Method and system for evaluating radiation coefficient of overhead transmission conductor

Abstract

The invention provides an overhead transmission conductor radiation coefficient evaluation method and system, and the method comprises the steps: A1, obtaining the operation data and environment data of a transmission conductor in a preset time period, and enabling the operation data to comprise a conductor temperature collection value; a2, establishing a heat balance equation according to the operation data and the environment data; and A3, solving the transient differential equation based on the established heat balance equation to obtain a conductor temperature calculation value, and obtaining a radiation coefficient evaluation value of the transmission conductor based on the conductor temperature acquisition value and the conductor temperature calculation value. Based on a heat balance equation of the conductor, an optimization solving model of the conductor radiation coefficient is established, so that accurate solving of the transmission conductor radiation coefficient is realized, and the problem that the current transmission conductor radiation coefficient is difficult to effectively and accurately obtain is solved. The accuracy of the evaluation result of the thermal stability limit of the power transmission line and the power supply reliability of a power system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission and overhead power transmission lines, and in particular to a method and system for evaluating the radiation coefficient of an overhead power transmission line. Background Art

[0002] Overhead transmission lines are the most commonly used method of power transmission, used to transmit the electricity generated by power plants from power plants to cities, industrial areas and residential areas. As an efficient, economical, flexible and reliable method of power transmission, overhead transmission lines are of great significance in the power system. They support the long-distance and large-capacity needs of power transmission, promote the development and utilization of renewable energy, improve the reliability and maintainability of the power system, and provide a stable and reliable power supply for social and economic development.

[0003] Improving the current-carrying capacity of transmission lines can significantly increase their transmission capacity and alleviate the current problem of insufficient power supply. The current-carrying capacity of overhead transmission lines mainly depends on their thermal stability limit. The thermal stability limit refers to the maximum temperature limit that the conductor can withstand. The thermal stability limit is determined based on the characteristics of the conductor material and design considerations. This upper limit is determined based on factors such as the thermal characteristics of the conductor material, the conductor cross-sectional area, environmental conditions, and the cooling method of the line. Temperatures exceeding the thermal stability limit will cause increased thermal expansion of the conductor material and increased conductor sag, which will affect the safe operation of the line. Therefore, mastering the thermal stability limit of overhead transmission lines is very important for the operation and maintenance of the line.

[0004] The thermal stability limit of the transmission line is related to the parameters of the conductor itself and the environmental conditions. The conductor will generate Joule heat when the current passes through it, the conductor will absorb heat due to radiation due to sunlight, the conductor will radiate heat to the surrounding environment, and the wind blowing through the conductor will enhance convection heat dissipation. The temperature of the conductor is determined by the balance process of the above heat absorption and heat dissipation. By measuring the operating current, ambient temperature, wind speed and direction, and sunshine intensity of the conductor in real time, combined with the two characteristic parameters of the conductor itself - the radiation heat absorption coefficient and the radiation heat dissipation coefficient, the thermal stability limit of the transmission line can be accurately calculated.

[0005] The above environmental parameters can be easily obtained through online monitoring, and the current sensors and monitoring technologies are very mature; however, there is no good way to obtain the radiation heat absorption coefficient and radiation heat dissipation coefficient of overhead transmission lines. These two coefficients are closely related to the material (metal material type), structure (conductor shape and twisting method), surface state (wear, oxidation, and contamination) of the conductor itself, and the service life (the coefficient value will continue to change with the increase in commissioning time). There is currently no good quantitative characterization method, and they can only be measured in the laboratory through complex and expensive instruments. Inaccurate radiation heat absorption coefficient and radiation heat dissipation coefficient will lead to incorrect assessment of the current carrying capacity of the transmission line, which will in turn cause safety hazards to the normal operation and dynamic capacity increase operation of the line, and even cause serious accidents such as disconnection of overhead transmission lines and regional power outages. Therefore, measures must be taken to accurately obtain the radiation heat absorption coefficient and radiation heat dissipation coefficient values ​​of the conductor. Summary of the invention

[0006] Based on the above records, the present invention provides a method and system for evaluating the radiation coefficient of an overhead power transmission line, aiming to solve technical problems in the prior art such as the difficulty in accurately evaluating the radiation coefficient of an overhead power transmission line.

[0007] A method for evaluating the radiation coefficient of an overhead transmission line comprises: step A1, obtaining operation data and environmental data of the transmission line within a preset time period, wherein the operation data comprises a temperature acquisition value of the line; step A2, establishing a heat balance equation according to the operation data and the environmental data; step A3, solving a transient differential equation based on the established heat balance equation to obtain a calculated temperature value of the line, and obtaining an evaluation value of the radiation coefficient of the transmission line based on the collected temperature value of the line and the calculated temperature value of the line.

[0008] Furthermore, in step A1, the operation data also includes the collected value of the conductor current, and the environmental data includes the collected value of the sunshine intensity around the transmission line, the collected value of the wind speed, the collected value of the wind direction angle and the collected value of the ambient temperature.

[0009] Furthermore, in step A1, there are two preset time periods, namely, a daytime time period and an evening time period; in step A2, a first heat balance equation is established according to the operation data and environmental data of the daytime time period, and a second heat balance equation is established according to the operation data and environmental data of the evening time period; step A3 includes: step A31, solving the calculated value of the wire temperature of the evening time period based on the established second heat balance equation; step A32, obtaining a radiation heat dissipation coefficient evaluation value based on the wire temperature acquisition value and the wire temperature calculation value of the evening time period; step A33, solving the calculated value of the wire temperature of the daytime time period based on the established first heat balance equation and the radiation heat dissipation coefficient evaluation value; step A34, obtaining a radiation heat absorption coefficient evaluation value based on the wire temperature acquisition value and the wire temperature calculation value of the daytime time period.

[0010] Furthermore, in step A31, a series of values ​​of the radiation heat dissipation coefficient are selected, each value of the radiation heat dissipation coefficient is substituted into the second heat balance equation, the transient differential equation is solved, and a group of conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient are obtained; step A32 includes: step A321, for a group of conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient, calculating the overall error between the conductor temperature collection value and the conductor temperature calculation value in the evening time period; step A322, based on the principle of minimizing the overall error, the value of the radiation heat dissipation coefficient corresponding to the minimum value of the overall error is used as the evaluation value of the radiation heat dissipation coefficient.

[0011] Furthermore, in step A33, a series of values ​​of the radiation heat absorption coefficient are selected, and the evaluation value of the radiation heat dissipation coefficient and each value of the radiation heat absorption coefficient are substituted into the first heat balance equation, and the transient differential equation is solved to obtain a group of conductor temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient; step A34 includes: step A341, for a group of conductor temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient, calculating the overall error between the conductor temperature collection value and the conductor temperature calculation value during the daytime period; step A342, based on the principle of minimizing the overall error, taking the value of the radiation heat absorption coefficient corresponding to the minimum value of the overall error as the evaluation value of the radiation heat absorption coefficient.

[0012] A radiation coefficient evaluation system for an overhead power transmission line is used to execute the aforementioned radiation coefficient evaluation method for an overhead power transmission line, comprising: an operation data acquisition device, used to obtain the operation data of the power transmission line within a preset time period, the operation data including the collected value of the conductor temperature; an environmental data acquisition device, used to obtain the environmental data of the power transmission line within the preset time period; a data processing device, respectively connected to the operation data acquisition device and the environmental data acquisition device, used to: establish a heat balance equation according to the operation data and the environmental data, solve a transient differential equation based on the established heat balance equation to obtain a calculated value of the conductor temperature, and obtain a radiation coefficient evaluation value of the power transmission line based on the collected value of the conductor temperature and the calculated value of the conductor temperature.

[0013] Furthermore, the operation data acquisition device includes: a wire temperature acquisition module, used to obtain the wire temperature acquisition value; a wire current acquisition module, used to obtain the wire current acquisition value; a first energy supply module, used to provide power for the operation data acquisition device; a first wireless communication module, used to transmit the wire temperature acquisition value and the wire current acquisition value to the data processing device.

[0014] Furthermore, the environmental data acquisition device includes: an environmental temperature acquisition module, which is used to obtain the environmental temperature acquisition value around the transmission line; a wind speed and direction acquisition module, which is used to obtain the wind speed acquisition value and wind direction angle acquisition value around the transmission line; a sunshine intensity acquisition module, which is used to obtain the sunshine intensity acquisition value around the transmission line; a second energy supply module, which is used to provide electric energy for the environmental data acquisition device; a second wireless communication module, which is used to transmit the sunshine intensity acquisition value, wind speed acquisition value, wind direction angle acquisition value and environmental temperature acquisition value to the data processing device.

[0015] Furthermore, the data processing device includes: a data receiving module, used to obtain operating data and environmental data; a data storage module, connected to the data receiving module, used to store operating data and environmental data; a data processing module, connected to the data storage module, used to: establish a thermal balance equation based on the operating data and environmental data, solve the transient differential equation based on the established thermal balance equation to obtain the calculated value of the conductor temperature, and calculate the radiation coefficient evaluation value of the transmission conductor based on the conductor temperature acquisition value and the conductor temperature calculated value.

[0016] Furthermore, there are two preset time periods, namely, a daytime time period and an evening time period; the data processing module comprises: an equation establishing unit, used to establish a first heat balance equation according to the operation data and environmental data of the daytime time period, and to establish a second heat balance equation according to the operation data and environmental data of the evening time period; a first temperature calculation unit, connected to the equation establishing unit, used to solve the wire temperature calculation value of the evening time period based on the established second heat balance equation; a heat dissipation coefficient determination unit, connected to the first temperature calculation unit, used to obtain a radiation heat dissipation coefficient evaluation value based on the wire temperature acquisition value and the wire temperature calculation value of the evening time period; a second temperature calculation unit, respectively connected to the equation establishing unit and the heat dissipation coefficient determination unit, used to solve the wire temperature calculation value of the daytime time period based on the established first heat balance equation and the radiation heat dissipation coefficient evaluation value; a heat absorption coefficient determination unit, connected to the second temperature calculation unit, used to obtain a radiation heat absorption coefficient evaluation value based on the wire temperature acquisition value and the wire temperature calculation value of the daytime time period.

[0017] The beneficial technical effect of the present invention is that the present invention collects the operating data and environmental data of the overhead transmission line, relies on the thermal balance equation of the line, establishes an optimization solution model for the radiation coefficient of the line, and then realizes the accurate solution of the radiation coefficient of the transmission line, so as to solve the problem that the radiation coefficient of the transmission line is difficult to obtain effectively and accurately at present, and helps to improve the accuracy of the thermal stability limit assessment results of the transmission line and improve the power supply reliability of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1-4 A flowchart of the steps of a method for evaluating the radiation coefficient of an overhead power transmission line provided by the present invention; Figure 5-6 A module schematic diagram of a radiation coefficient evaluation system for overhead power transmission lines provided by the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0022] See also Figure 1 The present invention provides a method for evaluating the radiation coefficient of an overhead transmission line, comprising: step A1, obtaining operation data and environmental data of the transmission line within a preset time period, wherein the operation data includes a temperature acquisition value of the line; step A2, establishing a heat balance equation according to the operation data and the environmental data; step A3, solving a transient differential equation based on the established heat balance equation to obtain a calculated temperature value of the line, and obtaining an evaluation value of the radiation coefficient of the transmission line based on the collected temperature value of the line and the calculated temperature value of the line.

[0023] Furthermore, in step A1, there are two preset time periods: a daytime period and an evening period.

[0024] In step A1, operation data and environmental data of the power transmission line are acquired during a period of time during the day and at night.

[0025] Specifically, the daytime time period should be set between 11:00 and 15:00 to collect daytime operation data and environmental data, and the weather should be sunny.

[0026] Specifically, the night time period should be set to 0:00~04:00 to collect operation data and environmental data at night, and the weather should be rainless.

[0027] Furthermore, in step A1, the operation data also includes the collected value of the conductor current.

[0028] Furthermore, in step A1, the environmental data includes the collected values ​​of sunshine intensity, wind speed, wind direction angle and ambient temperature around the transmission line.

[0029] The operation data and the environment data are both discrete values, that is, within a preset time period, the operation data and the environment data are collected once at every preset time interval Δt.

[0030] The operating data includes the wire current acquisition value I c (Unit: A), wire temperature acquisition value T c (Unit: ℃).

[0031] Environmental data includes sunshine intensity collection value J s (Unit: W / m2), wind speed collection value V f (Unit: m / s), wind direction angle θ f (Unit: degrees), ambient temperature T a (Unit: ℃).

[0032] The preset time period is marked as T span In T span During the time period, the operation data and environmental data of the transmission line are collected every Δt (unit: minutes), and a total of N data sets are collected, forming N data sets. Among them, the number of data sets N = T span (minutes) / Δt (minutes).

[0033] For N groups of collected data during the daytime period, the first group of data is recorded as {I cb(1) , T cb(1) , J sb(1) , V fb(1) ,θ fb(1) , T ab(1)}, the second set of data is recorded as {I cb(2) , T cb(2) , J sb(2) , V fb(2) , θ fb(2) , T ab(2)}, ..., the Nth group of data is recorded as {I cb(N) , T cb(N) , J sb(N) , V fb(N) , θ fb(N) , T ab(N)}. The subscript “b” indicates data collected during the day.

[0034] For N groups of collected data in the evening time period, the first group of data is recorded as {I cy(1) , T cy(1) , J sy(1) , V fy(1) ,θ fy(1) , T ay(1)}, the second set of data is recorded as {I cy(2) , Tc y(2) , J sy(2), V fy(2) , θ fy(2) , T ay(2)}, ..., the Nth group of data is recorded as {I cy(N) , T cy(N) , J sy(N) , V fy(N) , θ fy(N) , T ab(N)}. The subscript “y” indicates the data collected at night.

[0035] It should be noted that the duration of the daytime period and the evening period may be different, because the N value during the day and the N value during the evening may be different.

[0036] Preferably, T span It should be greater than 60 minutes and Δt should be less than 2 minutes.

[0037] More preferably, T span is 120 minutes and Δt is 1 minute.

[0038] In step A2, a heat balance equation of the overhead power transmission line is established based on multiple sets of operation data and environmental data acquired during the daytime and nighttime periods.

[0039] The heat balance equation is expressed as follows: the heat change of the transmission wire per unit time = the Joule heat generated by the current passing through the transmission wire + the heat generated by the transmission wire absorbing sunlight radiation - the heat carried away by convection when the wind blows - the radiation heat dissipated by the transmission wire to the surrounding environment.

[0040] When the transmission line is in operation, its heat generation, heat dissipation, and conductor temperature change are always in a thermal equilibrium state. The corresponding thermal balance equation is shown in the following formula 1:

[0041] in: Q Ic(i) The Joule heat generated by the current passing through the transmission wire; Q Js(i) The heat generated by the transmission wires absorbing solar radiation; Q Vf(i) The heat carried away by wind through convection; Q Ta(i) It is the amount of heat radiated from the transmission line to the surrounding environment.

[0042] in, i =1, 2, 3, ..., N, the number of data groups N collected in the preset time period.

[0043] in, m c all is the total mass heat capacity of the transmission line. For steel core aluminum stranded wire,m c all = m 1 c 1+ m 2 c 2, where m 1. c 1 are the mass and specific heat capacity of aluminum stranded wire per unit length respectively; m 2. c 2 are the mass and specific heat capacity of the steel core per unit length respectively.

[0044] The design manual for transmission lines can be consulted to obtain m 1. c 1. m 2. c Specific value of 2, for example, for LGJ-400 / 35 conductor, m 1 = 1.107 kg / m, c 1 = 950 J / (kg·℃), m 2 = 0.2798 kg / m, c 2=480 J / (kg·℃).

[0045] Specifically, the Joule heat Q generated by the current passing through the transmission wire is Ic(i) The calculation formula is as follows: Formula 2:

[0046] In Formula 2: R 20 It is the resistance per unit length of the transmission line at 20°C, in Ω / m, and its value is related to the line model; α 20 The temperature coefficient of the conductor material at 20°C, the unit is 1 / °C, and its value is related to the material used for the conductor; R 20 With α 20 The value of can be obtained by referring to the transmission line design manual. For example, for LGJ-400 / 35 conductor, R 20 It can be taken as 7.39×10 -5 Ω / m, α 20 The recommended value is 0.004℃ -1 .

[0047] Specifically, the heat generated by the conductor absorbing solar radiation is Q Js(i) The calculation formula is as follows: Formula 3:

[0048] In formula 3, β is the radiation heat absorption coefficient to be solved; D is the diameter of the transmission line, in meters.

[0049] The heat Q removed by convection when the wind blows Vf(i) The calculation formula is as follows: Formula 4:

[0050] In Formula 4, K θf is the wind direction angle influencing factor, and the calculation formula is as follows:

[0051] The amount of heat radiated from the conductor to the surrounding environment is Q Ta(i) The calculation formula is as follows: Formula 5:

[0052] In formula 5, ε is the radiation heat dissipation coefficient to be solved.

[0053] Specifically, in step A2, the transient differential equation is solved based on the established heat balance equation to obtain the calculated value of the conductor temperature. According to the established heat balance equation, the calculated value of the conductor temperature T cjs Step increment dT cjs The following formula 6 is satisfied:

[0054] The initial value of the wire temperature calculation is T cjs(1) = T c(1) , the iterative calculation formula for the wire temperature calculation value is shown in Formula 7 below:

[0055] in, .

[0056] By using Formula 6 and Formula 7, the calculated values ​​of the series conductor temperature during the daytime period and the calculated values ​​of the conductor temperature during the nighttime period can be calculated.

[0057] See also Figure 2 Further, in step A2, a first heat balance equation is established according to the operation data and environmental data of the daytime period, and a second heat balance equation is established according to the operation data and environmental data of the evening period; step A3 includes: step A31, and solving the calculated value of the wire temperature of the evening period based on the established second heat balance equation; step A32, obtaining the radiation heat dissipation coefficient evaluation value based on the wire temperature collection value and the wire temperature calculation value of the evening period; step A33, and solving the calculated value of the wire temperature of the daytime period based on the established first heat balance equation and the radiation heat dissipation coefficient evaluation value; step A34, obtaining the radiation heat absorption coefficient evaluation value based on the wire temperature collection value and the wire temperature calculation value of the daytime period.

[0058] See also Figure 3 Further, in step A31, a series of values ​​of the radiation heat dissipation coefficient is selected, each value of the radiation heat dissipation coefficient is substituted into the second heat balance equation, the transient differential equation is solved, and a group of conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient are obtained; step A32 includes: step A321, for a group of conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient, the overall error between the conductor temperature acquisition value and the conductor temperature calculation value in the evening time period is calculated; step A322, based on the principle of minimizing the overall error, the value of the radiation heat dissipation coefficient corresponding to the minimum value of the overall error is used as the evaluation value of the radiation heat dissipation coefficient.

[0059] For the operation data and environmental data collected during the night time, due to the sunlight intensity J s is zero, so the heat Q caused by the transmission line absorbing solar radiation Js =βDJ s =0, so the second heat balance equation of the conductor has nothing to do with the radiation heat absorption coefficient β, and only the radiation heat dissipation coefficient ε is the unknown quantity to be determined.

[0060] Therefore, in steps A31-A32, based on the N sets of data collected at night, the radiation heat dissipation coefficient ε is traversed, and the traversal value range is 0.2~1.0. ε is substituted into the second heat balance equation to obtain the overall error ΔH between the wire temperature collection value and the wire temperature calculation value under different ε values. y , the overall error ΔH y The calculation method is shown in Formula 8 below:

[0061] Here is the T c(i) and T cjs(i) They are the wire temperature collection values ​​collected during the night time period and the wire temperature calculation values ​​obtained by substituting ε into the second heat balance equation, and Δ H y (ε=0.2), Δ H y (ε=0.3),…,Δ H y (ε=1.0), which can make ΔH y The ε corresponding to the minimum value is taken as the evaluation value of the radiation heat dissipation coefficient of the transmission line solved by this method.

[0062] See also Figure 4Further, in step A33, a series of values ​​of the radiation heat absorption coefficient are selected, the radiation heat dissipation coefficient evaluation value and each value of the radiation heat absorption coefficient are substituted into the first heat balance equation, the transient differential equation is solved, and a group of wire temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient are obtained; step A34 includes: step A341, for a group of wire temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient, the overall error between the wire temperature collection value and the wire temperature calculation value during the daytime period is calculated; step A342, based on the principle of minimizing the overall error, the value of the radiation heat absorption coefficient corresponding to the minimum value of the overall error is used as the radiation heat absorption coefficient evaluation value.

[0063] For the daytime data, the radiation heat dissipation coefficient ε and the radiation heat absorption coefficient β are both unknown quantities to be determined, but in the previous step, the value of the radiation heat dissipation coefficient ε has been obtained. The value of ε is only related to the state of the transmission line itself, and has nothing to do with day and night, so the value of ε is known. Therefore, in the heat balance equation, only the radiation heat absorption coefficient β remains as an unknown quantity to be determined.

[0064] Based on N sets of data collected during the daytime, the radiation heat absorption coefficient β is traversed, and the traversal value range is 0.3~0.9. β is substituted into the first heat balance equation to calculate the overall error ΔH between the collected and calculated values ​​of the conductor temperature under different β values. b , the overall error ΔH b The calculation method is shown in Formula 9 below:

[0065] Here is the T c(i) and T cjs(i) They are the wire temperature collection value collected during the daytime and the wire temperature calculation value obtained by substituting ε into the first heat balance equation to obtain Δ H b (β=0.3), Δ H y (β=0.4),…,Δ H y (β=0.9), which can make ΔH b The β corresponding to the minimum value is taken as the evaluation value of the radiation heat absorption coefficient of the transmission line solved by this method.

[0066] See also Figure 5The present invention also provides an overhead transmission line radiation coefficient evaluation system for executing the above-mentioned overhead transmission line radiation coefficient evaluation method, comprising: an operation data acquisition device (1), used to obtain the operation data of the transmission line within a preset time period, the operation data including the conductor temperature acquisition value; an environmental data acquisition device (2), used to obtain the environmental data of the transmission line within the preset time period; a data processing device (3), respectively connected to the operation data acquisition device and the environmental data acquisition device, used to: establish a heat balance equation according to the operation data and the environmental data, solve the transient differential equation based on the established heat balance equation to obtain the conductor temperature calculation value, and obtain the radiation coefficient evaluation value of the transmission line based on the conductor temperature acquisition value and the conductor temperature calculation value.

[0067] The operation data collection device (1) is installed on the transmission line and is responsible for collecting the operation data of the transmission line.

[0068] Furthermore, the operation data acquisition device (1) comprises: a wire temperature acquisition module (11) for acquiring wire temperature acquisition values; a wire current acquisition module (12) for acquiring wire current acquisition values; a first energy supply module (13) for providing electric energy to the operation data acquisition device; and a first wireless communication module (14) for transmitting the wire temperature acquisition values ​​and the wire current acquisition values ​​to a data processing device.

[0069] The conductor temperature acquisition module is connected to a temperature sensor for collecting the conductor temperature of the overhead transmission line. The sensor type is, for example, PT100, and the temperature measurement range is, for example, -40~180°C, with a measurement error of less than ±1°C.

[0070] The conductor current acquisition module is connected to a current sensor for collecting conductor current of an overhead transmission line. The sensor type is, for example, a Rogowski coil, the current measurement range is, for example, 0 to 1000 A, and the measurement accuracy is 0.5 level.

[0071] The first energy supply module is connected to an inductive power supply unit for providing the energy required for the normal operation of the data acquisition device. The inductive power supply unit includes, for example, a power supply core, a multi-turn winding coil, a rectifier circuit, an energy dissipation circuit, and a voltage conversion circuit.

[0072] The first wireless communication module is connected to a first wireless communication antenna, which is used to wirelessly communicate with the data processing device, and send the collected wire temperature collection value, wire current collection value, operating data collection device working condition data, etc. to the data processing device. The first wireless communication antenna is, for example, a passive antenna, and any one of 2G / 3G / 4G / 5G antennas can be used.

[0073] Furthermore, the environmental data collection device (2) comprises: an environmental temperature collection module (21) for obtaining an environmental temperature collection value around the power transmission line; a wind speed and wind direction collection module (22) for obtaining a wind speed collection value and a wind direction angle collection value around the power transmission line; a sunshine intensity collection module (23) for obtaining a sunshine intensity collection value around the power transmission line; a second power supply module (24) for providing electric energy to the environmental data collection device; and a second wireless communication module (25) for transmitting the sunshine intensity collection value, the wind speed collection value, the wind direction angle collection value and the environmental temperature collection value to the data processing device (3).

[0074] The environmental data collection device is installed on the transmission tower and is responsible for collecting environmental data around the transmission wires.

[0075] The ambient temperature acquisition module is connected to a temperature sensor for collecting the ambient temperature around the overhead transmission line. The sensor type is PT100, the temperature measurement range is -40~70℃, and the measurement error is less than ±0.5℃.

[0076] The wind speed and direction acquisition module is connected to a wind speed and direction sensor, which is used to collect the wind speed and wind direction angle around the overhead transmission lines. The sensor type is, for example, ultrasonic, with a wind speed measurement range of 0~60m / s and an accuracy of ±3%. The wind direction measurement range is 0~360°, with an error of less than ±5°.

[0077] The sunshine intensity acquisition module is connected with a light sensor for collecting sunshine intensity around the overhead transmission line. The sensor type is, for example, a photoresistor type. The sunshine intensity measurement range is 0~2000W / m2, and the measurement error is less than ±5%.

[0078] The second energy supply module is connected with a solar panel and is used to convert solar energy into electric energy required for normal operation of the environmental data acquisition device. The second energy supply module also includes a battery and a surge protection circuit.

[0079] The second wireless communication module is connected to a second wireless communication antenna, which is used to wirelessly communicate with the data processing device, and send the collected ambient temperature collection value, wind speed and direction collection value, sunshine intensity collection value, working condition data of the environmental data collection device, etc. to the data processing device. The second wireless communication antenna is, for example, a passive antenna, and any one of 2G / 3G / 4G / 5G antennas can be used.

[0080] Furthermore, the data processing device (3) comprises: a data receiving module (31) for acquiring operation data and environmental data; a data storage module (32) connected to the data receiving module (31) for storing the operation data and environmental data; and a data processing module (33) connected to the data storage module (32) for: establishing a heat balance equation according to the operation data and environmental data, solving a transient differential equation based on the established heat balance equation to obtain a calculated value of conductor temperature, and calculating an evaluation value of the radiation coefficient of the transmission conductor based on the collected value of the conductor temperature and the calculated value of the conductor temperature.

[0081] Specifically, the data processing main station is deployed in the computer room to receive the collected data, and based on the proposed overhead transmission line radiation coefficient evaluation method, execute the processing program, store and output the radiation coefficient calculation results.

[0082] The data receiving module is connected to a third wireless communication antenna, which is used to communicate with the operation data acquisition device and the environmental data acquisition device, and receive the sent wire temperature acquisition values, wire current acquisition values, environmental temperature acquisition values, wind speed and direction acquisition values, sunshine intensity acquisition values, device operating data, etc. The third wireless communication antenna is a passive antenna, and any one of the 2G / 3G / 4G / 5G antennas can be used.

[0083] The data storage module is responsible for storing the data received by the data receiving module from the operation data acquisition device and the environmental data acquisition device, as well as storing the calculated radiation coefficient assessment value. The internal memory type of the storage module can be a mechanical hard disk (HDD) or a solid state drive (SSD). The hard disk capacity should be greater than 4GB, and the data will not be lost after power failure.

[0084] See also Figure 6 ,Furthermore, the system also includes a display module, which includes a display, a keyboard, and a mouse, and is used to display operating data, environmental data, and calculated radiation coefficient evaluation values.

[0085] Furthermore, there are two preset time periods, namely a daytime period and an evening period; the data processing module (33) comprises: an equation establishing unit (331), used to establish a first heat balance equation according to the operation data and environmental data of the daytime period, and to establish a second heat balance equation according to the operation data and environmental data of the evening period; a first temperature calculation unit (332), connected to the equation establishing unit (331), used to solve the wire temperature calculation value of the evening period based on the established second heat balance equation; a heat dissipation coefficient determination unit (333), connected to the first temperature calculation unit (332), used to obtain a radiation heat dissipation coefficient evaluation value based on the wire temperature collection value and the wire temperature calculation value of the evening period; a second temperature calculation unit (334), respectively connected to the equation establishing unit (331) and the heat dissipation coefficient determination unit (333), used to solve the wire temperature calculation value of the daytime period based on the established first heat balance equation and the radiation heat dissipation coefficient evaluation value; and a heat absorption coefficient determination unit (335), connected to the second temperature calculation unit (334), used to obtain a radiation heat absorption coefficient evaluation value based on the wire temperature collection value and the wire temperature calculation value of the daytime period.

[0086] The present invention collects the operating data (conductor current, conductor temperature) and environmental data (ambient temperature, sunshine intensity, wind speed, wind direction angle) that affect the heating and heat dissipation process of overhead transmission lines, and relies on the thermal balance equation of the transmission line to establish an optimization solution model for the conductor radiation heat absorption coefficient and radiation heat dissipation coefficient, and then accurately solves the radiation heat absorption coefficient and radiation heat dissipation coefficient based on the idea of ​​minimizing the overall error of the thermal balance equation, so as to solve the problem that the radiation heat absorption coefficient and radiation heat dissipation coefficient of the current transmission line are difficult to obtain effectively and accurately. The method has the advantages of simple implementation, accurate results, and does not affect the normal operation of the transmission line. It effectively improves the accuracy of the thermal stability limit assessment results of the transmission line, improves the reliability of power supply of the power grid, and has significant application value.

[0087] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for evaluating the radiation coefficient of an overhead transmission line, characterized in that: include: Step A1, obtaining operation data and environmental data of the power transmission line within a preset time period, wherein the operation data includes a temperature acquisition value of the line; Step A2, establishing a heat balance equation according to the operating data and the environmental data; Step A3, solving a transient differential equation based on the established heat balance equation to obtain a conductor temperature calculation value, and obtaining a radiation coefficient evaluation value of the transmission conductor based on the conductor temperature acquisition value and the conductor temperature calculation value, wherein the radiation coefficient evaluation value includes a radiation heat dissipation coefficient evaluation value and a radiation heat absorption coefficient evaluation value; In the step A1, there are two preset time periods: a daytime period and an evening period; In the step A2, a first heat balance equation is established according to the operation data and the environmental data of the daytime period, and a second heat balance equation is established according to the operation data and the environmental data of the evening period, wherein the first heat balance equation includes a radiation heat dissipation coefficient and a radiation heat absorption coefficient, and the second heat balance equation includes a radiation heat dissipation coefficient; the step A3 includes: step A31, and solving the calculated value of the wire temperature in the evening period based on the established second heat balance equation; Step A32, obtaining a radiation heat dissipation coefficient evaluation value based on the wire temperature collection value and the wire temperature calculation value in the evening time period; Step A33, solving the wire temperature calculation value in the daytime time period based on the established first heat balance equation and the radiation heat dissipation coefficient evaluation value; Step A34, obtaining a radiation heat absorption coefficient evaluation value based on the wire temperature collection value and the wire temperature calculation value in the daytime time period.

2. The method for evaluating the radiation coefficient of an overhead power transmission line according to claim 1, characterized in that: In the step A1, the operation data also includes the collected value of the conductor current, and the environmental data includes the collected value of the sunshine intensity around the transmission line, the collected value of the wind speed, the collected value of the wind direction angle and the collected value of the ambient temperature.

3. The method for evaluating the radiation coefficient of an overhead power transmission line according to claim 1, characterized in that: In the step A31, a series of values ​​of the radiation heat dissipation coefficient are selected, each value of the radiation heat dissipation coefficient is substituted into the second heat balance equation, and the transient differential equation is solved to obtain a set of the conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient; The step A32 includes: step A321, for a group of the conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient, calculating the overall error between the conductor temperature acquisition value and the conductor temperature calculation value in the evening time period; step A322, based on the principle of minimizing the overall error, taking the value of the radiation heat dissipation coefficient corresponding to the minimum value of the overall error as the radiation heat dissipation coefficient evaluation value.

4. The method for evaluating the radiation coefficient of an overhead power transmission line according to claim 1, characterized in that: In the step A33, a series of values ​​of the radiation heat absorption coefficient are selected, the radiation heat dissipation coefficient evaluation value and each value of the radiation heat absorption coefficient are substituted into the first heat balance equation, and the transient differential equation is solved to obtain a set of the conductor temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient; The step A34 includes: step A341, for a group of the conductor temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient, calculating the overall error between the conductor temperature acquisition value and the conductor temperature calculation value during the daytime period; step A342, based on the principle of minimizing the overall error, taking the value of the radiation heat absorption coefficient corresponding to the minimum value of the overall error as the radiation heat absorption coefficient evaluation value.

5. An overhead power transmission line radiation coefficient evaluation system, characterized in that: A method for evaluating the radiation coefficient of an overhead power transmission line according to any one of claims 1 to 4, comprising: an operation data acquisition device for acquiring operation data of the power transmission line within a preset time period, wherein the operation data includes a temperature acquisition value of the line; an environmental data acquisition device for acquiring environmental data of the power transmission line within a preset time period; a data processing device, connected to the operation data acquisition device and the environmental data acquisition device, respectively, for: establishing a heat balance equation according to the operation data and the environmental data, solving a transient differential equation based on the established heat balance equation to obtain a calculated value of the line temperature, and obtaining an evaluation value of the radiation coefficient of the power transmission line based on the collected value of the line temperature and the calculated value of the line temperature, wherein the evaluation value of the radiation coefficient includes an evaluation value of the radiation heat dissipation coefficient and an evaluation value of the radiation heat absorption coefficient; having two preset time periods, namely a daytime time period and a nighttime time period; a data processing module comprising: an equation establishing unit, for: establishing a first heat balance equation according to the operation data and the environmental data in the daytime time period; A heat balance equation is established according to the operation data and the environmental data of the evening time period, wherein the first heat balance equation includes a radiation heat dissipation coefficient and a radiation heat absorption coefficient, and the second heat balance equation includes a radiation heat dissipation coefficient; a first temperature calculation unit is connected to the equation establishment unit and is used to solve the wire temperature calculation value of the evening time period based on the established second heat balance equation; a heat dissipation coefficient determination unit is connected to the first temperature calculation unit and is used to obtain a radiation heat dissipation coefficient evaluation value based on the wire temperature acquisition value and the wire temperature calculation value of the evening time period; a second temperature calculation unit is respectively connected to the equation establishment unit and the heat dissipation coefficient determination unit and is used to solve the wire temperature calculation value of the daytime time period based on the established first heat balance equation and the radiation heat dissipation coefficient evaluation value; a heat absorption coefficient determination unit is connected to the second temperature calculation unit and is used to obtain a radiation heat absorption coefficient evaluation value based on the wire temperature acquisition value and the wire temperature calculation value of the daytime time period.

6. An overhead power line radiation coefficient evaluation system as claimed in claim 5, characterized in that: The operation data acquisition device includes: a wire temperature acquisition module, used to obtain the wire temperature acquisition value; a wire current acquisition module, used to obtain the wire current acquisition value; a first energy supply module, used to provide power to the operation data acquisition device; a first wireless communication module, used to transmit the wire temperature acquisition value and the wire current acquisition value to the data processing device.

7. The overhead power line radiation coefficient evaluation system according to claim 5, characterized in that: The environmental data acquisition device includes: an environmental temperature acquisition module, which is used to obtain the environmental temperature acquisition value around the transmission line; a wind speed and wind direction acquisition module, which is used to obtain the wind speed acquisition value and wind direction angle acquisition value around the transmission line; a sunshine intensity acquisition module, which is used to obtain the sunshine intensity acquisition value around the transmission line; a second energy supply module, which is used to provide electric energy for the environmental data acquisition device; and a second wireless communication module, which is used to transmit the sunshine intensity acquisition value, the wind speed acquisition value, the wind direction angle acquisition value and the environmental temperature acquisition value to the data processing device.

8. The overhead power line radiation coefficient evaluation system according to claim 5, characterized in that: The data processing device includes: a data receiving module, used to obtain the operating data and the environmental data; a data storage module, connected to the data receiving module, used to store the operating data and the environmental data; a data processing module, connected to the data storage module, used to: establish a thermal balance equation according to the operating data and the environmental data, solve a transient differential equation based on the established thermal balance equation to obtain a conductor temperature calculation value, and calculate the radiation coefficient evaluation value of the transmission conductor based on the conductor temperature acquisition value and the conductor temperature calculation value.

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