soft threshold are set to 0 to remove high-frequency interference; wavelet coefficients with absolute values ​​greater than the soft threshold are retained after subtracting the soft threshold to preserve effective signal features; approximate components remain unchanged. This yields the filtered and denoised approximate and detail components, which are then processed. An inverse wavelet transform is performed on the processed approximate and detail components to automatically reconstruct the intermediate current signal that has had high-frequency electromagnetic interference removed. and intermediate voltage signal This process yields reconstructed current and voltage signals, ensuring that the reconstructed current and voltage signals are perfectly time-aligned with the continuous analog voltage signal and the original analog voltage signal, respectively. Subsequently, the consistency of the sampling points of the two reconstructed signals is verified, and the intermediate current signal is... Defined as the filtered full current signal Then the intermediate voltage signal Defined as the filtered disturbed PT voltage signal ;

[0077] S3 includes the following method steps:

[0078] When the filtered full current signal and the disturbed PT voltage signal are obtained, the surge arrester state self-diagnosis and reference adaptive switching are performed first:

[0079] Obtain the initial value of the fundamental resistive current during normal operation of the surge arrester. (Referring to the average fundamental effective value of the resistive current during the first 72 hours of operation) as a benchmark, the initial value of the resistive current harmonics is obtained synchronously. (The effective value of the average resistive current harmonic components during the first 72 hours of operation of the device), and then perform a Fast Fourier Transform (FFT) on the filtered full current signal again to locate the fundamental current phasors corresponding to the 3rd (150Hz), 5th (250Hz), and 7th (350Hz) harmonics. , , Then, using the fundamental phasor of the corrected and compensated PT voltage or the fundamental phasor of the compensated PT voltage as a reference, the fundamental phasors of each harmonic current are projected onto the in-phase direction of the fundamental phasor of the corrected and compensated PT voltage or the fundamental phasor of the compensated PT voltage, respectively, to obtain the fundamental phasor of the resistive current corresponding to each harmonic. , , The effective values ​​of the fundamental frequency of each harmonic resistive current are extracted and superimposed to obtain the effective values ​​of the resistive current harmonic components. Based on the fundamental effective value of the resistive current Calculate the fundamental frequency increment from the initial value of the resistive current fundamental frequency. Then, the harmonic increment is calculated based on the effective value of the resistive current harmonic component and the initial value of the resistive current harmonic. ;

[0080] via fundamental frequency increment Harmonic increment The surge arrester undergoes self-diagnosis: when the fundamental frequency increment is less than or equal to 20% and the harmonic frequency increment is less than or equal to 30%, the surge arrester is determined to have no inherent fault, and the inherent characteristic of the full current fundamental frequency phase (leading the normal PT voltage fundamental frequency phase by 90°) is valid, and the full current fundamental frequency phase continues to be used as the calibration reference; when the fundamental frequency increment is greater than 20% or the harmonic frequency increment is greater than 30%, the surge arrester is determined to have a real fault, and it automatically switches back to the traditional PT reference (the interference-free PT secondary voltage signal output by the external bus voltage monitoring device), skipping the subsequent PT voltage compensation process based on the full current fundamental frequency phase reference, and directly entering the S5 fault determination;

[0081] After completing the reference switching, the full current signal is automatically processed. Performing a Fast Fourier Transform (FFT) automatically converts the discrete-time current signal into frequency-domain complex components. These frequency-domain complex components contain the amplitude and phase characteristics of each frequency component in the signal. Then, from the transformed frequency-domain complex components, the signal is automatically located... The frequency components corresponding to the fundamental power frequency, and based on The frequency component corresponding to the power frequency fundamental wave is automatically calculated, and the effective value of the total current fundamental wave component is extracted. Phase of the full current fundamental frequency The extraction of the RMS value of the total current includes the following steps:

[0082] Step 1: Sample points from arrive Iterate through the filtered full current signal corresponding to each sampling point. and Multiply them, then sum all the products together. This refers to the total number of discrete sampling points of the full current signal;

[0083] Step 2: Sample points from arrive Iterate through the filtered full current signal corresponding to each sampling point. and Multiply them, then sum all the products together;

[0084] Step 3: Square the two sums above and add them together. Multiply the sum by [missing information]. Then, take the square root of the final result to obtain the RMS value of the fundamental component of the total current. The specific algorithm formula for the effective value of the total current fundamental component is as follows:

[0085] ;

[0086] Extracting the fundamental phase of the total current includes the following steps:

[0087] Take the second cumulative term (sine term summation) from step 2 above as the numerator, and the first cumulative term (cosine term summation) as the denominator, and calculate the ratio between the two based on the numerator and denominator;

[0088] Perform the arctangent function by comparing the values ​​( The operation yields the fundamental phase of the total current fundamental component. The specific algorithm formula for the phase of the fundamental wave of the full current is as follows: ;

[0089] Simultaneously, upon obtaining the filtered disturbed PT voltage signal, a Fast Fourier Transform (FFT) is automatically performed on the disturbed PT voltage signal to extract the effective value of the disturbed PT voltage. and the fundamental phase of the disturbed PT voltage The steps for extracting the RMS value and fundamental phase of the disturbed PT voltage are the same as those for extracting the RMS value and fundamental phase of the total current.

[0090] Obtain the fundamental phase of the normal PT voltage If the current mode is the full-current fundamental phase reference mode (the surge arrester itself is fault-free), the initial phase difference is based on the calibration done 72 hours after the first commissioning. (ideal value) (Actual measured value), calculated based on the fundamental phase of the total current and the fundamental phase of the disturbed PT voltage. Set the allowable fluctuation range of phase difference (Adapting to slight influences from environmental factors such as temperature, humidity, and dirt levels), if the actual phase difference is within the allowable fluctuation range of the phase difference, then the determination is made. The core characteristics of the leading relationship remain valid, and the full-current fundamental phase continues to be used as the calibration reference. If the actual phase difference exceeds the allowable fluctuation range of the phase difference (indicating that the full-current fundamental phase relationship has been distorted due to early faults or severe environmental influences), it automatically switches to the traditional PT reference (the interference-free PT secondary voltage signal output by the external bus voltage monitoring device), and stops using the traditional PT reference (interference-free PT secondary voltage signal output by the external bus voltage monitoring device). The reference PT voltage is compensated to avoid introducing systematic errors;

[0091] Based on the fact that the fundamental phase of the total current of the surge arrester leads the fundamental phase of the normal PT voltage under normal operating conditions... The inherent electrical characteristics of ", based on the fundamental phase of the interfered voltage Phase of the fundamental current Phase with the fundamental frequency of normal PT voltage Automatically calculate the phase shift of the disturbed PT voltage Then obtain the nominal value of the secondary voltage of the substation PT. (usually) ), and the effective value of the disturbed PT voltage Combined with calculation of the amplitude deviation of the disturbed PT voltage Based on the amplitude deviation of the disturbed PT voltage and the nominal value of the secondary voltage of the substation PT Calculate amplitude deviation rate Quantify the degree of amplitude deviation, and then according to Calculate the power frequency angular frequency based on the frequency components corresponding to the fundamental power frequency. Phase offset based on the disturbed PT voltage and amplitude deviation rate For the disturbed PT voltage signal Point-by-point corrections are performed on the amplitude deviation rate and phase offset to obtain the compensated PT voltage signal. Specific algorithm formula:

[0092] ;

[0093] in, This refers to the power frequency angular frequency. This refers to the sampling time corresponding to the sampling point. This refers to the fundamental phase of the interfered voltage;

[0094] When the compensated PT voltage signal is obtained, it is based on the fundamental phase of the compensated PT voltage. Phase of the full current fundamental frequency Calculate the compensated phase error Then set the trigger threshold to The system uses the compensated phase error and the trigger threshold to determine whether to trigger S4. When the compensated phase error is less than or equal to the trigger threshold, there is no need to start S4, and the compensated PT voltage signal is directly input into step S5. When the compensated phase error is greater than the trigger threshold, the S4 supplementary correction process is triggered, and the compensated PT voltage signal is used as input into S4 to ensure seamless layer connection.

[0095] To address the shortcomings of PT voltage signal deviation caused by electromagnetic interference in substations, this method utilizes the inherent characteristics of the fundamental phase of the surge arrester's full current (under normal operating conditions, the fundamental phase of the full current leads the normal PT voltage phase by 90°) as a reference source unaffected by the same electromagnetic interference. It calculates the amplitude deviation and phase shift of the interfered PT voltage signal in real time, completing the automatic correction of the voltage signal. This overcomes the limitations of passive reception of PT voltage signals in traditional devices. Using the surge arrester's own full current signal as the calibration benchmark, it achieves self-sensing, self-correction, and self-adaptation of the PT voltage signal. In electromagnetic interference scenarios, it restores the resistive current measurement accuracy to above the nominal accuracy, while avoiding fault misjudgment or missed judgment caused by signal deviation.

[0096] S4 includes the following steps:

[0097] The maximum phase synchronization error is used as the maximum phase synchronization error threshold. The maximum phase synchronization error threshold and the phase synchronization error are used to determine whether to perform phase pre-correction on the digitized PT voltage signal. When the phase synchronization error exceeds the maximum phase synchronization error threshold, it is determined that phase pre-correction should be performed on the digitized PT voltage signal, thereby obtaining the corrected PT voltage signal. Specific algorithm formula: ,in, This refers to the imaginary unit, which in electrical engineering and signal processing is defined as follows: Complex domain phase compensation is equivalent to phase offset correction of the time-domain PT voltage signal;

[0098] The corrected PT voltage signal is input into a digital notch filter to avoid phase deviation caused by time asynchrony at the sampling source, thereby outputting the filtered corrected PT voltage signal. The process of obtaining the filtered corrected PT voltage signal and the filtered disturbed PT voltage signal is the same. When the filtered corrected PT voltage signal is obtained, a compensation attenuation coefficient is introduced. ( ,default ), call the phase offset of the disturbed PT voltage and amplitude deviation rate The amplitude and phase of the filtered corrected PT voltage signal are jointly compensated point by point to obtain the compensated corrected PT voltage signal. Specific algorithm formula: ,in, This is the amplitude deviation rate compensation coefficient. To compensate for the phase offset and avoid signal distortion caused by overcorrection, the phase error after compensation in S3 is recorded. and the pre-corrected phase error in S4 Using the compensated phase error in S3 and the pre-corrected phase error in S4 Determine whether to perform subsequent joint compensation, when the compensated phase error Smaller than the pre-corrected phase error If the condition is met, perform subsequent joint compensation; otherwise, terminate the S4 process and use the S3 compensation result to ensure the effectiveness of the correction.

[0099] Perform a Fast Fourier Transform (FFT) on the compensated PT voltage signal to extract the effective value of the PT voltage. and correction of PT voltage fundamental phase The steps for extracting the RMS value and fundamental phase of the corrected PT voltage are the same as those for extracting the RMS value and fundamental phase of the total current. Based on the fundamental phase of the total current... and correction of PT voltage fundamental phase Calculate phase error Then set the phase error threshold to Verification using phase error and phase error threshold Whether the phase relationship is restored, among which, When the phase error is less than or equal to the phase error threshold, verification is performed. Phase relationship recovery: If the phase error exceeds the phase error threshold, it is verified that the normal phase relationship is not met, and the compensation process is automatically repeated (up to 3 times). If it still does not meet the requirement, a two-dimensional judgment mechanism is activated.

[0100] Dimension 1: When the fundamental frequency increment is less than or equal to 20% and the harmonic frequency increment is less than or equal to 30%, the surge arrester has no fault of its own and is judged to be abnormal in the PT body or secondary circuit (signal interference or hardware failure), triggering a special alarm for PT abnormality.

[0101] Dimension 2: When the fundamental frequency increment exceeds 20%, or the harmonic frequency increment exceeds 30%, the surge arrester itself is faulty, determined to be a surge arrester insulation deterioration fault, triggering a surge arrester fault-specific alarm, and simultaneously displaying fault characteristics (such as moisture). ,aging: );

[0102] To meet real-time monitoring requirements, the calculation delay control for repetitive processing includes the following steps:

[0103] S4 calls the results extracted from the Fourier transform in S3 (only providing phase pre-correction calculation), obtains the single-run time of S4 process, the total time of 3 repeated compensations in S4, and the sampling period of S4, and then obtains the pre-set single-run time threshold (2ms), total compensation time threshold (6ms), and S4 sampling period threshold (10ms) in the database. It uses the single-run time of S4 process, the total time of 3 repeated compensations, and the sampling period of S4 to determine whether the computational load meets the real-time requirements. When the single-run time of S4 process is less than or equal to the single-run time threshold, the total time of 3 repeated compensations is less than or equal to the total compensation time threshold, and the sampling period of S4 does not exceed the sampling period threshold of S4, the determination method meets the real-time requirements. When the single-run time of S4 process exceeds 2ms (extreme electromagnetic interference scenario), the supplementary correction is automatically terminated, and the compensation result of S3 is used to prioritize the real-time monitoring.

[0104] S5 includes the following method steps:

[0105] Perform a Fast Fourier Transform (FFT) on the compensated PT voltage signal or the PT voltage signal after compensation to extract the effective value of the compensated PT voltage. and correction compensation PT voltage fundamental phase Or compensate for the effective value of the PT voltage and compensation PT voltage fundamental phase The steps for extracting the RMS voltage value and fundamental voltage phase are the same as those for extracting the RMS total current value and fundamental voltage phase, based on the RMS voltage value of the PT after correction and compensation. and correction compensation PT voltage fundamental phase Or compensate for the effective value of the PT voltage and compensation PT voltage fundamental phase The compensated PT voltage signal or the PT voltage signal after compensation is converted into vector form to obtain the fundamental phasor of the compensated PT voltage. Or the fundamental phasor of the PT voltage after compensation ,in, This refers to a special separator in polar coordinate phasor representation, used to clearly express the two core properties of a phasor, and then based on the effective value of the total current. Phase of the full current fundamental frequency The filtered full-current signal is converted into vector form, thereby obtaining the full-current fundamental phasor. Using the corrected and compensated PT voltage fundamental phasor or the compensated PT voltage fundamental phasor as the reference phasor, the total current fundamental phasor is projected onto the in-phase direction of the corrected and compensated PT voltage fundamental phasor or the compensated PT voltage fundamental phasor. According to the phase of the fundamental wave of the total current and correction compensation PT voltage fundamental phase Or compensate for the fundamental phase of the PT voltage Calculate the phase difference or Then based on the phase difference value or and the RMS value of the total current Calculate the fundamental effective value of resistive current. or ,in, The in-phase projection factor is determined because the resistive current is in phase with the fundamental phasor of the corrected / compensated PT voltage or the fundamental phasor of the compensated PT voltage. Therefore, it is based on the effective value of the fundamental resistive current and the fundamental phase of the corrected / compensated PT voltage. Or compensate for the fundamental phase of the PT voltage Constructing the fundamental phasor of resistive current or ;

[0106] Project the total current fundamental phasor onto the orthogonal direction of the corrected and compensated PT voltage fundamental phasor or the compensated PT voltage fundamental phasor. Using sinusoidal projection coefficients based on phase difference values or and the RMS value of the total current Calculate the effective value of capacitive current or Since the effective value of the capacitive current is calculated, the phase lead of the capacitive current is used to compensate the fundamental phasor of the PT voltage or the fundamental phasor of the compensated PT voltage. Therefore, based on the effective value of the capacitive current and the fundamental phase of the corrected compensation PT voltage, Or compensate for the fundamental phase of the PT voltage Constructing the fundamental phasor of capacitive current or Then, calculate the resistance-capacitance ratio based on the fundamental phasor of the resistive current and the fundamental phasor of the capacitive current. ;

[0107] Perform a Fast Fourier Transform (FFT) again on the filtered full current signal to locate the fundamental current phasors corresponding to the 3rd (150Hz), 5th (250Hz), and 7th (350Hz) harmonics. , , Then, using the fundamental phasor of the corrected and compensated PT voltage or the fundamental phasor of the compensated PT voltage as a reference, the fundamental phasors of each harmonic current are projected onto the in-phase direction of the fundamental phasor of the corrected and compensated PT voltage or the fundamental phasor of the compensated PT voltage, respectively, to obtain the fundamental phasor of the resistive current corresponding to each harmonic. , , The effective values ​​of the fundamental frequency of each harmonic resistive current are extracted and superimposed to obtain the effective values ​​of the resistive current harmonic components. ;

[0108] Obtain the initial value of the fundamental resistive current during normal operation of the surge arrester. Using the average fundamental effective value of the resistive current during the first 72 hours of operation as a benchmark, the initial value of the resistive current harmonics is obtained synchronously. (The effective value of the average resistive current harmonic components during the first 72 hours of operation) Calculate the fundamental frequency increment based on the effective value and initial value of the fundamental resistive current. Then, the harmonic increment is calculated based on the effective value of the resistive current harmonic component and the initial value of the resistive current harmonic. Based on the fault characteristics of surge arresters (significant increase in fundamental frequency when damp, significant increase in harmonic frequency when aging), dynamic warning thresholds are set using the fundamental frequency increment, harmonic frequency increment, and resistance-capacitance ratio to determine whether the surge arrester is in normal state, in warning state, or in fault state.

[0109] When the fundamental frequency increment is less than or equal to 10%, the harmonic frequency increment is less than or equal to 15%, and the resistance-capacitance ratio is in the range of [0.05, 0.5], it meets the resistance-capacitance ratio measurement range of the XAQX-BL1 device, and the surge arrester is determined to be in normal condition. If the fundamental phase of the full current is 90° ahead of the fundamental phase of the PT voltage, then the inherent characteristic of the full current fundamental phase is valid, and the full current fundamental phase continues to be used as the calibration reference, and PT voltage compensation is performed using the full current fundamental phase as the reference; when the fundamental increment is greater than 10% and less than or equal to 20%, or the harmonic increment is greater than 15% and less than or equal to 30%, the surge arrester is determined to be in a warning state. When the fundamental frequency increment is greater than 20%, the harmonic frequency increment is greater than 30%, or the resistance-capacitance ratio is not in the range of [0.05, 0.5], the surge arrester is determined to be in a fault state. The full current fundamental frequency phase reference calibration is skipped, the original characteristics of the interfered PT voltage signal are preserved, the reference failure is avoided from masking the fault, and the system automatically switches back to the traditional PT reference (the externally input interference-free PT secondary voltage signal). The resistive or capacitive current decomposition is completed based on the traditional PT reference to ensure that the fault parameters are not tampered with by the distorted traditional PT reference, and to completely avoid fault omission.

[0110] When the surge arrester is in a warning or fault state, an environmental correction factor (temperature or humidity linkage) is introduced to correct the effective value of the fundamental frequency of the resistive current in real time, and then the background harmonics of the power grid are removed (by strengthening the separation of the 3rd / 5th / 7th harmonics through notch filtering). The surge arrester type has a preset threshold range. Based on the statistical analysis of 5000 sets of historical data and ROC curve analysis, the optimal decision boundary is determined, and then the environmental-voltage level comprehensive coefficient is obtained. According to the environmental-voltage level comprehensive coefficient The corrected threshold is obtained: normal state ( ), warning status ( Then, the surge arrester status, total current RMS value, and resistive current fundamental RMS value are recorded. The effective value of capacitive current, the resistance-capacitance ratio, and the fault characteristics of the surge arrester are displayed locally in real time via the LCD display module.

[0111] In summary, since S3 in this case is a mandatory basic compensation that covers all operating conditions, while S4 is a condition-triggered supplementary correction that is only executed when the requirements are still not met after S3 compensation, S3 is applicable to all operating conditions (such as normal operation or early warning of the surge arrester) and solves the problem of amplitude deviation and phase shift of PT voltage signal caused by electromagnetic interference. At the same time, S4 is only applicable to abnormal operating conditions where the actual phase difference of PT voltage after S3 compensation exceeds the allowable fluctuation range of phase difference, and solves the phase deviation caused by time synchronization error. It is an enhanced supplement to the basic compensation. Therefore, the triggering condition for S3 and S4 is that S3 compensation must be completed first and the actual phase difference must be verified. S4 supplementary correction is only started when the actual phase difference exceeds ±3° to avoid logic conflicts caused by parallel triggering. Through phase pre-correction and notch filtering, as well as three-level series correction of joint compensation, it can adapt to extreme scenarios of strong interference and time synchronization deviation, so that the monitoring method can stably cope with the complex electromagnetic environment of substations and can adapt to complex operating conditions of substations, thereby improving the overall robustness.

[0112] The second objective of this invention is to provide a system for operating the aforementioned intelligent resistive current monitoring method for surge arresters based on real-time analysis. The system includes a digital signal unit 1, which acquires analog signals in real time and inputs them to an AD converter to obtain digitized full current signals and PT voltage signals. The system then records the sampling timestamps to calculate the phase synchronization error. The system further includes:

[0113] The filtering signal unit 2 is used to receive the full current signal and PT voltage signal in the digital signal unit 1 and input them into the digital notch filter to obtain the filtered full current signal and the disturbed PT voltage signal.

[0114] The extraction compensation unit 3 is used to receive the full current signal and the disturbed PT voltage signal in the filtering signal unit 2 and perform Fourier transform to extract the effective value of the full current and calculate the phase offset of the disturbed PT voltage. Based on the phase offset of the disturbed PT voltage, the disturbed PT voltage signal is corrected point by point to obtain the compensated PT voltage signal.

[0115] The correction and compensation unit 4 is used to receive the PT voltage signal in the digital signal unit 1 and perform phase pre-correction to obtain the corrected PT voltage signal and perform joint compensation to obtain the compensated corrected PT voltage signal.

[0116] The monitoring status unit 5 is used to receive the compensated PT voltage signal after compensation in the correction compensation unit 4 or extract the compensated PT voltage signal after compensation in the compensation unit 3, perform Fourier transform, calculate the effective value of the fundamental wave of the resistive current, calculate the harmonic increment and the fundamental wave increment according to the effective value of the fundamental wave of the resistive current, and use the harmonic increment and the fundamental wave increment to determine the status of the surge arrester.

[0117] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for intelligent monitoring of resistive current in surge arresters based on real-time analysis, characterized in that: The methods and steps include the following: S1. Real-time acquisition of analog signals and input to AD converter to obtain digitized full current signal and PT voltage signal, and then recording sampling timestamps to calculate phase synchronization error; S2. Input the full current signal and PT voltage signal into the digital notch filter to obtain the filtered full current signal and the disturbed PT voltage signal; S3. Perform Fourier transform on the full current signal and the disturbed PT voltage signal, extract the effective value of the full current and calculate the phase offset of the disturbed PT voltage, and correct the disturbed PT voltage signal point by point based on the phase offset of the disturbed PT voltage to obtain the compensated PT voltage signal. S4. Perform phase pre-correction on the PT voltage signal to obtain the corrected PT voltage signal and perform joint compensation to obtain the compensated corrected PT voltage signal. S5. Perform Fourier transform on the compensated PT voltage signal or the compensated PT voltage signal and calculate the effective value of the fundamental wave of the resistive current. Calculate the harmonic increment and the fundamental wave increment according to the effective value of the fundamental wave of the resistive current. Use the harmonic increment and the fundamental wave increment to determine the state of the surge arrester.

2. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The method steps for obtaining the digitized full current signal and PT voltage signal are as follows: The system acquires raw current and voltage analog signals, obtains the maximum time deviation preset in the database, and then filters out the maximum phase synchronization error that is less than or equal to the maximum time deviation. The original analog current signal is converted into a continuous analog voltage signal, which is then synchronously input into the AD converter along with the original analog voltage signal. The instantaneous amplitude of the continuous analog voltage signal and the original analog voltage signal is automatically captured. The instantaneous amplitude of the analog signal is mapped to a discrete binary digital quantity, thereby generating a set of current and voltage digital quantities corresponding to the time moment, which are defined as the digitized full current signal and PT voltage signal, respectively.

3. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The process of obtaining the filtered full current signal and the disturbed PT voltage signal includes the following steps: The full current signal and PT voltage signal are input into a digital notch filter to construct an attenuation channel at a frequency of 50Hz and attenuate the harmonic components derived from the 50Hz power frequency fundamental wave in the two signals, and output intermediate current and voltage signals. Using the db4 wavelet as the basis function, the intermediate current and voltage signals are decomposed into three levels of approximate and detail components. The absolute value wavelet coefficients are extracted, and the wavelet coefficients are processed by elimination and retention based on the absolute value wavelet coefficients to obtain the processed approximate and detail components. The processed approximate components and detail components are subjected to inverse wavelet transform to automatically reconstruct the intermediate current and voltage signals that have been freed from high-frequency electromagnetic interference, and these signals are defined as the filtered full current signal and the interfered PT voltage signal, respectively.

4. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The extraction of the RMS value of the total current includes the following steps: Step 1: Sample points from arrive Iterate through the full current signal corresponding to each sampling point. and Multiply them, then sum all the products together. This refers to the total number of discrete sampling points of the full current signal; Step 2: Sample points from arrive Traverse the total current signal corresponding to each sampling point. and Multiply them, then sum all the products together; Step 3: Square the two sums above and add them together. Multiply the sum by [missing information]. Then, take the square root of the final result to obtain the RMS value of the fundamental component of the total current. The specific algorithm formula for the effective value of the total current fundamental component is as follows: ； It also includes the following method steps for phasing the fundamental frequency of the entire current: Take the second accumulated term from step 2 above as the numerator and the first accumulated term as the denominator, and calculate the ratio between the two based on the numerator and the denominator. The fundamental phase of the total current component is obtained by performing an arctangent function operation on the comparison value. The specific algorithm formula for the phase of the fundamental wave of the full current is as follows: .

5. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The compensated PT voltage signal includes the following steps: Based on the fact that the fundamental phase of the total current of the surge arrester leads the fundamental phase of the normal PT voltage under normal operating conditions. Based on the inherent electrical characteristics of the PT, the phase offset of the PT voltage is calculated according to the fundamental phase of the PT voltage and the fundamental phase of the full current. Obtain the nominal value of the secondary voltage of the substation PT, calculate the amplitude deviation of the affected PT voltage with the effective value of the affected PT voltage, and then calculate the amplitude deviation rate based on the amplitude deviation and the nominal value of the secondary voltage of the substation PT. Phase shift based on the disturbed PT voltage and amplitude deviation rate For the disturbed PT voltage signal Point-by-point correction is performed to obtain the compensated PT voltage signal. Specific algorithm formula: ;in, This refers to the power frequency angular frequency.

6. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The corrected PT voltage signal includes the following method steps: The maximum phase synchronization error is used as the maximum phase synchronization error threshold. The maximum phase synchronization error threshold and the phase synchronization error are used to determine whether to perform phase pre-correction on the digitized PT voltage signal. When the phase synchronization error exceeds the maximum phase synchronization error threshold, it is determined that phase pre-correction should be performed on the digitized PT voltage signal to obtain the corrected PT voltage signal. Specific algorithm formula: ,in, This refers to the imaginary unit, which in electrical engineering and signal processing is defined as follows: , This refers to phase synchronization error.

7. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The compensated PT voltage signal includes the following steps: The corrected PT voltage signal is input into a digital notch filter, and the filtered corrected PT voltage signal is output. ; Call the phase offset of the disturbed PT voltage and amplitude deviation rate The filtered corrected PT voltage signal is jointly compensated to obtain the compensated corrected PT voltage signal. Specific algorithm formula: ,in, This is the amplitude deviation rate compensation coefficient. This is the phase offset compensation term.

8. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The calculation of the fundamental effective value of the resistive current includes the following steps: Perform a Fast Fourier Transform on the compensated PT voltage signal or the compensated PT voltage signal to extract parameters; Based on parameters, the compensated PT voltage signal or the compensated PT voltage signal is converted into the fundamental phasor of the compensated PT voltage or the fundamental phasor of the compensated PT voltage. Based on the effective value of the total current and the fundamental phase of the total current, the total current signal is converted into the fundamental phasor of the total current. The phase difference is calculated based on the fundamental phase of the full current and the fundamental phase of the corrected or compensated PT voltage, and the effective value of the fundamental resistive current is calculated based on the phase difference and the effective value of the full current. Construct the fundamental phasor of the resistive current based on the effective value of the fundamental wave of the resistive current and the fundamental phase of the corrected or compensated PT voltage; The effective value of capacitive current is calculated based on the phase difference and the effective value of the total current. The fundamental phase phasor of capacitive current is constructed based on the effective value of capacitive current and the fundamental phase of the corrected or compensated PT voltage.

9. The intelligent monitoring method for resistive current of surge arresters based on real-time analysis according to claim 1, characterized in that: The calculation of the resistance-capacitance ratio, harmonic increment, and fundamental frequency increment includes the following steps: The resistance-capacitance ratio is calculated based on the fundamental phasor of resistive current and the fundamental phasor of capacitive current. Perform a fast Fourier transform on the full current signal again to obtain the fundamental phasor of the resistive current. After superimposing these phasors, the effective value of the harmonic components of the resistive current is obtained. The fundamental frequency increment and harmonic frequency increment are calculated based on the effective value of the fundamental frequency of the resistive current and the effective value of the harmonic components of the resistive current, respectively. Dynamic warning thresholds are set using fundamental frequency increment, harmonic frequency increment, and resistance-capacitance ratio to determine whether the surge arrester is in normal state, in warning state, or in fault state.

10. A system for operating the resistive current intelligent monitoring method for surge arresters based on real-time analysis according to any one of claims 1-9, comprising a digital signal unit (1), wherein the digital signal unit (1) acquires analog signals in real time and inputs them into an AD converter to obtain digitized full current signals and PT voltage signals, and then records the sampling timestamps to calculate the phase synchronization error; characterized in that: Also includes: The filtering signal unit (2) is used to receive the full current signal and PT voltage signal in the digital signal unit (1) and input them into the digital notch filter, so as to obtain the filtered full current signal and the disturbed PT voltage signal. Extraction compensation unit (3) is used to receive the full current signal and the disturbed PT voltage signal in the filter signal unit (2) and perform Fourier transform, extract the effective value of the full current and calculate the phase offset of the disturbed PT voltage, and perform point-by-point correction on the disturbed PT voltage signal based on the phase offset of the disturbed PT voltage to obtain the compensated PT voltage signal. The correction and compensation unit (4) is used to receive the PT voltage signal in the digital signal unit (1) and perform phase pre-correction to obtain the corrected PT voltage signal and perform joint compensation to obtain the compensated corrected PT voltage signal. The monitoring status unit (5) is used to receive the compensated PT voltage signal after compensation in the correction compensation unit (4) or extract the compensated PT voltage signal after compensation in the compensation unit (3) to perform Fourier transform and calculate the effective value of the fundamental wave of the resistive current. Based on the effective value of the fundamental wave of the resistive current, the harmonic increment and the fundamental wave increment are calculated respectively, and the state of the surge arrester is determined by the harmonic increment and the fundamental wave increment.

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