Current-carrying capability comprehensive evaluation method and system for compatibility of high-voltage cable and overhead line

Abstract

The invention discloses a current-carrying capability comprehensive evaluation method and system for compatibility of a high-voltage cable and an overhead line, and relates to the technical field of current-carrying evaluation, and the method comprises the following steps: obtaining line operation parameters under a parallel operation or switching operation condition, and building a temperature dynamic response model of the cable and the overhead line, generating temperature response characteristics; combining the temperature response characteristic with a line power flow distribution process, and calculating an instantaneous impedance increment according to a line temperature change rate to obtain a power flow distribution result; based on a power flow distribution result, tracking the temperature rise trend of the cable and the overhead line, and adjusting the allowable current-carrying capacity of the two types of lines; and judging the compatibility of the cable and the overhead line in a given operation scene according to the allowable current-carrying capacity. According to the method, the temperature dynamic response model is coupled with the power flow distribution process, so that the compatibility of the cable and the overhead line is accurately evaluated, and the problem that an existing static current-carrying calculation method cannot reflect the influence of temperature change on the power flow dynamic state is solved.

Description

Technical Field

[0001] This invention relates to the field of current-carrying capacity assessment technology, and more specifically, to a comprehensive assessment method and system for the current-carrying capacity of high-voltage cables and overhead lines. Background Technology

[0002] In power systems, high-voltage cables and overhead lines often need to operate in parallel or switch within the same transmission corridor or channel to meet power supply reliability and load dispatching requirements. However, due to differences in structure and heat dissipation conditions, cables and overhead lines exhibit significant differences in thermal inertia, resulting in different temperature rise responses under the same current. Current technologies for assessing the current-carrying capacity of cables and overhead lines primarily employ static calculation methods, analyzing only rated temperature and average load, neglecting the dynamic temperature characteristics of the line during load changes or power flow adjustments. This method cannot accurately represent the dynamic impact of temperature changes on power flow redistribution, easily leading to biased assessments of actual current-carrying capacity, thus making it difficult to reliably determine the compatibility of cables and overhead lines under parallel or switch operation conditions. Due to the lack of coupled analysis methods for temperature dynamic response and power flow distribution, existing methods struggle to simultaneously ensure safe line operation and load optimization, limiting the flexibility and reliability of power grid planning and operation.

[0003] The above-disclosed technical solutions have at least the following technical problems: In parallel or switching operation scenarios of cables and overhead lines, due to the significant difference in thermal inertia between the two, the existing static current carrying capacity calculation methods cannot express the dynamic impact of temperature changes on power flow redistribution, resulting in deviations in current carrying capacity assessment and making it difficult to accurately judge the compatibility of the two under joint operation conditions. Summary of the Invention

[0004] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a comprehensive evaluation method and system for the current-carrying capacity of high-voltage cables and overhead lines. By coupling a temperature dynamic response model with the power flow distribution process, impedance is dynamically adjusted with temperature, power flow distribution is continuously updated, and allowable current carrying capacity is dynamically optimized. This accurately evaluates the compatibility of cables and overhead lines under parallel or switching operating conditions, solving the problem that existing static current-carrying calculation methods cannot reflect the dynamic impact of temperature changes on power flow.

[0005] To achieve the above objectives, the present invention provides the following technical solution: On the one hand, a comprehensive evaluation method for the current-carrying capacity of high-voltage cables and overhead lines includes the following steps: obtaining line operating parameters under parallel or switching operation conditions; establishing temperature dynamic response models for cables and overhead lines based on the line operating parameters to generate temperature response characteristics; combining the temperature response characteristics with the line power flow distribution process, calculating the instantaneous impedance increment based on the line temperature change rate, and obtaining the power flow distribution result over time; and based on the power flow distribution result, tracking the temperature rise trend of cables and overhead lines, and adjusting the allowable current-carrying capacity of the two types of lines accordingly based on the temperature rise trend. The compatibility of cables and overhead lines under a given operating scenario is determined based on the allowable current carrying capacity.

[0006] In a preferred embodiment, temperature dynamic response models for cables and overhead lines are established based on line operating parameters to generate temperature response characteristics; the temperature change process of the lines under load changes is extracted based on the temperature and environmental parameters of the cables and overhead lines; based on the temperature change process, the temperature rise curve and fall curve formed by the lines under different load steps are extracted, and the time constants of the cables and overhead lines are fitted accordingly; the time constants are correlated with the laying structure and heat dissipation conditions of the lines to construct a temperature dynamic response model; and temperature response characteristics reflecting the temperature change trend are generated through the temperature dynamic response model.

[0007] In a preferred embodiment, the step of associating the time constant with the laying structure and heat dissipation conditions of the line to construct a dynamic temperature response model specifically involves: determining the thermal environment parameters of the line based on the time constant of the cable and overhead line, combined with the laying method, laying depth, and environmental heat dissipation conditions; addressing the problem that traditional temperature response models are insufficient in predicting the rate of temperature rise and fall under rapid load changes, a step change in load is introduced into the model. By coupling the instantaneous impact of load change on conductor temperature with the time constant, a dynamic response characteristic that can simultaneously reflect the temperature rise and fall stages is formed; a first-order thermal equivalent model is used to simulate the line temperature, and parameters are adjusted in the model to match the temperature dynamics caused by load changes, resulting in the final dynamic temperature response model, generating temperature response characteristics that can characterize the temperature change trend of the line.

[0008] In a preferred embodiment, the calculation of the instantaneous impedance increment includes: calculating the time change of conductor resistance based on the line conductor temperature and the temperature coefficient of metal resistance, and injecting the change into the impedance matrix of the power flow iteration process.

[0009] In a preferred embodiment, combining the temperature response characteristics with the power flow distribution process specifically involves: determining the temperature change trend of each line at different time points based on the temperature response characteristics of cables and overhead lines; dynamically correcting the line impedance based on the temperature change trend, so that the impedance adjusts with temperature changes; using the corrected impedance as input during power flow distribution, so that the power flow distribution reflects the influence of temperature changes on current distribution; tracking the changes in power flow distribution results over time to form a power flow distribution sequence that is dynamically updated with temperature response characteristics; the power flow distribution result at each time point depends on the temperature response characteristics and impedance correction at the previous time point, forming a continuous dynamic response closed loop.

[0010] In a preferred embodiment, the dynamic correction of the line impedance characteristics based on the temperature change trend, so that the impedance of the cable and overhead line is adjusted accordingly with temperature changes, specifically involves: obtaining the conductor temperature of each cable and overhead line at each time point based on temperature response characteristics; calculating the instantaneous increment of conductor resistance over time based on conductor temperature and metal resistance temperature coefficient; adding the instantaneous increment to the line impedance matrix in the power flow iteration process, so that the total line impedance is dynamically adjusted with temperature changes; repeating the above steps to dynamically update all time points, so that the power flow distribution can continuously reflect the influence of line temperature on resistance and current distribution.

[0011] In a preferred embodiment, the step of tracking the temperature rise trend of cables and overhead lines based on power flow distribution results specifically involves: obtaining the current distribution of each line at each time point through the power flow distribution sequence; combining the temperature dynamic response model and time constant generated in the previous steps to map the current change of each line to the predicted value of conductor temperature change; using real-time monitoring or simulated temperature data to compare the predicted temperature with the actual measured temperature, calculating the temperature rise deviation, and performing rolling updates to form a dynamic temperature rise trend sequence.

[0012] In a preferred embodiment, the step of determining the compatibility of the cable and overhead line under a given operating scenario based on the allowable current carrying capacity specifically involves: comparing the dynamic allowable current carrying capacity sequence of each line with the actual power flow distribution at the corresponding time point to obtain the safety margin ratio of each line at time t; calculating the current carrying ratio of each line at the same time point for parallel or switching operating conditions of the cable and overhead line combination, and forming a joint compatibility matrix with the safety margin ratio; determining the compatibility status of the cable and overhead line under the operating scenario based on the joint compatibility matrix; and outputting the compatibility determination result as a dynamic compatibility status table of the cable and overhead line under the target operating scenario.

[0013] On the other hand, a comprehensive current-carrying capacity evaluation system for the compatibility of high-voltage cables and overhead lines includes the following modules: a data acquisition module for acquiring line operating parameters under parallel or switching operating conditions; a response characteristic generation module for establishing temperature dynamic response models for cables and overhead lines based on the line operating parameters, and generating temperature response characteristics; a power flow distribution module for combining the temperature response characteristics with the line power flow distribution process, calculating the instantaneous impedance increment based on the line temperature change rate, and obtaining the power flow distribution result over time; an allowable current-carrying capacity adjustment module for tracking the temperature rise trend of cables and overhead lines based on the power flow distribution result, and adjusting the allowable current-carrying capacity of the two types of lines accordingly based on the temperature rise trend; and a compatibility judgment module for judging the compatibility of cables and overhead lines under a given operating scenario based on the allowable current-carrying capacity.

[0014] The technical effects and advantages of the comprehensive evaluation method and system for current-carrying capacity compatibility between high-voltage cables and overhead lines of this invention are as follows: This invention tightly couples the temperature dynamic response characteristics of cables and overhead lines with the power flow distribution process, enabling dynamic adjustment of line impedance with temperature, continuous updating of power flow distribution, real-time tracking of temperature rise trends, and dynamic optimization of allowable current carrying capacity. This allows for accurate assessment of the compatibility of cables and overhead lines under different operating conditions, achieving a balance between safe line operation and load utilization, and improving the reliability and scheduling flexibility of the power grid. Attached Figure Description

[0015] Figure 1 This is a flowchart illustrating the comprehensive evaluation method for the current-carrying capacity of high-voltage cables and overhead lines according to the present invention. Figure 2 This is a schematic diagram of the current-carrying capacity comprehensive evaluation system for the compatibility of high-voltage cables and overhead lines according to the present invention. Detailed Implementation

[0016] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] Example 1, Figure 1 This invention provides a comprehensive evaluation method for the current-carrying capacity of high-voltage cables and overhead lines, comprising the following steps: S1, obtain the line operating parameters under parallel operation or switching operation conditions; In this embodiment, the line operating parameters include the conductor temperature, sheath temperature, soil thermal resistance, and cable time constant of the cable, and the conductor temperature, meteorological conditions, and overhead line time constant of the overhead line. The acquisition of line operating parameters under parallel operation or switching operation conditions specifically includes: The conductor temperature, sheath temperature, and ambient temperature of the cable are collected through an online cable monitoring device. The overhead line meteorological monitoring unit collects conductor temperature, wind speed, wind direction, and ambient temperature. It combines the line laying method, corridor environment and real-time load information to characterize the actual operating status of parallel lines.

[0018] S2, Based on the line operating parameters, establish temperature dynamic response models for cables and overhead lines respectively, and generate temperature response characteristics; In this embodiment, temperature dynamic response models for cables and overhead lines are established based on line operating parameters to generate temperature response characteristics. Based on the temperature and environmental parameters of cables and overhead lines, extract the temperature change process of the lines under load changes; Based on the temperature change process, the temperature rise curve and fall curve formed by the line under different load steps are extracted, and the time constants of the cable and overhead line are fitted accordingly to characterize the thermal response speed of the two types of lines. By associating the time constant with the laying structure and heat dissipation conditions of the line, a dynamic temperature response model that can describe the temperature change with load is constructed. The temperature dynamic response model generates temperature response characteristics that reflect the temperature change trend, providing dynamic temperature constraints for subsequent power flow allocation steps.

[0019] The process involves associating the time constant with the laying structure and heat dissipation conditions of the line to construct a dynamic temperature response model that describes the temperature variation with load. Specifically, the dynamic temperature response model is as follows: Based on the time constant of cables and overhead lines, and combined with the laying method (such as underground, overhead or cable tray laying), laying depth and environmental heat dissipation conditions (such as soil thermal conductivity, wind speed and ambient temperature), the thermal environment parameters of the line are determined. To address the problem that traditional temperature response models are insufficient in predicting the rate of temperature rise and fall under rapid load changes, a step change in load is introduced into the model. By coupling the instantaneous effect of load change on conductor temperature with the time constant, a dynamic response characteristic that can simultaneously reflect the temperature rise and fall stages is formed. A first-order thermal equivalent model is used to simulate the line temperature, and the parameters in the model are adjusted to match the temperature dynamics caused by load changes, so that the model can accurately reflect the temperature response under different load conditions. The model generates temperature response characteristics that characterize the trend of line temperature changes, which are then used in the subsequent power flow allocation process and allow for current carrying capacity adjustment.

[0020] S3, combine the temperature response characteristics with the line power flow distribution process, calculate the instantaneous impedance increment based on the line temperature change rate, and obtain the power flow distribution result that changes with time. In this embodiment, the calculation of the instantaneous impedance increment includes: The time-varying change in conductor resistance is calculated based on the conductor temperature and the temperature coefficient of metal resistance, and this change is injected into the impedance matrix of the power flow iteration process.

[0021] The process of combining the temperature response characteristics with the power flow distribution process of the line, calculating the instantaneous impedance increment based on the line temperature change rate, and obtaining the power flow distribution result that changes over time is as follows: Based on the temperature response characteristics of cables and overhead lines, the temperature change trend and rate of change of each line at different time points were determined. Based on the aforementioned temperature change trend, the impedance characteristics of the line are dynamically corrected so that the impedance of the cable and overhead line is adjusted accordingly with temperature changes. During the power flow distribution process, the corrected line impedance is used as input to enable the power flow distribution to reflect the effect of temperature changes on current distribution. Track the changes in power flow distribution results over time to form a power flow distribution sequence that is dynamically updated with temperature response characteristics, which is used for subsequent real-time temperature rise monitoring and allowable flow rate adjustment; The power flow distribution result at each time point depends on the temperature response characteristics and impedance correction at the previous time point, forming a continuous dynamic response closed loop.

[0022] The instantaneous impedance increment is calculated using the following formula:

[0023]

[0024] in, Let be the conductor resistance at time t. Reference temperature The conductor resistance below, The temperature coefficient of resistance of a conductor metal. Let be the conductor temperature at time t. This represents the instantaneous impedance increment.

[0025] The impedance characteristics of the line are dynamically corrected based on the temperature change trend, so that the impedance of the cable and overhead line is adjusted accordingly with temperature changes. Specifically: Based on temperature response characteristics, the conductor temperature of each cable and overhead line at each time point is obtained; Calculate the instantaneous increment of conductor resistance over time based on conductor temperature and the temperature coefficient of metal resistance; Instantaneous increments are incorporated into the line impedance matrix during the power flow iteration process, so that the total line impedance is dynamically adjusted with temperature. Repeat the above steps to dynamically update all time points, so that the power flow distribution can continuously reflect the influence of line temperature on resistance and current distribution.

[0026] The specific calculation formula for dynamically adjusting the total impedance of the line with temperature is as follows:

[0027] in, Let be the total impedance of the line at time t. The imaginary unit is used to distinguish reactance from resistance. Reactance represents the reactive power impedance capability of a line to alternating current. This represents the imaginary part of the reactance in the complex impedance. The conductor resistance at the reference temperature, This represents the instantaneous impedance increment.

[0028] S4, based on the power flow distribution results, tracks the temperature rise trend of cables and overhead lines, and adjusts the allowable current carrying capacity of the two types of lines accordingly based on the temperature rise trend; In this embodiment, tracking the temperature rise trend of cables and overhead lines based on power flow distribution results specifically includes: The current distribution of each line at each time point is obtained through the power flow distribution sequence; Combining the temperature dynamic response model and time constant generated in the previous steps, the current change of each line is mapped to the predicted value of conductor temperature change; By using real-time monitoring or simulated temperature data, the predicted temperature is compared with the actual measured temperature, the temperature rise deviation is calculated, and the data is updated on a rolling basis to form a dynamic temperature rise trend sequence. In the temperature rise trend sequence, identify line segments that exceed the safety threshold or points of abnormal temperature change to provide a basis for subsequent allowable current carrying capacity adjustments.

[0029] The adjustment of the allowable current carrying capacity of the two types of lines according to the temperature rise trend is specifically as follows: Based on the temperature rise trend sequence, the difference between the actual temperature rise and the design safe temperature of each line at each time point is determined; For line sections where the temperature rise is close to or exceeds the safe temperature, the maximum allowable current increment is calculated based on the line's thermal response time constant and temperature rise rate to prevent overheating. The maximum current increment is applied to the power flow distribution results to dynamically adjust the allowable current carrying capacity of each line. For line sections where the temperature rise is not close to the safety threshold, the allowable current carrying capacity can be appropriately increased based on the power flow distribution results and load demand to improve line utilization, while ensuring that the temperature rise does not exceed the safety limit. Repeat the above steps to form a dynamic time-adjusted sequence of allowable current carrying capacity for each line, which will be used for subsequent comprehensive compatibility assessment of cables and overhead lines.

[0030] The allowed flow rate is specifically as follows:

[0031] in, To allow for high throughput, The rated current carrying capacity of the line, To couple the temperature rise with the time constant into a function that allows for adjustment of the current carrying capacity, The actual temperature rise at time t. The line temperature time constant, The rate of temperature change is predicted by the temperature dynamic response model.

[0032] S5 determines the compatibility of cables and overhead lines in a given operating scenario based on the allowable current carrying capacity.

[0033] The compatibility assessment is based on one or more of the following conditions: The cable conductor temperature exceeds its maximum allowable temperature; the conductor temperature corresponding to the sag of the overhead line exceeds the safety distance limit; the dynamic power flow exceeds the instantaneous thermal stability limit of the line.

[0034] In this embodiment, determining the compatibility of the cable and overhead line under a given operating scenario based on the allowable current carrying capacity specifically involves: The safety margin ratio for each line at time t is obtained by comparing the dynamic allowable carrying capacity sequence of each line with the actual power flow distribution at the corresponding time point. For parallel or switching operation of cable and overhead line combination, the current carrying ratio of each line at the same time point is calculated and a joint compatibility matrix is ​​formed with the safety margin ratio. Based on the joint compatibility matrix, determine the compatibility status of cables and overhead lines in the operating scenario; The compatibility judgment results are output as a dynamic compatibility status table of cables and overhead lines under the target operating scenario.

[0035] The process of determining the compatibility status of cables and overhead lines in the operational scenario based on the joint compatibility matrix is ​​as follows: If the current carrying ratio of all lines is greater than or equal to the preset threshold, the compatibility is good and the line can operate normally according to the power flow distribution. If the current carrying capacity of all lines is less than the preset threshold, then there is incompatibility or potential overload risk, and the operation plan needs to be adjusted by measures such as load redistribution, current limiting, or adding spare lines.

[0036] Example 2, Figure 2 This invention presents a comprehensive current-carrying capacity evaluation system for the compatibility of high-voltage cables with overhead lines, comprising the following modules: Data acquisition module: used to acquire line operating parameters under parallel operation or switching operation conditions; Response characteristic generation module: used to establish dynamic temperature response models for cables and overhead lines based on line operating parameters, and generate temperature response characteristics; Power flow distribution module: used to combine the temperature response characteristics with the line power flow distribution process, calculate the instantaneous impedance increment based on the line temperature change rate, and obtain the power flow distribution result that changes with time; Allowable current carrying capacity adjustment module: used to track the temperature rise trend of cables and overhead lines based on power flow distribution results, and adjust the allowable current carrying capacity of the two types of lines accordingly based on the temperature rise trend; Compatibility assessment module: used to determine the compatibility between cables and overhead lines in a given operating scenario based on the allowable current carrying capacity.

[0037] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0038] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product.

[0039] Those skilled in the art will recognize that the modules and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0040] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0041] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0042] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for comprehensive evaluation of the current-carrying capacity of high-voltage cable and overhead line compatibility, characterized in that, The method comprises the following steps: Obtaining line operation parameters under parallel operation or switching operation conditions; Based on the line operation parameters, temperature dynamic response models of the cable and overhead line are established respectively, and temperature response characteristics are generated; The temperature response characteristics are combined with the line power flow distribution process, the instantaneous impedance increment is calculated according to the line temperature change rate, and the time-varying power flow distribution result is obtained; Based on the power flow distribution result, the temperature rise trend of the cable and overhead line is tracked, and the allowable ampacity of the two types of lines is adjusted accordingly; The compatibility of the cable and overhead line under the given operation scenario is judged according to the allowable ampacity.

2. A method of comprehensive assessment of the current-carrying capacity of high-voltage cables for compatibility with overhead lines according to claim 1, characterised in that, The temperature dynamic response models of the cable and overhead line are established respectively based on the line operation parameters, and the temperature response characteristics are generated; According to the temperature and environmental parameters of the cable and overhead line, the temperature change process of the line under load change is extracted; Based on the temperature change process, the temperature rise curve and the temperature drop curve formed under different load steps are extracted, and the time constant of the cable and overhead line is fitted accordingly; The time constant is associated with the laying structure and heat dissipation condition of the line to construct the temperature dynamic response model; The temperature response characteristics reflecting the temperature change trend are generated through the temperature dynamic response model.

3. The method for comprehensive evaluation of the current-carrying capacity of high-voltage cable compatibility with overhead lines according to claim 2, characterized in that, The time constant is associated with the laying structure and heat dissipation condition of the line to construct the temperature dynamic response model, specifically: Based on the time constant of the cable and overhead line, the laying method, laying depth and environmental heat dissipation condition of the line are combined to determine the thermal environmental parameters of the line; In order to solve the problem that the traditional temperature response model cannot predict the temperature rise and cooling rate under rapid load change, the load step change is introduced into the model, the instantaneous influence of load change on conductor temperature is coupled with the time constant, and the dynamic response characteristics reflecting the temperature rise and cooling stage are formed; A first-order thermal equivalent model is used to simulate the line temperature, and the parameters in the model are adjusted to match the temperature dynamics caused by load change, so as to obtain the final temperature dynamic response model and generate the temperature response characteristics reflecting the line temperature change trend.

4. The method for comprehensive evaluation of the current-carrying capacity of high-voltage cable compatibility with overhead lines according to claim 3, characterized in that, The calculation of the instantaneous impedance increment comprises: According to the line conductor temperature and the metal resistance temperature coefficient, the time variation of the conductor resistance is calculated, and the variation is injected into the impedance matrix of the power flow iteration process.

5. A method of comprehensive assessment of the current-carrying capacity of high-voltage cables for compatibility with overhead lines according to claim 4, characterised in that, The temperature response characteristics are combined with the line power flow distribution process, specifically: Based on the temperature response characteristics of the cable and overhead line, the temperature change trend of each line at different time points is determined; The impedance of the line is dynamically corrected according to the temperature change trend, so that the impedance is adjusted with the temperature change; In the power flow distribution process, the corrected impedance is taken as the input, so that the power flow distribution reflects the influence of temperature change on current distribution; The change of the power flow distribution result with time is tracked to form a power flow distribution sequence dynamically updated according to the temperature response characteristics; The power flow distribution result at each time point depends on the temperature response characteristics and impedance correction at the previous time point, forming a continuous dynamic response closed loop.

6. A method of comprehensive assessment of the current-carrying capacity of high-voltage cables for compatibility with overhead lines according to claim 5, characterised in that, The impedance characteristics of the line are dynamically corrected according to the temperature change trend, so that the impedance of the cable and overhead line is adjusted accordingly with the temperature change, specifically: Based on the temperature response characteristics, the conductor temperature of each cable and overhead line at each time point is obtained; According to the conductor temperature and the metal resistance temperature coefficient, the instantaneous increment of the conductor resistance with time is calculated; The instantaneous increment is added to the line impedance matrix of the power flow iteration process, so that the total impedance of the line is dynamically adjusted with the change of temperature; The above steps are repeated for dynamic updating at all time points, so that the power flow distribution can continuously reflect the influence of line temperature on resistance and current distribution.

7. A method of comprehensive assessment of the current-carrying capacity of high-voltage cables for compatibility with overhead lines according to claim 6, characterised in that, Based on the power flow distribution results, the temperature rise trend of the cable and overhead line is tracked, specifically: Through the power flow distribution sequence, the current distribution of each line at each time point is obtained; Combined with the temperature dynamic response model and time constant generated in the previous step, the current change of each line is mapped to the predicted value of conductor temperature change; By using real-time monitoring or simulation temperature data, the predicted temperature is compared with the actual measured temperature, the temperature rise deviation is calculated, and the dynamic temperature rise trend sequence is formed by rolling update.

8. A method of comprehensive assessment of the current-carrying capacity of high-voltage cables for compatibility with overhead lines according to claim 7, characterised in that, According to the allowable current-carrying capacity, the compatibility of the cable and overhead line under the given operating scenario is judged, specifically: Based on the comparison between the dynamic allowable current-carrying capacity sequence of each line and the actual power flow distribution at the corresponding time point, the safety margin ratio of each line at time t is obtained; For the parallel or switching operation condition of the combination of cable and overhead line, the current-carrying ratio of each line at the same time point is calculated, and the joint compatibility matrix is formed with the safety margin ratio; According to the joint compatibility matrix, the compatibility state of the cable and overhead line under the operating scenario is judged; The compatibility judgment result is output as the dynamic compatibility state table of the cable and overhead line under the target operating scenario.

9. A system for using the method for comprehensive evaluation of the current-carrying capacity of high-voltage cables compatible with overhead lines according to any one of claims 1-8, characterized in that, The following modules are included: Data acquisition module: used for acquiring line operating parameters under parallel operation or switching operation condition; Response characteristic generation module: used for establishing temperature dynamic response model of cable and overhead line based on line operating parameters respectively, and generating temperature response characteristics; Power flow distribution module: used for combining the temperature response characteristics with the line power flow distribution process, calculating the instantaneous impedance increment according to the line temperature change rate, and obtaining the power flow distribution result changing with time; Allowable current-carrying capacity adjustment module: used for tracking the temperature rise trend of the cable and overhead line based on the power flow distribution result, and adjusting the allowable current-carrying capacity of the two types of lines correspondingly according to the temperature rise trend; Compatibility judgment module: used for judging the compatibility of the cable and overhead line under the given operating scenario according to the allowable current-carrying capacity.

Images