A power transmission channel risk early warning evaluation method and system

Abstract

The application discloses a power transmission channel risk early warning evaluation method and system, relates to the technical field of power transmission channel abnormal situation early warning, and comprises the following steps: monitoring voltage harmonic distortion rate, analyzing the current waveform distortion degree caused by nonlinear load in the power transmission line, and evaluating the influence of harmonics on line and equipment insulation aging and heating loss; analyzing the real-time gradient of the conductor temperature, judging the abnormal heating condition of different sections of the conductor, and evaluating the abnormal rising degree of the conductor temperature caused by overload and poor contact factors and potential thermal damage accumulation; through the monitoring and analysis of multi-dimensional indexes such as voltage harmonic distortion rate, real-time gradient of the conductor temperature, dynamic deviation rate of sag, and corona discharge intensity, the application helps to solve the deficiency of traditional monitoring means in the aspect of abnormal heating risk evaluation.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power transmission channel abnormal situation early warning, and particularly relates to a power transmission channel risk early warning evaluation method and system. BACKGROUND

[0002] In the operation process of the power transmission channel, the abnormal heating problem is an important hidden danger threatening the safety of the power grid. On the one hand, with the wide access of industrial equipment, electronic devices and other nonlinear loads, the voltage harmonic distortion phenomenon in the power transmission line is increasingly serious. The harmonics not only cause the insulation of the line and equipment to age rapidly, but also increase the heat loss and bury the safety hazard. On the other hand, the temperature anomaly of the conductor caused by overload, poor contact and other factors may cause the mechanical performance of the conductor to decline, the heat damage to accumulate, and even cause the conductor to break. In addition, the change of the conductor sag and the intensification of the corona discharge also threaten the safety of the power transmission channel, and the traditional monitoring means cannot comprehensively and accurately evaluate these risks. SUMMARY

[0003] The purpose of the present application is to provide a power transmission channel risk early warning evaluation method and system, which solves the technical problems of the deficiencies of the traditional monitoring means in the aspect of abnormal heating risk evaluation in the prior art.

[0004] A power transmission channel risk early warning evaluation method, comprising:

[0005] By monitoring the voltage harmonic distortion rate, the degree of current waveform distortion caused by nonlinear loads in the power transmission line is analyzed, and the influence of harmonics on the insulation aging and heat loss of the line and equipment is evaluated.

[0006] The real-time gradient of the conductor temperature is analyzed to determine the abnormal heating condition of different sections of the conductor, and the degree of abnormal temperature rise and potential heat damage accumulation of the conductor caused by overload and poor contact factors is evaluated. According to the influence of the voltage harmonic distortion rate on the insulation aging and heat loss of the equipment and the abnormal temperature condition of the conductor reflected by the real-time gradient of the conductor temperature, it is determined whether the power transmission line has an abnormal heating risk. When the power transmission line has an abnormal heating risk: by analyzing the sag dynamic deviation rate, the sag change condition of the conductor caused by temperature change and mechanical stress factors is evaluated, and it is determined whether the distance of the conductor to the ground meets the safety standard; by monitoring the corona discharge intensity, the intensification of the corona discharge on the surface of the conductor caused by heating and damage factors is evaluated, and the degree of insulation performance degradation is determined; the conductor spatial position change reflected by the sag dynamic deviation rate and the degree of insulation performance degradation reflected by the corona discharge intensity are comprehensively analyzed, the risk level of the power transmission channel operation is evaluated, and early warning is performed.

[0007] As a further scheme of the present application: the voltage harmonic distortion rate is monitored, the current waveform distortion degree caused by the nonlinear load in the power transmission line is analyzed, and the influence of the harmonic on the insulation aging and the heating loss of the line and the equipment is evaluated, including:

[0008] The three-phase voltage signals are collected in real time, the harmonic content of each order is calculated through spectrum analysis, and the voltage harmonic distortion rate is calculated according to the standard formula;

[0009] A correlation model of the voltage harmonic distortion rate and the insulation aging rate is established to evaluate the damage of the harmonic to the insulation life;

[0010] The additional heating loss caused by the harmonic is calculated to evaluate the influence on the current carrying capacity of the conductor.

[0011] As a further scheme of the present application: the real-time gradient of the conductor temperature is analyzed to judge the abnormal heating of different sections of the conductor, and the abnormal temperature rise degree and the potential thermal damage accumulation of the conductor caused by overload and poor contact factors are evaluated, including:

[0012] Distributed temperature measurement points are arranged on the conductor at intervals, and the temperature difference and distance ratio of adjacent temperature measurement points are calculated as ΔT;

[0013] A thermal damage accumulation model is established to evaluate the thermal damage accumulation degree according to the duration of ΔT exceeding the warning threshold and the thermal damage accumulation rate;

[0014] When the ΔT of a section exceeds the warning threshold and the thermal damage accumulation rate is greater than a first preset value, it is determined that there is an abnormal heating risk, and the continuous monitoring is started;

[0015] When the ΔT of a section is greater than a second preset value for a continuous preset time, it is directly determined that there is a serious heating risk.

[0016] As a further scheme of the present application: according to the influence of the voltage harmonic distortion rate on the insulation aging and the heating loss of the equipment and the abnormal temperature situation of the conductor reflected by the real-time gradient of the conductor temperature, it is judged whether the power transmission line has an abnormal heating risk, including:

[0017] A risk matrix is constructed, the horizontal axis is the voltage harmonic distortion rate level, and the vertical axis is the real-time gradient level of the conductor temperature;

[0018] When the risk matrix falls into the warning area, the abnormal heating warning is triggered, and the sag and corona monitoring is started.

[0019] As a further scheme of the present application: the sag dynamic deviation rate is analyzed to evaluate the sag change of the conductor caused by temperature change and mechanical stress factors, and it is judged whether the distance of the conductor to the ground meets the safety standard, including:

[0020] Obtain the wire spatial coordinates through unmanned aerial vehicle laser radar scanning or image recognition, and calculate the real-time value of the sag;

[0021] Calculate the dynamic deviation rate of the sag;

[0022] According to the mapping relationship between the dynamic deviation rate of the sag and the distance from the ground, it is evaluated whether it is lower than the safety threshold.

[0023] As a further scheme of the present application, the corona discharge intensity is monitored to evaluate the intensification of the corona discharge on the wire surface due to heating and damage factors, and to determine the degree of attenuation of the insulation performance, and specifically includes:

[0024] The number of corona discharge photons or the electric field intensity is measured by using an ultraviolet imager or an electric field sensor, and is converted into the discharge intensity;

[0025] A correlation model of the corona discharge intensity and the insulation aging is established, and when the discharge intensity exceeds the preset multiple of the corona onset voltage and the remaining life of the insulation is less than half, it is determined that the insulation performance is seriously attenuated.

[0026] As a further scheme of the present application, the spatial position change reflected by the dynamic deviation rate of the sag and the degree of attenuation of the insulation performance reflected by the corona discharge intensity are comprehensively analyzed, and specifically includes: the spatial risk coefficient corresponding to the dynamic deviation rate of the sag and the insulation risk coefficient corresponding to the corona discharge intensity are normalized respectively, and the normalized spatial risk coefficient and the normalized insulation risk coefficient are calculated.

[0027] A preset comprehensive risk coefficient threshold is set, and the comprehensive risk coefficient is compared with the comprehensive risk coefficient threshold: when the comprehensive risk coefficient is less than or equal to the comprehensive risk coefficient threshold, it indicates that the operation risk of the power transmission channel is low; and when the comprehensive risk coefficient is greater than the comprehensive risk coefficient threshold, it indicates that the operation risk of the power transmission channel is high.

[0028] As a further scheme of the present application, the spatial risk coefficient is determined by the following way:

[0029] Based on the obtained dynamic deviation rate data of the sag, the deviation degree thereof from the historical normal operation data is calculated, and the deviation degree is converted into the spatial risk coefficient by using a preset mapping function, the mapping function being a monotonically increasing function, and the greater the deviation degree, the greater the spatial risk coefficient.

[0030] As a further scheme of the present application, the insulation risk coefficient is determined by the following way: based on the obtained corona discharge intensity data, the ratio of the corona discharge intensity to the corona onset voltage is calculated, and the ratio is converted into the insulation risk coefficient by using a preset mapping function, the mapping function being a monotonically increasing function, and the greater the ratio, the greater the insulation risk coefficient.

[0031] In a second aspect, the application provides a power transmission channel risk early warning evaluation system, which comprises:

[0032] A monitoring module, which analyzes the degree of current waveform distortion caused by nonlinear load in the power transmission line by monitoring the voltage harmonic distortion rate, and evaluates the influence of harmonics on the insulation aging and heat loss of the line and equipment;

[0033] An analysis module, which analyzes the real-time gradient of conductor temperature, judges the abnormal heating condition of different sections of the conductor, and evaluates the degree of abnormal temperature rise and potential thermal damage accumulation of the conductor caused by overload and poor contact factors; a judgment module, which judges whether the power transmission line has an abnormal heating risk according to the influence of the voltage harmonic distortion rate on the insulation aging and heat loss of the equipment and the abnormal condition of the conductor temperature reflected by the real-time gradient of the conductor temperature; an evaluation module, which, when the power transmission line has an abnormal heating risk: evaluates the change of sag caused by temperature change and mechanical stress factors of the conductor by analyzing the dynamic deviation rate of sag, judges whether the distance of the conductor to the ground meets the safety standard; evaluates the aggravation of corona discharge caused by heating and damage factors on the surface of the conductor by monitoring the intensity of corona discharge, and judges the degree of insulation performance degradation; and an early warning module, which comprehensively analyzes the change of the spatial position of the conductor reflected by the dynamic deviation rate of sag and the degree of insulation performance degradation reflected by the intensity of corona discharge, evaluates the risk level of the operation of the power transmission channel and gives an early warning.

[0034] Compared with the prior art, the application has the following advantages:

[0035] The application, by monitoring and analyzing multiple-dimensional indicators such as the voltage harmonic distortion rate, the real-time gradient of conductor temperature, the dynamic deviation rate of sag, and the intensity of corona discharge, helps to solve the deficiencies of traditional monitoring methods in abnormal heating risk evaluation. From harmonic influence evaluation and conductor temperature abnormality judgment to in-depth analysis of sag and insulation performance under abnormal heating risk, to the final risk level evaluation and early warning, a complete risk evaluation system is formed, which can accurately identify potential risks in the operation of the power transmission channel, issue early warnings in advance, provide scientific decision-making basis for operation and maintenance personnel, effectively reduce the failure rate of power transmission lines, and ensure the safe and stable operation of the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The figure is a schematic diagram of the method framework structure of the application. DETAILED DESCRIPTION

[0037] The technical solutions of the application will be described below in conjunction with the embodiments, obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0038] In a first aspect, refer to Figure 1 The application provides a power transmission channel risk early warning evaluation method, comprising:

[0039] By monitoring the voltage harmonic distortion rate, the degree of current waveform distortion caused by nonlinear load in the power transmission line is analyzed, and the influence of harmonics on the insulation aging and heating loss of the line and equipment is evaluated;

[0040] The real-time gradient of the conductor temperature is analyzed to determine the abnormal heating condition of different sections of the conductor, and the degree of abnormal temperature rise and potential thermal damage accumulation of the conductor caused by overload and poor contact factors is evaluated. According to the influence of voltage harmonic distortion rate on equipment insulation aging and heating loss and the abnormal temperature condition of conductor temperature reflected by real-time gradient, it is determined whether the power transmission line has abnormal heating risk;

[0041] Wherein, the abnormal temperature condition of the conductor refers to the degree of abnormal temperature rise and potential thermal damage accumulation. When the power transmission line has abnormal heating risk: by analyzing the arc drop dynamic deviation rate, the arc drop change caused by temperature change and mechanical stress factors of the conductor is evaluated, and it is determined whether the distance of the conductor to the ground meets the safety standard; by monitoring the corona discharge intensity, the intensification of corona discharge on the surface of the conductor caused by heating and damage factors is evaluated, and the degree of insulation performance degradation is determined; the spatial position change of the conductor reflected by the arc drop dynamic deviation rate and the degree of insulation performance degradation reflected by the corona discharge intensity are comprehensively analyzed, the risk level of the power transmission channel operation is evaluated and early warning is given.

[0042] Wherein, in actual operation, nonlinear loads (such as frequency converters, electric arc furnaces and other equipment) will inject a large amount of harmonic current into the power grid, causing voltage waveform distortion. When the voltage harmonic distortion rate exceeds a certain threshold, the harmonic current will produce additional loss in the power transmission line and equipment, accelerating the aging of insulation materials. Excessive harmonic distortion rate significantly increases the heating loss of the line and transformer, speeds up the insulation aging, and seriously shortens the service life of the equipment;

[0043] Therefore, by analyzing the real-time gradient of the conductor temperature, the abnormal heating condition of different sections of the conductor can be effectively determined. Under normal operating conditions, the temperature of each section of the conductor is relatively uniform. If a certain section is overloaded (such as sudden increase of line load) or has poor contact (such as loose wire clamp), the local temperature will rise, forming a clear temperature gradient. By collecting temperature data of each point of the conductor through distributed temperature sensors, a temperature gradient model can be constructed to intuitively present the temperature distribution of the conductor. For example, during the peak load period of a certain section of power transmission line, the temperature of the conductor near a tension clamp is found to be 15℃ higher than that of other sections through temperature gradient analysis, indicating that the clamp has poor contact. If not treated in time, the accumulation of thermal damage may cause a conductor breakage accident;

[0044] According to the influence of voltage harmonic distortion rate on equipment insulation aging and heat loss, and the abnormal situation of conductor temperature reflected by the real-time gradient of conductor temperature, it is comprehensively judged whether there is abnormal heating risk in the power transmission line. When the voltage harmonic distortion rate is too high and the conductor temperature is obviously abnormal, it means that there is a greater abnormal heating risk in the power transmission line. For example, the voltage harmonic distortion rate of a certain power transmission line reaches 7%, and the temperature gradient of the conductor is abnormal, which is conducive to showing that the heat loss caused by harmonics and the abnormal heating of the conductor itself are superimposed on each other, at this time the possibility of line failure increases significantly, and measures need to be taken immediately to assess the risk;

[0045] When there is an abnormal heating risk in the power transmission line, further in-depth assessment work is carried out. By analyzing the dynamic deviation rate of sag, the change of sag of the conductor caused by temperature change and mechanical stress factors is evaluated. With the increase of conductor temperature, its thermal expansion will make the sag increase, if the sag exceeds the safe range, the distance between the conductor and the ground will decrease, which may cause safety accidents. At the same time, by monitoring the intensity of corona discharge, the intensification of corona discharge on the surface of the conductor caused by heating and damage factors is evaluated. Corona discharge can accelerate the oxidation of the surface of the conductor and reduce the insulation performance, when the intensity of corona discharge increases, it means that the insulation performance of the conductor is deteriorating. For example, under the condition of abnormal heating, the dynamic deviation rate of sag of a certain section of power transmission line reaches 10%, which exceeds the normal range, and the intensity of corona discharge is significantly enhanced, which indicates that the distance between the conductor and the ground may not meet the safety standards, and the insulation performance is also declining, which needs to be paid attention to;

[0046] The change of the spatial position of the conductor reflected by the dynamic deviation rate of sag and the degree of insulation performance degradation reflected by the intensity of corona discharge are comprehensively analyzed, the risk level of the operation of the power transmission channel is evaluated and early warning is carried out. According to the pre-set risk assessment model, the risk level is divided into three levels: low risk, medium risk and high risk. When the sag deviation is small and the intensity of corona discharge is within the normal range, it is determined as low risk; when the sag deviation is large or the intensity of corona discharge is significantly enhanced, it is determined as medium risk; when the sag is seriously out of standard and the intensity of corona discharge is extremely high, it is determined as high risk, and the corresponding level of early warning information is immediately sent out. For example, after evaluation, a certain power transmission channel is determined as high risk, the system will quickly send early warning to the operation and maintenance personnel, prompting to take measures as soon as possible, such as adjusting the line load, replacing the damaged conductor, etc., to ensure the safe operation of the power transmission channel.

[0047] The monitoring and analysis of multi-dimensional indexes such as voltage harmonic distortion rate, real-time gradient of conductor temperature, dynamic deviation rate of sag, and corona discharge intensity can help solve the deficiencies of traditional monitoring methods in the risk assessment of abnormal heating. From harmonic influence assessment, conductor temperature anomaly judgment, to in-depth analysis of sag and insulation performance under abnormal heating risk, to the final risk level assessment and early warning, a complete risk assessment system is formed, which can accurately identify potential risks in the operation process of the power transmission channel, provide scientific decision-making basis for operation and maintenance personnel, effectively reduce the failure rate of the transmission line, and ensure the safe and stable operation of the power grid.

[0048] As an optional embodiment, by monitoring the voltage harmonic distortion rate, the degree of current waveform distortion caused by nonlinear load in the transmission line is analyzed, and the influence of harmonics on the insulation aging and heating loss of the line and equipment is evaluated, including:

[0049] Real-time acquisition of three-phase voltage signals, calculation of harmonic content of each order by spectrum analysis, and calculation of voltage harmonic distortion rate according to standard formula;

[0050] Establish a correlation model between voltage harmonic distortion rate and insulation aging rate to evaluate the impact of harmonics on insulation life;

[0051] Calculate the additional heating loss caused by harmonics to evaluate the impact on the current-carrying capacity of the conductor.

[0052] Specifically, in modern power systems, with the widespread application of industrial frequency converters, new energy inverters, and other nonlinear devices, the problem of harmonic pollution of transmission lines is becoming increasingly serious. Traditional harmonic monitoring only stays at the content detection level and cannot quantify the actual harm of harmonics to the line and equipment: on the one hand, the high-frequency electromagnetic field generated by harmonic current can accelerate the electrical aging of insulation materials, leading to a reduction in the service life of equipment, but there is a lack of quantitative evaluation methods, making it difficult to predict the risk of insulation failure; on the other hand, the additional heating loss caused by harmonics can reduce the current-carrying capacity of the conductor and even cause conductor overheating failure, but existing methods cannot accurately calculate the impact, thereby increasing the safety hazards of power grid operation;

[0053] Therefore, by real-time acquisition of three-phase voltage signals, spectrum analysis techniques such as Fast Fourier Transform (FFT) are used to accurately calculate the harmonic content of each order. For example, in a certain industrial area, the monitoring device collects 1000 sets of three-phase voltage data per second, and through spectrum analysis, it is found that the 5th harmonic content is 6% and the 7th harmonic content is 3.5%. Subsequently, according to the national standard formula where is the effective value of the hth harmonic voltage, is the effective value of the fundamental voltage, The square root of the square sum of the effective values of all harmonic voltages from 2 times to H times represents the overall amplitude of the harmonic components, and the voltage harmonic distortion rate is calculated. The larger the value, the higher the proportion of harmonic components in the voltage signal, the worse the power quality, and the more significant the impact on the insulation aging, heating loss, etc. of power equipment (such as transformers and motors). Thus, the real-time and accuracy of harmonic parameters are ensured, and reliable data basis is provided for subsequent analysis.

[0054] Among them, based on a large amount of experimental data and long-term field monitoring, a correlation model of voltage harmonic distortion rate and insulation aging rate is established. Research shows that when the harmonic distortion rate increases by 1%, the dielectric loss angle tangent of oil-paper insulation will rise by 0.5%, accelerating the molecular chain rupture of insulation materials. For example, in the monitoring of a transformer in a certain substation, it is found through model calculation that when the voltage harmonic distortion rate reaches 8%, the insulation life is shortened by 30% compared with normal working conditions. This model quantifies the relationship between harmonics and insulation aging, helping operation and maintenance personnel to predict insulation failure risk in advance and reasonably arrange equipment maintenance period;

[0055] Among them, for the additional heating loss caused by harmonics, a multi-physical field coupling model can be established to consider factors such as skin effect and proximity effect to calculate the additional loss caused by harmonics. For example, in a steel-cored aluminum stranded conductor with a load current of 800A, when the 5th harmonic content reaches 5%, the additional heating loss makes the conductor temperature rise by 8℃, resulting in a decrease of about 6% in the current-carrying capacity. Through this quantitative analysis, the actual impact of harmonics on the current-carrying capacity of the conductor can be evaluated, providing a scientific basis for line load scheduling and equipment selection;

[0056] By establishing a quantitative relationship between harmonic distortion rate and insulation aging, the insulation life loss risk is transformed from fuzzy evaluation to accurate prediction; then, by using a multi-physical field model to quantify the harmonic heating loss, the influence degree of the harmonic heating loss on the current-carrying capacity of the conductor is determined, thereby forming a complement with other monitoring indicators of the transmission line (such as conductor temperature and sag change), which can help operation and maintenance personnel to fully understand the harm of harmonics and timely adjust the operation strategy, reduce the risk of insulation failure and conductor overheating of equipment, and is conducive to significantly improving the operation reliability of the transmission channel.

[0057] As an optional embodiment, the real-time gradient of the conductor temperature is analyzed to judge the heating abnormality of different sections of the conductor, evaluate the degree of abnormal temperature rise of the conductor caused by overload and poor contact factors and the accumulation of potential thermal damage, which specifically includes:

[0058] Distributed temperature measurement points are arranged at intervals on the conductor, and the temperature difference and distance ratio of adjacent temperature measurement points are calculated as ΔT;

[0059] A thermal damage accumulation model is established to evaluate the degree of thermal damage accumulation according to the duration of ΔT exceeding the warning threshold and the thermal damage accumulation rate.

[0060] When a certain section ΔT exceeds the early warning threshold and the thermal damage accumulation rate is greater than the first preset value, it is determined that there is an abnormal heating risk, and continuous monitoring is started;

[0061] When a certain section ΔT is greater than the second preset value for a continuous preset time, it is directly determined that there is a serious heating risk.

[0062] Specifically, in the operation of the power transmission line, the problem of conductor thermal damage accumulation has long been faced with monitoring blind spots and risk misjudgments. Traditional single-point temperature measurement cannot capture the temperature gradient changes of the conductor section. For example, when the strain clamp contact is poor, the local high temperature may only change significantly within a few meters, and single-point temperature measurement is prone to miss detection. Moreover, static threshold early warning does not consider the cumulative effect of thermal damage. For example, if the temperature gradient of a certain section continues to be slightly over-standard but does not trigger an alarm, long-term operation may lead to a decrease in the mechanical strength of the conductor. In addition, the lack of quantitative analysis of the duration of temperature gradient abnormalities makes it difficult to distinguish between transient load fluctuations and persistent defects, resulting in misallocation of operation and maintenance resources.

[0063] Therefore, first, distributed temperature measurement points are arranged at intervals on the conductor (such as one optical fiber temperature measurement node every 50 meters), and after real-time collection of temperature data, the ratio ΔT (unit: ℃ / m) of the temperature difference and the distance of adjacent temperature measurement points is calculated. For example, the temperatures of two adjacent points of a certain section of conductor are 65℃ and 50℃, and the distance is 100 meters, then ΔT=(65-50) / 100=0.15℃ / m. This parameter directly reflects the spatial variation rate of the conductor temperature. Under normal operation, ΔT is usually less than 0.1℃ / m, while ΔT of a poor contact or overload section can reach more than 0.3℃ / m;

[0064] Based on the Arrhenius equation, a thermal damage accumulation model is established to analyze the duration t of ΔT exceeding the early warning threshold (such as 0.2℃ / m) and the thermal damage accumulation rate k. Experimental data show that when ΔT=0.25℃ / m, the creep damage rate k of the conductor aluminum alloy material is 0.01 / h, and if it lasts for 24 hours, the thermal damage accumulation degree D=0.24 (the full value is 1). The model calculates the D value by real-time integration. When D≥0.5, the tensile strength of the conductor decreases to 80% of the original value, and maintenance intervention is required.

[0065] When a certain section ΔT exceeds the early warning threshold (0.2℃ / m) and the thermal damage accumulation rate k>0.005 / h (the first preset value), it is determined that there is an abnormal heating risk. For example, ΔT=0.22℃ / m and k=0.008 / h, the system automatically starts high-frequency monitoring every 10 minutes to track the damage development trend.

[0066] If the section ΔT is greater than 0.3℃ / m (the second preset value) for 4 hours (the preset time), it is directly determined as a serious risk. At this time, the conductor temperature may exceed 120℃, the oxide layer between the strands is intensified, the contact resistance increases exponentially, and power outage maintenance needs to be arranged within 2 hours;

[0067] The conductor temperature gradient analysis scheme improves the spatial monitoring accuracy of local thermal anomalies of the conductor to the preset interval through distributed temperature measurement and temperature gradient ΔT calculation, increases the abnormal recognition rate, and solves the problem that the traditional single-point temperature measurement is difficult to capture local thermal hazards. Two is to use the thermal damage accumulation model to quantify the continuous impact of temperature gradient anomalies, combined with grading measures, to improve the early warning accuracy, avoid fault misjudgment due to neglect of thermal damage accumulation effect, and form a complement with harmonic influence evaluation, sag change monitoring and other modules. It can help operation and maintenance personnel to timely grasp the thermal safety state of the conductor, reasonably arrange maintenance strategy, which is conducive to reducing the risk of conductor overheating, insulation failure and other risks, and significantly improving the safety and reliability of the power transmission channel operation.

[0068] As an optional embodiment, according to the influence of voltage harmonic distortion rate on equipment insulation aging and heat loss and the conductor temperature real-time gradient reflecting the conductor temperature abnormal situation, it is judged whether the power transmission line exists abnormal heating risk, which specifically includes:

[0069] A risk matrix is constructed, with the horizontal axis being the voltage harmonic distortion rate level and the vertical axis being the conductor temperature real-time gradient level.

[0070] When the risk matrix falls into the early warning area, an abnormal heating early warning is triggered, and sag and corona monitoring is started.

[0071] Specifically, in the power transmission channel operation monitoring, single index evaluation of abnormal heating risk has significant limitations. On the one hand, relying only on voltage harmonic distortion rate evaluation may overlook temperature abnormalities caused by conductor contact failure, overload, etc. On the other hand, simply judging according to the conductor temperature gradient is easy to miss the problem of intensified insulation aging and heat loss caused by harmonics. In addition, when the harmonic distortion rate is slightly over-standard but the conductor temperature gradient is significantly abnormal, it is difficult to quickly judge the risk level, which is easy to cause early warning lag or misjudgment, and cannot meet the efficient decision-making needs of the safe operation of the power transmission line;

[0072] Therefore, in order to solve the above problems, the voltage harmonic distortion rate and the conductor temperature real-time gradient are quantified and graded by constructing a risk matrix.

[0073] Among them, the horizontal axis represents the voltage harmonic distortion rate level, which is divided into low (THD_V < 5%), medium (5% ≤ THD_V < 8%) and high (THD_V ≥ 8%) three levels according to national standards and equipment tolerance ability;

[0074] The vertical axis represents the real-time gradient level of the conductor temperature, which is divided into normal level (ΔT < 0.1 ℃ / m), warning level (0.1 ℃ / m ≤ ΔT < 0.2 ℃ / m) and serious level (ΔT ≥ 0.2 ℃ / m) according to the temperature difference and distance ratio ΔT of adjacent temperature measuring points. In this way, the continuous monitoring data is converted into discrete risk dimensions, which is convenient for intuitive analysis and rapid judgment;

[0075] When the data point in the risk matrix falls into the warning area, the system triggers an abnormal heating warning. For example, if the voltage harmonic distortion rate level is "medium" and the real-time gradient level of the conductor temperature is "warning", which corresponds to the high-risk area in the risk matrix, the system immediately issues a warning signal, thereby avoiding the limitations of traditional single-index alarm and comprehensively considering the synergistic effect of harmonic and temperature abnormalities. Moreover, after triggering the warning, the system automatically starts the sag and corona monitoring to deeply analyze the spatial position change and insulation performance decay of the conductor, thereby providing more dimensional data support for subsequent risk assessment, which helps to solve the problem of insufficient multi-factor coupling risk assessment in traditional monitoring, and changes the one-sidedness of single-index judgment by quantifying and grading two key indicators to form a matrix, making the risk assessment more comprehensive and accurate; The determination rule of the warning and above area realizes the rapid identification of the synergistic effect of harmonic and temperature abnormalities, which is conducive to avoiding the lag or misjudgment of the warning caused by single index. At the same time, the linkage mechanism of sag and corona monitoring after the warning is triggered further improves the risk assessment system.

[0076] As an optional embodiment, by analyzing the sag dynamic deviation rate, the sag change of the conductor caused by temperature change and mechanical stress factors is evaluated to determine whether the distance of the conductor to the ground meets the safety standard, which specifically includes:

[0077] The spatial coordinates of the conductor are obtained by unmanned aerial vehicle laser radar scanning or image recognition, and the real-time value of the sag is calculated;

[0078] The sag dynamic deviation rate is calculated;

[0079] According to the mapping relationship between the sag dynamic deviation rate and the distance to the ground, it is evaluated whether it is lower than the safety threshold.

[0080] Specifically, in the operation and maintenance of the power transmission line, the change of the conductor sag directly threatens the safe operation of the line, and the traditional monitoring method faces many challenges. The existing technology lacks quantitative correlation analysis of sag and distance to the ground, making it difficult for the operation and maintenance personnel to quickly determine whether the conductor is in a safe operating state, which may lead to safety accidents such as electric shock and discharge.

[0081] The spatial coordinates of the conductor are obtained by the UAV carrying a laser radar scanning or image recognition technology. The laser radar can scan the conductor profile with millimeter-level precision and obtain three-dimensional point cloud data; the image recognition uses a high-definition camera to collect conductor images and extracts conductor feature point coordinates through computer vision algorithms. Based on the obtained spatial coordinates, combined with the information of the suspension points at both ends of the conductor, the real-time value of the sag is calculated using a parabolic model or a catenary equation. For example, in the monitoring of a certain cross-river transmission line, after scanning by the UAV laser radar, it is calculated that the current sag is 12.5 meters, which is 1.2 meters more than the design value;

[0082] The dynamic deviation rate of the sag is calculated, which reflects the degree of change of the conductor sag relative to the design value or the historical stable value. The calculation formula is: sag dynamic deviation rate = (sag real-time value - sag reference value) / sag reference value x 100%. The sag reference value can be selected as the design sag of the line or the sag value during the recent stable operation. For example, if the design sag of a certain section of conductor is 10 meters and the current real-time sag is 11 meters, then the sag dynamic deviation rate = (11-10) / 10 x 100% = 10%. Through this index, the change amplitude of the conductor sag can be quantified directly;

[0083] According to the pre-established mapping relationship between the dynamic deviation rate of the sag and the distance to the ground, it is evaluated whether the distance of the conductor to the ground is below the safety threshold. This mapping relationship is constructed based on the design parameters of the line, terrain data and mechanical models, for example, when the dynamic deviation rate of the sag exceeds 8%, the distance of the conductor to the ground may be below the safety standard requirement of 7 meters. Once the system detects that the dynamic deviation rate of the sag triggers the threshold, it immediately issues a warning, prompting the operation and maintenance personnel that the conductor has a safety hazard and needs to take timely measures to adjust the sag or other protective measures;

[0084] In summary, by using the UAV laser radar and image recognition technology, the real-time high-precision acquisition of the spatial coordinates of the conductor is realized, breaking through the limitations of low efficiency and poor precision of manual inspection; the calculation of the dynamic deviation rate of the sag quantifies the change of the sag, avoiding the ambiguity of relying on experience alone; the safety evaluation based on the mapping relationship establishes a direct link between the change of the sag and the distance to the ground, solving the problem that the traditional method cannot quickly judge the safety state. This scheme cooperates with other transmission line monitoring modules, which is conducive to significantly improving the perception and early warning ability of the conductor sag anomaly, effectively reducing the risk of safety accidents caused by the change of the sag, and ensuring the safe and stable operation of the transmission line.

[0085] As an optional embodiment, by monitoring the intensity of corona discharge, the intensification of corona discharge on the surface of the conductor due to heating and damage factors is evaluated, and the degree of degradation of the insulation performance is judged, which specifically includes:

[0086] The ultraviolet imager or electric field sensor is used to measure the number of photons of the corona discharge or the electric field intensity, and the discharge intensity is converted;

[0087] A correlation model of the corona discharge intensity and the insulation aging is established, when the discharge intensity exceeds a preset multiple of the corona inception voltage and the insulation remaining life is less than half, it is determined that the insulation performance is seriously degraded.

[0088] Specifically, during the operation of the power transmission line, the degradation of the insulation performance is a potential hidden danger threatening the safety of the power grid. On the one hand, it is difficult to find the aging of the internal insulation material, such as the internal crack of the insulator or the electric corrosion of the outer insulation of the conductor, by relying on manual inspection to observe the surface damage of the conductor. On the other hand, there is a lack of quantitative analysis of the corona discharge, which is a key indicator of insulation degradation. The corona discharge not only accelerates the aging of the insulation material, but also may cause power loss and electromagnetic interference. However, the traditional method cannot accurately determine the relationship between the discharge intensity and the degradation of the insulation performance, which leads to the inability to timely find the degradation of the insulation performance and easily causes equipment failure or even power outage accidents.

[0089] Firstly, the ultraviolet imager or electric field sensor is used to measure the corona discharge intensity. The ultraviolet imager can capture the ultraviolet photons generated by the corona discharge, and the discharge intensity is quantified by counting the number of photons per unit time. The electric field sensor measures the electric field intensity by sensing the electric field change caused by the discharge, and converts it into the corresponding discharge intensity. For example, in a certain high-voltage power transmission line inspection, the ultraviolet imager detects that the number of photons of the corona discharge per unit time reaches 1000, and the current corona discharge intensity is 20 μA through conversion algorithm; or the electric field sensor measures the electric field intensity change value, and the discharge intensity is 18 μA after conversion. These measurement methods realize real-time and non-contact monitoring of the corona discharge intensity;

[0090] Then, a correlation model of the corona discharge intensity and the insulation aging is established, which is based on a large amount of experimental data and field operation experience. The model sets the key determination conditions: when the corona discharge intensity exceeds a preset multiple (such as 1.5 times) of the corona inception voltage, and the model calculates that the insulation remaining life is less than half, it is determined that the insulation performance is seriously degraded. The corona inception voltage is the critical voltage at which the conductor starts to produce corona discharge, and exceeding this multiple means that the discharge phenomenon is intensified and the erosion of the insulation material is accelerated. For example, the corona inception voltage of a certain section of conductor is 30 kV, when the monitored corona discharge intensity corresponds to a voltage of 45 kV (i.e. 1.5 times the corona inception voltage), and the model calculates that the insulation remaining life is only 40%, the system immediately issues a warning of serious degradation of the insulation performance;

[0091] In summary, the precise measurement of corona discharge intensity is achieved by using the ultraviolet imager and electric field sensor, which makes up for the limitations of manual inspection. The established correlation model between corona discharge intensity and insulation aging changes the previous fuzzy judgment based on experience by converting the abstract insulation performance decay into quantifiable judgment conditions. By setting double thresholds of corona inception voltage multiple and insulation residual life, the severe decay of insulation performance can be accurately identified, and the equipment failure and power outage caused by insulation problems can be avoided. This scheme cooperates with the conductor sag monitoring, harmonic influence evaluation and other modules to provide comprehensive protection for the safe operation of the transmission line, and significantly improves the reliability and stability of the power grid operation.

[0092] As an optional embodiment, the spatial position change reflected by the dynamic deviation rate of the sag and the insulation performance decay degree reflected by the corona discharge intensity are comprehensively analyzed, specifically including: normalizing the spatial risk coefficient corresponding to the dynamic deviation rate of the sag and the insulation risk coefficient corresponding to the corona discharge intensity, and calculating the normalized spatial risk coefficient and the normalized insulation risk coefficient.

[0093] A preset comprehensive risk coefficient threshold is compared with the comprehensive risk coefficient: when the comprehensive risk coefficient is less than or equal to the comprehensive risk coefficient threshold, it indicates that the operation risk of the transmission channel is low; when the comprehensive risk coefficient is greater than the comprehensive risk coefficient threshold, it indicates that the operation risk of the transmission channel is high.

[0094] Specifically, in the operation management of the transmission channel, the risk assessment in a single dimension cannot fully reflect the real safety state of the line. On the one hand, judging the spatial position risk of the conductor only according to the dynamic deviation rate of the sag may ignore the potential threat brought by the decay of insulation performance; on the other hand, simply evaluating the insulation risk through the corona discharge intensity is difficult to take into account the safety hidden danger caused by insufficient conductor-to-ground distance. In addition, different risk indicators have different dimensions and different numerical ranges (for example, the sag deviation rate is measured in percentage, and the corona discharge intensity is measured in current or electric field strength unit), and the traditional independent analysis method cannot realize the unified quantification and comprehensive judgment of the risk, which makes it difficult for the operation and maintenance personnel to quickly locate the high-risk area, and risk misjudgment or delay in disposal may occur;

[0095] To solve the above problems, first, the spatial risk coefficient corresponding to the dynamic deviation rate of the sag and the insulation risk coefficient corresponding to the corona discharge intensity are normalized. Since the original value ranges of the two types of risk coefficients are different, direct calculation may lead to unbalanced weights of some indicators. Normalization maps data to the [0, 1] interval, eliminates the dimension difference, and makes different risk dimensions comparable. For example, the original value of the spatial risk coefficient is 0.7, and the original value of the insulation risk coefficient is 0.6. After normalization, they are converted to 0.7 / (0.7+0.3)=0.7 and 0.6 / (0.6+0.4)=0.6 respectively, ensuring the scientificity and accuracy of subsequent calculation;

[0096] After normalization, the comprehensive risk coefficient is calculated by calculating the two types of risk coefficients, which can be calculated by weighted summation (such as assigning weights to spatial risk and insulation risk according to historical accident data) or product model. At the same time, the threshold of the comprehensive risk coefficient is preset, which is based on the design standard of the transmission line, the historical operation data and the safety specification. Compare the calculated comprehensive risk coefficient with the threshold value:

[0097] It should be noted that the calculation formula can also be selected as: for calculation, wherein R is the comprehensive risk coefficient; δ is the spatial risk coefficient; is the insulation risk coefficient; and δi and δj are weight parameters of the spatial risk coefficient and the insulation risk coefficient respectively, and ;

[0098] When the comprehensive risk coefficient is less than or equal to the threshold value of the comprehensive risk coefficient (such as the threshold value is 0.6 and the calculated value is 0.5), it is determined that the operation risk of the transmission channel is low, and the conventional inspection frequency can be maintained.

[0099] When the comprehensive risk coefficient is greater than the threshold value of the comprehensive risk coefficient (such as the calculated value is 0.8), it indicates that the operation risk of the transmission channel is high, and the emergency response mechanism needs to be started immediately and special maintenance is arranged.

[0100] In summary, by normalizing the dimensional differences of spatial risk and insulation risk, the problem of multiple indexes that cannot be directly compared is solved; then the comprehensive risk coefficient calculation model is constructed to integrate single-dimensional risk into a unified quantitative index, avoiding the risk misjudgment caused by one-sided evaluation; finally, based on the threshold comparison, the risk level is quickly classified, compared with the traditional dispersed analysis mode, which improves the identification efficiency of high-risk areas. The scheme cooperates with the harmonic influence evaluation module, conductor temperature monitoring module and other modules to form an intelligent evaluation system covering multiple dimensions of the transmission channel risk, providing a scientific basis for operation and maintenance decision-making, which is conducive to significantly reducing the probability of line failure caused by compound risk and ensuring the safe and stable operation of the power grid.

[0101] As an optional embodiment, the spatial risk coefficient is determined by the following method:

[0102] Based on the obtained dynamic sag deviation rate data, the deviation degree from the historical normal operation data is calculated, and the deviation degree is converted into a spatial risk coefficient by a preset mapping function. The mapping function is a monotonically increasing function, and the greater the deviation degree, the greater the spatial risk coefficient.

[0103] As an optional embodiment, the insulation risk coefficient is determined by the following way: based on the acquired corona discharge intensity data, the ratio of the corona discharge intensity to the corona inception voltage is calculated, the ratio is converted into the insulation risk coefficient by a preset mapping function, and the mapping function is a monotonically increasing function, the larger the ratio, the larger the insulation risk coefficient.

[0104] Specifically, in the operation safety assessment of the power transmission line, the traditional technology is difficult to judge the potential risks brought by the spatial position change of the conductor and the decline of the insulation performance. On the one hand, the quantitative assessment of the dynamic change of the sag is lacking, and the spatial collision risk caused by the insufficient distance between the conductor and the ground cannot be intuitively reflected; on the other hand, the correlation between the corona discharge intensity and the insulation aging is only qualitative, and it is difficult to accurately measure the possibility of insulation failure, so that potential risks may be ignored and safety accidents may be caused;

[0105] Based on the acquired dynamic deviation rate data of the sag, the deviation degree of the data from the historical normal operation data is first calculated. For example, the dynamic deviation rate of the sag of a certain section of conductor is stable within ±2% in the historical normal operation, and the current detection value is 8%, so the deviation degree is 6%. Subsequently, the deviation degree is converted into a spatial risk coefficient by a preset monotonically increasing mapping function. Due to the characteristics of the mapping function, the larger the deviation degree, the higher the converted spatial risk coefficient. Assuming that when the deviation degree is 2%, the spatial risk coefficient is 0.2; when the deviation degree reaches 8%, the spatial risk coefficient is increased to 0.7. Thus, the risk of the change of the sag of the conductor can be intuitively presented, and the risk level can be quickly identified by the operation and maintenance personnel;

[0106] For the corona discharge intensity data, the ratio of the corona discharge intensity to the corona inception voltage is calculated. For example, the corona inception voltage of a certain conductor is 40kV, and the voltage corresponding to the current corona discharge intensity is 60kV, so the ratio is 1.5. Then, the ratio is converted into an insulation risk coefficient by a preset monotonically increasing mapping function. As the ratio increases, the insulation risk coefficient also increases accordingly. For example, when the ratio is 1.2, the insulation risk coefficient is 0.3; when the ratio reaches 1.5, the insulation risk coefficient is increased to 0.6. Through this quantitative conversion, the influence of the corona discharge on the insulation performance is converted into a specific value, which provides an accurate basis for the insulation risk assessment;

[0107] The risk coefficient determination scheme effectively solves the core problem in the traditional transmission line risk assessment by quantitatively analyzing the sag dynamic deviation rate and the corona discharge intensity. The deviation of the sag change from the historical data and the ratio of the corona discharge intensity to the corona inception voltage are respectively converted into spatial risk coefficients and insulation risk coefficients through a monotonically increasing mapping function, thereby realizing accurate quantification of the spatial position risk and insulation performance risk of the conductor. Compared with the traditional fuzzy evaluation method, this quantitative method makes the risk level clear at a glance, helps the operation and maintenance personnel quickly locate the high-risk area, and formulates the maintenance plan, which helps to avoid safety accidents caused by spatial collision or insulation failure, and significantly improves the accuracy and effectiveness of the operation safety assessment of the transmission line.

[0108] In a second aspect, the present application further provides a transmission channel risk early warning evaluation system, which comprises the following steps:

[0109] The monitoring module analyzes the degree of current waveform distortion caused by nonlinear load in the transmission line by monitoring the voltage harmonic distortion rate, and evaluates the influence of harmonics on line and equipment insulation aging and heating loss.

[0110] The analysis module analyzes the real-time gradient of the conductor temperature, judges the abnormal heating condition of different sections of the conductor, and evaluates the degree of abnormal temperature rise and potential thermal damage accumulation of the conductor caused by overload and poor contact factors. The judgment module judges whether the transmission line has an abnormal heating risk according to the influence of the voltage harmonic distortion rate on the equipment insulation aging and heating loss and the abnormal conductor temperature condition reflected by the real-time gradient of the conductor temperature. When the transmission line has an abnormal heating risk, the evaluation module: evaluates the sag change of the conductor caused by temperature change and mechanical stress factors by analyzing the sag dynamic deviation rate, judges whether the distance between the conductor and the ground meets the safety standard; evaluates the aggravation of corona discharge on the surface of the conductor caused by heating and damage factors by monitoring the corona discharge intensity, and judges the degree of insulation performance degradation; the early warning module comprehensively analyzes the conductor spatial position change reflected by the sag dynamic deviation rate and the insulation performance degradation degree reflected by the corona discharge intensity, evaluates the risk level of the transmission channel operation and gives an early warning.

[0111] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical scope disclosed in the present application, which shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A power transmission channel risk pre-warning assessment method, characterized in that, The method comprises the following steps: By monitoring the voltage harmonic distortion rate, the degree of current waveform distortion caused by nonlinear load in the transmission line is analyzed, and the influence of harmonics on the insulation aging and heating loss of the line and equipment is evaluated; The real-time gradient of the conductor temperature is analyzed to determine the abnormal heating condition of different sections of the conductor, and the degree of abnormal temperature rise and potential thermal damage accumulation of the conductor caused by overload and poor contact factors is evaluated; according to the influence of the voltage harmonic distortion rate on the insulation aging and heating loss of the equipment and the abnormal conductor temperature reflected by the real-time gradient of the conductor temperature, it is determined whether the transmission line has an abnormal heating risk; A risk matrix is constructed, with the horizontal axis representing the voltage harmonic distortion rate level and the vertical axis representing the real-time gradient level of the conductor temperature; When the risk matrix falls into the early warning area, the abnormal heating early warning is triggered, and the sag and corona monitoring are started; when the transmission line has an abnormal heating risk: By analyzing the sag dynamic deviation rate, the sag change of the conductor caused by temperature change and mechanical stress factors is evaluated, and it is determined whether the distance of the conductor to the ground meets the safety standard; By monitoring the corona discharge intensity, the intensification of corona discharge on the surface of the conductor caused by heating and damage factors is evaluated, and the degree of insulation performance degradation is determined; the spatial position change of the conductor reflected by the sag dynamic deviation rate and the degree of insulation performance degradation reflected by the corona discharge intensity are comprehensively analyzed, the risk level of the transmission channel operation is evaluated, and early warning is performed.

2. The method of claim 1, wherein, The method for monitoring the voltage harmonic distortion rate, analyzing the degree of current waveform distortion caused by nonlinear load in the transmission line, and evaluating the influence of harmonics on the insulation aging and heating loss of the line and equipment comprises the following steps: Real-time acquisition of three-phase voltage signals, calculation of harmonic content by frequency spectrum analysis, and calculation of voltage harmonic distortion rate according to standard formula; A correlation model of voltage harmonic distortion rate and insulation aging rate is established to evaluate the damage of harmonics to insulation life; The additional heating loss caused by harmonics is calculated to evaluate the influence on the current carrying capacity of the conductor.

3. The method of claim 1, wherein, The real-time gradient of the conductor temperature is analyzed to determine the abnormal heating condition of different sections of the conductor, and the degree of abnormal temperature rise and potential thermal damage accumulation of the conductor caused by overload and poor contact factors is evaluated, which specifically comprises the following steps: Distributed temperature measurement points are arranged on the conductor at intervals, and the temperature difference and distance ratio of adjacent temperature measurement points are calculated as ΔT; A thermal damage accumulation model is established, and the thermal damage accumulation degree is evaluated according to the duration of ΔT exceeding the early warning threshold and the thermal damage accumulation rate; When the ΔT of a section exceeds the early warning threshold and the thermal damage accumulation rate is greater than a first preset value, it is determined that there is an abnormal heating risk, and the continuous monitoring is started; When the ΔT of a section is greater than a second preset value for a continuous preset time, it is directly determined that there is a serious heating risk.

4. The method of claim 1, wherein, By analyzing the sag dynamic deviation rate, the sag change of the conductor caused by temperature change and mechanical stress factors is evaluated, and it is determined whether the distance of the conductor to the ground meets the safety standard, which specifically comprises the following steps: The spatial coordinates of the conductor are obtained by unmanned aerial vehicle laser radar scanning or image recognition, and the real-time value of the sag is calculated; The sag dynamic deviation rate is calculated; According to the mapping relationship between the sag dynamic deviation rate and the distance to the ground, it is evaluated whether it is lower than the safety threshold.

5. The method of claim 1, wherein: By monitoring the corona discharge intensity, the aggravation of corona discharge on the surface of the conductor due to heating and damage factors is evaluated, and the degree of degradation of the insulation performance is judged, specifically including: The number of corona discharge photons or the electric field intensity is measured by using an ultraviolet imager or an electric field sensor, and converted into discharge intensity; A correlation model of corona discharge intensity and insulation aging is established, and when the discharge intensity exceeds the preset multiple of the corona inception voltage and the remaining life of the insulation is less than half, it is determined that the insulation performance is seriously degraded.

6. The method of claim 1, wherein, The spatial position change reflected by the dynamic sag deviation rate and the degree of insulation performance degradation reflected by the corona discharge intensity are comprehensively analyzed, specifically including: the spatial risk coefficient corresponding to the dynamic sag deviation rate and the insulation risk coefficient corresponding to the corona discharge intensity are normalized respectively, and the normalized spatial risk coefficient and insulation risk coefficient are calculated; A preset comprehensive risk coefficient threshold is set, and the comprehensive risk coefficient is compared with the comprehensive risk coefficient threshold: when the comprehensive risk coefficient is less than or equal to the comprehensive risk coefficient threshold, it means that the operation risk of the power transmission channel is low; when the comprehensive risk coefficient is greater than the comprehensive risk coefficient threshold, it means that the operation risk of the power transmission channel is high.

7. The method of risk pre-warning evaluation of power transmission channel according to claim 6, characterized in that, The spatial risk coefficient is determined by the following method: Based on the obtained dynamic sag deviation rate data, the deviation degree from the historical normal operation data is calculated, and the deviation degree is converted into a spatial risk coefficient through a preset mapping function, the mapping function is a monotonically increasing function, the greater the deviation degree, the greater the spatial risk coefficient.

8. The method of claim 6, wherein, The insulation risk coefficient is determined by the following method: based on the obtained corona discharge intensity data, the ratio of the corona discharge intensity to the corona inception voltage is calculated, and the ratio is converted into an insulation risk coefficient through a preset mapping function, the mapping function is a monotonically increasing function, the greater the ratio, the greater the insulation risk coefficient.

9. A power transmission channel risk early warning assessment system suitable for the power transmission channel risk early warning assessment method of any one of claims 1 to 8, characterized in that, The system includes: The monitoring module analyzes the degree of current waveform distortion caused by nonlinear load in the transmission line by monitoring the voltage harmonic distortion rate, and evaluates the influence of harmonics on line and equipment insulation aging and heating loss; The analysis module analyzes the real-time gradient of the conductor temperature, judges the abnormal heating condition of different sections of the conductor, evaluates the degree of abnormal temperature rise and potential thermal damage accumulation of the conductor caused by overload and poor contact factors; the judgment module judges whether there is an abnormal heating risk in the transmission line according to the influence of voltage harmonic distortion rate on equipment insulation aging and heating loss and the abnormal temperature condition reflected by the real-time gradient of the conductor temperature; A risk matrix is constructed, with the horizontal axis representing the voltage harmonic distortion rate level and the vertical axis representing the conductor temperature real-time gradient level; When the data point in the risk matrix falls into the early warning and above area, it is determined that the power transmission line has an abnormal heating risk; when the power transmission line has an abnormal heating risk, the evaluation module: by analyzing the sag dynamic deviation rate, evaluating the sag change of the conductor caused by temperature change and mechanical stress factors, judging whether the conductor-to-ground distance meets the safety standard; by monitoring the corona discharge intensity, evaluating the intensification of the corona discharge on the conductor surface caused by heating and damage factors, and judging the degree of insulation performance degradation; the early warning module comprehensively analyzes the conductor spatial position change reflected by the sag dynamic deviation rate and the degree of insulation performance degradation reflected by the corona discharge intensity, evaluates the risk level of the power transmission channel operation, and performs early warning.

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