CN114221345B - Power grid transmission characteristic acquisition method, system, storage medium and equipment - Google Patents
Power grid transmission characteristic acquisition method, system, storage medium and equipment Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
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Abstract
The invention relates to a method, a system, a storage medium and equipment for acquiring transmission characteristics of a power grid, which comprise the following steps: constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, and acquiring a transmission line current model based on electric heating parameters by using the electric heating coupling analysis model; acquiring meteorological and geographic condition data of a surrounding space of an overhead power transmission line, and importing the meteorological and geographic condition data into a tide model to obtain a power transmission line current model based on electric parameters; combining the electric transmission line current model based on the electric heating parameters and the electric transmission line current model based on the electric parameters to obtain an electric heating coupling model of the electric transmission line; based on the electric heating coupling model of the power transmission line and the node power balance equation, an electric heating coupling unified power flow model containing environment factor variables is obtained, and the electric heating coupling unified power flow model is utilized to output power grid transmission performance parameters by changing the environment factor variables. The method solves the problem that the influence of environmental factors is ignored to cause errors in the power flow calculation process in the power grid transmission performance analysis.
Description
Technical Field
The invention relates to the field of power engineering, in particular to a method, a system, a storage medium and equipment for acquiring transmission characteristics of a power grid.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The operation state of the power system not only depends on the electric parameters of the power grid, but also is influenced by environmental factors such as wind speed, air temperature, altitude, illumination intensity and the like, and the specific power grid operation characteristic index is usually closely related to key meteorological elements.
In recent years, grid accidents causing serious consequences are indistinguishable from the influence of extreme weather conditions. For example, the minimum temperature of 118 appears in New York in the United states in 2014, the explosive cyclone influence of east coast in the United states in 1 month in 2018 breaks the minimum record in the last century, the extreme initial cold flow in 3 months in the same year sweeps across Europe, the minimum air temperature of Kazakhstan in 2 months in 2019 drops to-40 ℃, most areas in the west in the United states in 2020 encounter extremely high temperature weather, the maximum air temperature in the Bebank city in the north of the center of los Angeles reaches 46.1 ℃ on the same day, the air temperature in the palm spring city closer to the inland desert reaches 50 ℃ and the like.
Similar extreme weather often causes shortage of regional power grid source network load situation, influences the performance of electric power facilities, and increases the probability of serious power failure accidents. At present, many researches are carried out on the operation related direction of the electric power system considering electric heating coupling at home and abroad, and research results show that the electric heating coupling is considered to have obvious influence on the operation of a power transmission line and the electric power system, but the current fine modeling and analysis method capable of showing the power transmission characteristics of the electric power network with the difference of weather and geographic factors is less, the transmission characteristics of the electric power network are difficult to determine under the influence of the weather and geographic conditions, and further the influence of the difference of the environmental factors such as wind speed, altitude, environmental temperature and illumination intensity on the power transmission characteristics of the electric power network cannot be analyzed, so that effective data support is difficult to be provided for the subsequent evaluation of the operation state of the electric power network.
Disclosure of Invention
In order to solve the technical problems in the background art, the invention provides a power grid transmission characteristic acquisition method, a system, a storage medium and equipment, wherein a power grid transmission characteristic determination process under the influence of weather and geographic conditions is converted into a mathematical problem, a power transmission line conductor heat balance equation is combined with a conventional power flow equation to solve simultaneously, weather and geographic information around the power transmission line are introduced into a power flow model in a variable form, and a Newton iteration process based on an expansion jacobian matrix is deduced and constructed. According to the algorithm, the influence of the differences of the wind speed, the altitude, the ambient temperature, the illumination intensity and other environmental factors on the power transmission characteristic of the power grid can be analyzed, so that the meteorological elements influencing the power transmission characteristic are identified.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
a first aspect of the present invention provides a power grid transmission characteristic acquisition method, including the steps of:
constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, and acquiring a transmission line current model based on electric heating parameters by using the electric heating coupling analysis model;
acquiring meteorological and geographic condition data of a surrounding space of an overhead power transmission line, and importing the meteorological and geographic condition data into a tide model to obtain a power transmission line current model based on electric parameters;
combining the electric transmission line current model based on the electric heating parameters and the electric transmission line current model based on the electric parameters to obtain an electric heating coupling model of the electric transmission line;
based on the electric heating coupling model of the power transmission line and the node power balance equation, an electric heating coupling unified power flow model containing environment factor variables is obtained, and the electric heating coupling unified power flow model is utilized to output power grid transmission performance parameters by changing the environment factor variables.
In the process of constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, the sum of the heat emitted by the line due to surface radiation and the heat emitted by the line due to air convection is equal to the sum of the heat absorbed by the line due to solar radiation and the heat generated by the current flowing through the line with the set length.
The heat dissipated by the wire due to surface radiation includes a function of the conductor temperature, the conductor ambient temperature, the conductor diameter, and the emissivity as independent variables.
The heat dissipated by the line due to air convection includes a function of the conductor temperature, the conductor ambient temperature, altitude, the line ambient wind speed, conductor diameter, and wind direction angle as independent variables.
The heat absorbed by the line due to solar radiation includes as a function of the independent variables altitude, conductor diameter, conductor absorption for light, solar light intensity, solar declination, time angle, geographic latitude, solar and line azimuth.
And obtaining an output result of the electrothermal coupling unified power flow model based on the Newton method.
The output results include line resistance, temperature, active and reactive losses.
A second aspect of the present invention provides a power grid transmission characteristic acquisition system based on the above method, including:
a first model building module configured to: constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, and acquiring a transmission line current model based on electric heating parameters by using the electric heating coupling analysis model; acquiring meteorological and geographic condition data of a surrounding space of an overhead power transmission line, and importing the meteorological and geographic condition data into a tide model to obtain a power transmission line current model based on electric parameters;
a second model building module configured to: combining the electric transmission line current model based on the electric heating parameters and the electric transmission line current model based on the electric parameters to obtain an electric heating coupling model of the electric transmission line; based on the electric heating coupling model of the power transmission line and a node power balance equation, an electric heating coupling unified power flow model containing environmental factor variables is obtained;
an output module configured to: and obtaining the transmission performance parameters of the power grid by changing the environment factor variable by using the electrothermal coupling unified power flow model.
A third aspect of the present invention provides a computer-readable storage medium.
A computer readable storage medium having stored thereon a computer program which when executed by a processor realizes the steps in a power grid transmission characteristic acquisition method as described above.
A fourth aspect of the invention provides a computer device.
A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps in the grid transmission characteristic acquisition method as described above when the program is executed.
Compared with the prior art, the above technical scheme has the following beneficial effects:
the influence of meteorological information and geographic information on the transmission performance of the power grid is considered, the error caused by neglecting the influence of environmental factors to the power flow calculation process in the power grid transmission analysis process is solved, the environmental factors such as wind speed, altitude, environmental temperature and illumination intensity are respectively changed, the influence of the environmental factors on the power transmission characteristic of the power grid and the characteristics of the environmental factors can be quantitatively analyzed, the solving process of the model is simple and easy, and the convergence is good.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention.
FIG. 1 is a flow diagram of a grid transmission characteristics determination process provided by one or more embodiments of the invention.
Detailed Description
The invention will be further described with reference to the drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.
As described in the background art, the differences of the wind speed, altitude, ambient temperature, illumination intensity and other environmental factors affect the power transmission characteristics of the power grid, and for a power transmission line, there is a process that a thermal balance equation of a conductor of the power transmission line characterizes heat transfer between the conductor and the surrounding air until the temperatures are equal, and the air around the conductor is changed under the influence of the illumination, altitude, ambient temperature and wind speed. For the power transmission characteristics of the power grid, the power flow calculation is to determine the steady-state operation state parameters of each part of the power system according to given power grid structure and parameters and the operation conditions of elements such as generators, loads and the like. Typically given operating conditions are power at various power and load points in the system, pivot point voltage, balance point voltage and phase angle. The operation state parameters to be solved comprise the voltage amplitude and phase angle of each bus node of the power grid, the power distribution of each branch, the power loss of the network and the like, and the transmission characteristics of the power grid can be reflected through load flow calculation.
Therefore, the following embodiments provide a method, a system, a storage medium and equipment for acquiring the transmission characteristics of a power grid, which introduce weather and geographic information around a power transmission line into a tide model in a variable form, deduce and construct a Newton iteration process based on an extended Jacobian matrix, so as to analyze the influence of differences of environmental factors such as wind speed, altitude, environmental temperature, illumination intensity and the like on the power transmission characteristics of the power grid.
Embodiment one:
as shown in fig. 1, the method for acquiring the transmission characteristics of the power grid includes the following steps:
firstly, an electric heating coupling analysis equation of the overhead transmission line is established, wherein the electric heating coupling analysis equation takes environmental factors into account. And acquiring data such as tide calculation data, weather and geographic information, setting a PQ node voltage amplitude and a phase angle, and setting an initial value, iteration times and convergence conditions of the resistance of the non-transformer power transmission line of the PV node voltage amplitude. And deducing a calculation formula of the current of the power transmission line according to a static heat balance equation of the power transmission line.
And secondly, establishing an electrothermal coupling unified power flow calculation model considering environmental factors. And (3) combining the electric transmission line current formula calculated by using the electric heating parameters with the electric transmission line current formula calculated by using the electric parameters to obtain an electric heating coupling equation of the electric transmission line. The electric heating coupling equation and the node power balance equation of the line are combined, meteorological and geographic information around the overhead transmission line is introduced into power flow calculation in a variable form, a jacobian matrix is deduced and expanded, and an electric heating coupling unified power flow model considering environmental factors is constructed.
And finally, solving the electric heating coupling unified power flow model which is built in the last step and considers the environmental factors by adopting a Newton method. And calculating the power transmission characteristics such as the line resistance, the temperature, the active power loss, the reactive power loss and the like. By changing the differences of the wind speed, the altitude, the ambient temperature, the illumination intensity and other environmental factors, the influence degree of the influence degree on the line resistance, the temperature, the active and reactive losses can be obtained, and the meteorological elements influencing the power transmission characteristics can be identified.
The specific process is as follows:
step one: and acquiring data such as tide calculation data, weather and geographic information, setting a PQ node voltage amplitude and a phase angle, and setting an initial value, iteration times and convergence conditions of the resistance of the non-transformer power transmission line of the PV node voltage amplitude.
And (3) the electric-thermal coupling analysis of the overhead transmission line taking environmental factors into consideration adopts a static heat balance equation. As described in formula (1):
wherein: i a The current-carrying capacity of the circuit; r is (r) a The actual series resistance of the circuit; l is the length of the line; assuming uniform conductor temperature distribution, T c For the conductor temperature, T a To the ambient temperature of the conductor, H e For altitude, V l The wind speed around the line, D is the conductor diameter, epsilon is the emissivity,for wind direction angle, α is the absorptivity of the conductor to light, Q s The sun illumination intensity is delta, the declination angle of the sun, omega is the hour angle, L a For geographical latitude, Z c And Z l Azimuth angles of the sun and the wires, respectively; q r For the heat emitted by the circuit due to surface radiation, it takes the form of T c 、T a D and ε are functions of the arguments; q c As heat emitted by the circuit due to air convection, it takes the form of T c 、T a 、H e 、V l D and->As a function of the argument; q s As heat absorbed by solar radiation in the circuit, it is H e 、D、α、Q s 、δ、ω、L a 、Z c And Z l As a function of the argument.
In practice, the line resistance is closely related to the temperature, the line temperature and the resistance are approximately linear within a specified range, and the ohmic resistance r a Can be approximately represented as T c The calculation formula is as follows:
r a (T c )＝R+σ(T c (t)-T) (2)
wherein: sigma is the temperature coefficient of resistance, R is the resistance of the conductor per unit length at rated ambient temperature T; t (T) c For the conductor temperature, T c And (t) is the conductor temperature at time t.
The electric coupling parameters can be utilized to calculate the electric transmission line current formula by deriving the formula (1), as shown in the formula (3).
Wherein:
wherein: r is (r) (l) 、I (l) Respectively r a 、I a Unit value of (2); s is S b 、Z b 、I b 、U b Respectively power, impedance, current, voltage reference values.
Step two: and establishing an electrothermal coupling unified power flow calculation model considering environmental factors and a solving algorithm thereof. And introducing meteorological and geographic factors into traditional power flow calculation, and establishing an electrothermal coupling unified power flow calculation model taking environmental factors into consideration. Assuming that the overhead lines of the power grid are all star-shaped, the phase current is equal to the line current, and the expression formula is as follows:
wherein: θ i、 θ j The voltage phase angles of the node i and the node j are respectively; v (V) i 、V j The voltage amplitudes of the node i and the node j are respectively; r is (r) (l) The resistance of line l; x is X ij Reactance from node i to node j; θ ij Is the voltage phase angle difference between node i and node j.
The electric transmission line current formula calculated by using the electric heating parameters and the electric transmission line current formula calculated by using the electric parameters are combined to obtain a line electric heating coupling equation, wherein the line electric heating coupling equation comprises various environment parameter values, the influence of the environment parameter values is displayed, and the calculation formula is as follows:
h (l) (v,θ,r)＝h 1 (r (l) )-h 2 (V i ,V j ,θ i ,θ j ,r (l) )＝0 (7)
the electric heating coupling equation of the line and the node power balance equation are combined to obtain an electric heating coupling unified power flow model considering environmental factors, and the electric heating coupling unified power flow model is shown as follows:
wherein: n is the number of nodes of the network; l is the number of overhead transmission lines; vector r represents the series resistance; vector v represents the node voltage phase angle; vector θ represents the node voltage phase angle. F (v, θ, r) is a power balance equation; h (v, θ, r) represents the electrothermal coupling equation for each transmission line, which is a function of v, θ, and r as independent variables.
The newton method iteration relationship of the solution formula (8) is shown as follows:
wherein: k and k+1 represent the number of iteration steps; the iteration ends when the absolute value of the vector deltaz element is the largest and smaller than the preset precision parameter. J in formula (9) E To extend the jacobian matrix, a specific description is shown in formula (10).
J in equation (10) is a conventional jacobian matrix, where the partial derivative of F with respect to r can be calculated according to equation (11).
Wherein:
the partial derivative of H with respect to v in equation (10) can be calculated according to equation (13). The matrix elements are only connected with the line l ij Is related to the voltage amplitude at the first and last nodes.
The partial derivative of H with θ in equation (10) can be calculated according to equation (14). The matrix elements are only connected with the line l ij Is related to the first and last node voltage phase angle.
The partial derivative of H with r in equation (10) can be calculated according to equation (14). The matrix elements of which are connected with the circuit r only (l) Is related to the first and last node voltage phase angle.
Wherein: d, d qr /dr (l) 、dq cfl /dr (l) 、dq cfh /dr (l) 、dq cn /dr (l) Dq is as follows s /dr (l) The expression of (2) is well known to those skilled in the art.
1)q r The derivative of r is calculated as follows:
2) The derivative of qcfl to r is calculated as follows:
wherein dk f /dr (l) ，dρ f /dr (l) And dμ f /dr (l) The expression is as follows:
3)q cfh the derivative of r is calculated as follows:
4)q cn the derivative of r is calculated as follows:
5) Factor q s There is no relation to temperature, and it leads to r being 0.
Step three: and (3) solving the electric heating coupling unified power flow model which is built in the step two and considers the environmental factors by using a Newton method. And calculating the power transmission characteristics such as the line resistance, the temperature, the active power loss, the reactive power loss and the like. The influence degree of the wind speed, the altitude, the ambient temperature, the illumination intensity and other environmental factors on the line resistance, the temperature, the active and reactive losses is quantitatively analyzed through changing the difference of the wind speed, the altitude, the ambient temperature, the illumination intensity and other environmental factors, and meteorological factors influencing the power transmission heat can be screened.
The above procedure proposes a method of grid transmission characteristics acquisition taking into account meteorological and geographical factors. The method has the advantages that meteorological and geographic information are considered, errors caused by neglecting the influence of environmental factors on power flow calculation are solved, the environmental factors such as wind speed, altitude, environmental temperature and illumination intensity are respectively changed, the influence of the environmental factors on power transmission characteristics of a power grid and the characteristics of the environmental factors can be quantitatively analyzed, the solving process of the model is simple and easy, and the convergence is good.
Embodiment two:
the embodiment provides a system for realizing the method, which comprises the following steps:
a first model building module configured to: constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, and acquiring a transmission line current model based on electric heating parameters by using the electric heating coupling analysis model; acquiring meteorological and geographic condition data of a surrounding space of an overhead power transmission line, and importing the meteorological and geographic condition data into a tide model to obtain a power transmission line current model based on electric parameters;
a second model building module configured to: combining the electric transmission line current model based on the electric heating parameters and the electric transmission line current model based on the electric parameters to obtain an electric heating coupling model of the electric transmission line; based on the electric heating coupling model of the power transmission line and a node power balance equation, an electric heating coupling unified power flow model containing environmental factor variables is obtained;
an output module configured to: and obtaining the transmission performance parameters of the power grid by changing the environment factor variable by using the electrothermal coupling unified power flow model.
The system considers meteorological information and geographic information, solves the problem of errors caused by neglecting the influence of environmental factors on power flow calculation, respectively changes the environmental factors such as wind speed, altitude, environmental temperature, illumination intensity and the like, can quantitatively analyze the influence of the system on the power transmission characteristics of the power grid and the characteristics of the system, and has the advantages of simple and easy solving process and good convergence.
Example III
The present embodiment provides a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps in the grid transmission characteristic acquisition method as set forth in the above embodiment one.
In the power grid transmission characteristic acquisition method, meteorological information and geographic information are considered, errors caused by neglecting the influence of environmental factors on power flow calculation are solved, the environmental factors such as wind speed, altitude, environmental temperature and illumination intensity are respectively changed, the influence of the environmental factors on the power transmission characteristic of the power grid and the characteristics of the environmental factors can be quantitatively analyzed, the solving process of the model is simple and easy, and the convergence is good.
Example IV
The present embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and capable of running on the processor, where the processor executes the program to implement the steps in the power grid transmission characteristic obtaining method set forth in the first embodiment.
In the power grid transmission characteristic acquisition method executed by the processor, meteorological and geographic information are considered, errors caused by neglecting influence of environmental factors to power flow calculation are solved, the influence of wind speed, altitude, environmental temperature, illumination intensity and other environmental factors on the power grid power transmission characteristic and the characteristics thereof can be quantitatively analyzed, and the solving process of the model is simple and easy to implement and has good convergence.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of a hardware embodiment, a software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, magnetic disk storage, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Those skilled in the art will appreciate that implementing all or part of the above-described methods in accordance with the embodiments may be accomplished by way of a computer program stored on a computer readable storage medium, which when executed may comprise the steps of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a read-only memory, a random access memory, or the like. The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The power grid transmission characteristic acquisition method is characterized by comprising the following steps of: the method comprises the following steps:
constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, and acquiring a transmission line current model based on electric heating parameters by using the electric heating coupling analysis model;
electric heating coupling analysis of the overhead transmission line adopts a static heat balance equation; as described by the following formula:
wherein I is a The current-carrying capacity of the circuit; r is (r) a The actual series resistance of the circuit; l is the length of the line; assuming uniform conductor temperature distribution, T c For the conductor temperature, T a To the ambient temperature of the conductor, H e For altitude, V l Is wind speed around the line, D is conductor diameter, epsilon is emissivity, phi is wind direction angle, alpha is absorptivity of the conductor to illumination, Q s The sun illumination intensity is delta, the declination angle of the sun, omega is the hour angle, L a For geographical latitude, Z c And Z l Azimuth angles of the sun and the wires, respectively; q r For the heat emitted by the circuit due to surface radiation, it takes the form of T c 、T a D and ε are functions of the arguments; q c As heat emitted by the circuit due to air convection, it takes the form of T c 、T a 、H e 、V l D and φ are functions of the arguments; q s As heat absorbed by solar radiation in the circuit, it is H e 、D、α、Q s 、δ、ω、L a 、Z c And Z l As a function of the argument;
ohmic resistor r a Denoted as T c The calculation formula is as follows:
r a (T c )＝R+σ(T c (t)-T)
wherein sigma is the temperature coefficient of resistance, R is the resistance of the conductor per unit length at rated ambient temperature T; r is (r) a The actual series resistance of the circuit; t (T) c Is the conductor temperature; t (T) c (t) is the conductor temperature at time t;
the static heat balance equation is deduced, and an electric heating coupling parameter is utilized to calculate a current formula of the power transmission line, wherein the formula is shown as follows;
wherein:
wherein r is (l) 、I (l) Respectively r a 、I a Unit value of (2); s is S b 、Z b 、I b 、U b Respectively power, impedance, current and voltage reference values;
acquiring meteorological and geographic condition data of a surrounding space of an overhead power transmission line, and importing the meteorological and geographic condition data into a tide model to obtain a power transmission line current model based on electric parameters;
combining the electric transmission line current model based on the electric heating parameters and the electric transmission line current model based on the electric parameters to obtain an electric heating coupling model of the electric transmission line;
based on the electric heating coupling model of the power transmission line and a node power balance equation, an electric heating coupling unified power flow model containing environment factor variables is obtained, and the electric heating coupling unified power flow model is utilized to output power grid transmission performance parameters by changing the environment factor variables;
establishing an electrothermal coupling unified power flow calculation model considering environmental factors and a solving algorithm thereof; introducing meteorological and geographic factors into traditional power flow calculation, and establishing an electrothermal coupling unified power flow calculation model taking environmental factors into consideration; assuming that the overhead lines of the power grid are all star-shaped, the phase current is equal to the line current, and the expression formula is as follows:
wherein I is (l) For the current-carrying capacity I of the line a Unit value of (2); θ i 、θ j The voltage phase angles of the node i and the node j are respectively; v (V) i 、V j The voltage amplitudes of the node i and the node j are respectively; r is (r) (l) The resistance of line l; x is X ij Reactance from node i to node j; i (l) Is I a Unit value of (2); θ ij Is the voltage phase angle difference between node i and node j.
2. The power grid transmission characteristic acquisition method according to claim 1, wherein: in the process of constructing the electric heating coupling analysis model of the overhead transmission line based on the static heat balance equation, the sum of the heat emitted by the line due to surface radiation and the heat emitted by the line due to air convection is equal to the sum of the heat absorbed by the line due to solar radiation and the heat generated by the current flowing through the line with the set length.
3. The power grid transmission characteristic acquisition method according to claim 2, wherein: the heat dissipated by the wire due to surface radiation includes a function of the conductor temperature, the conductor ambient temperature, the conductor diameter, and the emissivity as independent variables.
4. The power grid transmission characteristic acquisition method according to claim 2, wherein: the heat dissipated by the line due to air convection includes as a function of the independent variables conductor temperature, conductor ambient temperature, altitude, line ambient wind speed, conductor diameter, and wind direction angle.
5. The power grid transmission characteristic acquisition method according to claim 2, wherein: the heat absorbed by the line due to solar radiation includes, as a function of the independent variables, altitude, conductor diameter, conductor absorption for light, solar light intensity, solar declination, time angle, geographic latitude, azimuth angles of the sun and the line,
6. the power grid transmission characteristic acquisition method according to claim 1, wherein: and obtaining an output result of the electrothermal coupling unified power flow model based on the Newton method.
7. The power grid transmission characteristic acquisition method according to claim 6, wherein: the output results include line resistance, temperature, active and reactive losses.
8. The utility model provides a electric wire netting transmission characteristic acquisition system which characterized in that: comprising the following steps:
a first model building module configured to: constructing an electric heating coupling analysis model of the overhead transmission line based on a static heat balance equation, and acquiring a transmission line current model based on electric heating parameters by using the electric heating coupling analysis model; acquiring meteorological and geographic condition data of a surrounding space of an overhead power transmission line, and importing the meteorological and geographic condition data into a tide model to obtain a power transmission line current model based on electric parameters;
electric heating coupling analysis of the overhead transmission line adopts a static heat balance equation; as described by the following formula:
wherein I is a The current-carrying capacity of the circuit; r is (r) a The actual series resistance of the circuit; l is the length of the line; assuming uniform conductor temperature distribution, T c For the conductor temperature, T a To the ambient temperature of the conductor, H e For altitude, V l Is wind speed around the line, D is conductor diameter, epsilon is emissivity, phi is wind direction angle, alpha is absorptivity of the conductor to illumination, Q s The sun illumination intensity is delta, the declination angle of the sun, omega is the hour angle, L a For geographical latitude, Z c And Z l Azimuth angles of the sun and the wires, respectively; q r For the heat emitted by the circuit due to surface radiation, it takes the form of T c 、T a D and ε are functions of the arguments; q c As heat emitted by the circuit due to air convection, it takes the form of T c 、T a 、H e 、V l D and φ are functions of the arguments; q s As heat absorbed by solar radiation in the circuit, it is H e 、D、α、Q s 、δ、ω、L a 、Z c And Z l As a function of the argument;
ohmic resistor r a Denoted as T c The calculation formula is as follows:
r a (T c )＝R+σ(T c (t)-T)
wherein sigma is the temperature coefficient of resistance, R is the resistance of the conductor per unit length at rated ambient temperature T; r is (r) a The actual series resistance of the circuit; t (T) c Is the conductor temperature; t (T) c (t) is the conductor temperature at time t;
the static heat balance equation is deduced, and an electric heating coupling parameter is utilized to calculate a current formula of the power transmission line, wherein the formula is shown as follows;
wherein:
wherein r is (l) 、I (l) Respectively r a 、I a Unit value of (2); s is S b 、Z b 、I b 、U b Respectively power, impedance, current and voltage reference values;
a second model building module configured to: combining the electric transmission line current model based on the electric heating parameters and the electric transmission line current model based on the electric parameters to obtain an electric heating coupling model of the electric transmission line; based on the electric heating coupling model of the power transmission line and a node power balance equation, an electric heating coupling unified power flow model containing environmental factor variables is obtained;
establishing an electrothermal coupling unified power flow calculation model considering environmental factors and a solving algorithm thereof; introducing meteorological and geographic factors into traditional power flow calculation, and establishing an electrothermal coupling unified power flow calculation model taking environmental factors into consideration; assuming that the overhead lines of the power grid are all star-shaped, the phase current is equal to the line current, and the expression formula is as follows:
wherein I is (l) For the current-carrying capacity I of the line a Unit value of (2); θ i 、θ j The voltage phase angles of the node i and the node j are respectively; v (V) i 、V j The voltage amplitudes of the node i and the node j are respectively; r is (r) (l) The resistance of line l; x is X ij Reactance from node i to node j; i (l) Is I a Unit value of (2); θ ij The voltage phase angle difference between the node i and the node j;
an output module configured to: and obtaining the transmission performance parameters of the power grid by changing the environment factor variable by using the electrothermal coupling unified power flow model.
9. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the steps of the grid transmission characteristic acquisition method as claimed in any one of claims 1-7.
10. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the grid transmission characteristic acquisition method according to any one of claims 1-7 when the program is executed.
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