An evaluation method and system for the radiation coefficient of an overhead transmission line

Abstract

The present invention provides a method and system for evaluating the radiation coefficient of an overhead transmission line. In step A1, operating data and environmental data of the transmission line within a preset time period are obtained, and the operating data includes the collected value of the conductor temperature. In step A2, a heat balance equation is established based on the operating data and the environmental data. In step A3, the transient differential equation is solved based on the established heat balance equation to obtain the calculated value of the conductor temperature, and the evaluation value of the radiation coefficient of the overhead transmission line is obtained based on the collected value of the conductor temperature and the calculated value of the conductor temperature. Relying on the heat balance equation of the conductor, an optimized solution model for the conductor radiation coefficient is established, thereby realizing the accurate solution of the radiation coefficient of the overhead transmission line, solving the problem that it is difficult to effectively and accurately obtain the radiation coefficient of the current overhead transmission line, and helping to improve the accuracy of the evaluation result of the thermal stability limit of the transmission line and the power supply reliability of the power system.

Description

Technical Field

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

[0002] Overhead transmission lines are the most commonly used power transmission method, used to transmit the electric energy generated by power plants from power stations to urban, industrial, and residential areas. As an efficient, economical, flexible, and reliable power transmission method, overhead transmission lines are of great significance in the power system. It supports the long-distance and large-capacity requirements of power transmission, promotes the development and utilization of renewable energy, improves the reliability and maintainability of the power system, and provides 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 is 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 value is comprehensively determined based on factors such as the thermal characteristics of the conductor material, the cross-sectional area of the conductor, environmental conditions, and the cooling method of the line. Temperatures exceeding the thermal stability limit will cause an increase in the thermal expansion of the conductor material and an increase in the sag of the conductor, thereby affecting 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 lines.

[0004] The thermal stability limit of a transmission line is related to the parameters of the conductor itself and environmental conditions. When the conductor passes an electric current, Joule heat is generated. The conductor absorbs heat by radiation due to sunlight irradiation, radiates heat to the surrounding environment, and convective heat dissipation is enhanced when the wind blows over the conductor. 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 solar radiation intensity of the conductor in real time, and combining with 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 environmental parameters mentioned above can be easily obtained through online monitoring, and the current sensor and monitoring technologies are already 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 of the wire itself (metal material type), structure (wire shape and stranding method), surface condition (wear, oxidation, pollution accumulation), and operation years (as the operation time increases, the coefficient values will also change continuously). Currently, there is no good quantitative characterization method, and it can only be measured in the laboratory with complex and expensive instruments. The inaccuracy of the radiation heat absorption coefficient and radiation heat dissipation coefficient will lead to an incorrect assessment of the current-carrying capacity of the transmission line, which will pose a safety hazard to the normal operation and dynamic capacity increase operation of the line, and even cause malignant accidents such as overhead transmission line breakage and large-scale regional power outages. Therefore, measures must be taken to accurately obtain the values of the radiation heat absorption coefficient and radiation heat dissipation coefficient of the wire. Summary of the Invention

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

[0007] A method for evaluating the radiation coefficient of overhead transmission lines includes:

[0008] Step A1: Obtain the operation data and environmental data of the transmission line within a preset time period. The operation data includes the collected value of the wire temperature.

[0009] Step A2: Establish a heat balance equation based on the operation data and environmental data.

[0010] Step A3: Solve the transient differential equation based on the established heat balance equation to obtain the calculated value of the wire temperature, and obtain the evaluation value of the radiation coefficient of the transmission line based on the collected value of the wire temperature and the calculated value of the wire temperature.

[0011] Further, in Step A1, the operation data further includes the collected value of the wire current, and the environmental data includes the collected value of the sunlight intensity, the collected value of the wind speed, the collected value of the wind direction angle, and the collected value of the environmental temperature around the transmission line.

[0012] Further, in Step A1, there are two preset time periods: the daytime period and the nighttime period.

[0013] In Step A2, establish the first heat balance equation based on the operation data and environmental data in the daytime period, and establish the second heat balance equation based on the operation data and environmental data in the nighttime period.

[0014] Step A3 includes:

[0015] Step A31, and solve the calculated value of the conductor temperature in the evening period based on the established second heat balance equation;

[0016] Step A32, obtain the evaluation value of the radiation heat dissipation coefficient based on the measured value and the calculated value of the conductor temperature in the evening period;

[0017] Step A33, and solve the calculated value of the conductor temperature in the daytime period based on the established first heat balance equation and the evaluation value of the radiation heat dissipation coefficient;

[0018] Step A34, obtain the evaluation value of the radiation heat absorption coefficient based on the measured value and the calculated value of the conductor temperature in the daytime period.

[0019] Furthermore, in step A31, select a series of values of the radiation heat dissipation coefficient, substitute each value of the radiation heat dissipation coefficient into the second heat balance equation, solve the transient differential equation, and obtain a set of calculated values of the conductor temperature corresponding to each value of the radiation heat dissipation coefficient;

[0020] Step A32 includes:

[0021] Step A321, for a set of calculated values of the conductor temperature corresponding to each value of the radiation heat dissipation coefficient, calculate the overall error between the measured value and the calculated value of the conductor temperature in the evening period;

[0022] Step A322, based on the principle of minimizing the overall error, take the value of the radiation heat dissipation coefficient corresponding to the minimum overall error as the evaluation value of the radiation heat dissipation coefficient.

[0023] Furthermore, in step A33, select a series of values of the radiation heat absorption coefficient, substitute the evaluation value of the radiation heat dissipation coefficient and each value of the radiation heat absorption coefficient into the first heat balance equation, solve the transient differential equation, and obtain a set of calculated values of the conductor temperature corresponding to each value of the radiation heat absorption coefficient;

[0024] Step A34 includes:

[0025] Step A341, for a set of calculated values of the conductor temperature corresponding to each value of the radiation heat absorption coefficient, calculate the overall error between the measured value and the calculated value of the conductor temperature in the daytime period;

[0026] Step A342, based on the principle of minimizing the overall error, take the value of the radiation heat absorption coefficient corresponding to the minimum overall error as the evaluation value of the radiation heat absorption coefficient.

[0027] An overhead transmission line conductor radiation coefficient evaluation system for implementing the foregoing overhead transmission line conductor radiation coefficient evaluation method, comprising:

[0028] An operating data acquisition device, configured to acquire the operating data of a transmission line within a preset time period, where the operating data includes the acquired value of the conductor temperature;

[0029] An environmental data acquisition device, configured to acquire the environmental data of the transmission line within a preset time period;

[0030] A data processing device, respectively connected to the operating data acquisition device and the environmental data acquisition device, and configured to: establish a heat balance equation based on the operating 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 an evaluation value of the radiation coefficient of the transmission line based on the acquired value of the conductor temperature and the calculated value of the conductor temperature.

[0031] Furthermore, the operating data acquisition device includes:

[0032] A conductor temperature acquisition module, configured to acquire the acquired value of the conductor temperature;

[0033] A conductor current acquisition module, configured to acquire the acquired value of the conductor current;

[0034] A first power supply module, configured to supply power to the operating data acquisition device;

[0035] A first wireless communication module, configured to transmit the acquired value of the conductor temperature and the acquired value of the conductor current to the data processing device.

[0036] Furthermore, the environmental data acquisition device includes:

[0037] An environmental temperature acquisition module, configured to acquire the acquired value of the environmental temperature around the transmission line;

[0038] A wind speed and direction acquisition module, configured to acquire the acquired value of the wind speed magnitude and the acquired value of the wind direction angle around the transmission line;

[0039] A solar radiation intensity acquisition module, configured to acquire the acquired value of the solar radiation intensity around the transmission line;

[0040] A second power supply module, configured to supply power to the environmental data acquisition device;

[0041] A second wireless communication module, configured to transmit the acquired value of the solar radiation intensity, the acquired value of the wind speed magnitude, the acquired value of the wind direction angle, and the acquired value of the environmental temperature to the data processing device.

[0042] Furthermore, the data processing device includes:

[0043] A data receiving module, configured to acquire the operating data and the environmental data;

[0044] A data storage module, connected to the data receiving module, and configured to store the operating data and the environmental data;

[0045] A data processing module, connected to the data storage module, is configured to: establish a heat balance equation based on the operating data and environmental data, solve the transient differential equation based on the established heat balance equation to obtain the calculated value of the conductor temperature, and calculate the evaluation value of the radiation coefficient of the transmission line based on the measured value and the calculated value of the conductor temperature.

[0046] Furthermore, it has two preset time periods: the daytime period and the nighttime period;

[0047] The data processing module includes:

[0048] An equation establishment unit, configured to: establish a first heat balance equation based on the operating data and environmental data in the daytime period, and establish a second heat balance equation based on the operating data and environmental data in the nighttime period;

[0049] A first temperature calculation unit, connected to the equation establishment unit, is configured to solve the calculated value of the conductor temperature in the nighttime period based on the established second heat balance equation;

[0050] A heat dissipation coefficient determination unit, connected to the first temperature calculation unit, is configured to obtain the evaluation value of the radiation heat dissipation coefficient based on the measured value and the calculated value of the conductor temperature in the nighttime period;

[0051] A second temperature calculation unit, connected to the equation establishment unit and the heat dissipation coefficient determination unit respectively, is configured to solve the calculated value of the conductor temperature in the daytime period based on the established first heat balance equation and the evaluation value of the radiation heat dissipation coefficient;

[0052] An endothermic coefficient determination unit, connected to the second temperature calculation unit, is configured to obtain the evaluation value of the radiation endothermic coefficient based on the measured value and the calculated value of the conductor temperature in the daytime period.

[0053] The beneficial technical effects of the present invention are as follows: By collecting the operating data and environmental data of the overhead transmission line, relying on the heat balance equation of the conductor, an optimized solution model for the radiation coefficient of the conductor is established, thereby realizing the accurate solution of the radiation coefficient of the transmission line, solving the problem that it is difficult to effectively and accurately obtain the radiation coefficient of the current transmission line, and helping to improve the accuracy of the evaluation result of the thermal stability limit of the transmission line and the power supply reliability of the power system. Description of the Drawings

[0054] Figures 1-4 It is a flowchart of the steps of a method for evaluating the radiation coefficient of an overhead transmission line provided by the present invention;

[0055] Figures 5-6 It is a schematic diagram of the modules of a system for evaluating the radiation coefficient of an overhead transmission line provided by the present invention. Detailed Embodiments

[0056] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0057] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0058] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but it is not limited to the present invention.

[0059] See Figure 1 , the present invention provides a method for evaluating the radiation coefficient of an overhead transmission line conductor, including:

[0060] Step A1, obtaining the operation data and environmental data of the transmission line conductor within a preset time period, where the operation data includes the collected value of the conductor temperature;

[0061] Step A2, establishing a heat balance equation based on the operation data and environmental data;

[0062] Step A3, and solving the transient differential equation based on the established heat balance equation to obtain the calculated value of the conductor temperature, and obtaining the evaluation value of the radiation coefficient of the transmission line conductor based on the collected value of the conductor temperature and the calculated value of the conductor temperature.

[0063] Further, in step A1, there are two preset time periods, namely the daytime period and the nighttime period.

[0064] In step A1, the operation data and environmental data of the transmission line conductor are obtained respectively during the day and at night within a period of time.

[0065] Specifically, the daytime period should be set during 11:00~15:00 to collect the operation data and environmental data during the day, and the weather is sunny.

[0066] Specifically, the nighttime period should be set to collect during 0:00~04:00 to collect the operation data and environmental data at night, and there is no rain.

[0067] Further, in step A1, the operation data also includes the collected value of the conductor current.

[0068] Further, in step A1, the environmental data includes the collected value of the sunlight intensity around the transmission line conductor, the collected value of the wind speed, the collected value of the wind direction angle, and the collected value of the environmental temperature.

[0069] Both the operating data and the environmental data are discrete values, that is, within a preset time period, the operating data and the environmental data are collected every preset time interval Δt.

[0070] The operating data includes the collected value of the conductor current I c (unit: A), and the collected value of the conductor temperature T c (unit: °C).

[0071] The environmental data includes the collected value of the sunshine intensity J s (unit: W / m2), the collected value of the wind speed V f (unit: m / s), the wind direction angle θ f (unit: degree), and the environmental temperature T a (unit: °C).

[0072] The preset time period is marked as T span . During T span time period, the operating data and the environmental data of the transmission line are collected every Δt (unit: minute), and a total of N times are collected, forming N groups of data. Among them, the number of data groups N = T span (minute) / Δt (minute).

[0073] For the N groups of collected data in 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 group 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" represents the collected data in the daytime.

[0074] For the N groups of collected data in the evening 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 group of data is recorded as {I cy(2) , Tc y(2) , J sy(2), V fy(2) , θ fy(2) , T ay(2)}, …, the data of the Nth group is denoted as {I cy(N) , T cy(N) , J sy(N) , V fy(N) , θ fy(N) , T ab(N)}. The subscript "y" represents the data collected at night.

[0075] It should be noted that the durations of the daytime period and the nighttime period can be different because the values of N during the day and at night can be different.

[0076] Preferably, T span should be greater than 60 minutes, and Δt should be less than 2 minutes.

[0077] More preferably, T span is 120 minutes, and Δt is 1 minute.

[0078] In step A2, based on the multiple groups of operation data and environmental data obtained during the daytime period and the nighttime period, a heat balance equation for the overhead transmission line is established.

[0079] The expression of the heat balance equation is as follows:

[0080] The change in the heat of the transmission line per unit time = the Joule heat generated by the current passing through the transmission line + the heat generated by the transmission line absorbing solar radiation - the heat carried away by convection when the wind blows - the radiant heat dissipated by the transmission line to the surrounding environment.

[0081] When the transmission line is in operation, its heat generation, heat dissipation, and the change in wire temperature are always in a heat balance state. The corresponding heat balance equation is shown in formula 1 below:

[0082] ;

[0083] Where:

[0084] Q Ic(i) is the Joule heat generated by the current passing through the transmission line;

[0085] Q Js(i) is the heat generated by the transmission line absorbing solar radiation;

[0086] Q Vf(i) is the heat carried away by convection when the wind blows;

[0087] Q Ta(i) is the radiant heat dissipated by the transmission line to the surrounding environment.

[0088] Among them, i= 1, 2, 3, …, N, where N is the number of data sets collected in the preset time period.

[0089] Among them, m c all is the total mass heat capacity of the transmission line. For ACSR conductors, m c all = m 1 c 1 + m 2 c 2, where m 1, c 1 are the mass and specific heat capacity per unit length of the aluminum conductor respectively; m 2, c 2 are the mass and specific heat capacity per unit length of the steel core respectively.

[0090] The specific values of m 1, c 1, m 2, c 2 can be obtained by referring to the design manual of the transmission line. For example, for LGJ-400 / 35 conductors, m 1 = 1.107 kg / m, c 1 = 950 J / (kg·℃), m 2 = 0.2798 kg / m, c 2 = 480 J / (kg·℃).

[0091] Specifically, the Joule heat Q Ic(i) generated by the current passing through the transmission line is calculated by the following formula 2:

[0092] ;

[0093] In formula 2:

[0094] R 20 is the resistance per unit length of the transmission line at 20℃, with the unit of Ω / m, and its value is related to the conductor type;

[0095] α 20 is the temperature coefficient of the conductor material at 20℃, with the unit of 1 / ℃, and its value is related to the material used for the conductor;

[0096] R 20 and α 20 values can be obtained by referring to the design manual of the transmission line. For example, for LGJ-400 / 35 conductors, R 20 can be taken as 7.39×10 -5 Ω / m, and α 20 can be taken as 0.004℃ -1 .

[0097] Specifically, the calorific value Q generated by the wire absorbing solar radiation Js(i) is calculated by the following formula 3:

[0098] ;

[0099] In formula 3, β is the radiation heat absorption coefficient to be solved; D is the diameter of the transmission wire, with the unit of m.

[0100] The heat quantity Q carried away by the wind through convection Vf(i) is calculated by the following formula 4:

[0101] ;

[0102] Among them, in formula 4, K θf is the wind direction angle influence factor, and its calculation formula is as follows:

[0103] ;

[0104] The radiative heat dissipation quantity Q of the wire to the surrounding environment Ta(i) is calculated by the following formula 5:

[0105] ;

[0106] In formula 5, ε is the radiative heat dissipation coefficient to be solved.

[0107] Specifically, in step A2, based on the established heat balance equation, the transient differential equation is solved to obtain the calculated value of the wire temperature. According to the established heat balance equation, the step increment dT cjs of the calculated value of the wire temperature cjs satisfies the following formula 6:

[0108] ;

[0109] The initial value of the calculated value of the wire temperature is T cjs(1) = T c(1) The iterative calculation formula of the calculated value of the wire temperature is shown in the following formula 7:

[0110] ;

[0111] Among them, .

[0112] Through formula 6 and formula 7, a series of calculated values of the wire temperature during the daytime period and the calculated value of the wire temperature during the nighttime period can be calculated.

[0113] See Figure 2, Further, in step A2, a first heat balance equation is established based on the operation data and environmental data during the daytime period, and a second heat balance equation is established based on the operation data and environmental data during the nighttime period;

[0114] Step A3 includes:

[0115] Step A31, and based on the established second heat balance equation, solve for the calculated value of the conductor temperature during the nighttime period;

[0116] Step A32, obtain an evaluation value of the radiation heat dissipation coefficient based on the measured value and calculated value of the conductor temperature during the nighttime period;

[0117] Step A33, and based on the established first heat balance equation and the evaluation value of the radiation heat dissipation coefficient, solve for the calculated value of the conductor temperature during the daytime period;

[0118] Step A34, obtain an evaluation value of the radiation heat absorption coefficient based on the measured value and calculated value of the conductor temperature during the daytime period.

[0119] See Figure 3 , Further, in step A31, select a series of values of the radiation heat dissipation coefficient, substitute each value of the radiation heat dissipation coefficient into the second heat balance equation, solve the transient differential equation, and obtain a set of calculated values of the conductor temperature corresponding to each value of the radiation heat dissipation coefficient;

[0120] Step A32 includes:

[0121] Step A321, for a set of calculated values of the conductor temperature corresponding to each value of the radiation heat dissipation coefficient, calculate the overall error between the measured value and calculated value of the conductor temperature during the nighttime period;

[0122] Step A322, based on the principle of minimizing the overall error, take the value of the radiation heat dissipation coefficient corresponding to the minimum overall error as the evaluation value of the radiation heat dissipation coefficient.

[0123] For the operation data and environmental data collected during the nighttime period, since the solar radiation intensity J s is zero, the heat generation Q Js of the transmission conductor caused by absorbing solar radiation is s =βDJ y =0. Therefore, the second heat balance equation of the conductor is independent of the radiation heat absorption coefficient β, and only the radiation heat dissipation coefficient ε is the unknown quantity to be solved.

[0124] Therefore, in steps A31 - A32, based on the N groups of data collected at night, traverse the radiation heat dissipation coefficient ε, the traversal value range is 0.2 - 1.0, substitute ε into the second heat balance equation, and calculate the overall error ΔH between the measured value and calculated value of the conductor temperature for different values of ε y , the overall error ΔHy The calculation method is as shown in Formula 8 below:

[0125] ;

[0126] Here, T c(i) and T cjs(i) are respectively the measured wire temperature values collected during the evening time period and the calculated wire temperature values obtained by substituting ε into the second heat balance equation. After obtaining Δ H y (ε = 0.2), Δ H y (ε = 0.3), …, Δ H y (ε = 1.0), the ε corresponding to the minimum value of ΔH y is taken as the evaluation value of the radiation heat dissipation coefficient of the transmission wire obtained by solving this method.

[0127] See Figure 4 . Further, 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 to solve the transient differential equation, obtaining a set of calculated wire temperature values corresponding to each value of the radiation heat absorption coefficient;

[0128] Step A34 includes:

[0129] Step A341: For a set of calculated wire temperature values corresponding to each value of the radiation heat absorption coefficient, calculate the overall error between the measured wire temperature values during the daytime period and the calculated wire temperature values;

[0130] Step A342: Based on the principle of minimizing the overall error, take the value of the radiation heat absorption coefficient corresponding to the minimum overall error as the evaluation value of the radiation heat absorption coefficient.

[0131] For the daytime data, both the radiation heat dissipation coefficient ε and the radiation heat absorption coefficient β are unknowns to be solved. However, 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 wire itself and has nothing to do with daytime and nighttime. Therefore, the value of ε is known. Thus, in the heat balance equation, only the radiation heat absorption coefficient β remains as the unknown to be solved.

[0132] Based on the N groups of data collected during the daytime period, traverse the radiation heat absorption coefficient β, with the traversal value range being 0.3 to 0.9. Substitute β into the first heat balance equation to find the overall error ΔH b between the measured wire temperature values and the calculated values for different values of β. The overall error ΔH b is calculated as shown in Formula 9 below:

[0133] ;

[0134] The T here c(i) and T cjs(i) are respectively the wire temperature acquisition value collected during the daytime period and the wire temperature calculation value obtained by substituting ε into the first heat balance equation, and Δ is obtained H b (β = 0.3), Δ H y (β = 0.4), …, Δ H y (β = 0.9), and then, among them, the β corresponding to the minimum value of ΔH b is taken as the evaluation value of the radiation heat absorption coefficient of the transmission wire obtained by solving this method.

[0135] Referring to Figure 5 , the present invention also provides an overhead transmission wire radiation coefficient evaluation system for implementing the foregoing method for evaluating the radiation coefficient of an overhead transmission wire, including:

[0136] An operation data acquisition device (1) for acquiring operation data of the transmission wire within a preset time period, where the operation data includes a wire temperature acquisition value;

[0137] An environmental data acquisition device (2) for acquiring environmental data of the transmission wire within a preset time period;

[0138] A data processing device (3), connected to the operation data acquisition device and the environmental data acquisition device respectively, for: establishing a heat balance equation based on the operation data and the environmental data, solving a transient differential equation based on the established heat balance equation to obtain a wire temperature calculation value, and obtaining an evaluation value of the radiation coefficient of the transmission wire based on the wire temperature acquisition value and the wire temperature calculation value.

[0139] The operation data acquisition device (1) is installed on the transmission wire and is responsible for acquiring the operation data of the transmission wire.

[0140] Furthermore, the operation data acquisition device (1) includes:

[0141] A wire temperature acquisition module (11) for acquiring a wire temperature acquisition value;

[0142] A wire current acquisition module (12) for acquiring a wire current acquisition value;

[0143] A first power supply module (13) for supplying power to the operation data acquisition device;

[0144] A first wireless communication module (14) for transmitting the wire temperature acquisition value and the wire current acquisition value to the data processing device.

[0145] The wire temperature acquisition module is connected to a temperature sensor for acquiring the wire temperature of an overhead transmission line. The sensor type is, for example, PT100, the temperature measurement range is, for example, -40~180°C, and the measurement error is less than ±1°C.

[0146] The wire current acquisition module is connected to a current sensor for acquiring the wire current of an overhead transmission line. The sensor type is, for example, a Rogowski coil, the current measurement range is, for example, 0~1000A, and the measurement accuracy is 0.5 level.

[0147] The first power supply module is connected to an inductive power taking unit for providing the energy required for the normal operation of the operation data acquisition device. The inductive power taking unit includes, for example, a power taking iron core, a multi-turn winding coil, a rectifying circuit, a discharging circuit, and a voltage conversion circuit.

[0148] The first wireless communication module is connected to a first wireless communication antenna for performing wireless communication with the data processing device and sending the acquired wire temperature acquisition value, wire current acquisition value, operation data acquisition device condition data, etc. to the data processing device. The first wireless communication antenna is, for example, a passive antenna and can use any one of 2G / 3G / 4G / 5G antennas.

[0149] Further, the environmental data acquisition device (2) includes:

[0150] An ambient temperature acquisition module (21) for obtaining the ambient temperature acquisition value around the transmission wire;

[0151] A wind speed and direction acquisition module (22) for obtaining the wind speed acquisition value and wind direction angle acquisition value around the transmission wire;

[0152] A solar radiation intensity acquisition module (23) for obtaining the solar radiation intensity acquisition value around the transmission wire;

[0153] A second power supply module (24) for providing electric energy for the environmental data acquisition device;

[0154] A second wireless communication module (25) for transmitting the solar radiation intensity acquisition value, wind speed acquisition value, wind direction angle acquisition value, and ambient temperature acquisition value to the data processing device (3).

[0155] The environmental data acquisition device is installed on the transmission tower and is responsible for acquiring the environmental data around the transmission wire.

[0156] The ambient temperature acquisition module is connected to a temperature sensor for acquiring the ambient temperature around the overhead transmission wire. The sensor type is PT100, the temperature measurement range is -40~70°C, and the measurement error is less than ±0.5°C.

[0157] The wind speed and direction acquisition module is connected to a wind speed and direction sensor, which is used to collect the wind speed magnitude and wind direction angle around the overhead transmission line. The sensor type is, for example, ultrasonic. The wind speed measurement range is 0 - 60 m / s, the accuracy is ±3%, the wind direction measurement range is 0 - 360°, and the error is less than ±5°.

[0158] The sunshine intensity acquisition module is connected to a light sensor, which is used to collect the sunshine intensity around the overhead transmission line. The sensor type is, for example, a photoresistor. The sunshine intensity measurement range is 0 - 2000 W / m2, and the measurement error is less than ±5%.

[0159] The second power supply module is connected to a solar panel, which is used to convert solar energy into electrical energy required for the normal operation of the environmental data acquisition device. The second power supply module also includes a storage battery and a surge protection circuit.

[0160] The second wireless communication module is connected to a second wireless communication antenna, which is used to communicate with the data processing device wirelessly and send the collected environmental temperature acquisition value, wind speed and direction acquisition value, sunshine intensity acquisition value, working condition data of the environmental data acquisition device, etc. to the data processing device. The second wireless communication antenna is, for example, a passive antenna and can use any one of 2G / 3G / 4G / 5G antennas.

[0161] Further, the data processing device (3) includes:

[0162] A data receiving module (31), which is used to obtain operation data and environmental data;

[0163] A data storage module (32), connected to the data receiving module (31), which is used to store operation data and environmental data;

[0164] A data processing module (33), connected to the data storage module (32), which is used to: establish a heat balance equation based on the operation data and environmental data, solve the transient differential equation based on the established heat balance equation to obtain the calculated value of the conductor temperature, and calculate the evaluation value of the radiation coefficient of the transmission line based on the conductor temperature acquisition value and the calculated value of the conductor temperature.

[0165] Specifically, the data processing master station is deployed in the computer room, which is used to receive the collected data, execute the processing program based on the proposed evaluation method for the radiation coefficient of the overhead transmission line, and store and output the calculation result of the radiation coefficient.

[0166] 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 transmitted conductor temperature acquisition value, conductor current acquisition value, environmental temperature acquisition value, wind speed and direction acquisition value, sunshine intensity acquisition value, device working condition data, etc. The third wireless communication antenna is a passive antenna and can use any one of 2G / 3G / 4G / 5G antennas.

[0167] 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 evaluated values of the calculated radiation coefficients. The internal memory type of the storage module can select a mechanical hard disk (HDD) or a solid state drive (SSD). The hard disk capacity should be greater than 4GB, and the data is not lost after power failure.

[0168] See Figure 6 , further, the system further includes a display module, and the display module includes a display, a keyboard, and a mouse, which are used to display the operation data, environmental data, and the evaluated values of the calculated radiation coefficients.

[0169] Further, there are two preset time periods: the daytime time period and the nighttime time period;

[0170] The data processing module (33) includes:

[0171] An equation establishment unit (331) for: establishing a first heat balance equation according to the operation data and environmental data in the daytime time period, and establishing a second heat balance equation according to the operation data and environmental data in the nighttime time period;

[0172] A first temperature calculation unit (332), connected to the equation establishment unit (331), for solving the calculated value of the wire temperature in the nighttime time period based on the established second heat balance equation;

[0173] A heat dissipation coefficient determination unit (333), connected to the first temperature calculation unit (332), for obtaining the evaluated value of the radiation heat dissipation coefficient based on the measured value and the calculated value of the wire temperature in the nighttime time period;

[0174] A second temperature calculation unit (334), respectively connected to the equation establishment unit (331) and the heat dissipation coefficient determination unit (333), for solving the calculated value of the wire temperature in the daytime time period based on the established first heat balance equation and the evaluated value of the radiation heat dissipation coefficient;

[0175] An endothermic coefficient determination unit (335), connected to the second temperature calculation unit (334), for obtaining the evaluated value of the radiation endothermic coefficient based on the measured value and the calculated value of the wire temperature in the daytime time period.

[0176] The present invention collects the operation data (conductor current, conductor temperature) and environmental data (ambient temperature, solar radiation intensity, wind speed, wind direction angle) that affect the heating and heat dissipation processes of overhead transmission conductors. Relying on the heat balance equation of the transmission conductor, an optimization solution model for the radiation heat absorption coefficient and radiation heat dissipation coefficient of the conductor is established. Furthermore, based on the idea of minimizing the overall error of the heat balance equation, the accurate solutions of the radiation heat absorption coefficient and radiation heat dissipation coefficient are realized, so as to solve the problem that it is difficult to effectively and accurately obtain the radiation heat absorption coefficient and radiation heat dissipation coefficient of the current transmission conductor. The method has the advantages of simple implementation, accurate results, and does not affect the normal operation of the transmission line, effectively improving the accuracy of the evaluation result of the thermal stability limit of the transmission line, enhancing the power supply reliability of the power grid, and having significant application value.

[0177] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention. For those skilled in the art, it should be realized that all the equivalent replacements and obvious changes made by using the description and drawings 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 operation data and the environmental data; Step A3, solving a transient differential equation based on the established heat balance equation to obtain a calculated value of the conductor temperature, and obtaining 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, wherein the evaluation value of the radiation coefficient includes an evaluation value of a radiation heat dissipation coefficient and an evaluation value of a radiation heat absorption coefficient; 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 nighttime 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 comprises: Step A31, selecting a series of values ​​of the radiation heat dissipation coefficient, substituting each value of the radiation heat dissipation coefficient into the second heat balance equation, solving the transient differential equation, and obtaining a set of wire temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient in the evening time period; Step A32, obtaining an evaluation value of the radiation heat dissipation coefficient based on the collected value of the wire temperature and the calculated value of the wire temperature in the evening time period; Step A33, solving the calculated value of the conductor temperature during the daytime period based on the established first heat balance equation and the evaluation value of the radiation heat dissipation coefficient; Step A34, obtaining an evaluation value of the radiation heat absorption coefficient based on the collected value of the wire temperature during the daytime period and the calculated value of the wire temperature; The step A32 comprises: Step A321, for a group of the conductor temperature calculation values ​​corresponding to each value of the radiation heat dissipation coefficient, calculate 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 overall error minimization principle, taking the value of the radiation heat dissipation coefficient corresponding to the minimum value of the overall error as the evaluation value of the radiation heat dissipation coefficient; In the 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 set of calculated values ​​of the conductor temperature corresponding to each value of the radiation heat absorption coefficient; The step A34 comprises: Step A341, for a group of the conductor temperature calculation values ​​corresponding to each value of the radiation heat absorption coefficient, calculate 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 overall error minimization, the value of the radiation heat absorption coefficient corresponding to the minimum value of the overall error is used as the evaluation value of the radiation heat absorption coefficient.

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. 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 2, comprising: An operation data acquisition device, used to acquire the 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, used to obtain 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 conductor temperature calculation value, and obtaining an evaluation value of the radiation coefficient of the transmission conductor based on the conductor temperature acquisition value and the conductor temperature calculation value, wherein the evaluation value of the radiation coefficient includes an evaluation value of a radiation heat dissipation coefficient and an evaluation value of a radiation heat absorption coefficient; There are two preset time periods: a daytime period and an evening period; The data processing module includes: an equation establishing unit, for establishing a first heat balance equation according to the operation data and the environmental data of the daytime period, and establishing a second heat balance equation according to the operation data and the environmental data of the nighttime 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, connected to the equation establishment unit, for solving a calculated value of the wire temperature in 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, and configured to obtain an evaluation value of the radiation heat dissipation coefficient based on the wire temperature collection value and the wire temperature calculation value in the evening time period; a second temperature calculation unit, connected to the equation establishment unit and the heat dissipation coefficient determination unit, respectively, for solving a calculated value of the conductor temperature during the daytime period based on the established first heat balance equation and the evaluation value of the radiation heat dissipation coefficient; The heat absorption coefficient determination unit is connected to the second temperature calculation unit and is used to obtain an evaluation value of the radiation heat absorption coefficient based on the wire temperature collection value and the wire temperature calculation value during the daytime period.

4. The radiation coefficient evaluation system for overhead power transmission lines according to claim 3, characterized in that: The operation data acquisition device comprises: The conductor temperature acquisition module is used to obtain the conductor temperature acquisition value; A conductor current acquisition module is used to obtain conductor current acquisition values; A first energy supply module, used to provide electrical energy to the operation data acquisition device; The first wireless communication module is used to transmit the wire temperature collection value and the wire current collection value to the data processing device.

5. The overhead power line radiation coefficient evaluation system according to claim 3, characterized in that: The environmental data acquisition device comprises: An ambient temperature acquisition module is used to acquire the ambient temperature value around the transmission line; The wind speed and direction acquisition module is used to obtain the wind speed and wind direction angle values ​​around the transmission line; A sunshine intensity collection module is used to obtain sunshine intensity collection values ​​around the transmission line; A second energy supply module, used to provide electrical energy to the environmental data acquisition device; The second wireless communication module is used to transmit the sunshine intensity collection value, the wind speed collection value, the wind direction angle collection value and the ambient temperature collection value to the data processing device.

6. The overhead power line radiation coefficient evaluation system according to claim 3, characterized in that: The data processing device comprises: A data receiving module, used for acquiring the operation data and the environment data; A data storage module, connected to the data receiving module, and used to store the operation data and the environmental data; A data processing module is connected to the data storage module and is used to: establish a heat balance equation according to the operating 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 calculate an evaluation value of the radiation coefficient of the transmission conductor based on the collected conductor temperature value and the calculated conductor temperature value.

Images