Electrothermal coupling load flow calculation method and system

Abstract

The invention discloses an electrothermal coupling load flow calculation method and system, and the method comprises the steps: building a power transmission line load flow balance model of a target power system, and solving the power transmission line load flow balance model of the target power system, and obtaining a first calculation result; updating the power transmission line temperature and the branch resistance; and the first calculation result is corrected again according to the updated power transmission line temperature and branch resistance, and loop iteration is carried out. And meanwhile, the interaction between the power flow change of the power system and the temperature of the system can be clearly displayed. According to the method, the system temperature is calculated through a heat balance equation, the electrical parameters of the system are corrected, the temperature iterative calculation process is outside a power flow iterative loop to balance convergence and accuracy, and therefore completely-coupled electric heating power flow calculation is simplified. Due to decoupling of the heat balance equation and the power flow equation, a traditional power flow calculation structure is reserved, so that a power flow equation calculation part possibly adopts a more efficient and quicker power flow algorithm in the future, and a good application prospect is shown.

Description

Technical Field

[0001] The present invention relates to the technical field of electrothermal coupling power flow calculation, and in particular to an electrothermal coupling power flow calculation method and system. Background Art

[0002] At present, building a new power system with a high proportion of renewable energy and power electronic equipment has become the key to the development and progress of the power industry. The rapid growth of renewable energy installed capacity, coupled with the dispersion of energy and load, has posed a major challenge to energy consumption. This requires a new power system with higher transmission capacity and stronger stability and security. Options such as building new transmission channels or changing the grid structure to increase the transmission capacity of transmission lines have problems such as high investment cost, large land resource occupation, and long investment payback period. Therefore, under the premise of meeting the safety margin requirements of the power system, increasing and making full use of the load capacity of existing transmission lines is a more feasible solution.

[0003] In power systems, thermal rating technology is usually used to evaluate the load capacity of components, including static thermal rating and dynamic thermal rating. This evaluation method usually stays at the component level and is not integrated with the operation and control of the power grid. However, in reality, the temperature of the transmission line will affect the branch impedance, thereby affecting the power flow. Thermal rating technology mostly stays at the component level without being combined with the operation and regulation of the power grid. Neither STR technology nor DTR technology considers the mutual influence between temperature and power flow distribution. But in fact, the temperature of the line will affect the power flow distribution by affecting the branch impedance, and the system power flow will affect the temperature of the line by generating heat through current. Therefore, there is a strong coupling relationship between the power flow distribution and the operating temperature. Research on power flow calculation considering electrothermal coupling can further study the mutual influence mechanism between temperature and power flow, so as to better monitor the operating status of the system.

[0004] In existing studies, researchers introduced elements such as conductor temperature and sheath temperature as state variables in the power flow model. They combined the thermoelectric equivalent (TEE) model of the cable with the power flow calculation model to establish a power flow calculation model that considers the thermal-electric coupling of the cable. In addition, a thermal resistance model that considers the linear relationship between device temperature rise and system loss was developed and incorporated into the power flow calculation to explain the thermal effect of current in the power flow calculation. However, these studies mainly focus on the heating of components during operation without considering the impact of the environment on the operation of the power system. Recently, some methods have been developed to consider weather conditions in power system state estimation and power flow studies. Some studies incorporate thermal balance models into traditional power flow calculations, consider the wind speed of wind farms as the main factor in thermal balance calculations, and examine its impact on system power flow; add electrothermal coupling phenomena in the study of power system safety correction control, and correct the system power flow under the dual standards of safety and economy. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides an electrothermal coupling power flow calculation method and system, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides an electrothermal coupled power flow calculation method, comprising:

[0010] Establishing a target power system transmission line power flow balance model, and solving the target power system transmission line power flow balance model to obtain a first calculation result;

[0011] Update transmission line temperature and branch resistance;

[0012] The first calculation result is recalibrated according to the updated transmission line temperature and branch resistance, and a loop iteration is performed.

[0013] As a preferred solution of the electrothermal coupling power flow calculation method of the present invention, the updating of the transmission line temperature and branch resistance includes:

[0014] updating the transmission line temperature according to the first heat balance model;

[0015] The branch resistance is updated according to the temperature variation model of the transmission line resistivity of the target power system.

[0016] As a preferred solution of the electrothermal coupling power flow calculation method of the present invention, the recalibration of the first calculation result according to the updated transmission line temperature and branch resistance and the iterative loop includes:

[0017] Update the target power system transmission line power flow balance model according to the updated transmission line temperature and branch resistance;

[0018] Solving the updated target power system transmission line power flow balance model to obtain a second calculation result;

[0019] Update transmission line temperature and branch resistance;

[0020] The second calculation result is recalibrated according to the updated transmission line temperature and branch resistance, and a loop iteration is performed.

[0021] As a preferred solution of the electrothermal coupling power flow calculation method described in the present invention, the cyclic iteration includes: stopping the iteration when the target power system transmission line reaches electrothermal balance.

[0022] As a preferred solution of the electric-thermal coupling power flow calculation method described in the present invention, wherein: the target power system transmission line power flow balance model includes: taking temperature as a state quantity in the power flow calculation.

[0023] As a preferred solution of the electrothermal coupling power flow calculation method described in the present invention, wherein: the updating of the transmission line temperature and branch resistance also includes:

[0024] updating the transmission line temperature according to the first heat balance model;

[0025] Inputting the updated transmission line temperature into the target power system transmission line resistivity versus temperature variation model to obtain the updated branch resistance;

[0026] The updated transmission line temperature and branch resistance are input into the target power system transmission line power flow balance model to obtain new power flow calculation results.

[0027] As a preferred solution of the electric-thermal coupling power flow calculation method described in the present invention, wherein: the first thermal balance model is an arbitrary model used to represent the relationship between current, temperature and external environmental conditions.

[0028] In a second aspect, the present invention provides an electrothermal coupling power flow calculation system, comprising:

[0029] A power flow calculation module, used for establishing a power flow balance model of a target power system transmission line, and solving the power flow balance model of the target power system transmission line to obtain a first calculation result;

[0030] An updating module, used for updating the temperature of the transmission line and the branch resistance;

[0031] The iteration module is used to recalibrate the first calculation result according to the updated transmission line temperature and branch resistance, and perform cyclic iteration.

[0032] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0033] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0034] Compared with the prior art, the invention has the following beneficial effects: the invention proposes an electrothermal coupling power flow calculation method and system, establishes a target power system transmission line power flow balance model, solves the target power system transmission line power flow balance model, obtains a first calculation result; updates the transmission line temperature and branch resistance; re-corrects the first calculation result according to the updated transmission line temperature and branch resistance, and performs cyclic iteration. At the same time, it can clearly display the interaction between the power system power flow change and the system temperature. It calculates the system temperature and corrects the electrical parameters of the system through the thermal balance equation. The temperature iteration calculation process is outside the power flow iteration cycle to balance convergence and accuracy, thereby simplifying the fully coupled electrothermal power flow calculation. Although the algorithm separates the thermal balance calculation from the power flow calculation, it accurately describes the interaction mechanism between them. Through the current and temperature of the transmission line, a closely connected electrothermal coupling relationship is formed, showing good adaptability. In addition, due to the decoupling of the thermal balance equation and the power flow equation, the structure of the traditional power flow calculation is retained, so that the power flow equation calculation part may adopt a more efficient and faster power flow algorithm in the future, showing a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0036] Figure 1 A method flow chart of an electrothermal coupling power flow calculation method and system provided in one embodiment of the present invention;

[0037] Figure 2 A schematic diagram of the change of electrothermal coupling power flow of an electrothermal coupling power flow calculation method and system provided by one embodiment of the present invention;

[0038] Figure 3 A comparison diagram of calculation results of an IEEE-30 system of an electrothermal coupling power flow calculation method and system provided by one embodiment of the present invention;

[0039] Figure 4 A schematic diagram of the calculation convergence trend of an IEEE-30 system of an electrothermal coupling power flow calculation method and system provided by an embodiment of the present invention;

[0040] Figure 5 An internal structural diagram of a computer device of an electrothermal coupling power flow calculation method and system provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0042] Example 1

[0043] Reference Figure 1-Figure 5 , which is the first embodiment of the present invention, and provides an electrothermal coupling power flow calculation method and system.

[0044] There are some shortcomings in the existing related technologies. For example, when dealing with electrothermal coupling problems, traditional methods often ignore the impact of temperature on the power system, or it is difficult to simultaneously ensure the accuracy and convergence speed of the calculation during the calculation process.

[0045] The present application provides a method that can effectively solve the above-mentioned problems. Next, multiple embodiments will be combined to explain in detail how to implement the electrothermal coupling power flow calculation method.

[0046] Figure 1 A method flow chart of an electrothermal coupling power flow calculation method and system is shown, including:

[0047] S101, establishing a target power system transmission line power flow balance model, and solving the target power system transmission line power flow balance model to obtain a first calculation result;

[0048] In an optional embodiment, the target power system transmission line power flow balance model can be established by using a traditional transmission line power flow balance model, or based on a DC power flow model, an AC power flow model, a linearized power flow model, a distribution factor method, or the like;

[0049] In an optional embodiment, the DC power flow model is a simplified power flow calculation method suitable for high-voltage transmission systems, especially for the study of system stability and economic dispatch. Its main assumptions include: ignoring line resistance and only considering reactance. Ignoring the reactive component of voltage drop, that is, assuming that all node voltage amplitudes are the same. Power loss is negligible.

[0050] In an optional embodiment, the AC power flow model takes into account the changes in voltage amplitude and phase angle, which is suitable for more accurate system analysis.

[0051] In an optional embodiment, the linearized power flow model linearizes the nonlinear equations through Taylor series expansion, which is suitable for fast calculation and real-time control.

[0052] In an optional embodiment, the distribution factor method uses pre-calculated distribution factors to quickly estimate power flow changes, which is suitable for online analysis and control.

[0053] In the embodiment of the present application, it is necessary to establish a power flow equation that does not consider the influence of temperature changes, so the traditional power flow calculation equation is selected here.

[0054] In the embodiment of the present application, the original power flow equation is maintained as follows, where the admittance of each branch remains unchanged:

[0055]

[0056] Among them, P i , Q i are the active and reactive power of node i, U i , U j are the voltage phasors of nodes i and j, respectively, and Y ij is the admittance of the branch formed by node ij.

[0057] In an embodiment of the present application, the target power system transmission line power flow balance model includes: using temperature as a state quantity in power flow calculation.

[0058] Therefore, when considering the electrothermal coupling, the branch admittance in the power flow balance equation varies with the branch temperature, as shown in the following equation. Compared with the traditional power flow calculation, introducing temperature as a state variable and solving this equation can obtain the actual power flow and temperature of each branch in the system under thermal balance:

[0059]

[0060] Where T is the branch temperature at thermal equilibrium, G ij , B ij are the conductance and susceptance of the branch between nodes i and j when the temperature is T, r ij is the transformer ratio. When there is no transformer, it is 1; x i is the branch reactance.

[0061] R ref is the resistance value of the transmission line per unit length at the reference temperature (Ω / m), α is the resistance temperature coefficient of the conductor (ppm / ℃), which indicates the relative change of the resistance value when the temperature changes by 1℃, T refis the reference temperature (℃), usually 25℃.

[0062] It should be noted that the target power system transmission line power flow balance model is established and solved to obtain the first calculation result, which can provide a preliminary power flow distribution for the power system. However, since the influence of temperature on the power system cannot be ignored, it is necessary to further consider the influence of temperature factors on power flow calculation.

[0063] S102, updating the transmission line temperature and branch resistance;

[0064] In an embodiment of the present application, updating the transmission line temperature and branch resistance includes:

[0065] updating the transmission line temperature according to the first heat balance model;

[0066] The branch resistance is updated according to the temperature variation model of the transmission line resistivity of the target power system.

[0067] In an optional embodiment, the first thermal balance model can be obtained by measuring the real-time temperature data of the transmission line. It can also be predicted by establishing a mathematical model based on historical data and environmental parameters. The resistivity variation model of the transmission line with temperature can be established based on the resistance temperature coefficient of the material, which describes the characteristic of the material resistance variation with temperature. The step of updating the transmission line temperature and branch resistance is a key step to ensure that the power flow calculation takes temperature effects into account.

[0068] In the embodiment of the present application, the first thermal balance model is an arbitrary model used to represent the relationship between current, temperature and external environmental conditions.

[0069] In an embodiment of the present application, the flow calculation of electrothermal coupling is considered, the system temperature and the flow distribution are combined through the heat balance equation, and the temperature is used as the state quantity in the flow calculation. This method decouples the heat balance equation in the form of a differential equation from the traditional flow calculation equation in the form of an algebraic equation, thereby reducing the calculation difficulty and improving the calculation efficiency.

[0070] In the embodiment of the present application, due to the influence of the thermal effect of the current, the temperature of the transmission line is affected by the magnitude of the current. The impedance of the transmission line is a thermal element, and its resistance value changes with temperature, as shown in formula (1):

[0071] R(t)=R ref ·(1+α(T(t)-T ref )) (1)

[0072] Among them, R refis the resistance value of the transmission line per unit length at the reference temperature (Ω / m), α is the resistance temperature coefficient of the conductor (ppm / ℃), which means that when the temperature changes by 1℃, resistance The relative change of the value, T ref is the reference temperature (℃), usually 25℃.

[0073] At the same time, the temperature of the transmission line is not only affected by the thermal effect of current, but also by environmental factors such as wind speed, sunshine, etc. The thermal balance model can represent the relationship between current, temperature and external environmental conditions, and R(t) represents the impedance of the transmission line at time t during the iteration process.

[0074] In the embodiment of the present application, the allowable current carrying capacity calculation model specified in the national standard GB 50545-2010 is used as the first thermal balance model, as shown in formula (2):

[0075]

[0076] Among them, mC p is the heat capacity of the conductor (J / m·℃), T is the temperature of the conductor, q i is the heat generated by the current per unit length of the wire, q s is the solar heat absorption per unit length of the conductor, q c is the convection heat dissipation per unit length of wire, q r is the radiation heat dissipation per unit length of wire.

[0077] In an optional embodiment, the system power flow will affect the line impedance, and the change of line impedance will in turn affect the power flow distribution of the entire system, thus forming a cycle, such as Figure 2 As shown. In the power system flow calculation process, the changes in resistor temperature and resistance value are often ignored to avoid updating the admittance matrix and reduce the calculation speed. For example, in the state estimation calculation, the resistance value is regarded as a constant, which leads to the minimum error in the voltage calculation; however, in the loss calculation, since the resistance value is interdependent with the loss and temperature, ignoring the resistance change will significantly affect the accuracy of the calculation. If the branch resistance is not adjusted in time according to the temperature during the calculation process, the error of the total system loss may be as high as 30% under heavy load conditions, and the error of a single branch loss may be as high as 30%. Such a high error in loss estimation may have a negative impact on power system analysis that relies on accurate line loss estimation.

[0078] In the embodiment of the present application, updating the transmission line temperature and branch resistance further includes:

[0079] updating the transmission line temperature according to the first heat balance model;

[0080] Inputting the updated transmission line temperature into the target power system transmission line resistivity versus temperature variation model to obtain the updated branch resistance;

[0081] The updated transmission line temperature and branch resistance are input into the target power system transmission line power flow balance model to obtain new power flow calculation results.

[0082] In the embodiment of the present application, the essence of electrothermal coupling is the influence of temperature on the size of system impedance. Under this influence, the stable operation of the power system requires the realization of a dual balance of power flow and heat. However, only the dynamic thermal balance equation is a differential equation. Therefore, the present invention proposes a differential-algebraic decoupling algorithm to calculate the power flow calculation considering electrothermal coupling, in which the power flow balance model is calculated separately from the thermal balance model of the transmission line. Use formula (3) to calculate the temperature change rate, and then select the temperature rise time to calculate the line operating temperature, as shown in (3):

[0083]

[0084] It should be noted that in the embodiment of the present application, the use of the differential-algebraic decoupling algorithm allows the power flow calculation and the thermal balance model to be performed independently, thereby simplifying the calculation process. The power flow balance model mainly deals with the relationship between current and voltage, while the thermal balance model focuses on temperature changes and the transfer of heat flow. In this way, the electrothermal coupling effect can be effectively incorporated into the power flow calculation while avoiding the problem of solving complex coupling equations.

[0085] In practical applications, the preliminary power flow distribution is first calculated using the power flow balance model, and then the temperature distribution of the transmission line is calculated using the thermal balance model. According to the temperature distribution, the power flow balance model is then modified to reflect the impact of temperature changes on system impedance. This process is iterated until the power flow distribution and temperature distribution reach a stable state, thus obtaining the final power flow calculation result that takes into account the electrothermal coupling effect.

[0086] S103, recalibrating the first calculation result according to the updated transmission line temperature and branch resistance, and performing a loop iteration.

[0087] In the embodiment of the present application, recalibrating the first calculation result according to the updated transmission line temperature and branch resistance, and performing a loop iteration includes:

[0088] Update the target power system transmission line power flow balance model according to the updated transmission line temperature and branch resistance;

[0089] Solving the updated target power system transmission line power flow balance model to obtain a second calculation result;

[0090] Update transmission line temperature and branch resistance;

[0091] The second calculation result is recalibrated according to the updated transmission line temperature and branch resistance, and a loop iteration is performed.

[0092] In an optional embodiment, the criterion for stopping iteration may be reaching a predetermined temperature change threshold, for example, when the temperature change is less than 0.1°C, the system is considered to have reached a thermal equilibrium state. Alternatively, when the change in the power flow distribution is less than a set threshold, for example, less than 0.01%, the power flow calculation may be considered to have converged. In addition, a maximum number of iterations may be set, and when the number of iterations reaches the maximum value, the iteration is stopped even if the above two conditions are not met. These criteria may be used alone or in combination to ensure the accuracy and efficiency of the calculation.

[0093] In the embodiment of the present application, performing the cyclic iteration includes: stopping the iteration when the target power system transmission line reaches the electric-thermal balance, wherein the electric-thermal balance is to achieve the dual balance of the flow and the heat, and to achieve the "double balance" mode.

[0094] In an optional embodiment, the power flow calculation is regarded as an inner loop iteration and the system temperature is regarded as an outer loop iteration. During the iteration process, the system temperature is not integrated into the state variables of the power flow calculation (fully coupled electrothermal coupled power flow calculation algorithm), but the system temperature is updated by calculating the heat balance equation to correct the system impedance. This helps to reduce the number of nonlinear equations and variables to be solved in the power flow calculation, thereby simplifying the calculation and reducing the difficulty of solving.

[0095] In the embodiment of the present application, the method initially performs a conventional power flow calculation, and then uses the converged calculation results to update the temperature and branch resistance. Subsequently, it performs power flow correction in a repeated cycle until a dual balance of power flow and heat is achieved, reaching a "double balance" mode. The algorithm decouples the solution of the power flow equation for updating the system power flow from the solution of the heat balance equation for updating the temperature, thereby reducing the computational complexity and the computational load of each cycle.

[0096] In summary, the present invention proposes an electrothermal coupling power flow calculation method, establishes a target power system transmission line power flow balance model, solves the target power system transmission line power flow balance model, obtains a first calculation result; updates the transmission line temperature and branch resistance; re-corrects the first calculation result according to the updated transmission line temperature and branch resistance, and performs cyclic iteration. At the same time, it can clearly display the interaction between the power system power flow change and the system temperature. It calculates the system temperature and corrects the electrical parameters of the system through the thermal balance equation. The temperature iteration calculation process is outside the power flow iteration cycle to balance convergence and accuracy, thereby simplifying the fully coupled electrothermal power flow calculation. Although the algorithm separates the thermal balance calculation from the power flow calculation, it accurately describes the interaction mechanism between them. Through the current and temperature of the transmission line, a closely connected electrothermal coupling relationship is formed, showing good adaptability. In addition, due to the decoupling of the thermal balance equation and the power flow equation, the structure of the traditional power flow calculation is retained, so that the power flow equation calculation part may adopt a more efficient and faster power flow algorithm in the future, showing a good application prospect.

[0097] This embodiment also provides an electrothermal coupling power flow calculation system, including:

[0098] A power flow calculation module, used to establish a power flow balance model of a target power system transmission line, and solve the power flow balance model of the target power system transmission line to obtain a first calculation result;

[0099] An updating module, used for updating the temperature of the transmission line and the branch resistance;

[0100] The iteration module is used to recalibrate the first calculation result according to the updated transmission line temperature and branch resistance, and perform cyclic iteration.

[0101] The above-mentioned unit modules may be embedded in or independent of a processor in a computer device in the form of hardware, or may be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to the above-mentioned modules.

[0102] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 5As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, an electrothermal coupling power flow calculation method is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0103] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0104] Establishing a power flow balance model for a transmission line of a target power system, and solving the power flow balance model for the transmission line of the target power system to obtain a first calculation result;

[0105] Update transmission line temperature and branch resistance;

[0106] The first calculation result is recalibrated according to the updated transmission line temperature and branch resistance, and a loop iteration is performed.

[0107] Example 2

[0108] Reference Figure 3-Figure 4 , which is an embodiment of the present invention, provides an electrothermal coupling power flow calculation method and system. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0109] The IEEE-30 system is used as a simulation example in MATLAB to verify the effectiveness of the algorithm proposed in this invention. The overhead transmission line in the test system uses LGJ240 / 40 steel-core aluminum stranded wire, with a resistance of 0.1209Ω / km (at 20℃), an outer diameter of 21.7mm, and a resistivity of 0.0039Ω·℃;

[0110] The conventional algorithm and the algorithm proposed in this invention are used to perform the electric-thermal coupled power flow of the IEEE-30 system. The result data are as follows: Figure 3 shown. Figure 3Middle horizontal axis (Bus Number): The horizontal axis represents different bus numbers (Bus Number), from 0 to 39. Vertical axis 1 (Voltage Magnitude in pu): The left vertical axis represents the voltage magnitude (Voltage Magnitude), the unit is per unit (pu). The range is approximately from 0.9 to 1.1. Vertical axis 2 (Deviation): The right vertical axis represents the deviation (Deviation), the unit is not clearly given, but from the numerical value, it may be a percentage or some error metric. The blue solid line and blue dots represent the "Basic Algorithm". The red bar graph represents the "Proposed Algorithm". The upper part of the chart: shows the change in voltage magnitude. The results of the basic algorithm are represented by the blue line, and the results of the improved algorithm are represented by the red bar graph. It can be seen that at some nodes, the voltage magnitude of the improved algorithm is significantly different from that of the basic algorithm. The lower part of the chart: shows the change in voltage phase angle. Similarly, the results of the basic algorithm are represented by the blue line, and the results of the improved algorithm are represented by the red bar graph. It can be seen that at some nodes, the voltage phase angle of the improved algorithm is also significantly different from that of the basic algorithm. The right vertical axis (Deviation): The right vertical axis shows the deviation value, which is used to measure the difference between the results of the two algorithms. As can be seen from the figure, the deviation of most nodes is small, but there is a large deviation at a few nodes. From the results, it can be seen that the proposed algorithm method has almost no difference in the flow calculation results compared with the most accurate traditional method, and the calculation accuracy is not affected by the decoupling of flow and temperature iteration. It meets the most basic requirements of the algorithm: when considering electrothermal coupling, correctly solve the flow distribution and thermal equilibrium temperature of each branch.

[0111] The convergence trend during the calculation process is as follows Figure 4 As shown. The x-axis (Iteration): represents the number of iterations, from 0 to 15. The y-axis (Largest Imbalance (kg)): represents the maximum imbalance, in kilograms (kg), using a logarithmic scale. Curve color and markings: The red dotted line and diamond mark represent the "Basic Algorithm". The blue solid line and circular mark represent the "Proposed Algorithm". It can be seen from the figure that the maximum imbalance of the basic algorithm (red dotted line) gradually decreases with the increase of the number of iterations, but the rate of decrease is slow. The maximum imbalance of the improved algorithm (blue solid line) decreases rapidly in the first few iterations, and reaches a very low level within a relatively small number of iterations. From the comparison of the convergence trends, it can be seen that the algorithm proposed in the present invention simplifies the calculation matrix of the fully coupled algorithm, so that the number of iterations of the tidal iteration part is smaller and the convergence is faster.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0113] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0114] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0115] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0116] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.

[0117] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0118] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A method for calculating an electrothermal coupled power flow, characterized in that: include: Establishing a target power system transmission line power flow balance model, and solving the target power system transmission line power flow balance model to obtain a first calculation result; Update transmission line temperature and branch resistance; The first calculation result is recalibrated according to the updated transmission line temperature and branch resistance, and a loop iteration is performed.

2. The method for calculating the electric-thermal coupling power flow according to claim 1, characterized in that: The updating of the transmission line temperature and branch resistance comprises: updating the transmission line temperature according to the first heat balance model; The branch resistance is updated according to the temperature variation model of the transmission line resistivity of the target power system.

3. The method for calculating the electric-thermal coupling power flow according to claim 2, characterized in that: The recalibrating the first calculation result according to the updated transmission line temperature and branch resistance and performing cyclic iterations includes: Update the target power system transmission line power flow balance model according to the updated transmission line temperature and branch resistance; Solving the updated target power system transmission line power flow balance model to obtain a second calculation result; Update transmission line temperature and branch resistance; The second calculation result is recalibrated according to the updated transmission line temperature and branch resistance, and a loop iteration is performed.

4. The method for calculating the electric-thermal coupling power flow according to claim 3, characterized in that: The loop iteration includes: when the target power system transmission line reaches electric heat balance, stopping the iteration.

5. The method for calculating the electric-thermal coupling power flow according to claim 4, characterized in that: The target power system transmission line power flow balance model includes: taking temperature as a state quantity in power flow calculation.

6. The method for calculating the electric-thermal coupling power flow according to claim 5, characterized in that: The updating of the transmission line temperature and branch resistance also includes: updating the transmission line temperature according to the first heat balance model; Inputting the updated transmission line temperature into the target power system transmission line resistivity versus temperature variation model to obtain the updated branch resistance; The updated transmission line temperature and branch resistance are input into the target power system transmission line power flow balance model to obtain new power flow calculation results.

7. The method for calculating the electric-thermal coupling power flow according to claim 6, characterized in that: The first thermal balance model is an arbitrary model for representing the relationship between current, temperature and external environmental conditions.

8. An electrothermal coupling power flow calculation system, characterized in that: include: A power flow calculation module, used for establishing a power flow balance model of a target power system transmission line, and solving the power flow balance model of the target power system transmission line to obtain a first calculation result; An updating module, used for updating the temperature of the transmission line and the branch resistance; The iteration module is used to recalibrate the first calculation result according to the updated transmission line temperature and branch resistance, and perform cyclic iteration.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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