Method and system for correcting transmission parameters based on a thermal balance-based line temperature calculation model

Abstract

This invention relates to the field of high-voltage transmission line parameter calculation technology, specifically to a method and system for correcting transmission parameters based on a line temperature calculation model using thermal balance. The method includes: correcting line impedance parameters under different ambient temperatures based on established patterns; establishing a line temperature correction model based on the conductor thermal balance equation and using the model to calculate the real-time conductor temperature; calculating the conductor specific load based on the calculated conductor temperature and ambient wind speed and establishing a multi-factor sag correction model to correct conductor sag under different spans; calculating and correcting the average height to ground at each span height according to the proportion of each span at different erection heights of the transmission corridor, comprehensively obtaining the average height to ground of the entire transmission corridor according to the proportions, and correcting the transmission corridor susceptance parameters based on this average height to ground; and integrating the correction results to form a multi-factor correction model for transmission line parameters, which is used to output the corrected line impedance and susceptance parameters.

Description

Technical Field

[0001] This invention relates to the field of high-voltage transmission line parameter calculation technology, specifically to a method and system for correcting transmission parameters based on a line temperature calculation model based on thermal balance. Background Technology

[0002] In the operation of high-voltage transmission lines, conductor temperature directly affects the line's current-carrying capacity, power frequency parameters, and sag shape, making it one of the key parameters determining the safe and economical operation of the power grid. Power frequency parameters of transmission lines include positive-sequence impedance, zero-sequence impedance, positive-sequence capacitance, zero-sequence capacitance, and line mutual inductance. Accurate power frequency parameters are crucial for stable power system operation, relay protection settings, power grid planning and design, fault location and diagnosis, and power quality analysis. Therefore, high-precision calculation of power frequency parameters is essential.

[0003] The temperature rise of transmission lines primarily stems from the Joule heating effect generated when current flows through them, and is influenced by various meteorological factors such as wind speed, solar radiation intensity, ambient temperature, and humidity. However, traditional parameter calculation models are often based on steady-state or quasi-steady-state assumptions, failing to fully consider the dynamic changes in meteorological conditions over time and the differences in spatial distribution along the transmission line. This simplification leads to significant deviations in conductor temperature estimation under actual operating conditions, affecting not only the accurate assessment of the dynamic current-carrying capacity of transmission lines and restricting the full utilization of transmission capacity, but also potentially causing safety hazards such as conductor overheating, increased sag, and even line breakage due to inaccurate temperature predictions, posing a potential threat to the reliable operation of the power grid. For transmission line parameters, conductor temperature changes directly affect conductor sag and AC resistivity, further impacting the accuracy of the overall parameter calculation results. Therefore, it is necessary to further explore the impact of environmental factors on the power frequency parameters of transmission lines to improve the accuracy of calculation results and ensure the safety and economy of power grid operation.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the general background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] This invention provides a method and system for correcting transmission parameters based on a line temperature calculation model of thermal balance, thereby effectively solving the problems in the background art.

[0006] To achieve the above objectives, the technical solution adopted by this invention is: a method for correcting transmission parameters based on a line temperature calculation model of thermal balance, comprising the following steps: Determine the impedance constraint conditions of ambient temperature on the power frequency impedance parameters of transmission lines, and correct the line impedance parameters under different ambient temperatures based on the impedance constraint conditions. Based on the conductor heat balance equation, considering Joule heating, solar heat absorption, convective heat dissipation and radiative heat dissipation, a line temperature correction model is established. The line temperature is calculated using the line temperature correction model under different ambient temperatures, solar radiation intensity, current carrying capacity and ambient wind speed. The sag constraints of line temperature, ambient wind speed and span on line sag are analyzed and determined. Based on the sag constraints, a multi-factor sag correction model is established to correct the conductor sag under different spans. The proportion of each span of the transmission corridor at different erection heights is obtained and statistically analyzed. The average height to the ground at each erection height is calculated and corrected based on the span proportion. The susceptance parameters at different erection heights are combined with the average height to the ground according to the proportion to obtain the average height to the ground of the entire transmission corridor. The susceptance parameters of the transmission corridor are corrected based on the average height to the ground of the entire line. A multi-factor correction model for transmission line parameters is constructed based on the corrected transmission corridor susceptance parameters and the line impedance parameters, which is used to output the corrected line impedance and susceptance parameters.

[0007] Furthermore, the impedance constraint condition for determining the effect of ambient temperature on the power frequency impedance parameters of the transmission line includes: The power frequency impedance parameter samples of transmission lines in the temperature range of -10℃ to 50℃ are calculated and collected using a theoretical calculation program. The samples are then curve-fitted to obtain an empirical fitting formula for online rapid correction of impedance parameters under any ambient temperature.

[0008] Furthermore, the heat balance equation for the conductor is derived from the Joule heat of the conductor I. 2 R a Solar radiation P S Convection heat dissipation P P Radiative heat dissipation P R It consists of four items, and the expression is: ; ; ; ; In the formula, I 2 R a The heat balance equation for the conductor is derived from the Joule heat of the conductor and P. S For solar radiation, P P For convection cooling, for P R Radiative heat dissipation; This represents the DC resistance of the conductor at 20°C. The AC / DC resistance ratio of the conductor should take into account the skin effect; t is the temperature coefficient of the conductor;M Temperature of the conductor, in °C; t a Ambient temperature, in °C; The heat absorption coefficient; Solar radiation intensity, W / m 2 ; σ is the outer diameter of the conductor, in meters; v is the ambient wind speed, in meters per second; ɛ is the surface radiation constant of the conductor, determined by the color of the conductor's outer sheath; σ is the Stefan-Boltzmann constant.

[0009] Furthermore, the line temperature correction model is as follows: ; In the formula, I 2 R a For Joule heating of the conductor, P S For solar radiation, P P For convection heat dissipation, P R For radiative heat dissipation.

[0010] Furthermore, the correction of conductor sag under different spans includes the following steps: Select the line based on whether the environment is icy, skip the icy section, and then calculate the conductor specific load together with the ambient wind speed; Formula for calculating the load ratio in windy conditions without ice: ; In the formula, γ is the conductor specific load, in N / (m·mm). 2 m0 is the weight of the conductor itself, in kg / km. 2 S represents the cross-sectional area of ​​the conductor, in mm². 2 ;K z α is the wind pressure height variation coefficient; C is the non-uniformity coefficient under different wind speeds; d is the wind load shape coefficient of the line; v is the outer diameter of the conductor in mm; v is the wind speed in m / s. Establish the state equation for the conductor length, and use the calculated conductor specific load γ and the real-time conductor temperature t M Calculate the stress at the lowest point of the conductor: ; In the formula, L0 is the conductor erection length in meters (m), and σ0 and σ1 are the minimum stresses at the conductor under two different conditions, in MPa or N / (m·mm). 2 ); γ0 and γ1 represent the conductor specific loads under two different conditions, in N / (m·mm). 2 ); t0 and t1 are the temperatures of the conductor under the two conditions, in °C; l is the span distance, in meters; α is the coefficient of thermal expansion of the overhead line; E is the elastic coefficient; Calculate the conductor sag based on the obtained conductor stress and specific load: ; Expanded to: .

[0011] Further, the correction of the transmission corridor susceptance parameters based on the average height above ground along the entire line includes: Establish the equation for the catenary of the conductor, where , Here is the integration constant: ; Assuming x=0 and y=0, derive the formula for the average height of the traverse, where h0 is the height of the lowest point of the traverse: ; The formula for obtaining the average height of a conductor above the ground under a fixed span l is: ; In the formula h avg denoted as the average height of the conductor above the ground, and f as the conductor sag. The impact of span spacing at different transmission corridor installation heights on the average height above ground, corrected according to the proportion of span spacing at that installation height: ; By combining the susceptance parameters at different installation heights according to their proportions, the corrected average height above ground of the entire transmission corridor is obtained: ; The equivalent susceptance parameters of the transmission corridor are obtained by correcting the average height above the ground along the entire corridor.

[0012] Furthermore, the comprehensive multi-factor correction model simultaneously uses a direct empirical fitting formula to correct the influence of ambient temperature on line impedance, and uses a thermal balance equation and a multi-factor sag model to correct the susceptance parameter, thereby obtaining the corrected line impedance and susceptance parameters.

[0013] This invention also includes a system for correcting transmission parameters based on a line temperature calculation model of thermal balance, using the method described above, wherein the system includes: The temperature law correction unit is used to determine the impedance constraint conditions of ambient temperature on the power frequency impedance parameters of the transmission line, and to correct the line impedance parameters under different ambient temperatures based on the impedance constraint conditions. The real-time temperature calculation unit is used to establish a line temperature correction model based on the conductor heat balance equation, taking into account Joule heat, solar heat absorption, convective heat dissipation and radiative heat dissipation of the conductor, and to calculate the line temperature under different ambient temperature, solar radiation intensity, current carrying capacity and ambient wind speed conditions using the line temperature correction model. The conductor sag correction unit is used to analyze and determine the sag constraints of line temperature, ambient wind speed and span on line sag, and to establish a multi-factor sag correction model based on the sag constraints to correct the conductor sag under different spans. The susceptance parameter correction unit collects and statistically obtains the proportion of each span of the transmission corridor at different erection heights, and calculates and corrects the average ground height at each erection height based on the span proportion; it integrates the susceptance parameters at different erection heights according to the proportion and the average ground height to obtain the average ground height of the entire transmission corridor, and corrects the susceptance parameters of the transmission corridor based on the average ground height of the entire line. The modeling unit is used to construct a multi-factor correction model of the transmission line parameters based on the corrected transmission corridor susceptance parameters and the line impedance parameters, and to output the corrected line impedance and susceptance parameters. The present invention also includes a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the method as described above.

[0014] The present invention also includes a storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described above.

[0015] The beneficial effects of this invention are as follows: Addressing the issue of environmental influences on transmission line impedance parameters, a simple and direct correction method is proposed, solving the problem of lengthy calculation procedures for line impedance parameter correction. A method based on a thermal balance-based line temperature calculation model for correcting transmission parameters is also proposed, overcoming the problem of traditional calculation models neglecting line sag and avoiding parameter changes caused by conductor temperature variations. The principle is simple; by combining impedance parameter correction with susceptance parameter correction, a comprehensive multi-factor transmission line parameter correction model is proposed. This model integrates various environmental factors, enabling comprehensive correction of line parameters under diverse environmental conditions, exhibiting high reliability and facilitating engineering applications and promotion. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the method in Example 1; Figure 2 This is a schematic diagram of the system structure in Example 1; Figure 3This is a simulation model diagram of the measured parameters of the transmission line in Example 2; Figure 4 This is a flowchart of the method for correcting transmission parameters based on the line temperature calculation model of thermal balance in Example 2; Figure 5 This is a graph showing the effect of ambient temperature on transmission line parameters and the correction results in Example 2; Figure 6 This is a diagram showing the factors influencing line temperature based on the conductor heat balance equation in Example 2; Figure 7 This is a graph showing the relative error trends of each sequence parameter of the transmission line under a fixed small span in Example 2 as a function of sag and without considering the influence of sag. Figure 8 This is a diagram showing the corrected height of the entire transmission corridor covering different spans and different erection heights in Example 2; Figure 9 This is a schematic diagram of the structure of the computer device of the present invention. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Example 1:

[0019] like Figure 1 The following is a method for correcting transmission parameters based on a line temperature calculation model according to thermal balance, comprising the following steps: This study investigates the constraints of ambient temperature on the power frequency impedance parameters of transmission lines and corrects the line impedance parameters under different ambient temperatures based on the observed patterns. Based on the conductor heat balance equation, considering Joule heating, solar heat absorption, convective heat dissipation and radiative heat dissipation, a line temperature correction model is established. The model is used to calculate the real-time temperature of the conductor under different ambient temperatures, solar radiation intensity, current carrying capacity and wind speed conditions. Based on the calculated conductor temperature and ambient wind speed, the conductor specific load is calculated and a multi-factor sag correction model is established to correct the conductor sag under different spans. Based on the proportion of each span at different erection heights of the transmission corridor, the average height to the ground at each erection height is calculated and corrected. The average height to the ground of the entire transmission corridor is obtained by combining the proportions, and the electrical susceptance parameters of the transmission corridor are corrected based on this average height to the ground. The correction results are combined to form a multi-factor correction model for transmission line parameters, which is used to output the corrected line impedance and susceptance parameters.

[0020] To address the issue of environmental influences on transmission line impedance parameters, a simple and direct correction method is proposed, resolving the problem of lengthy calculation procedures for line impedance parameter correction. A line temperature calculation model based on thermal balance is also proposed to correct transmission parameters, overcoming the problem of traditional calculation models neglecting line sag and avoiding parameter changes caused by conductor temperature variations. The principle is simple; by combining impedance parameter correction with susceptance parameter correction, a comprehensive multi-factor transmission line parameter correction model is proposed. This model integrates various environmental factors, enabling comprehensive correction of line parameters under diverse environmental conditions, exhibiting high reliability and facilitating engineering applications and promotion.

[0021] In this embodiment, the constraints of ambient temperature on the power frequency impedance parameters of transmission lines are investigated, including: The theoretical calculation program was used to calculate and collect power frequency impedance parameter samples of transmission lines in the temperature range of -10℃ to 50℃. Curve fitting was performed on the samples to obtain an empirical fitting formula for online rapid correction of impedance parameters under any ambient temperature.

[0022] The thermal equilibrium equations for conductors include: ; ; ; ; In the formula, I 2 R a The heat balance equation for the conductor is derived from the Joule heat of the conductor and P. S For solar radiation, P P For convection cooling, for P R Radiative heat dissipation; This represents the DC resistance of the conductor at 20°C. The AC / DC resistance ratio of the conductor should take into account the skin effect; t is the temperature coefficient of the conductor; M t represents the conductor temperature in °C. a The ambient temperature is in °C. The heat absorption coefficient; Solar radiation intensity, W / m 2 ; denoted as the outer diameter of the conductor (m); v is the ambient wind speed (m / s); ɛ is the surface radiation constant of the conductor, determined by the color of the conductor's outer sheath; and σ is the Stefan-Boltzmann constant.

[0023] The line temperature correction model is as follows: .

[0024] The process involves calculating the conductor specific load based on the calculated conductor temperature and ambient wind speed, and establishing a multi-factor sag correction model to correct conductor sag under different spans. This includes the following steps: Select the line based on whether the environment is icy, skip the icy section, and then calculate the conductor specific load together with the ambient wind speed; Formula for calculating the load ratio in windy conditions without ice: ; In the formula, γ is the conductor specific load, N / (m·mm). 2 m0 is the weight of the conductor itself, kg / km 2 S is the cross-sectional area of ​​the conductor, in mm². 2 ;K z α is the wind pressure height variation coefficient; C is the non-uniformity coefficient under different wind speeds; d is the wind load shape coefficient of the line; v is the outer diameter of the conductor, mm; v is the wind speed, m / s. Establish the state equation for the conductor length, and use the calculated conductor specific load γ and the real-time conductor temperature t M Calculate the stress at the lowest point of the conductor: ; In the formula, L0 is the conductor erection length in meters, and σ0 and σ1 are the minimum stresses at the conductor under the two conditions, in MPa or N / (m·mm). 2 ); γ0 and γ1 are the conductor specific loads under two conditions, N / (m·mm). 2 ); t0 and t1 are the conductor temperatures under the two conditions, in °C; l is the span distance, in meters; α is the coefficient of thermal expansion of the overhead line; E is the elastic coefficient; Calculate the conductor sag based on the obtained conductor stress and specific load: ; Expanded to: .

[0025] As a preferred embodiment of the above, the average height to ground at each span height is calculated and corrected based on the proportion of each span at different erection heights of the transmission corridor. The average height to ground of the entire transmission corridor is then obtained by combining these proportions, and the electrical susceptance parameters of the transmission corridor are corrected based on this average height to ground, including: Establish the equation for the catenary of the conductor, where , Here is the integration constant: ; Assuming x=0 and y=0, derive the formula for the average height of the traverse, where h0 is the height of the lowest point of the traverse: ; The formula for obtaining the average height of a conductor above the ground under a fixed span l is: ; In the formula h avg denoted as the average height of the conductor above the ground, and f as the conductor sag. The impact of span spacing at different transmission corridor installation heights on the average height above ground, corrected according to the proportion of span spacing at that installation height: ; By combining the susceptance parameters at different installation heights according to their proportions, the corrected average height above ground of the entire transmission corridor is obtained: ; The equivalent susceptance of the transmission corridor is obtained by correcting the average height of the entire transmission corridor above the ground.

[0026] Among them, the comprehensive multi-factor correction model simultaneously uses a direct empirical fitting formula to correct the influence of ambient temperature on line impedance, and uses a thermal balance equation and a multi-factor sag model to correct the susceptance parameter, thereby obtaining the corrected line impedance and susceptance parameters.

[0027] like Figure 2 As shown, this embodiment also includes a system for correcting transmission parameters based on a line temperature calculation model of thermal balance. Using the method described above, the system includes: The temperature law correction unit is used to explore the constraints of ambient temperature on the power frequency impedance parameters of transmission lines, and to correct the line impedance parameters under different ambient temperatures based on the law. The real-time temperature calculation unit is used to establish a line temperature correction model based on the conductor heat balance equation, taking into account Joule heat, solar heat absorption, convective heat dissipation and radiative heat dissipation of the conductor. The model is used to calculate the real-time temperature of the conductor under different ambient temperatures, solar radiation intensity, current carrying capacity and wind speed conditions. The conductor sag correction unit is used to calculate the conductor specific load and establish a multi-factor sag correction model based on the calculated conductor temperature and ambient wind speed, and to correct the conductor sag under different spans. The susceptance parameter correction unit is used to calculate and correct the average height to the ground at each erection height according to the proportion of each span at different erection heights of the transmission corridor, and to obtain the average height to the ground of the entire transmission corridor according to the proportion, and to correct the susceptance parameter of the transmission corridor based on the average height to the ground. The modeling unit is used to integrate the correction results into a multi-factor correction model of the transmission line parameters, which is used to output the corrected line impedance and susceptance parameters. Example 2:

[0028] Please see Figure 3 and Figure 4 This invention provides a method for correcting transmission line impedance parameters using ambient temperature, comprising the following steps: Step 1: Investigate the constraints of ambient temperature on line impedance parameters and correct for the influence of ambient temperature on line impedance parameters. For details on the constraints of ambient temperature on line parameters, please refer to [link to relevant documentation]. Figure 5 Analysis revealed that the impedance parameters are most sensitive to changes in ambient temperature. Impedance parameters for the line at temperatures ranging from -10°C to 50°C were obtained through theoretical calculations, and the fitted results were as follows: (1) (2) (3) (4) Based on the above fitting formula, correct the impedance parameters at random temperatures. Please refer to [link / reference]. Figure 5 It can be seen that the direct correction value of the formula of the present invention fits well with the correction value of the theoretical calculation program.

[0029] Step 2: The heat balance equation for the conductor is derived from the Joule heat of the conductor I. 2 R a Solar radiation P S Convection heat dissipation P P and radiation heat dissipation P R Four components: (5) (6) (7) (8) In the formula, This represents the DC resistance of the conductor at 20°C. The AC / DC resistance ratio of the conductor should take into account the skin effect; t is the temperature coefficient of the conductor; M t represents the conductor temperature in °C. a The ambient temperature is in °C. The heat absorption coefficient; Solar radiation intensity, W / m 2 ; denoted as the outer diameter of the conductor (m); v as the ambient wind speed (m / s); ɛ as the surface radiation constant of the conductor, determined by the color of the conductor sheath, typically taken as 0.6; σ as the Stefan-Boltzmann constant, 5.670374419 × 10⁻⁶. -8 W·m -2 ·K -4 .

[0030] Based on the above equations, a line temperature calculation model is established: (9) Please see Figure 6 Based on the above model, a graph showing the temperature variation of the transmission line under different current-carrying capacity, ambient temperature, wind speed, and solar radiation intensity was plotted. Overall, current-carrying capacity is the most significant factor affecting conductor temperature; its increase causes an almost exponential rise in conductor temperature, exceeding 120℃ when the current-carrying capacity approaches 1000A, far exceeding the safety threshold. Wind speed is the most effective natural cooling factor, with a particularly noticeable cooling effect at lower wind speeds. Ambient temperature and solar radiation intensity have relatively mild effects on conductor temperature. In summary, this invention prioritizes monitoring and controlling current-carrying capacity, and calculates the line temperature in conjunction with local wind speed, ambient temperature, and solar radiation conditions.

[0031] Step 3: Analyze the effects of line temperature, wind speed, and span on line sag, establish a multi-factor sag correction model, and correct the line height above the ground for this span. The sag determination process is as follows: (1) Since the icing section only accounts for a small part, the present invention selects the line according to whether the environment is icy, skips the icing section, and then calculates the conductor specific load together with the wind speed; Formula for calculating the load ratio in windy conditions without ice: (10) In the formula, γ is the conductor specific load, N / (m·mm). 2 m0 is the weight of the conductor itself, kg / km 2 S is the cross-sectional area of ​​the conductor, in mm². 2 ;K z α is the wind pressure height variation coefficient; α is the non-uniformity coefficient under different wind speeds, which is taken as 1.0 under low wind speed (v < 20m / s); C is the wind load shape coefficient of the line. For the non-icing condition, when the outer diameter of the conductor is less than 17mm, C is taken as 1.2, otherwise C is taken as 1.1; d is the outer diameter of the conductor, mm; v is the wind speed, m / s.

[0032] GB / 50009-2012 "Code for Design of Building Structures" specifies the wind pressure height variation coefficient K. z The classification should be determined based on the type of ground roughness, which can be divided into four categories: Category A refers to nearshore sea surfaces, islands, coastlines, lake shores, and desert areas; Category B refers to fields, villages, forests, hills, and towns with relatively sparse housing; Category C refers to urban areas with dense building clusters; and Category D refers to urban areas with dense building clusters and tall buildings.

[0033] (11) In the formula, z is the height above the ground, in meters (m).

[0034] (2) Given the initial stress and specific load of the conductor, calculate the conductor stress according to the conductor state equation, using the calculated conductor specific load and the conductor temperature calculated in step 2; (12) In the formula, L0 is the conductor erection length, in meters; σ0 and σ1 are the minimum stresses of the conductor under the two conditions, in MPa or N / (m·mm). 2 ); γ0 and γ1 are the conductor specific loads under two conditions, N / (m·mm). 2 ); t0 and t1 are the conductor temperatures under the two conditions, in °C; l is the span distance, in meters; α is the coefficient of thermal expansion of the overhead line; E is the elastic coefficient. Taking steel-cored aluminum stranded wire as an example, let the cross-sectional area of ​​the conductor core be A. s The cross-sectional area of ​​the aluminum stranded wire is A. a The corresponding elastic modulus E of the steel core s The elastic modulus E of aluminum wire a The overall elastic modulus E of the conductor is obtained by combining the results: (13) (3) Calculate the conductor sag based on the obtained conductor stress and specific load: (14) when When the size is small, the above formula can be expanded as: (15) Please see Figure 7 Based on the above model, the relative error trends of each sequence parameter of the transmission line under a fixed small span with respect to sag and without considering the influence of sag are plotted. Figure 7 (a) The measured parameters are from Figure 1 The established PSCAD simulation model, Figure 7 (b) The data comes from the line theoretical parameter calculation model. It can be seen that under small spans, sag has a significant impact on the zero-sequence susceptance parameter, and this impact continues to increase with the increase of sag. In actual engineering, larger spans are often used to erect towers. For example, under an 800m span, the actual sag of LGJ400 / 50 conductor at 50℃ can even reach 40 meters. The impact of sag on the line susceptance parameter cannot be ignored. The multi-factor sag correction model in step three comprehensively considers the influence of multiple factors such as temperature, wind speed, icing, and span, and realizes dynamic correction of sag.

[0035] Step 4: Determining the average height above ground of the entire transmission corridor. First, based on Step 3, derive the average height above ground of the conductor under a fixed span l, and establish the catenary equation for the conductor. , Here is the integration constant: (16) Assuming x=0 and y=0, the formula for the average height of the traverse can be derived, where h0 is the height of the lowest point of the traverse: (17) Finally, by integrating the formulas, we can obtain the formula for the average height of the conductor above the ground under a fixed span l: (18) In the formula h avg Let f be the average height of the conductor above the ground, and let f be the sag of the conductor.

[0036] In actual engineering projects, power transmission corridors have different installation heights. Based on the span ratio at different installation heights, the average height above the ground at that installation height is adjusted. (19) Finally, the susceptance parameters at different installation heights are combined according to their proportions to obtain the corrected average height above ground for the entire transmission corridor: (20) Please refer to Table 1 to calculate the average height of the transmission corridor above the ground based on the approximate proportion of each span on a 220kV line.

[0037] Table 1. Approximate proportion of each span on a 220kV line. Please see Figure 8 The results show the corrected average height above ground along the entire 100km-long 220kV transmission corridor, with different spans and different installation heights.

[0038] Step 5: Based on the above steps, design a multi-factor transmission line parameter correction model. This correction model uses direct calculation formulas to correct the influence of ambient temperature on line impedance parameters; it uses ambient temperature, solar radiation intensity, current carrying capacity, wind speed, and span to comprehensively correct conductor sag; then, it corrects the average height above ground of the entire transmission corridor according to the proportion of different erection heights and different span proportions, and finally corrects the electrical susceptance parameters of the transmission corridor.

[0039] Please see Figure 9 The diagram shows a structural schematic of a computer device provided in an embodiment of this application. An embodiment of this application provides a computer device 400, including a processor 410 and a memory 420. The memory 420 stores a computer program executable by the processor 410. When the computer program is executed by the processor 410, it performs the method described above.

[0040] This application embodiment also provides a storage medium 430, on which a computer program is stored, and the computer program is executed by a processor 410 to perform the above method.

[0041] The storage medium 430 can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0042] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. "A plurality of" means two or more, unless otherwise explicitly specified.

[0043] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] Any process or method description in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of the invention includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as will be understood by those skilled in the art to which embodiments of the invention pertain.

[0046] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0047] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0048] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, the program includes one or a combination of the steps of the method embodiments.

[0049] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for correcting transmission parameters based on a line temperature calculation model according to thermal balance, characterized in that, Includes the following steps: Determine the impedance constraint conditions of ambient temperature on the power frequency impedance parameters of transmission lines, and correct the line impedance parameters under different ambient temperatures based on the impedance constraint conditions. Based on the conductor heat balance equation, considering Joule heating, solar heat absorption, convective heat dissipation and radiative heat dissipation, a line temperature correction model is established. The line temperature is calculated using the line temperature correction model under different ambient temperatures, solar radiation intensity, current carrying capacity and ambient wind speed. The sag constraints of line temperature, ambient wind speed and span on line sag are analyzed and determined. Based on the sag constraints, a multi-factor sag correction model is established to correct the conductor sag under different spans. The proportion of each span of the transmission corridor at different erection heights is obtained and statistically analyzed. The average height to the ground at each erection height is calculated and corrected based on the span proportion. The susceptance parameters at different erection heights are combined with the average height to the ground according to the proportion to obtain the average height to the ground of the entire transmission corridor. The susceptance parameters of the transmission corridor are corrected based on the average height to the ground of the entire line. Based on the corrected transmission corridor susceptance parameters and the line impedance parameters, a multi-factor correction model for transmission line parameters is constructed to output the corrected line impedance and susceptance parameters.

2. The method for correcting transmission parameters based on the line temperature calculation model according to claim 1, characterized in that, The impedance constraint conditions for determining the effect of ambient temperature on the power frequency impedance parameters of transmission lines include: The power frequency impedance parameter samples of transmission lines in the temperature range of -10℃ to 50℃ are calculated and collected using a theoretical calculation program. The samples are then curve-fitted to obtain an empirical fitting formula for online rapid correction of impedance parameters under any ambient temperature.

3. The method for correcting transmission parameters based on the line temperature calculation model according to claim 1, characterized in that, The thermal balance equation for the conductor is derived from the Joule heat of the conductor. 2 R a Solar radiation P S Convection heat dissipation P P Radiative heat dissipation P R It consists of four items, and the expression is: ； ； ； ； In the formula, This represents the DC resistance of the conductor at 20°C. The AC / DC resistance ratio of the conductor should take into account the skin effect; t is the temperature coefficient of the conductor; M t represents the conductor temperature in °C. a The ambient temperature is in °C. The heat absorption coefficient; Solar radiation intensity, unit: W / m 2 ; σ is the outer diameter of the conductor, in meters; v is the ambient wind speed, in meters per second; ɛ is the surface radiation constant of the conductor, determined by the color of the conductor's outer sheath; σ is the Stefan-Boltzmann constant.

4. The method for correcting transmission parameters based on the line temperature calculation model according to claim 3, characterized in that, The line temperature correction model is as follows: 。 5. In the formula, I 2 R a For Joule heating of the conductor, P S For solar radiation, P P For convection heat dissipation, P R For radiative heat dissipation.

6. The method for correcting transmission parameters based on the line temperature calculation model according to claim 1, characterized in that, The method for correcting conductor sag under different spans includes the following steps: Select the line based on whether the environment is icy, skip the icy section, and then calculate the conductor specific load together with the ambient wind speed; Formula for calculating the load ratio in windy conditions without ice: ； In the formula, γ is the conductor specific load, in N / (m·mm). 2 m0 is the weight of the conductor itself, in kg / km. 2 S represents the cross-sectional area of ​​the conductor, in mm². 2 ;K z α is the wind pressure height variation coefficient; C is the non-uniformity coefficient under different wind speeds; d is the wind load shape coefficient of the line; v is the outer diameter of the conductor in mm; v is the wind speed in m / s. Establish the state equation for the conductor length, and use the calculated conductor specific load γ and the real-time conductor temperature t M Calculate the stress at the lowest point of the conductor: ； In the formula, L0 is the conductor erection length in meters (m), and σ0 and σ1 are the minimum stresses at the conductor under two different conditions, in MPa or N / (m·mm). 2 ); γ0 and γ1 represent the conductor specific loads under two different conditions, in N / (m·mm). 2 ); t0 and t1 are the temperatures of the conductor under the two conditions, in °C; l is the span, in meters; α is the coefficient of thermal expansion of the overhead line; E is the elastic coefficient; Calculate the conductor sag based on the obtained conductor stress and specific load: ； Expanded to: 。 7. The method for correcting transmission parameters based on the line temperature calculation model according to claim 5, characterized in that, The correction of the transmission corridor's susceptance parameters based on the average height above ground along the entire line includes: Establish the equation for the catenary of the conductor, where , Here is the integration constant: ； Assuming x=0 and y=0, derive the formula for the average height of the traverse, where h0 is the height of the lowest point of the traverse: ； The formula for obtaining the average height of a conductor above the ground under a fixed span l is: ； In the formula h avg denoted as the average height of the conductor above the ground, and f as the conductor sag. The impact of span spacing at different transmission corridor installation heights on the average height above ground, corrected according to the proportion of span spacing at that installation height: ； By combining the susceptance parameters at different installation heights according to their proportions, the corrected average height above ground of the entire transmission corridor is obtained: ； The equivalent susceptance parameters of the transmission corridor are obtained by correcting the average height above the ground along the entire corridor.

8. The method for correcting transmission parameters based on the line temperature calculation model according to claim 1, characterized in that, The multi-factor correction model simultaneously uses a direct empirical fitting formula to correct the influence of ambient temperature on line impedance, and uses a thermal balance equation and a multi-factor sag model to correct the susceptance parameter, thereby obtaining the corrected line impedance and susceptance parameters.

9. A system for correcting transmission parameters based on a line temperature calculation model of thermal balance, characterized in that, Using the method of any one of claims 1 to 7, the system comprises: The temperature law correction unit is used to determine the impedance constraint conditions of ambient temperature on the power frequency impedance parameters of the transmission line, and to correct the line impedance parameters under different ambient temperatures based on the impedance constraint conditions. The real-time temperature calculation unit is used to establish a line temperature correction model based on the conductor heat balance equation, taking into account Joule heat, solar heat absorption, convective heat dissipation and radiative heat dissipation of the conductor, and to calculate the line temperature under different ambient temperature, solar radiation intensity, current carrying capacity and ambient wind speed conditions using the line temperature correction model. The conductor sag correction unit is used to analyze and determine the sag constraints of line temperature, ambient wind speed and span on line sag, and to establish a multi-factor sag correction model based on the sag constraints to correct the conductor sag under different spans. The susceptance parameter correction unit collects and statistically obtains the proportion of each span of the transmission corridor at different erection heights, and calculates and corrects the average ground height at each erection height based on the span proportion; it integrates the susceptance parameters at different erection heights according to the proportion and the average ground height to obtain the average ground height of the entire transmission corridor, and corrects the susceptance parameters of the transmission corridor based on the average ground height of the entire line. The modeling unit is used to construct a multi-factor correction model of the transmission line parameters based on the corrected transmission corridor susceptance parameters and the line impedance parameters, and to output the corrected line impedance and susceptance parameters.

10. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1-7.

11. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the method as described in any one of claims 1-7.

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