Active power coordination optimization method and device for multi-terminal direct current system and alternating current power grid

Abstract

The invention discloses an active power coordination optimization method and device for a multi-terminal direct current system and an alternating current power grid, and the method comprises the steps: determining the active power fed into a plurality of load partitions by the multi-terminal direct current system as an optimization variable; determining a multi-terminal direct current system output power constraint and a load partition converter station output power constraint as constraint conditions; on the basis of the optimization variables, an objective function is constructed by taking minimization of the load rate of the alternating current channels between the load partitions as an optimization objective, and an optimization model is constructed in combination with the constraint conditions; and solving the optimization model to obtain an optimal value of the optimization variable, and performing active coordination optimization control of the multi-terminal direct current system and the alternating current power grid based on the optimal value of the optimization variable. According to the technical scheme, the active power fed into each load partition by the multi-terminal direct current system can be reasonably distributed, the power transmission capacity of a power grid can be improved, and the risk that the thermal stability margin of an alternating current line is insufficient can be reduced.

Description

Technical Field

[0001] This application relates to the field of power grid planning technology, specifically to a method and apparatus for coordinating and optimizing the active power of a multi-terminal DC system and an AC power grid. Background Technology

[0002] With the large-scale integration of DC power supply and the continuous growth of electricity demand, regional power grids face the risks of rising load rates and insufficient thermal stability margins on the original AC grid.

[0003] Multi-terminal DC systems, directly fed into 220kV load zones (220kV AC grids) at the receiving end, are a novel power transmission technology with advantages such as rapid and flexible power regulation, low losses, and reduced power flow pressure on the 525kV grid, leading to their increasing application in regional power grids. However, existing active power coordination and allocation methods for multi-terminal DC systems often determine power directly based on electricity demand, frequently resulting in unreasonable active power allocation among different load zones, thus affecting the grid's transmission capacity. Summary of the Invention

[0004] This application provides a method and apparatus for coordinating and optimizing the active power of a multi-terminal DC system and an AC power grid. It can reasonably allocate the active power fed into each load zone by the multi-terminal DC system, improve the power grid transmission capacity, and reduce the risk of insufficient thermal stability margin of AC lines.

[0005] Firstly, this application provides a method for active power coordination optimization between a multi-terminal DC system and an AC power grid, including:

[0006] The active power fed into multiple load zones by the multi-terminal DC system is determined as the optimization variable;

[0007] The constraints are determined to be the power output constraints of the multi-terminal DC system and the output power constraints of the load-zoned converter stations.

[0008] Based on the optimization variables, an objective function is constructed with the goal of minimizing the load rate of the AC channels between the load partitions, and an optimization model is constructed in conjunction with the constraints.

[0009] The optimization model is solved to obtain the optimal values ​​of the optimization variables, and the active power coordination optimization control of the multi-terminal DC system and the AC grid is performed based on the optimal values ​​of the optimization variables.

[0010] Secondly, this application provides an active power coordination optimization device for a multi-terminal DC system and an AC power grid, comprising:

[0011] The optimization variable determination module is used to determine the active power fed into multiple load zones by the multi-terminal DC system as the optimization variable;

[0012] The constraint determination module is used to determine the constraints based on the power output constraints of the multi-terminal DC system and the output power constraints of the load-zoned converter stations.

[0013] A construction module is used to construct an objective function based on the optimization variables, with the goal of minimizing the load rate of the AC channels between the load partitions, and to construct an optimization model in conjunction with the constraints.

[0014] The coordination and optimization module is used to solve the optimization model to obtain the optimal values ​​of the optimization variables, and to perform active power coordination and optimization control between the multi-terminal DC system and the AC grid based on the optimal values ​​of the optimization variables.

[0015] Thirdly, this application provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the method provided in the embodiments of this application.

[0016] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the method provided in the embodiments of this application.

[0017] The technical solution provided in this application constructs an optimization model by using the active power fed into multiple load zones by a multi-terminal DC system as the optimization variable, the output power constraint of the multi-terminal DC system and the output power constraint of the converter stations in the load zones as the constraint conditions, and minimizing the load rate of the AC channels between the load zones as the optimization objective. By solving the optimization model, the optimal value of the optimization variable is obtained, and active power coordination optimization control is performed using the optimal value. That is, when the multi-terminal DC system feeds active power into the load zones, the load rate of the AC channels between the load zones is considered, which can reasonably allocate the active power fed into each load zone by the multi-terminal DC system, improve the power transmission capacity of the power grid, and reduce the risk of insufficient thermal stability margin of AC lines. Attached Figure Description

[0018] Figure 1 This is a flowchart of an active power coordination optimization method for a multi-terminal DC system and an AC power grid, provided in an embodiment of this application.

[0019] Figure 2 This is a schematic diagram of a multi-terminal DC system feeding into load zones;

[0020] Figure 3 This is a structural block diagram of a multi-terminal DC system and AC power grid active power coordination optimization device provided in an embodiment of this application;

[0021] Figure 4 This is a schematic diagram of an electronic device structure provided in an embodiment of this application. Detailed Implementation

[0022] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Figure 1 This is a flowchart illustrating a method for active power coordination and optimization between a multi-terminal DC system and an AC power grid. This method can be executed by a device for active power coordination and optimization between a multi-terminal DC system and an AC power grid. This device can be implemented using software and / or hardware and can be configured in electronic devices such as computers. Figure 1 As shown, the method includes the following steps:

[0024] S110: Determine the active power fed into multiple load zones by the multi-terminal DC system as the optimization variable.

[0025] In this embodiment, the multi-terminal DC system can be a new energy multi-terminal DC system or other types of multi-terminal DC systems. The multi-terminal DC system can be a multi-terminal embedded DC system or a non-embedded multi-terminal DC system. The multi-terminal DC system has multiple (more than two) endpoints in the load zone, and can supply power to the load zone through the load zone converter station. The load zone can be a load zone of a 220kV AC power grid.

[0026] Without considering DC losses, the active power fed into the load zone by the multi-terminal DC system is the output power of the corresponding load zone converter station, and the output power of the load zone converter station can be used as the optimization variable.

[0027] In this embodiment, the optional optimization variables are P1, P2, ..., P N P1 represents the output power of the first load zone converter station, and P2 represents the output power of the second load zone converter station. N Let be the output power of the Nth load zone converter station.

[0028] S120: Determine the constraints as the power output constraints of the multi-terminal DC system and the output power constraints of the load-zoned converter stations.

[0029] In this embodiment, optionally, the power output constraint of the multi-terminal DC system is: P1+P2+...+P N =X ren .

[0030] X ren The power delivered to the multi-terminal DC system.

[0031] In this embodiment, optionally, the output power constraint of the load-zone converter station is:

[0032] 0≤Pi ≤P imax ,i=1,2,...,N; where P i Let P be the output power of the i-th load converter station. imax Let be the maximum output power of the i-th load converter station.

[0033] In this embodiment, the optimization variables can be determined based on the number of load zoning converter stations under constant P control in the multi-terminal DC system. For a multi-terminal DC system feeding into N 220kV load zoning areas, the sending end uses constant DC voltage control, and the receiving end has N load zoning converter stations (DC converter stations) under constant P control. Therefore, the optimization variables can be P1, P2, ..., P N This satisfies the above-mentioned power output constraints of the multi-terminal DC system.

[0034] In this embodiment, the output power of the N load-zone converter stations is limited by the capacity of the load-zone converter stations. Therefore, the output power of the load-zone converter stations satisfies the above-mentioned output power constraints of the load-zone converter stations.

[0035] S130: Based on the optimization variables, construct an objective function with the goal of minimizing the load rate of the AC channels between the load partitions, and construct an optimization model in conjunction with the constraints.

[0036] In this embodiment, the objective function is:

[0037]

[0038] Where Z is the sum of the load rates of the AC channels among the N load zones, and S i,j Let Z and S be the load factors of the AC channel between load zone i and load zone j. i,j All are greater than 0.

[0039] In this embodiment, exemplarily, a schematic diagram of a multi-terminal DC system embedded in a load partition can be referred to... Figure 2 G represents a generator, S represents a switch-type load, D represents a general load, M represents a motor, F represents a surge arrester, and FL represents a fuse (used for circuit protection). The AC path between load zones has two meanings: first, two 220kV load zones under the same 500kV busbar are connected via a 220kV AC line (passing through a common point); second, two 220kV load zones under different 500kV busbars are connected via both a 220kV AC line and a 500kV AC line. Figure 2The AC channel in the example is merely one instance (it does not represent common points). In a multi-terminal DC system supplying power to the AC grid, if a line in one load zone fails, another load area may need to handle a larger output power, potentially leading to overload. Therefore, in optimizing the active power coordination between the multi-terminal DC system and the AC grid, the load rate of the AC channels between load zones needs to be considered. Consequently, based on the optimization variables, an objective function is constructed with the goal of minimizing the load rate of the AC channels between load zones.

[0040] In this embodiment, the optimization model constructed by combining the objective function with constraints can take the following form:

[0041]

[0042] S140: Solve the optimization model to obtain the optimal values ​​of the optimization variables, and perform active power coordination optimization control of the multi-terminal DC system and AC grid based on the optimal values ​​of the optimization variables.

[0043] In this embodiment, optionally, solving the optimization model includes: solving the optimization model using a fixed-step-size iterative method; wherein, during the iteration process, simulation software is used to calculate the load rate of the AC channel under different combinations of optimization variables. The solution process of the above optimization model is a linear programming problem solution process, enumerating the values ​​of different combinations of optimization variables and selecting the value of the optimization variable corresponding to the minimum load rate as the optimization result. Specifically, during the iteration process, simulation software is used to simulate the multi-terminal DC transmission system and AC power grid conditions. The simulation software can be used to simulate the corresponding values ​​of different combinations of optimization variables to calculate the load rate of the AC channel between load zones under the simulated conditions.

[0044] In this embodiment, after obtaining the optimal value of the optimization variable, the optimal value of the optimization variable is used as the reference value of the output power of the load-zone converter station for active power coordination optimization control.

[0045] In related technologies, the active power coordination and allocation method of multi-terminal DC systems often determines the power directly based on the power demand without considering the load rate of the AC channels between load zones. For example, when the AC lines of some load zones fail, they cannot carry the output power of the multi-terminal DC system. Other load zones need to carry a large output power of the multi-terminal DC system, which may lead to overload and other problems. Therefore, not considering the load rate of the AC channels between load zones may lead to unreasonable allocation of active power fed into each load zone by the multi-terminal DC system, affecting the power transmission capacity of the power grid and posing a risk of insufficient thermal stability margin.

[0046] The technical solution provided in this application uses the active power fed into multiple load zones by a multi-terminal DC system as the optimization variable, the power output constraint of the multi-terminal DC system and the output power constraint of the converter stations in the load zones as the constraint conditions, and the objective function is to minimize the load rate of the AC channels between the load zones. This constructs an optimization model, and by solving the optimization model, the optimal value of the optimization variable is obtained. The optimal value is then used for active power coordination optimization control. That is, when the multi-terminal DC system feeds active power into the load zones, the load rate of the AC channels between the load zones is considered, which can reasonably allocate the active power fed into each load zone by the multi-terminal DC system, improve the power transmission capacity of the power grid, and reduce the risk of insufficient thermal stability margin of AC lines.

[0047] For example, parameters of a multi-terminal DC system: if N = 2 load zones, the output power X of the multi-terminal DC system is... ren =300MW, the capacity limit of converter stations in each load zone is P 1max =200MW, P 2max =250MW; iteration step size is 50MW.

[0048] The possible combinations of optimization variables P1 and P2 are: (200,100), (150,150), (100,200), and (50,250). Power flow calculations in power system simulation software yielded load rates of 30%, 35%, 40%, and 45% for the AC channels between the two load zones under the four schemes.

[0049] Iteration result: The optimal allocation scheme is P1, calculated using the fixed step-size iteration method. * =200MW, P2 * =100MW, Z * =30%. Among them, P1 * =200MW, P2 * =100MW is used as a parameter to differentiate the output power of the converter station according to the corresponding load, so as to coordinate and optimize the active power of the multi-terminal DC system.

[0050] Figure 3 This is a block diagram of a multi-terminal DC system and AC power grid active power coordination optimization device, such as... Figure 3 As shown, the device includes:

[0051] The optimization variable determination module 310 is used to determine the active power fed into multiple load zones by the multi-terminal DC system as the optimization variable;

[0052] The constraint determination module 320 is used to determine the constraint conditions based on the power output constraint of the multi-terminal DC system and the output power constraint of the load zone converter station.

[0053] The construction module 330 is used to construct an objective function based on the optimization variables, with the goal of minimizing the load rate of the AC channels between the load partitions, and to construct an optimization model in combination with the constraints.

[0054] The coordination and optimization module 340 is used to solve the optimization model to obtain the optimal value of the optimization variable, and to perform active power coordination and optimization control between the multi-terminal DC system and the AC grid based on the optimal value of the optimization variable.

[0055] In an optional embodiment, determining the active power fed into multiple load zones by the multi-terminal DC system as an optimization variable includes:

[0056] Without considering DC losses, the active power fed into the load zone by the multi-terminal DC system is determined to be the output power of the corresponding load zone converter station, and the output power of the load zone converter station is used as the optimization variable.

[0057] In one optional embodiment, the optimization variables are P1, P2, ..., P N ;

[0058] P1 is the output power of the converter station in the first load zone, and P2 is the output power of the converter station in the second load zone; P N Let be the output power of the Nth load zone converter station, wherein the multi-terminal DC system supplies power to the load zone through the load zone converter station.

[0059] In an optional embodiment, the power output constraint of the multi-terminal DC system is:

[0060] P1+P2+...+P N =X ren

[0061] X ren The power delivered to the multi-terminal DC system.

[0062] In an optional embodiment, the output power constraint of the load-zone converter station is:

[0063] 0≤P i ≤P imax i = 1, 2, ..., N

[0064] Among them, P i Let P be the output power of the converter station in the i-th load zone. imax Let be the maximum output power of the converter station in the i-th load zone.

[0065] In an optional embodiment, the objective function is:

[0066]

[0067] Where Z is the sum of the load rates of the AC channels among the N load zones, and S i,j Let Z and S be the load factors of the AC channel between the i-th load zone and the j-th load zone. i,j All are greater than 0.

[0068] In one optional embodiment, solving the optimization model includes:

[0069] The optimization model is solved using a fixed-step-size iterative method; during the iteration process, simulation software is used to calculate the load rate of the AC channel under different combinations of optimization variables and their corresponding values.

[0070] like Figure 4 As shown in the figure, this application provides an electronic device, including a processor 111, a communication interface 112, a memory 113, and a communication bus 114, wherein the processor 111, the communication interface 112, and the memory 113 communicate with each other through the communication bus 114.

[0071] Memory 113 is used to store computer programs;

[0072] In one embodiment of this application, when the processor 111 executes a program stored in the memory 113, it implements the method provided in any of the foregoing method embodiments, including:

[0073] The active power fed into multiple load zones by the multi-terminal DC system is determined as the optimization variable;

[0074] The constraints are determined to be the power output constraints of the multi-terminal DC system and the output power constraints of the load-zoned converter stations.

[0075] Based on the optimization variables, an objective function is constructed with the goal of minimizing the load rate of the AC channels between the load partitions, and an optimization model is constructed in conjunction with the constraints.

[0076] The optimization model is solved to obtain the optimal values ​​of the optimization variables, and the active power coordination optimization control of the multi-terminal DC system and the AC grid is performed based on the optimal values ​​of the optimization variables.

[0077] This application also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the method provided in any of the foregoing method embodiments.

[0078] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0079] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0080] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.

Claims

1. A method for active power coordination optimization between a multi-terminal DC system and an AC power grid, characterized in that, include: The active power fed into multiple load zones by the multi-terminal DC system is determined as the optimization variable; The constraints are determined to be the power output constraints of the multi-terminal DC system and the output power constraints of the load-zoned converter stations. Based on the optimization variables, an objective function is constructed with the goal of minimizing the load rate of the AC channels between the load partitions, and an optimization model is constructed in conjunction with the constraints. The optimization model is solved to obtain the optimal values ​​of the optimization variables, and the active power coordination optimization control of the multi-terminal DC system and the AC grid is performed based on the optimal values ​​of the optimization variables.

2. The method according to claim 1, characterized in that, The determination of the active power fed into multiple load zones by the multi-terminal DC system as the optimization variable includes: Without considering DC losses, the active power fed into the load zone by the multi-terminal DC system is determined to be the output power of the corresponding load zone converter station, and the output power of the load zone converter station is used as the optimization variable.

3. The method according to claim 2, characterized in that, The optimization variables are P1, P2, ..., P N ; P1 is the output power of the converter station in the first load zone, and P2 is the output power of the converter station in the second load zone; P N Let be the output power of the Nth load zone converter station, wherein the multi-terminal DC system supplies power to the load zone through the load zone converter station.

4. The method according to claim 3, characterized in that, The power output constraint of the multi-terminal DC system is: P1+P2+...+P N =X ren X ren The power delivered to the multi-terminal DC system.

5. The method according to claim 1, characterized in that, The output power constraint of the load zone converter station is: 0≤P i ≤P imax ,i=1,2,...,N Among them, P i Let P be the output power of the converter station in the i-th load zone. imax Let be the maximum output power of the converter station in the i-th load zone.

6. The method according to claim 1, characterized in that, The objective function is: Where Z is the sum of the load rates of the AC channels among the N load zones, and S i,j Let Z and S be the load factors of the AC channel between the i-th load zone and the j-th load zone. i,j All are greater than 0.

7. The method according to claim 1, characterized in that, Solving the optimization model includes: The optimization model is solved using a fixed-step-size iterative method; during the iteration process, simulation software is used to calculate the load rate of the AC channel under different combinations of optimization variables and their corresponding values.

8. A device for coordinating and optimizing active power between a multi-terminal DC system and an AC power grid, characterized in that, include: The optimization variable determination module is used to determine the active power fed into multiple load zones by the multi-terminal DC system as the optimization variable; The constraint determination module is used to determine the constraints based on the power output constraints of the multi-terminal DC system and the output power constraints of the load-zoned converter stations. A construction module is used to construct an objective function based on the optimization variables, with the goal of minimizing the load rate of the AC channels between the load partitions, and to construct an optimization model in conjunction with the constraints. The coordination and optimization module is used to solve the optimization model to obtain the optimal values ​​of the optimization variables, and to perform active power coordination and optimization control between the multi-terminal DC system and the AC grid based on the optimal values ​​of the optimization variables.

9. An electronic device, characterized in that, It includes a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, It stores a computer program that, when executed in a computer, causes the computer to perform the method described in any one of claims 1-7.

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