Method and system for calculating environmental factor-carrying capacity of overhead conductor based on consistency of GB, IEEE and CIGRE models

Abstract

The invention discloses an overhead conductor environmental factor-current-carrying capacity calculation method based on GB, IEEE and CIGRE model unification. The current-carrying capacity calculation method comprises the following steps: acquiring environmental parameters; performing unified judgment on convection working conditions around the wire according to the environmental parameters to obtain a working condition judgment result; performing parallel calculation on convective heat dissipation under three standards of GB, IEEE and CIGRE according to the working condition judgment result, and unifying the convective heat dissipation according to a unification principle to obtain unified convective heat dissipation; calculating radiation heat dissipation, sunlight heat absorption and effective alternating current resistance of the overhead conductor; and solving the current-carrying capacity by using the unified convection heat dissipation, the radiation heat dissipation, the sunlight heat absorption and the effective alternating current resistance. On the basis, a unified multi-standard current-carrying capacity calculation mode is realized, the prediction accuracy is improved, and the line current-carrying potential is released.

Description

Technical Field

[0001] This invention relates to the field of overhead conductor current carrying capacity technology, specifically to an overhead conductor environmental factor-current carrying capacity calculation method and system based on GB, IEEE, and CIGRE model consistency. Background Technology

[0002] Current carrying capacity refers to the maximum current a conductor can withstand under given operating conditions, provided the conductor temperature does not exceed the maximum permissible conductor temperature. The steady-state thermal balance equation is currently the core model used in electrical engineering to calculate the relationship between temperature and current carrying capacity of overhead lines under stable operating conditions. Its basic principle is based on the law of conservation of energy. The specific equations for calculating this relationship are as follows: (1)

[0003] In the formula, the thermal balance of overhead conductors under actual operating conditions mainly consists of four parts. Among them... This represents the heat generated by the resistance of the line itself, which is self-heating. I represents the current carrying capacity of the overhead line. This represents the AC resistance of the overhead conductor at the maximum permissible operating temperature; This represents the solar heat absorption power per unit length of overhead conductor under sunlight conditions. This represents the convective heat dissipation power per unit length of an overhead conductor during operation. This represents the radiative heat dissipation power per unit length of the overhead conductor. By solving equation (1), the formula for calculating the current carrying capacity of the overhead line can be obtained: (2)

[0004] (1) Overhead conductor convective heat dissipation

[0005] Convective heat dissipation refers to the energy transfer process in which a fluid carries heat from a high-temperature object to a low-temperature object during its flow. In overhead conductors, convective heat dissipation typically occurs when the air surrounding the conductor is heated by the rising temperature of the conductor. The temperature gradient changes from an ideal gas law equation to a change in air density gradient, thus generating airflow that carries away the heat from the conductor. Depending on the cause of the airflow, convective heat dissipation is often divided into natural convection and forced convection. Natural convection often refers to the phenomenon where, under windless conditions, the temperature difference between the overhead conductor and the surrounding air causes the high-temperature conductor to heat the air near it. This temperature gradient creates a density gradient, resulting in radial airflow and heat transport. Forced convection, on the other hand, originates from the mechanical disturbance of an external wind field. The increased airflow caused by external forces forms a forced convection boundary layer, carrying away the heat generated by the conductor. Forced convection is generally more effective at dissipating heat from the conductor than natural convection. The main differences among the three standards lie in convective heat dissipation.

[0006] (2) Overhead conductor radiation heat dissipation

[0007] Radiation heat dissipation of overhead conductors refers to the transfer of heat from the conductor itself to the surrounding environment through thermal radiation. Radiation heat dissipation is an inherent property of the conductor and is related to ambient temperature, conductor temperature, and line characteristics such as arrangement, number of branches, and conductor diameter. The calculation methods for radiation heat dissipation in the three standards are largely the same.

[0008] (3) Overhead conductors absorb heat from sunlight

[0009] Because overhead power lines are laid outdoors with their cores exposed, they inevitably receive sunlight, causing them to absorb heat from solar radiation. Generally, the amount of heat absorbed by the conductor from sunlight depends on the conductor's surface condition, diameter, and the intensity of solar radiation. The three standard calculation methods for solar heat absorption are similar.

[0010] (4) Resistance heating effect of overhead conductors

[0011] The resistance of overhead conductors is an inherent property of the material itself. Resistance generates heat when current flows through it, and this heat also contributes to the temperature rise of the overhead conductor itself according to the heat balance equation. While the formulas for calculating resistance do not differ significantly across standards, there are different regulations for calculating AC resistance.

[0012] Current overhead conductor current-carrying capacity assessments are mostly based on worst-case operating conditions, resulting in a long-term suppression of the projected current-carrying capacity of existing lines. Furthermore, inconsistencies exist in standards such as IEEE / CIGRE / GB regarding convective heat transfer, wind direction correction, and Reynolds number segmentation, leading to discrepancies in calculation results under the same operating conditions and making it difficult to establish a unified current-carrying capacity value. The inclusion of environmental factors such as wind speed / direction, ambient temperature, and solar radiation is also insufficient, and the lack of segmentation and switching rules for "natural convection / forced convection / transition zones" results in a lack of dynamic overload capacity assessment and easily fluctuating real-time results, hindering service dispatch. Given the difficulties and high investment costs of constructing new lines in China, these problems further contribute to low capacity utilization and resource waste. Summary of the Invention

[0013] To overcome the shortcomings of existing technologies, such as inconsistent results across standards, insensitivity to environmental changes, and difficulty in using real-time results for scheduling, this invention provides a method and system for calculating the environmental factors-current carrying capacity of overhead conductors based on GB, IEEE, and CIGRE model consistency. By achieving model consistency under multiple standards (GB / IEEE / CIGRE) and robustly solving for the current carrying capacity by incorporating environmental factors under the maximum allowable temperature constraint, this invention unifies the current carrying capacity calculation method, improves prediction accuracy, and unlocks the current carrying capacity potential of the line.

[0014] According to one aspect of this invention, a method for calculating the environmental factors—current carrying capacity—of overhead conductors based on a unified GB, IEEE, and CIGRE model is provided. The method includes: acquiring environmental parameters; uniformly determining the convective conditions around the conductor based on the environmental parameters to obtain a condition determination result; calculating convective heat dissipation under the GB, IEEE, and CIGRE standards in parallel based on the condition determination result and unifying it according to a consistency principle to obtain a unified convective heat dissipation; calculating radiative heat dissipation, solar heat absorption, and the effective AC resistance of the overhead conductor; and solving for the current carrying capacity using the unified convective heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance.

[0015] Furthermore, the environmental parameters include wind speed, wind direction angle, ambient temperature, and conductor outer diameter; a unified determination of the convective conditions around the conductor is made based on the environmental parameters, including: determining air density and kinematic viscosity based on ambient temperature; calculating the Reynolds number based on air density, kinematic viscosity, wind speed, and conductor outer diameter; calculating the crosswind component based on wind speed and wind direction angle; and jointly determining the convective conditions around the conductor based on the Reynolds number and the crosswind component to obtain the condition determination result.

[0016] Furthermore, the convective conditions around the conductor are determined jointly based on the Reynolds number and the crosswind component, including: when the crosswind component is less than the lower limit of wind speed or the Reynolds number is less than the lower limit of Reynolds number, it is determined to be natural convection; when the crosswind component is greater than the upper limit of wind speed or the Reynolds number is greater than the upper limit of Reynolds number, it is determined to be forced convection; when the crosswind component is greater than or equal to the lower limit of wind speed and less than or equal to the upper limit of wind speed, and the Reynolds number is greater than or equal to the lower limit of Reynolds number and less than or equal to the upper limit of Reynolds number, it is determined to be a transitional condition.

[0017] Furthermore, the determination of the convective conditions around the conductor based on the Reynolds number and the crosswind component further includes: if the previous moment was determined to be natural convection, the current moment is determined to be upgraded to a transitional condition or forced convection only if the crosswind component is greater than or equal to the sum of the lower wind speed limit and the wind speed hysteresis band, and the Reynolds number is greater than or equal to the sum of the lower Reynolds number limit and the Reynolds number hysteresis band; if the previous moment was determined to be forced convection, the current moment is determined to be downgraded to a transitional condition or natural convection only if the crosswind component is less than or equal to the difference between the upper wind speed limit and the wind speed hysteresis band, and the Reynolds number is less than or equal to the difference between the upper Reynolds number limit and the Reynolds number hysteresis band; if the previous moment was in a transitional condition, a weighted smooth transition is introduced between the natural convection and forced convection correlations at the current moment; the weight is determined by the normalization of the crosswind component or the Reynolds number.

[0018] Furthermore, based on the operating condition determination results, the convective heat dissipation under the GB, IEEE, and CIGRE standards is calculated in parallel and unified according to the consistency principle to obtain unified convective heat dissipation. This includes: when the dispersion or variance of convective heat dissipation under the three standards exceeds a preset threshold, the minimum value of convective heat dissipation under the GB, IEEE, and CIGRE standards is uniformly adopted as the unified convective heat dissipation; otherwise, segmented switching and transitional weighting are implemented between the GB, IEEE, and CIGRE standards based on the operating condition determination results to obtain unified convective heat dissipation.

[0019] Furthermore, based on the operating condition determination results, segmented switching and transitional weighting are implemented between the GB, IEEE, and CIGRE standards to obtain unified convection cooling, including: when it is determined to be natural convection, the minimum value of convection cooling under the GB and IEEE standards is uniformly adopted as the unified convection cooling; when it is determined to be forced convection, the minimum value of convection cooling under the IEEE and CIGRE standards is uniformly adopted as the unified convection cooling; when it is determined to be a transitional operating condition, weights are introduced to linearly transition the segmented results on both sides to obtain unified convection cooling.

[0020] Furthermore, after using the unified convective heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance to solve for the current carrying capacity, the current carrying capacity calculation method also includes applying safety margin constraints, time smoothing constraints, minimum hold duration constraints, slope limit constraints, anomaly degradation constraints, and boundary consistency constraints to the current carrying capacity.

[0021] According to one aspect of this invention, an overhead conductor environmental factor-current carrying capacity calculation system based on GB, IEEE, and CIGRE model standardization is provided, comprising: a parameter acquisition module for acquiring environmental parameters; a working condition determination module for uniformly determining the convection working conditions around the conductor based on the environmental parameters to obtain a working condition determination result; a convection heat dissipation unification module for parallel calculation of convection heat dissipation under the three standards of GB, IEEE, and CIGRE based on the working condition determination result and unifying it according to the standardization principle to obtain a unified convection heat dissipation; a parameter calculation module for calculating radiative heat dissipation, solar heat absorption, and the effective AC resistance of the overhead conductor; and a current carrying capacity solution module for solving the current carrying capacity using the unified convection heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance.

[0022] According to one aspect of the present invention, an electronic device is provided, including a memory and a processor, the memory storing program instructions that are executed by the processor, the processor calling the program instructions to execute the method for calculating the environmental factors-current carrying capacity of overhead conductors based on GB, IEEE, and CIGRE model uniformity.

[0023] According to one aspect of the present invention, a non-transitory computer-readable storage medium is provided, the non-transitory computer-readable storage medium storing computer instructions that cause the computer to execute the above-described method for calculating the environmental factors-current carrying capacity of overhead conductors based on GB, IEEE, and CIGRE model standardization.

[0024] The above technical solution involves determining the convection conditions around the conductor based on the acquired environmental parameters, including natural convection, transitional convection, and forced convection. This ensures the selection of appropriate convection cooling correlation formulas for parallel calculation of convection cooling under the GB, IEEE, and CIGRE standards under different conditions. Furthermore, the calculation is performed by switching between natural and forced segments, weighting transition segments, and applying the worst-case scenario principle when necessary, to output a single and auditable convection cooling result (i.e., unified convection cooling). Finally, the current carrying capacity is calculated based on the unified convection cooling, and engineering constraints such as safety margin, time smoothing, minimum hold time, slope limit, and anomaly degradation are applied to the current carrying capacity to obtain a stable current carrying capacity that can be used for operational deployment.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) Overcome the problem of excessively conservative static rating and achieve adaptive changes in the environment. The method can automatically adjust the current carrying capacity according to changes in wind speed, wind direction, ambient temperature and solar irradiance. Under favorable operating conditions, it releases the hidden capacity of the line and automatically converges to the conservative value under unfavorable operating conditions, avoiding the low utilization rate caused by long-term limits based on the most unfavorable operating conditions.

[0027] (2) Unify the multi-standard calculation method to form a single and auditable release caliber. By parallel calculation and regular aggregation (segmented switching, transition weighting and worst-case principle) of the three types of models GB, IEEE and CIGRE, the originally scattered results under the same working condition are unified into a single convection heat dissipation input and corresponding current carrying capacity release value, solving the problem of inconsistent calibers of multiple versions and difficulty in external use.

[0028] (3) Improve the accuracy of calculations and make the safety boundary controllable. The scheme explicitly models radiative heat dissipation and solar heat absorption, and uses the maximum allowable conductor temperature as a hard constraint, so that the published value is directly aligned with the temperature safety boundary. The impact of different allowable temperature settings on the published results can be quantified, reducing the risk of exceeding the limit.

[0029] (4) Improve release stability and operational availability. Mechanisms such as safety margin, time smoothing, minimum hold time, slope limit and anomaly degradation are introduced to transform real-time calculation results into stable and executable running values, suppress short-term fluctuations and frequent switching, and facilitate direct application by the scheduling side. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The flowchart illustrates a method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model standardization, as provided in this embodiment of the invention. Detailed Implementation

[0032] It should be noted that:

[0033] The terms “comprising” and “having”, and any variations thereof, in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, product, or apparatus that includes a series of steps or units, not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0034] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices. The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be decomposed, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In addition, the technical features of the various embodiments or individual embodiments provided by the present invention can be arbitrarily combined to form new technical solutions. Such combinations are not bound by the order of steps and / or structural composition patterns, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0036] This invention provides a method for calculating the current-carrying capacity of overhead conductors based on the consistency of models from GB, IEEE, and CIGRE. By achieving model consistency across multiple standards (GB / IEEE / CIGRE) and robustly solving for the current-carrying capacity by incorporating environmental factors under the constraint of maximum allowable temperature, this method unifies the current-carrying capacity calculation, improves prediction accuracy, and unlocks the current-carrying potential of the line. The main differences among the three standards (IEEE, CIGRE, and GB50545) lie in convective heat dissipation.

[0037] ①IEEE Computational Model

[0038] In calculating convective heat dissipation for overhead power lines, the IEEE model considers a complex array of influencing factors, including wind speed, wind direction angle, and even corrections for the impact of airflow density on convective heat dissipation at different altitudes. Furthermore, in addition to the two common classifications of convective heat dissipation mentioned above, the IEEE model further categorizes convective heat dissipation into three cases: forced convection under high wind speeds, forced convection under low wind speeds, and natural convection at zero wind speed. For calculations of convective heat dissipation under windy conditions, the IEEE model requires separate calculations for forced convection under high and low wind speeds, taking the larger value as the actual usable value. Under low wind speeds or even no wind, all three cases need to be calculated simultaneously, and the larger of the three results is used as a reference.

[0039] The IEEE formula for calculating forced convection cooling at high wind speeds is as follows: (3)

[0040] The IEEE formula for calculating forced convection cooling at low wind speeds is as follows: (4)

[0041] For natural convection cooling in windless conditions, the calculation formula is: (5)

[0042] In the above formula, For forced convection cooling under high wind speeds, For forced convection cooling at lower wind speeds, Natural convection cooling in windless conditions; The ambient temperature during operation, in °C; The temperature of the overhead conductor is expressed in °C. The thermal conductivity of air is expressed in W / (m·K). This is a wind direction angle correction factor; the more perpendicular the wind direction is to the guide wire, the larger the value. The Reynolds number is a dimensionless number that characterizes the flow pattern. It is used to determine whether the flow is laminar, transitional, or turbulent, and to select an appropriate heat dissipation calculation formula accordingly. Its calculation formula is: (6)

[0043] In the formula, D is the diameter of the conductor, in meters (m); V is the wind speed, in meters per second (m / s). Kinematic viscosity, unit: m 2 / s; Air density, unit: kg / m³ 3 .

[0044] ②CIGRE computational model

[0045] The CIGRE model only considers natural convection and forced convection. The formula for convection cooling under the CIGRE computational model is: (7)

[0046] In the formula, , and It has the same physical meaning as that expressed in the IEEE computational model; For convective heat dissipation under the CIGRE computational model; This represents the Nusselt coefficient, used only when considering forced convection cooling calculations, and its calculation formula is: (8)

[0047] Nusselt coefficients are related to the Reynolds number. The exponential function, where and n are functional parameters relating to the Reynolds number range and the surface roughness of the overhead conductor. The Reynolds number formula is the same as the IEEE standard calculation method, and the roughness judgment coefficient is... The calculation formula is: (9)

[0048] In the formula, d represents the diameter of a single strand in a single stranded layer, in meters; D represents the outer diameter of the overhead conductor (the overall conductor diameter).

[0049] The above calculation does not consider the influence of natural wind direction. If the influence of wind direction angle is considered in the CIGRE calculation model, a correction factor needs to be added. : (10)

[0050] In the formula, Let B1, B2, and m be the angle between the conductor's axis and the wind direction. The parameters.

[0051] ③GB50545 calculation model

[0052] The calculation of convective heat dissipation in the GB50545 standard is mainly based on Newton's law of cooling, that is, calculating the heat dissipation through the convective heat transfer coefficient, the surface area of ​​the object, and the temperature difference. The calculation equation before simplification is: (11)

[0053] Substituting the Reynolds number expression into (4.12), we get: (12)

[0054] In the formula, , and All are the same physical quantities as described above. Air density In national standards, C and p are often specified as 1, and their values ​​depend on the Reynolds number and the surface roughness of the overhead conductor. Surface roughness is incorporated into the calculation for auxiliary judgment. In GB50545, the calculation often uses both surface roughness and Reynolds number coefficients for a comprehensive judgment, and the correlation coefficient is selected after referring to a table based on their values.

[0055] Furthermore, in national standard calculations, only cases with Reynolds numbers less than 3000 are often considered, neglecting fluid turbulence at higher Reynolds numbers. Therefore, the C value is often set to 0.57, while the p value is often taken as 0.485. When considering the relevant parameters in the table and the actual operating conditions, some parameters can be simplified. The simplified calculation is commonly used domestically. The specific simplified calculation formula is as follows: (13)

[0056] This formula is often used as an empirical formula in the design and planning of related domestic projects, which can greatly simplify the calculation difficulty and improve accuracy.

[0057] Please refer to Figure 1 This invention provides a method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model standardization, which specifically includes the following steps:

[0058] Step S1: Obtain environmental parameters. Specifically, environmental parameters include wind speed, wind direction angle, ambient temperature, and conductor outer diameter.

[0059] Step S2: Based on environmental parameters, a unified judgment is made on the convection conditions around the conductor to obtain the condition judgment result.

[0060] In step S2, based on wind speed Wind direction - axial angle of the conductor (i.e., wind direction angle), ambient temperature With the outer diameter of the conductor A unified assessment of the convective conditions around the conductor is conducted to ensure convective heat dissipation. The selection of the crosswind component matches the subsequent standardized calculation caliber. Specifically, air density and kinematic viscosity are determined based on ambient temperature; the Reynolds number is calculated based on air density, kinematic viscosity, wind speed, and conductor outer diameter; the crosswind component is calculated based on wind speed and wind direction angle; and the convective condition is determined jointly based on the Reynolds number and crosswind component. The condition determination results include natural convection, forced convection, and transitional conditions. The convective condition is determined jointly based on the Reynolds number and crosswind component, including: when the crosswind component is less than the lower limit of wind speed or the Reynolds number is less than the lower limit of Reynolds number, it is judged as natural convection; when the crosswind component is greater than the upper limit of wind speed or the Reynolds number is greater than the upper limit of Reynolds number, it is judged as forced convection; when the crosswind component is greater than or equal to the lower limit of wind speed and less than or equal to the upper limit of wind speed, and the Reynolds number is greater than or equal to the lower limit of Reynolds number and less than or equal to the upper limit of Reynolds number, it is judged as a transitional condition. Step S2 will be further explained below with reference to the formula.

[0061] First, based on ambient temperature Determine air density With kinematic viscosity (The specific method for obtaining air density and kinematic viscosity based on ambient temperature is not specified here.) Based on this, the outer diameter of the conductor... Calculate the Reynolds number Re for the characteristic variables: (14)

[0062] When the wind angle When data is available, convective cooling is performed using crosswind components. As the dominant velocity quantity, the crosswind component is defined as: (15)

[0063] And when necessary, with crosswind component replace This leads to the calculation formula for the Reynolds number and the determination of the operating conditions. The determination of the operating conditions uses a joint "velocity-Reynolds number" criterion, divided into three categories: when the following conditions are met... or When this condition is met, it is determined to be natural convection. or When the above two conditions are not met, it is determined to be forced convection. Other cases are determined to be transient conditions. and .in, Indicates the lower limit of wind speed. Indicates the upper limit of wind speed. This indicates the lower bound of the Reynolds number. This indicates the upper limit of the Reynolds number. Understandably, the lower and upper limits of wind speed, Reynolds number, and Reynolds number can all be adjusted according to actual needs, and are not limited here.

[0064] Furthermore, to suppress frequent switching near the threshold, a hysteresis band is set on the velocity and Reynolds number criterion. and If the previous moment was determined to be natural convection, only when... and Only when the current moment is upgraded to a transitional operating condition / forced convection can it be determined; if the previous moment was forced convection, it can only be determined when... and Only then can it be determined that the current moment has been downgraded to a transitional condition / natural convection. If the previous moment was in a transitional condition, a weight is introduced between the natural convection and forced convection correlations at the current moment. Smooth transition ∈ [0,1], weights Determined by the normalization of velocity or Reynolds number: (16)

[0065] This invention uses weights Convective heat dissipation for natural / forced convection The calculation results are linearly combined to obtain a physically continuous convective heat dissipation term.

[0066] In the above embodiments, the present invention, in determining the operating conditions for convective heat transfer, divides the outflow of the conductor into natural convection, transition, and forced convection zones based on wind speed, wind direction, and air properties, and sets hysteresis and smooth transition to ensure that reasonable convection correlations are selected under different operating conditions and to avoid numerical discontinuities and jumps.

[0067] Step S3: Calculate the convection heat dissipation under GB, IEEE and CIGRE standards in parallel according to the working condition judgment results, and unify them according to the consistency principle to obtain unified convection heat dissipation.

[0068] In step S3, it is understandable that since the calculation formulas for convective heat dissipation under the three operating conditions (natural convection, forced convection, and transitional operating conditions) are different for any of the three standards (GB, IEEE, and CIGRE), each standard in step S3 needs to select the corresponding calculation formula for convective heat dissipation based on the operating condition determination result obtained in step S2. Then, the convective heat dissipation under the three standards (GB, IEEE, and CIGRE) is calculated in parallel to obtain the convective heat dissipation under the three standards. Furthermore, since the current-carrying capacity value is calculated based on convective heat dissipation, and the GB, IEEE, and CIGRE standards differ in their handling of convective heat dissipation under the same operating conditions, the current-carrying capacity values ​​calculated by different standards under the same operating conditions are discrete, making it difficult to form a unified current-carrying capacity value. Therefore, this invention also needs to calculate the convective heat dissipation under the three standards. Unification is performed according to the principle of consistency to obtain a single and auditable convective heat dissipation result (i.e., unified convective heat dissipation). ).

[0069] Furthermore, this invention aims to obtain a unified standard under multiple criteria. The standard switching rules (i.e., consistency principles) are as follows:

[0070] Firstly, as the basic standard for release, the conservative and consistent approach always adopts the worst-case scenario principle: (17)

[0071] in, These represent convection cooling under the GB, IEEE, and CIGRE standards, respectively. This indicates the unified convective heat dissipation (i.e., the aggregated result) obtained after unifying multiple standards.

[0072] Secondly, as a configurable option, segmented switching and transition weighting are implemented between standards based on the results of the operating condition assessment:

[0073] When determined to be natural convection, the following method is uniformly adopted: (18)

[0074] When it is determined to be forced convection, the following method is uniformly adopted: (19)

[0075] When a transitional operating condition is identified, a weight is introduced. Perform a linear transition on the segmented results on both sides: (20)

[0076] Among them, weight Please refer to equation (16). ∈[0,1].

[0077] Furthermore, to monitor cross-standard divergence and automatically converge when uncertainty is amplified, this invention also defines a discreteness. With variance These two metrics, when dispersion or variance Exceeding the threshold At that time, regardless of the working condition, the principle of reverting to the most unfavorable condition will be applied.

[0078] Furthermore, to avoid numerical out-of-bounds errors caused by cross-standard switching, this invention also optimizes the aggregation results. Boundary consistency constraints were applied: , , (twenty one)

[0079] in, This represents the minimum convective heat dissipation under the three standards. This represents the maximum convective heat dissipation under the three standards. The unified convective heat dissipation under the current operating condition is: (twenty two)

[0080] in, Indicates the temperature of the overhead conductor. This indicates the maximum temperature of the overhead conductor. It should be noted that this is a unified convection cooling system. For the follow-up The constraint-based solution for the current carrying capacity provides a stable input. This is based on unified convection cooling. Constrained by a fixed thermal balance caliber at the upper limit of the conductor temperature. The formula for calculating the current carrying capacity is as follows: (twenty three)

[0081] Where I represents the current carrying capacity, Indicates the upper limit of the conductor temperature. Indicates heat dissipation due to irradiation. This indicates that sunlight absorbs heat. Indicates the wire is in Effective AC resistance per unit length This represents the resistive heating effect of overhead conductors. It should be noted that this refers to uniform convection heat dissipation. Radiative heat dissipation Sunlight absorbs heat and resistance heating effect All of these are calories, and all four have the same unit.

[0082] Step S4: Calculate the radiative heat dissipation and solar heat absorption using a general formula, and obtain the effective AC resistance.

[0083] In step S4, it should be noted that since the differences among the three standards mainly lie in the calculation of convective heat dissipation, the calculation formulas for radiative heat dissipation and solar heat absorption are similar across the three standards. Therefore, the general formula is used to unify the calculation formulas for radiative heat dissipation and solar heat absorption.

[0084] 1) The formula for calculating irradiation heat dissipation is: (twenty four)

[0085] in, This represents the irradiation heat loss calculated using the general formula. Represents the emissivity of the conductor's surface. denoted by Stefan-Boltzmann constant, with a value of 5.67 × 10⁻⁸ W / (m²·K⁴), and D representing the outer diameter of the overhead conductor in meters.

[0086] 2) The formula for calculating solar heat absorption is: (25)

[0087] in, This indicates that the conductor absorbs heat under sunlight. denoted by , where G represents the heat absorption coefficient and G represents the solar irradiance.

[0088] 3) Effective AC resistance Take the wire at The effective AC resistance per unit length is calculated from the DC resistance at the reference temperature using a temperature coefficient. When parameters are missing, a conservative upper limit is used.

[0089] Step S5: Solve for the current carrying capacity using convection heat dissipation, radiation heat dissipation, solar heat absorption, and effective AC resistance.

[0090] In step S5, convection cooling is performed. Radiative heat dissipation Sunlight absorbs heat With effective AC resistance Substituting into equation (23) and rearranging, we obtain the current carrying capacity calculated by this invention: (26)

[0091] in, Indicates the maximum allowable current carrying capacity. This indicates the upper limit of conductor temperature, V represents wind speed, and q represents wind direction angle. express Radiative heat dissipation below, Indicates the wire is in Effective AC resistance per unit length. Additionally, when the wind direction angle... When something is missing or unreliable, take a conservative approach. Substitution complete The calculations are then performed, and the aggregation result is obtained according to the above-mentioned consistency principle. .

[0092] In summary, when the differences among the three standards are small and the operating conditions are stable, segmented / transitional standardization can provide representativeness while ensuring physical continuity. When the dispersion or variance exceeds a threshold, it automatically reverts to the worst-case scenario principle, making... It converges towards a smaller value, thus directly reducing the value in the above equation. This ensures that the calculated current carrying capacity is within a safe range. During numerical implementation, the given operating conditions are first determined. , Calculate according to the corresponding standard calculation method based on the criteria. And complete the aggregation, then calculate. , Finally Fixed to obtain If the convective correlation formula or physical properties used are... There is weak coupling, which can be Under the premise of and Perform one or a few iterations until two consecutive iterations are performed. If the change is below the set threshold, convergence is ensured.

[0093] Furthermore, in some feasible embodiments, in order to obtain the current carrying capacity... It can be stably used for operation and release. Without changing the thermal balance caliber, this invention proposes an operation-oriented engineering guarantee mechanism, namely, to implement engineering constraints such as safety margin, time smoothing, minimum hold time, slope limit, abnormal degradation and boundary consistency on the current carrying capacity, so as to improve the engineering usability of the current carrying capacity calculation results.

[0094] First, a safety margin coefficient based on cross-standard dispersion and variance is introduced. Release candidate carrying capacity Defined as: (27)

[0095] In the formula, To publish candidate carrier traffic, i.e. The value obtained after deducting the safety margin; This is the theoretical maximum current calculated from a fixed thermal equilibrium aperture under the constraint of the maximum allowable conductor temperature; For safety margin coefficient, This represents the dispersion, which is equivalent to the range. This is the variance, which is also the standard deviation. As the baseline margin, To achieve this, the parameter is increased when the worst-case scenario principle is executed or a rollback is triggered. This is to make the release converge.

[0096] Secondly, to suppress numerical fluctuations caused by short-term meteorological fluctuations, [the following measures are taken]. Applying time smoothing and minimum hold time, the smoothing value is given using first-order exponential smoothing: (28)

[0097] in, Let be the smoothed afterload current at time t. For time step, The published value, i.e., the final determined carrying capacity at the current time t. To determine the carrying capacity in the previous moment, A threshold is set to trigger the update of the load capacity only when the load capacity change exceeds a certain value. A keep-alive duration is also set. and trigger threshold Only when And the duration reached At that time, Fang Jiang Upgraded to the new release value Otherwise, maintain the previous published value. To avoid excessively rapid changes within a short period, the slope of the published changes is constrained: (29)

[0098] In the formula, This represents the maximum permissible change per unit time; any exceeding this limit will be truncated if necessary. Regarding boundary consistency and physical rationality, this invention guarantees: (30)

[0099] In the formula, The lower limit of the carrying capacity agreed upon by the operating side. This refers to the maximum current carrying capacity of the line or equipment. This is the calculated maximum allowable current carrying capacity. When the input data is missing, exceeds limits, or changes abruptly (e.g., ...), ... (quality marked as abnormal), or cross-standard dispersion exceeding the threshold ( or Triggering abnormal degradation: The worst-case scenario principle of equation (34) is uniformly adopted to obtain... ,improve to The release will be reverted to: (31)

[0100] In the formula, This is a fixed safety margin factor during the release phase. This is the minimum recommended current for static rated current or as specified for maintenance. The published value is guaranteed by engineering. Under the constraint of thermal balance, it ensures physical correctness and has a certain safety redundancy, and can be directly applied on the operation side without additional caliber conversion.

[0101] Based on the same technical concept as the aforementioned embodiments, this invention also provides an overhead conductor environmental factor-current carrying capacity calculation system based on GB, IEEE, and CIGRE model standardization, including a parameter acquisition module, a working condition determination module, a convection heat dissipation unification module, a parameter calculation module, and a current carrying capacity solution module. The parameter acquisition module is used to acquire environmental parameters. The working condition determination module is used to uniformly determine the convection conditions around the conductor based on the environmental parameters to obtain a working condition determination result. The convection heat dissipation unification module is used to calculate the convection heat dissipation under the three standards (GB, IEEE, and CIGRE) in parallel based on the working condition determination result and unify it according to the standardization principle to obtain a unified convection heat dissipation. The parameter calculation module is used to calculate radiative heat dissipation, solar heat absorption, and the effective AC resistance of the overhead conductor. The current carrying capacity solution module is used to solve for the current carrying capacity using the unified convection heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance.

[0102] Based on the same technical concept as the foregoing embodiments, the present invention also provides an electronic device, including a memory and a processor, wherein the memory stores program instructions that are executed by the processor, and the processor calls the program instructions to execute the above-mentioned method for calculating the environmental factors-current carrying capacity of overhead conductors based on GB, IEEE, and CIGRE model consistency.

[0103] Based on the same technical concept as the foregoing embodiments, the present invention also provides a non-transitory computer-readable storage medium, characterized in that the non-transitory computer-readable storage medium stores computer instructions, the computer instructions causing the computer to execute the above-described method for calculating the environmental factors-current carrying capacity of overhead conductors based on GB, IEEE, and CIGRE model consistency.

[0104] In summary, this invention, with unified thermal balance calculation as its core, is complemented by convection condition determination, multi-standard consistency, and engineering-based release assurance, forming a complete calculation scheme from input to release. Specifically, based on the acquired environmental parameters, the convection conditions around the conductor are determined as natural convection, transitional conditions, and forced convection. This ensures that reasonable convection cooling correlation formulas are selected for parallel calculation of convection cooling under the GB, IEEE, and CIGRE standards under different conditions. Aggregation is performed according to the segmented switching between natural and forced segments, weighted transition segments, and the worst-case scenario principle when necessary, to output a single and auditable convection cooling result (i.e., unified convection cooling). Finally, the current carrying capacity is calculated based on the unified convection cooling, and engineering constraints such as safety margin, time smoothing, minimum hold time, slope limit, and anomaly degradation are applied to the current carrying capacity to obtain a stable current carrying capacity that can be used for operational release. Therefore, this invention overcomes the problems of conservative scope, inconsistent results across standards, insensitivity to environmental changes, and difficulty in using real-time results for scheduling in the original schemes from a methodological perspective, realizing safe, unified, stable, and reusable calculation and release of overhead conductor current carrying capacity.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model standardization, characterized in that, The method for calculating the current carrying capacity includes: Obtain environmental parameters; The convection conditions around the conductor are uniformly determined based on environmental parameters to obtain the condition determination results; Based on the operating condition determination results, the convective heat dissipation under the three standards of GB, IEEE and CIGRE is calculated in parallel and unified according to the consistency principle to obtain unified convective heat dissipation. Calculate the radiative heat dissipation, solar heat absorption, and the effective AC resistance of overhead conductors; The current carrying capacity is determined by utilizing the unified convective heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance.

2. The method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model consistency as described in claim 1, characterized in that, The environmental parameters include wind speed, wind direction angle, ambient temperature, and conductor outer diameter; based on these environmental parameters, a unified assessment of the convection conditions around the conductor is performed, including: Air density and kinematic viscosity are determined based on ambient temperature. Calculate the Reynolds number based on air density, kinematic viscosity, wind speed, and conductor outer diameter; Calculate the crosswind component based on wind speed and wind direction angle; The convective conditions around the conductor are determined by combining the Reynolds number and the crosswind component to obtain the condition determination result.

3. The method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model consistency, as described in claim 2, is characterized in that... The convective conditions around the conductor are determined based on the Reynolds number and the crosswind component, including: When the crosswind component is less than the lower limit of wind speed or the Reynolds number is less than the lower limit of Reynolds number, it is determined to be natural convection; When the crosswind component is greater than the upper limit of wind speed or the Reynolds number is greater than the upper limit of Reynolds number, it is determined to be forced convection; When the crosswind component is greater than or equal to the lower limit of wind speed and less than or equal to the upper limit of wind speed, and the Reynolds number is greater than or equal to the lower limit of Reynolds number and less than or equal to the upper limit of Reynolds number, it is determined to be a transitional operating condition.

4. The method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model consistency as described in claim 3, characterized in that, The determination of the convective conditions around the conductor based on the Reynolds number and the crosswind component also includes: If the previous moment was determined to be natural convection, the current moment will be determined to be upgraded to transitional condition or forced convection only if the crosswind component is greater than or equal to the sum of the lower limit of wind speed and the wind speed hysteresis band, and the Reynolds number is greater than or equal to the sum of the lower limit of Reynolds number and the Reynolds number hysteresis band. If the previous moment was determined to be forced convection, the current moment will be determined to be downgraded to transitional condition or natural convection only if the crosswind component is less than or equal to the difference between the upper limit of wind speed and the wind speed hysteresis band, and the Reynolds number is less than or equal to the difference between the upper limit of Reynolds number and the Reynolds number hysteresis band. If the previous time step was in a transitional condition, a weighted smooth transition is introduced between the natural convection and forced convection correlations at the current time step; the weights are determined by the normalization of the crosswind component or the Reynolds number.

5. The method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model consistency as described in claim 1, characterized in that, Based on the operating condition determination results, the convective heat dissipation under the GB, IEEE, and CIGRE standards is calculated in parallel and unified according to the consistency principle to obtain unified convective heat dissipation, including: When the dispersion or variance of convective heat dissipation under the three standards exceeds the preset threshold, the minimum value of convective heat dissipation under the GB, IEEE and CIGRE standards shall be used as the unified convective heat dissipation; otherwise, segmented switching and transitional weighting shall be implemented between the GB, IEEE and CIGRE standards according to the working condition judgment result to obtain unified convective heat dissipation.

6. The method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model consistency as described in claim 5, characterized in that, Based on the operating condition determination results, segmented switching and transition weighting are implemented between GB, IEEE, and CIGRE standards to achieve unified convection cooling, including: When it is determined to be natural convection, the minimum value of convection heat dissipation under GB and IEEE standards shall be uniformly adopted as the unified convection heat dissipation. When it is determined to be forced convection, the minimum value of convection heat dissipation under the IEEE and CIGRE standards shall be uniformly adopted as the unified convection heat dissipation. When the condition is determined to be a transitional condition, weights are introduced to linearly transition the segmented results on both sides in order to obtain unified convection heat dissipation.

7. The method for calculating the environmental factors—current carrying capacity—of overhead conductors based on GB, IEEE, and CIGRE model consistency as described in claim 1, characterized in that, After solving for the current carrying capacity using the unified convective heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance, the current carrying capacity calculation method further includes applying safety margin constraints, time smoothing constraints, minimum hold duration constraints, slope limit constraints, anomaly degradation constraints, and boundary consistency constraints to the current carrying capacity.

8. A system for calculating the environmental factors and current carrying capacity of overhead conductors based on GB, IEEE, and CIGRE model standardization, characterized in that... include: The parameter acquisition module is used to acquire environmental parameters; The operating condition determination module is used to uniformly determine the convection conditions around the conductor based on environmental parameters in order to obtain the operating condition determination result. The convection cooling unification module is used to calculate the convection cooling under the three standards of GB, IEEE and CIGRE in parallel according to the working condition judgment result and unify them according to the consistency principle to obtain unified convection cooling. The parameter calculation module is used to calculate radiative heat dissipation, solar heat absorption, and the effective AC resistance of overhead conductors. The current carrying capacity calculation module is used to calculate the current carrying capacity using the unified convective heat dissipation, radiative heat dissipation, solar heat absorption, and effective AC resistance.

9. An electronic device, characterized in that, The device includes a memory and a processor. The memory stores program instructions that are executed by the processor. The processor calls the program instructions to execute the method for calculating the environmental factors-current carrying capacity of overhead conductors based on the GB, IEEE, and CIGRE model as described in any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, characterized in that, The non-transitory computer-readable storage medium stores computer instructions that cause the computer to execute the method for calculating the environmental factors-current carrying capacity of overhead conductors based on the GB, IEEE, and CIGRE model as described in any one of claims 1 to 7.

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