Cable state real-time early warning method, system and equipment based on harmonic disturbance analysis and medium

Abstract

The invention provides a cable state real-time early warning method, system and device based on harmonic disturbance analysis and a medium, and the method comprises the steps: obtaining the type, frequency and voltage amplitude of a harmonic component of a cable, inputting the types, frequency and voltage amplitude into a preset risk index calculation model, and calculating and outputting an insulation aging risk index value; the risk index calculation model is a mathematical model established based on thermal-electric coupling characteristics of the cable; based on the type of the harmonic component and a corresponding preset risk level threshold, obtaining state early warning information of the cable; according to the invention, the quantitative relation between the harmonic component and the cable insulation aging risk is determined through the thermal-electric coupling characteristic of the cable, so that the harmonic risk is directly associated with the insulation aging risk without depending on parameters such as the cable outer skin temperature which is difficult to accurately obtain in real time; real-time early warning of cable insulation aging failure risks caused by harmonic waves is realized; meanwhile, differentiated risk level thresholds are adopted for different harmonic component types, and the early warning accuracy is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power equipment monitoring, and particularly relates to a cable state real-time early warning method, system, device and medium based on harmonic disturbance analysis. BACKGROUND

[0002] With the wide application of new energy power generation, flexible power transmission, rail transit and power electronic equipment, the harmonic pollution problem in the power grid has become increasingly serious. High-frequency harmonics (frequency range 2kHz-150kHz) can cause skin effect and proximity effect on the surface of the conductor when transmitted through the cable due to their significant electromagnetic penetration characteristics, which not only leads to abnormal heating of the conductor, but also induces nonlinear dielectric response in the insulating medium. According to the Maxwell-Wagner polarization theory, the dielectric loss factor is proportional to the frequency, and high-frequency harmonics cause the polarization loss and conductance loss of cross-linked polyethylene (XLPE) and other insulating materials to increase exponentially. Experimental data show that at a frequency of 100kHz, the dielectric loss may be 30 to 50 times that of the power frequency state. This abnormal loss is particularly pronounced in the stress cone area of the cable terminal. Due to the difference in dielectric constant of different layer insulating materials, the high-frequency electric field distortion causes the space charge to oscillate violently, which in turn causes the local temperature of the stress grading layer to rise by 5-8℃ higher than the conventional working condition. The long-term thermal-electric synergistic effect accelerates the unzipping process of the crystalline region of the material, causing the breakdown field strength of XLPE to decrease at a rate of about 15% per year, and eventually a penetrating electric tree may be formed at the interface of the cable accessory, seriously endangering the safety of the cable. However, the traditional cable monitoring system mainly focuses on the monitoring of power frequency parameters (such as temperature, partial discharge), so it is difficult to effectively warn the operation safety and insulation failure risk caused by harmonics, especially high-frequency harmonics. SUMMARY

[0003] In order to overcome the shortcomings of the prior art, the present application provides a cable state real-time early warning method based on harmonic disturbance analysis, comprising: obtaining a harmonic disturbance signal of a cable; performing frequency spectrum analysis on the harmonic disturbance signal to obtain the type, frequency and voltage amplitude of the harmonic component; based on the type of the harmonic component, selecting a corresponding preset risk index calculation model, and inputting the frequency and voltage amplitude of the harmonic component into the risk index calculation model to calculate and output an insulation aging risk index value; the risk index calculation model is a mathematical model established based on the thermal-electric coupling characteristics of the cable; based on the type of the harmonic component, selecting a corresponding preset risk level threshold, and comparing the insulation aging risk index value with the risk level threshold to obtain the risk level of the harmonic component as the state early warning information of the cable.

[0004] Preferably, the step of selecting a corresponding preset risk index calculation model based on the type of harmonic components includes: When the harmonic component is a single-frequency harmonic, a preset single-frequency calculation model is selected as the risk indicator calculation model. When the harmonic component is a multi-narrowband harmonic, a preset multi-narrowband calculation model is selected as the risk indicator calculation model. When the harmonic component is a broadband harmonic, a preset broadband calculation model is selected as the risk indicator calculation model.

[0005] Preferably, the insulation aging risk index value in the single-frequency calculation model is equal to the ratio of the total power loss under the single-frequency harmonic to the rated total power loss, and the total power loss under the single-frequency harmonic is calculated based on the frequency and voltage amplitude of the single-frequency harmonic.

[0006] Preferably, the single-frequency calculation model is expressed as follows: ; in, This refers to the insulation aging risk index value in the single-frequency calculation model. and These represent the frequency and voltage amplitude of a single-frequency harmonic, respectively. and These are the rated frequency and rated voltage amplitude, respectively. This represents the total power loss under single-frequency harmonics. This represents the rated total power loss.

[0007] Preferably, the insulation aging risk index value in the multi-narrowband calculation model is equal to the sum of the normalized values ​​of the total power loss under each frequency harmonic in the multi-narrowband harmonics. The normalized value of the total power loss under each harmonic frequency is the ratio of the total power loss under each harmonic frequency to the rated total power loss; the total power loss under each harmonic frequency is calculated based on the frequency and voltage amplitude of each harmonic frequency.

[0008] Preferably, the multi-narrowband calculation model is expressed as follows: ; in, This refers to the insulation aging risk index value in the multi-narrowband calculation model. and The first The frequency and voltage amplitude of the subharmonics and These are the rated frequency and rated voltage amplitude, respectively. For the first The normalized value of total power loss under subharmonics, where N is the number of frequencies in the multi-narrowband harmonics.

[0009] Preferably, the wideband harmonics in the wideband calculation model are divided into multiple groups of sub-band harmonics according to a preset bandwidth, and the insulation aging risk index value in the wideband calculation model is equal to the sum of the total power loss normalized values of each group of sub-band harmonics. The total power loss normalized value of each group of sub-band harmonics is the ratio of the total power loss of each group of sub-band harmonics to the rated total power loss, and the total power loss of each group of sub-band harmonics is calculated according to the frequency and voltage amplitude of each group of sub-band harmonics.

[0010] Preferably, the wideband calculation model is represented as: ; Wherein, is the insulation aging risk index value in the wideband calculation model, and the number of groups of sub-band harmonics , represents the frequency range of the wideband harmonics, and is the frequency and voltage amplitude of the Bth group of sub-band harmonics, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss normalized value of the Bth group of sub-band harmonics.

[0011] Preferably, according to the type of harmonic component, a preset risk level threshold value is selected, including: When the harmonic component is a single-frequency harmonic, a preset single-frequency threshold value is selected as the risk level threshold value; the single-frequency threshold value includes a single-frequency low-risk threshold value, a single-frequency medium-risk threshold value, and a single-frequency high-risk threshold value; When the harmonic component is a multi-frequency harmonic, a preset multi-frequency threshold value is selected as the risk level threshold value; the multi-frequency threshold value includes a multi-frequency low-risk threshold value, a multi-frequency medium-risk threshold value, and a multi-frequency high-risk threshold value; the multi-frequency harmonic includes a multi-narrow-band harmonic and a wideband harmonic; The upper limit of the single-frequency low-risk threshold value is greater than the upper limit of the multi-frequency low-risk threshold value, the upper limit of the single-frequency medium-risk threshold value is greater than the upper limit of the multi-frequency medium-risk threshold value, and the lower limit of the single-frequency high-risk threshold value is greater than the lower limit of the multi-frequency high-risk threshold value.

[0012] Based on the same inventive concept, the application also provides a cable state real-time early warning system based on harmonic disturbance analysis, comprising: A signal acquisition module for acquiring a harmonic disturbance signal of a cable; An analysis module for performing frequency spectrum analysis on the harmonic disturbance signal to obtain the type, frequency, and voltage amplitude of the harmonic component; The index calculation module is used to select a corresponding preset risk index calculation model based on the type of the harmonic component, and input the frequency and voltage amplitude of the harmonic component into the risk index calculation model to calculate and output the insulation aging risk index value; the risk index calculation model is a mathematical model based on the thermal-electric coupling characteristics of the cable. The early warning module is used to select a corresponding preset risk level threshold based on the type of the harmonic component, and compare the insulation aging risk index value with the risk level threshold to obtain the risk level of the harmonic component, which serves as the status early warning information of the cable.

[0013] Preferably, the indicator calculation module is specifically used for: When the harmonic component is a single-frequency harmonic, a preset single-frequency calculation model is selected as the risk indicator calculation model. When the harmonic component is a multi-narrowband harmonic, a preset multi-narrowband calculation model is selected as the risk indicator calculation model. When the harmonic component is a broadband harmonic, a preset broadband calculation model is selected as the risk indicator calculation model.

[0014] Preferably, the insulation aging risk index value in the single-frequency calculation model is equal to the ratio of the total power loss under the single-frequency harmonic to the rated total power loss, and the total power loss under the single-frequency harmonic is calculated based on the frequency and voltage amplitude of the single-frequency harmonic.

[0015] Preferably, the single-frequency calculation model is expressed as follows: ; in, This refers to the insulation aging risk index value in the single-frequency calculation model. and These represent the frequency and voltage amplitude of a single-frequency harmonic, respectively. and These are the rated frequency and rated voltage amplitude, respectively. This represents the total power loss under single-frequency harmonics. This represents the rated total power loss.

[0016] Preferably, the insulation aging risk index value in the multi-narrowband calculation model is equal to the sum of the normalized values ​​of the total power loss under each frequency harmonic in the multi-narrowband harmonics. The normalized value of the total power loss under each harmonic frequency is the ratio of the total power loss under each harmonic frequency to the rated total power loss; the total power loss under each harmonic frequency is calculated based on the frequency and voltage amplitude of each harmonic frequency.

[0017] Preferably, the multi-narrowband calculation model is expressed as follows: ; wherein, is the insulation aging risk index value in the multi-narrow-band calculation model, and are the frequency and voltage amplitude of the Bth harmonic, respectively, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss normalized value under the Bth harmonic, and N is the number of frequencies in the multi-narrow-band harmonic. is the total power loss normalized value under the Bth harmonic, and N is the number of frequencies in the multi-narrow-band harmonic.

[0018] Preferably, the wide-band harmonic in the wide-band calculation model is divided into a plurality of groups of sub-band harmonics according to a preset bandwidth, and the insulation aging risk index value in the wide-band calculation model is equal to the sum of the total power loss normalized values under each group of sub-band harmonics; The total power loss normalized value under each group of sub-band harmonics is the ratio of the total power loss under each group of sub-band harmonics to the rated total power loss, and the total power loss under each group of sub-band harmonics is calculated according to the frequency and voltage amplitude of each group of sub-band harmonics.

[0019] Preferably, the wide-band calculation model is represented as: ; wherein, is the insulation aging risk index value in the wide-band calculation model, and the number of groups of sub-band harmonics , represents the frequency range of the wide-band harmonic, and are the frequency and voltage amplitude of the Bth group of sub-band harmonics, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss normalized value under the Bth group of sub-band harmonics.

[0020] Preferably, the early warning module is specifically used for: when the harmonic component is a single-frequency harmonic, a preset single-frequency threshold value is selected as the risk level threshold value; the single-frequency threshold value includes a single-frequency low-risk threshold value, a single-frequency medium-risk threshold value, and a single-frequency high-risk threshold value; when the harmonic component is a multi-frequency harmonic, a preset multi-frequency threshold value is selected as the risk level threshold value; the multi-frequency threshold value includes a multi-frequency low-risk threshold value, a multi-frequency medium-risk threshold value, and a multi-frequency high-risk threshold value; the multi-frequency harmonic includes a multi-narrow-band harmonic and a wide-band harmonic; ​The upper limit of the single-frequency low-risk threshold is greater than the upper limit of the multi-frequency low-risk threshold, the upper limit of the single-frequency medium-risk threshold is greater than the upper limit of the multi-frequency medium-risk threshold, and the lower limit of the single-frequency high-risk threshold is greater than the lower limit of the multi-frequency high-risk threshold.

[0021] Based on the same inventive concept, the present application also provides a computer device, comprising: one or more processors; a memory for storing one or more programs; When the one or more programs are executed by the one or more processors, a cable state real-time early warning method based on harmonic disturbance analysis is implemented.

[0022] Based on the same inventive concept, the present application also provides a computer readable storage medium having a computer program stored thereon, which, when executed, implements a cable state real-time early warning method based on harmonic disturbance analysis as described above.

[0023] Compared with the closest prior art, the present application has the following beneficial effects: The present application provides a cable state real-time early warning method, system, device and medium based on harmonic disturbance analysis, which comprises: obtaining a harmonic disturbance signal of a cable; performing frequency spectrum analysis on the harmonic disturbance signal to obtain the type, frequency and voltage amplitude of the harmonic component; based on the type of the harmonic component, selecting a corresponding preset risk index calculation model, and inputting the frequency and voltage amplitude of the harmonic component into the risk index calculation model to calculate and output an insulation aging risk index value; the risk index calculation model is a mathematical model established based on the thermal-electric coupling characteristics of the cable; based on the type of the harmonic component, selecting a corresponding preset risk level threshold, and comparing the insulation aging risk index value with the risk level threshold to obtain the risk level of the harmonic component as the state early warning information of the cable; the present application determines the quantitative relationship between the harmonic component and the cable insulation aging risk through the thermal-electric coupling characteristics of the cable, directly associates the harmonic risk with the insulation aging risk, does not need to rely on the cable outer skin temperature and other parameters which are difficult to obtain in real time, improves the accuracy of the risk index calculation model, realizes real-time early warning of the cable insulation aging failure risk caused by harmonics, and improves the early warning accuracy by using differentiated risk level thresholds for different harmonic component types. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A cable state real-time early warning method based on harmonic disturbance analysis provided by the present application is shown in the flowchart; Figure 2 A theoretical derivation flowchart of the cable state real-time early warning method based on harmonic disturbance analysis provided by the present application is shown in the flowchart; Figure 3 A schematic diagram of a real-time cable status early warning system based on harmonic disturbance analysis provided by the present invention; Figure 4 This is a schematic diagram of an electronic device structure provided by the present invention. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0026] Example 1: This invention provides a real-time early warning method for cable status based on harmonic disturbance analysis, such as... Figure 1 As shown, it includes: S1. Obtain the harmonic disturbance signal of the cable; S2. Perform spectrum analysis on the harmonic disturbance signal to obtain the type, frequency and voltage amplitude of the harmonic components; S3. Based on the type of the harmonic components, select the corresponding preset risk index calculation model, and input the frequency and voltage amplitude of the harmonic components into the risk index calculation model to calculate and output the insulation aging risk index value; the risk index calculation model is a mathematical model established based on the thermal-electric coupling characteristics of the cable; S4. Based on the type of the harmonic component, select the corresponding preset risk level threshold, and compare the insulation aging risk index value with the risk level threshold to obtain the risk level of the harmonic component, which serves as the status warning information of the cable.

[0027] Traditional cable monitoring systems primarily focus on monitoring power frequency parameters (such as temperature and partial discharge), making it difficult to effectively warn of operational safety and insulation failure risks caused by harmonics, especially high-frequency harmonics. This invention utilizes the thermo-electric coupling characteristics of cables to determine the quantitative relationship between harmonic components and cable insulation aging risk, establishing a direct correlation between harmonic risk and insulation aging risk. This eliminates the need to rely on parameters such as cable sheath temperature, which are difficult to obtain accurately in real time, thus improving the accuracy of the risk indicator calculation model and enabling real-time early warning of cable insulation aging failure risks caused by harmonics. Furthermore, differentiated risk level thresholds are used for different types of harmonic components to further enhance the accuracy of the early warning.

[0028] To determine the quantitative relationship between harmonic components and the risk of cable insulation aging, such as Figure 2 As shown, a multi-band sensor module is first used for signal acquisition, multi-band coverage, and environmental parameter acquisition. The multi-band sensor module can capture the disturbance signals of voltage and current at the beginning and end of the cable in real time, especially the harmonic components of the wideband disturbance signal from 2Hz to 150kHz, and simultaneously monitor the auxiliary parameter of cable surface temperature.

[0029] Specifically, the multi-band sensor module is deployed at the cable head and tail to synchronously collect the cable outer sheath temperature, voltage and current signals, including a high-frequency current transformer, a capacitive voltage sensor, a high-frequency voltage divider and an optical fiber temperature sensor, supporting high-precision measurement of power frequency (50 Hz) and wideband harmonic frequency band (2 Hz-150 kHz). The high-frequency current transformer is used to capture current harmonics and transient disturbances; the capacitive voltage sensor is used in combination with the voltage divider to obtain voltage harmonic components; the optical fiber temperature sensor is used to monitor the cable surface temperature distribution. After filtering and amplification, the sensor signals are converted into digital signals by an ADC analog-to-digital converter. The preprocessed data, i.e., digital signals, are sent to the temperature rise early warning analysis module through an optical fiber.

[0030] The temperature rise early warning analysis module includes a high-frequency disturbance analysis unit, a thermal-electric coupling calculation unit and a risk index calculation unit; wherein the high-frequency disturbance analysis unit and the thermal-electric coupling calculation unit are used to analyze and determine the quantitative relationship between harmonic components and cable insulation aging risk, and the risk index calculation unit is used to store a risk index calculation model to calculate the insulation aging risk index value.

[0031] Specifically, the high-frequency disturbance analysis unit performs data denoising and time alignment processing on the received original signals, and extracts high-frequency harmonic spectral features based on fast Fourier transform (FFT) and wavelet analysis, realizes spectral analysis, and calculates the voltage amplitude of each frequency band harmonic component; The thermal-electric coupling calculation unit calculates the dielectric loss power, the average power loss of the stress grading layer and the total power loss of the cable terminal in real time based on the cable thermal-electric coupling calculation model and the temperature rise calculation model; The basic assumptions of the cable thermal-electric coupling calculation model include: 1. The material properties (such as capacitance, loss factor, etc.) of the cable terminal remain unchanged when the frequency and voltage change, except for the conductivity of the stress grading material.

[0032] 2. The conductivity of the stress grading material is exponentially related to the electric field strength.

[0033] 3. The power loss of the cable terminal can be simplified into two parts: dielectric loss and stress grading loss.

[0034] 4. The system is linear and can apply the superposition principle.

[0035] The cable thermal-electric coupling calculation model includes a power loss model and a temperature rise model. The power loss model includes a dielectric loss model, a stress grading loss model and a total power loss model.

[0036] Dielectric loss is caused by capacitive current in cable insulation materials. The dielectric loss power may be expressed as: ; where: C is the total capacitance of the cable insulation, is the loss factor of the material, is the angular frequency of the voltage (ω = 2πf, where f is the frequency of the harmonic component), , is the frequency of the harmonic component, is the voltage amplitude.

[0037] The loss of the stress grading layer is due to the resistive properties of the material. The conductivity of the stress grading material is exponentially related to the electric field strength : ; where, and are experimental constants of the material.

[0038] Assuming that the conductivity of the stress grading layer is directly proportional to the frequency of the voltage: ; where, is the dielectric constant of the material.

[0039] Therefore, the average power loss of the stress grading layer may be expressed as: ; where, is a coefficient related to the geometry of the cable termination.

[0040] The total power loss of the cable termination is the sum of the dielectric loss and the stress grading loss: ; The temperature rise calculation model includes the heat equation. Under steady-state conditions, the heat equation can be simplified as: ; where, is the temperature, is the total power loss, i.e., the heat source; is the thermal conductivity of the material, is the Laplace operator.

[0041] Through the sensing data of the multi-band sensor module, it can be assumed that the temperature rise is directly proportional to the power loss. Therefore, the amount of temperature rise may be expressed as: ; So far, the direct proportional relationship between the power loss caused by the harmonic component and the cable insulation aging risk caused by the temperature rise has been quantified.

[0042] After obtaining the quantitative relationship between the harmonic component and the cable insulation aging risk, in the above S1, the harmonic disturbance signal of the cable is obtained based on the multi-frequency sensor module; in the above S2, the type, frequency and voltage amplitude of the harmonic component are obtained based on the high-frequency disturbance analysis unit.

[0043] In the embodiment, in the above S3, based on the type of the harmonic component, the corresponding preset risk index calculation model can be selected, which can include: When the harmonic component is a single-frequency harmonic, a preset single-frequency calculation model is selected as the risk index calculation model; When the harmonic component is a multi-narrow-band harmonic, a preset multi-narrow-band calculation model is selected as the risk index calculation model; When the harmonic component is a wide-band harmonic, a preset wide-band calculation model is selected as the risk index calculation model.

[0044] The risk index calculation model is designed based on the quantitative relationship between the harmonic component and the cable insulation aging risk, and the insulation aging risk index in the risk index calculation model is a dimensionless normalized risk index based on the total power loss, which is used to quantify the local temperature rise caused by the harmonic, especially the high-frequency harmonic, to evaluate the influence of the harmonic component, especially the high-frequency harmonic, on the cable terminal. Considering the characteristics of different types of harmonic components, single-frequency calculation models are set for single-frequency harmonic risk index calculation, multi-narrow-band calculation models in multi-narrow-band harmonic scenarios and wide-band calculation models in wide-band harmonic scenarios are set for multi-frequency harmonic risk index calculation, and the specific calculation processes are different.

[0045] Specifically, in the embodiment, the insulation aging risk index value in the single-frequency calculation model is equal to the ratio of the total power loss under the single-frequency harmonic to the rated total power loss, and the total power loss under the single-frequency harmonic is calculated according to the frequency and voltage amplitude of the single-frequency harmonic.

[0046] In the embodiment, the single-frequency calculation model is represented as: ; Wherein, is the insulation aging risk index value in the single-frequency calculation model, and are the frequency and voltage amplitude of the single-frequency harmonic, respectively, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss under the single-frequency harmonic, is the rated total power loss.

[0047] In this embodiment, the insulation aging risk index value in the multi-narrowband calculation model is equal to the sum of the normalized values ​​of the total power loss under each frequency harmonic in the multi-narrowband harmonics. The normalized value of the total power loss under each harmonic frequency is the ratio of the total power loss under each harmonic frequency to the rated total power loss; the total power loss under each harmonic frequency is calculated based on the frequency and voltage amplitude of each harmonic frequency.

[0048] In this embodiment, the multi-narrowband calculation model is represented as follows: ; in, This refers to the insulation aging risk index value in the multi-narrowband calculation model. and The first The frequency and voltage amplitude of the subharmonics and These are the rated frequency and rated voltage amplitude, respectively. For the first The normalized value of total power loss under subharmonics, where N is the number of frequencies in the multi-narrowband harmonics.

[0049] In this embodiment, the broadband harmonics in the broadband computing model are divided into multiple sub-band harmonics according to a preset bandwidth, and the insulation aging risk index value in the broadband computing model is equal to the sum of the normalized values ​​of the total power loss under each sub-band harmonic. The normalized value of the total power loss under each group of sub-band harmonics is the ratio of the total power loss under each group of sub-band harmonics to the rated total power loss; the total power loss under each group of sub-band harmonics is calculated based on the frequency and voltage amplitude of each group of sub-band harmonics.

[0050] Preferably, the preset bandwidth is 2 kHz. The operation of dividing the preset bandwidth into multiple sub-band harmonics conforms to the IEC61000-4-30 standard.

[0051] In this embodiment, the broadband computing model is represented as follows: ; in, The insulation aging risk index value in the broadband calculation model, and the number of sub-band harmonic groups. , This indicates the frequency range of the broadband harmonics. and These are the frequency and voltage amplitude of the B group subband harmonics. and These are the rated frequency and rated voltage amplitude, respectively. The total power loss normalized value under the harmonic of the B group sub-band.

[0052] After obtaining the insulation aging risk index value, as shown in Figure 2 , the insulation aging risk index value is sent to the early warning information issuing module for further early warning processing of data.

[0053] Specifically, the early warning information issuing module includes an early warning grading unit, an information pushing unit, and a data storage unit.

[0054] The early warning grading unit includes single-frequency early warning information grading and multi-frequency early warning information grading; specifically, single-frequency harmonic risk level division and multi-frequency harmonic risk level division under multi-narrow-band harmonic and broadband harmonic scenarios.

[0055] In the above S4, based on the type of the harmonic component, the corresponding preset risk level threshold value can be selected in the embodiment. When the harmonic component is a single-frequency harmonic, a preset single-frequency threshold value is selected as the risk level threshold value; the single-frequency threshold value includes a single-frequency low-risk threshold value, a single-frequency medium-risk threshold value, and a single-frequency high-risk threshold value; When the harmonic component is a multi-frequency harmonic, a preset multi-frequency threshold value is selected as the risk level threshold value; the multi-frequency threshold value includes a multi-frequency low-risk threshold value, a multi-frequency medium-risk threshold value, and a multi-frequency high-risk threshold value; the multi-frequency harmonic includes multi-narrow-band harmonic and broadband harmonic; The upper limit of the single-frequency low-risk threshold value is greater than the upper limit of the multi-frequency low-risk threshold value, the upper limit of the single-frequency medium-risk threshold value is greater than the upper limit of the multi-frequency medium-risk threshold value, and the lower limit of the single-frequency high-risk threshold value is greater than the lower limit of the multi-frequency high-risk threshold value.

[0056] In an optional implementation, the single-frequency early warning information grading is divided into three levels according to the insulation aging risk index value in the single-frequency calculation model Low risk ( ), that is, the upper limit of the single-frequency low-risk threshold value is 10: the cable terminal is in a safe operating state, and the power loss caused by high-frequency harmonics is within an acceptable range. Regular monitoring is recommended, but no immediate action is required.

[0057] Medium risk ( ), that is, the upper limit of the single-frequency medium-risk threshold value is 20: there is a certain risk in the cable terminal, the power loss caused by high-frequency harmonics is high, and it may cause local temperature rise. Detailed evaluation is recommended, and measures to reduce high-frequency harmonic level or optimize cable terminal design are considered.

[0058] High risk ( ​), i.e. the lower limit of the single-frequency high-risk threshold is 20: there is a significant risk at the cable terminal, the power loss caused by high-frequency harmonics is high, which may lead to serious aging and failure. It is recommended to take immediate measures such as installing filters, adjusting system operating parameters or replacing the cable terminal.

[0059] The multi-frequency early warning information classification is divided into three levels according to the value of the multi-frequency risk index , wherein The value of the insulation aging risk index includes the insulation aging risk index value in the multi-narrow-band calculation model and the insulation aging risk index value in the wide-band calculation model . Low risk ( ), i.e. the upper limit of the multi-frequency low-risk threshold is 2.5: the cable terminal is in a safe operating state, and the power loss caused by high-frequency harmonics is within an acceptable range. It is recommended to monitor regularly, but no immediate action is required. Medium risk ( ), i.e. the upper limit of the multi-frequency medium-risk threshold is 5: there is a certain risk at the cable terminal, the power loss caused by high-frequency harmonics is high, which may lead to local temperature rise. It is recommended to conduct a detailed assessment and consider taking measures to reduce the level of high-frequency harmonics or optimize the design of the cable terminal. High risk ( ), i.e. the lower limit of the multi-frequency high-risk threshold is 5: there is a significant risk at the cable terminal, the power loss caused by high-frequency harmonics is high, which may lead to serious aging and failure. It is recommended to take immediate measures such as installing filters, adjusting system operating parameters or replacing the cable terminal.

[0060] According to the risk level information output by the early warning classification unit, the information pushing unit generates information such as "insulation aging risk level at the measurement point of phase A of cable A: high, recommended for repair within 48 hours". It can be uploaded to the SCADA system through the industrial protocol (Modbus TCP, IEC61850), sent to the operation and maintenance personnel through the 4G / 5G module, and trigger the sound and light alarm (≥90dB buzzer + red LED flashing). The data storage unit will record historical data and early warning events synchronously, supporting fault backtracking and model optimization.

[0061] Embodiment 2: Based on the same inventive concept, the present application also provides a cable state real-time early warning system based on harmonic disturbance analysis, as shown in Figure 3 , comprising: A signal acquisition module for acquiring harmonic disturbance signals of the cable; An analysis module for performing frequency spectrum analysis on the harmonic disturbance signals to obtain the type, frequency and voltage amplitude of the harmonic components; The index calculation module is configured to: select a preset risk index calculation model corresponding to the category of the harmonic component; and input the frequency and voltage amplitude of the harmonic component into the risk index calculation model, and calculate and output an insulation aging risk index value. The early warning module is configured to: select a preset risk level threshold corresponding to the category of the harmonic component; compare the insulation aging risk index value with the risk level threshold; and obtain a risk level of the harmonic component as state early warning information of the cable.

[0062] In this embodiment, the index calculation module is specifically configured to: select a preset single-frequency calculation model as the risk index calculation model when the harmonic component is a single-frequency harmonic; select a preset multi-narrow-band calculation model as the risk index calculation model when the harmonic component is a multi-narrow-band harmonic; and select a preset wide-band calculation model as the risk index calculation model when the harmonic component is a wide-band harmonic.

[0063] In this embodiment, the insulation aging risk index value in the single-frequency calculation model is equal to a ratio of total power loss under the single-frequency harmonic to rated total power loss, and the total power loss under the single-frequency harmonic is calculated according to the frequency and voltage amplitude of the single-frequency harmonic.

[0064] In this embodiment, the single-frequency calculation model is represented as: ; wherein, is the insulation aging risk index value in the single-frequency calculation model, and are the frequency and voltage amplitude of the single-frequency harmonic, respectively, and are a rated frequency and a rated voltage amplitude, respectively, is the total power loss under the single-frequency harmonic, and is the rated total power loss.

[0065] In this embodiment, the insulation aging risk index value in the multi-narrow-band calculation model is equal to a sum of normalized values of total power loss under each frequency harmonic in the multi-narrow-band harmonic. The normalized value of the total power loss under each frequency harmonic is a ratio of the total power loss under each frequency harmonic to the rated total power loss, and the total power loss under each frequency harmonic is calculated according to the frequency and voltage amplitude of each frequency harmonic.

[0066] In this embodiment, the multi-narrow-band calculation model is represented as: ; in, This refers to the insulation aging risk index value in the multi-narrowband calculation model. and The first The frequency and voltage amplitude of the subharmonics and These are the rated frequency and rated voltage amplitude, respectively. For the first The normalized value of total power loss under subharmonics, where N is the number of frequencies in the multi-narrowband harmonics.

[0067] In this embodiment, the broadband harmonics in the broadband computing model are divided into multiple sub-band harmonics according to a preset bandwidth, and the insulation aging risk index value in the broadband computing model is equal to the sum of the normalized values ​​of the total power loss under each sub-band harmonic. The normalized value of the total power loss under each group of sub-band harmonics is the ratio of the total power loss under each group of sub-band harmonics to the rated total power loss; the total power loss under each group of sub-band harmonics is calculated based on the frequency and voltage amplitude of each group of sub-band harmonics.

[0068] In this embodiment, the broadband computing model is represented as follows: ; in, The insulation aging risk index value in the broadband calculation model, and the number of sub-band harmonic groups. , This indicates the frequency range of the broadband harmonics. and These are the frequency and voltage amplitude of the B group subband harmonics. and These are the rated frequency and rated voltage amplitude, respectively. This is the normalized value of the total power loss under the B group subband harmonics.

[0069] In this embodiment, the early warning module is specifically used for: When the harmonic component is a single-frequency harmonic, a preset single-frequency threshold is selected as the risk level threshold; the single-frequency threshold includes a single-frequency low-risk threshold, a single-frequency medium-risk threshold, and a single-frequency high-risk threshold; When the harmonic component is a multi-frequency harmonic, a preset multi-frequency threshold is selected as the risk level threshold; the multi-frequency threshold includes a low-risk multi-frequency threshold, a medium-risk multi-frequency threshold, and a high-risk multi-frequency threshold; the multi-frequency harmonic includes narrowband harmonics and broadband harmonics. The upper limit of the single-frequency low-risk threshold is greater than the upper limit of the multi-frequency low-risk threshold, the upper limit of the single-frequency medium-risk threshold is greater than the upper limit of the multi-frequency medium-risk threshold, and the lower limit of the single-frequency high-risk threshold is greater than the lower limit of the multi-frequency high-risk threshold.

[0070] Embodiment 3 As shown in the figure, the present application also provides an electronic device, which can be a computer device, a single-chip microcomputer device, a smart mobile device, etc. The electronic device in this embodiment can include a processor, a memory, a transceiver component, etc. The memory, the processor and the transceiver component are connected through a bus; the memory can be used to store an execution program, and the exemplary execution program can include instructions; the processor is used to execute the instructions stored in the memory. The memory can also be used to store data, which can be called and / or modified when the instructions are executed. Figure 4

[0071] The processor can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), ready programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc., which are the computing core and control core of the terminal, and are suitable for implementing one or more instructions, and are specifically suitable for loading and executing one or more instructions in the storage medium to implement a corresponding method flow or a corresponding function, to implement the steps of the cable state real-time early warning method based on harmonic disturbance analysis in the above embodiment.

[0072] Embodiment 4 ​Based on the same inventive concept, the application further provides a readable storage medium, specifically, an electronic device readable storage medium (Memory). The electronic device readable storage medium is a memory device in the electronic device, and is used for storing programs and data. It can be understood that the storage medium herein can include a built-in storage medium in the electronic device, and of course can also include an extended storage medium supported by the electronic device. The storage medium provides a storage space, and the storage space stores an operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and the instructions can be one or more execution programs (including program codes). It should be noted that the storage medium herein can be a high-speed RAM memory or a non-volatile memory, for example, at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, so as to realize the steps of the cable state real-time early warning method based on harmonic disturbance analysis in the above embodiment.

[0073] Those skilled in the art should understand that the embodiments of the application can be provided as a method, a system, or a computer program product. Therefore, the application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage, etc.) containing computer-usable program code.

[0074] The application is described with reference to flowcharts and / or block diagrams of the method, device (system), and computer program product according to the embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device produce a device that implements the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1 The device that implements the function specified in one or more flows or blocks.

[0075] These computer program instructions can also be stored in a computer-readable memory capable of guiding the computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a product including instruction devices, which implement the flowcharts and / or block diagrams. Figure 1 The function specified in one or more flows and / or blocks Figure 1the function specified in the one or more blocks.

[0076] These computer program instructions can also be loaded into computer or other programmable data processing devices, so that a series of operation steps are performed on the computer or other programmable data processing devices to generate computer-implemented processes, and the instructions executed on the computer or other programmable data processing devices provide processes for implementing the flowcharts Figure 1 the flowcharts or the flowcharts and / or blocks Figure 1 the steps of the function specified in the one or more blocks.

[0077] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit the scope of protection, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand: after reading the present application, the applicant can make various changes, modifications or equivalent replacements to the specific embodiments, but these changes, modifications or equivalent replacements are all within the scope of protection of the claims of the present application.

Claims

1. A cable state real-time early warning method based on harmonic disturbance analysis, characterized in that, The method comprises the following steps: Harmonic disturbance signals of the cable are acquired; A frequency spectrum analysis is performed on the harmonic disturbance signals to obtain the type, frequency and voltage amplitude of harmonic components; Based on the type of the harmonic components, a preset risk index calculation model corresponding to the type is selected, and the frequency and voltage amplitude of the harmonic components are input into the risk index calculation model to calculate an insulation aging risk index value; The risk index calculation model is a mathematical model established based on the thermal-electric coupling characteristics of the cable; Based on the type of the harmonic components, a preset risk level threshold value corresponding to the type is selected, and the insulation aging risk index value is compared with the risk level threshold value to obtain a risk level of the harmonic components as the state early warning information of the cable.

2. The method of claim 1, wherein, The step of selecting, based on the type of the harmonic components, a preset risk index calculation model corresponding to the type comprises the following steps: When the harmonic component is a single-frequency harmonic, a preset single-frequency calculation model is selected as the risk index calculation model; When the harmonic component is a multi-narrow-band harmonic, a preset multi-narrow-band calculation model is selected as the risk index calculation model; When the harmonic component is a wide-band harmonic, a preset wide-band calculation model is selected as the risk index calculation model.

3. The method of claim 2, wherein, The insulation aging risk index value in the single-frequency calculation model is equal to the ratio of the total power loss under the single-frequency harmonic to the rated total power loss, and the total power loss under the single-frequency harmonic is calculated according to the frequency and voltage amplitude of the single-frequency harmonic.

4. The method of claim 3, wherein, The single-frequency calculation model is represented as follows: ； wherein is the insulation aging risk indicator value in the single frequency calculation model, and are the frequency and voltage amplitude of the single frequency harmonic, respectively, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss under the single frequency harmonic, is the rated total power loss.

5. The method according to any one of claims 2 to 4, wherein, The insulation aging risk index value in the multi-narrow-band calculation model is equal to the sum of the normalized values of the total power loss under each frequency harmonic in the multi-narrow-band harmonic; The normalized value of the total power loss under each frequency harmonic is the ratio of the total power loss under each frequency harmonic to the rated total power loss, and the total power loss under each frequency harmonic is calculated according to the frequency and voltage amplitude of each frequency harmonic.

6. The method of claim 5, wherein, The multi-narrow-band calculation model is represented as follows: ； in, This refers to the insulation aging risk index value in the multi-narrowband calculation model. and The first The frequency and voltage amplitude of the subharmonics and These are the rated frequency and rated voltage amplitude, respectively. For the first The normalized value of total power loss under subharmonics, where N is the number of frequencies in the multi-narrowband harmonics.

7. The method according to any one of claims 2 to 4, wherein, The wide-band harmonic in the wide-band calculation model is divided into a plurality of groups of sub-band harmonics according to a preset bandwidth, and the insulation aging risk index value in the wide-band calculation model is equal to the sum of the normalized values of the total power loss under each group of sub-band harmonics; The normalized value of the total power loss under each group of sub-band harmonics is the ratio of the total power loss under each group of sub-band harmonics to the rated total power loss, and the total power loss under each group of sub-band harmonics is calculated according to the frequency and voltage amplitude of each group of sub-band harmonics.

8. The method of claim 7, wherein, The wide-band calculation model is represented as follows: ； wherein is the insulation aging risk indicator value in the broadband calculation model, the number of groups of sub-band harmonics , denotes the frequency range of the broadband harmonics, and is the frequency and voltage amplitude of the Bth group of sub-band harmonics, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss normalized value under the Bth group of sub-band harmonics.

9. The method of any one of claims 2-4, wherein, The step of selecting, based on the type of the harmonic components, a preset risk level threshold value corresponding to the type comprises the following steps: When the harmonic component is a single-frequency harmonic, a preset single-frequency threshold value is selected as the risk level threshold value; the single-frequency threshold value comprises a single-frequency low-risk threshold value, a single-frequency medium-risk threshold value and a single-frequency high-risk threshold value; When the harmonic component is a multi-frequency harmonic, a preset multi-frequency threshold value is selected as the risk level threshold value; the multi-frequency threshold value comprises a multi-frequency low-risk threshold value, a multi-frequency medium-risk threshold value and a multi-frequency high-risk threshold value; the multi-frequency harmonic comprises a multi-narrow-band harmonic and a wide-band harmonic. An upper limit of the single-frequency low-risk threshold is greater than an upper limit of the multi-frequency low-risk threshold, an upper limit of the single-frequency medium-risk threshold is greater than an upper limit of the multi-frequency medium-risk threshold, and a lower limit of the single-frequency high-risk threshold is greater than a lower limit of the multi-frequency high-risk threshold.

10. A real-time cable condition early warning system based on harmonic disturbance analysis, characterized in that, Comprise: The signal acquisition module is used for acquiring a harmonic disturbance signal of the cable; The analysis module is used for performing frequency spectrum analysis on the harmonic disturbance signal to obtain a type, a frequency and a voltage amplitude of a harmonic component; The index calculation module is used for selecting a preset risk index calculation model corresponding to the type of the harmonic component, inputting the frequency and the voltage amplitude of the harmonic component into the risk index calculation model, and calculating and outputting an insulation aging risk index value; The risk index calculation model is a mathematical model established based on thermal-electric coupling characteristics of the cable; The early warning module is used for selecting a preset risk level threshold corresponding to the type of the harmonic component, comparing the insulation aging risk index value with the risk level threshold, and obtaining a risk level of the harmonic component as state early warning information of the cable.

11. The system of claim 10, wherein, The index calculation module is specifically used for: When the harmonic component is a single-frequency harmonic, a preset single-frequency calculation model is selected as the risk index calculation model; When the harmonic component is a multi-narrow-band harmonic, a preset multi-narrow-band calculation model is selected as the risk index calculation model; When the harmonic component is a wide-band harmonic, a preset wide-band calculation model is selected as the risk index calculation model.

12. The system of claim 11, wherein, The insulation aging risk index value in the single-frequency calculation model is equal to a ratio of total power loss under the single-frequency harmonic to rated total power loss, and the total power loss under the single-frequency harmonic is calculated according to the frequency and the voltage amplitude of the single-frequency harmonic.

13. The system of claim 12, wherein, The single-frequency calculation model is represented as: ； wherein is the insulation aging risk indicator value in the single frequency calculation model, and are the frequency and voltage amplitude of the single frequency harmonic, respectively, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss under the single frequency harmonic, is the rated total power loss.

14. The system of any one of claims 11-13, wherein, The insulation aging risk index value in the multi-narrow-band calculation model is equal to a sum of total power loss normalization values of each frequency harmonic in the multi-narrow-band harmonic; The total power loss normalization value of each frequency harmonic is a ratio of total power loss of each frequency harmonic to rated total power loss, and the total power loss of each frequency harmonic is calculated according to the frequency and the voltage amplitude of each frequency harmonic.

15. The system of claim 14, wherein, The multi-narrow-band calculation model is represented as: ； in, This refers to the insulation aging risk index value in the multi-narrowband calculation model. and The first The frequency and voltage amplitude of the subharmonics and These are the rated frequency and rated voltage amplitude, respectively. For the first The normalized value of total power loss under subharmonics, where N is the number of frequencies in the multi-narrowband harmonics.

16. The system of any one of claims 11-13, wherein, The wide-band harmonic in the wide-band calculation model is divided into a plurality of groups of sub-band harmonics according to a preset bandwidth, and the insulation aging risk index value in the wide-band calculation model is equal to a sum of total power loss normalization values of each group of sub-band harmonics; The total power loss normalization value of each group of sub-band harmonics is a ratio of total power loss of each group of sub-band harmonics to rated total power loss, and the total power loss of each group of sub-band harmonics is calculated according to the frequency and the voltage amplitude of each group of sub-band harmonics.

17. The system of claim 16, wherein, The wide-band calculation model is represented as: ； wherein is the insulation aging risk indicator value in the broadband calculation model, the number of groups of sub-band harmonics , denotes the frequency range of the broadband harmonics, and is the frequency and voltage amplitude of the Bth group of sub-band harmonics, and are the rated frequency and rated voltage amplitude, respectively, is the total power loss normalized value under the Bth group of sub-band harmonics.

18. The system of any of claims 11-13, wherein, The early warning module is specifically used for: When the harmonic component is a single-frequency harmonic, a preset single-frequency threshold is selected as the risk level threshold; the single-frequency threshold comprises a single-frequency low-risk threshold, a single-frequency medium-risk threshold and a single-frequency high-risk threshold; When the harmonic component is a multi-frequency harmonic, a preset multi-frequency threshold is selected as the risk level threshold; the multi-frequency threshold includes a multi-frequency low-risk threshold, a multi-frequency medium-risk threshold, and a multi-frequency high-risk threshold; the multi-frequency harmonic includes multi-narrow-band harmonics and wide-band harmonics; An upper limit of the single-frequency low-risk threshold is greater than an upper limit of the multi-frequency low-risk threshold, an upper limit of the single-frequency medium-risk threshold is greater than an upper limit of the multi-frequency medium-risk threshold, and a lower limit of the single-frequency high-risk threshold is greater than a lower limit of the multi-frequency high-risk threshold.

19. An electronic device, comprising: Comprise: At least one processor and a memory; The memory and the processor are connected through a bus; The memory is used for storing one or more programs; When the one or more programs are executed by the at least one processor, a cable state real-time early warning method based on harmonic disturbance analysis is realized.

20. A readable storage medium, characterized by, An execution program is stored thereon, and when the execution program is executed, a cable state real-time early warning method based on harmonic disturbance analysis is realized.

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