AC / DC distribution network control method and system for active power interaction management

Abstract

The present invention relates to the field of circuit technology for power supply or distribution, and in particular to a method and system for controlling an AC / DC distribution network for interactive active power management. The method comprises the following steps: establishing a typical operating scenario and model for instantaneous power limitation; establishing conditions for interactive active management of modular multilevel converters using projection operator constraints; converting the AC / DC distribution network power generation cost optimization operation problem into an iterative solution using a gradient descent method, thereby obtaining an iterative solution for a controller that considers active power management constraints; converting the integral process in the gradient descent method into an integral link of the controller, and adding a proportional link, thereby obtaining variables through iterative control of the proportional integral link of the modular multilevel converter, thereby realizing AC / DC distribution network control for interactive active power management. The method and system provided by the present invention can achieve real-time minimization of power generation costs and safe and stable operation of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply or distribution circuits, and in particular to an AC / DC power distribution network control method and system for active power interaction management. Background Art

[0002] Existing multi-terminal interconnected AC / DC hybrid distribution networks often ignore the instantaneous and transient interactive management of controller output power. The traditional scheduling plan formulation stage cannot consider short-term sudden power management needs. In emergency situations where power supply capacity is insufficient or line capacity is insufficient in some areas, instantaneous inappropriate and unoptimized interactive power may cause equipment downtime or instability of the AC / DC distribution system. On the other hand, traditional distributed control strategies can only achieve real-time optimization and control of power generation costs, and it is difficult to achieve other operational needs. The system's operating economy and emergency response capabilities need to be improved. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide an AC / DC distribution network control method and system for active power interaction management. Through distributed real-time coordinated control, real-time active management of multiple control power interactions and real-time minimization of system power generation costs are achieved, thereby improving the system operation economy and safety and stability.

[0004] The present invention is achieved through the following technical solutions:

[0005] The AC / DC distribution network control method for active power interactive management includes the following steps:

[0006] S1: Establish a typical operation scenario and model for a multi-terminal AC / DC hybrid distribution system with instantaneous power limitation when the AC distribution system has insufficient power supply capacity;

[0007] S2: Under the established typical operating scenario and model of a multi-terminal AC / DC hybrid distribution system with instantaneous power limitation, establish the interactive active management conditions of modular multilevel converters using projection operator constraints;

[0008] S3: Using the gradient descent method, the problem of optimizing the generation cost of AC / DC distribution networks with consideration of the interactive active management constraints of modular multilevel converters is transformed into an iterative solution. This results in an iterative solution for the controller with consideration of the active power management constraints.

[0009] S4: The integral process in the gradient descent method is converted into the integral link of the controller, and a proportional link is added. Then, through the iterative control of the proportional integral link of the modular multilevel converter, the node voltage of the modular multilevel converter, the Lagrange multiplier matching the interactive power management requirements, and the iterative value of the Lagrange multiplier matching the power supply constraint of the modular multilevel converter are obtained, thereby realizing AC / DC distribution network control for active power interactive management.

[0010] Specifically, the typical operation scenario and model of the instantaneous power limitation of the multi-terminal AC / DC hybrid distribution system under insufficient power supply capacity of the AC distribution system established in step S1 includes a DC distribution unit and multiple AC distribution units, the DC distribution unit includes a DC bus and multiple modular multilevel converters, the DC distribution unit uses the DC bus as a backbone network, the DC ports of the multiple modular multilevel converters are all connected to the DC bus, and each modular multilevel converter is locally configured with a corresponding controller, and the multiple AC distribution units are all connected to the DC distribution unit through the AC ports of the modular multilevel converter.

[0011] Preferably, the rated voltage of the DC bus is .

[0012] Preferably, the modular multi-level converter adopts a hybrid topology structure in which half-bridge sub-modules and full-bridge sub-modules are mixed.

[0013] Furthermore, the interactive active management condition of the modular multilevel converter using the projection operator constraint in step S2 is formula (1):

[0014] (1);

[0015] in: express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the interactive power management requirements. express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the interactive power management requirements. represents a set of interactive power management requirements, express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the power supply constraints of the modular multilevel converter. express The set of Lagrange multipliers that matches the power supply constraints of the modular multilevel converter is obtained when the solution to minimize the total system power generation cost is obtained at any time. represents the set of power supply constraints for the modular multilevel converter, Represents the projection operator.

[0016] Furthermore, the specific process of the interactive active management condition of the modular multilevel converter using projection operator constraints is as follows:

[0017] S21: When the power transfer capacity of an AC distribution system is limited, the output power of the modular multilevel converter connected to the AC distribution system is actively managed according to the constraint of formula (2):

[0018] (2);

[0019] in: Indicates the interactive power management requirements, Indicates the The interaction management needs to manage the limited power, Indicates the A modular multilevel converter supplies the required power, Indicates the The first interaction management requirement The coefficient corresponding to the power of a modular multilevel converter is, Indicates the Power supply constraints of a modular multilevel converter, Indicates the The node of the modular multilevel converter and the adjacent The conductance between nodes of a modular multilevel converter, Indicates the The node voltages of the modular multilevel converters, Indicates the The node voltages of the modular multilevel converters, Indicates participation in A modular multilevel converter set with interactive power management requirements, Indicates the The nodes of the modular multilevel converter are adjacent to the nodes of the modular multilevel converter A collection of Indicates the The power required by the node of a modular multilevel converter;

[0020] S22: Introducing Lagrange multipliers into equation (2) yields equation (3):

[0021] (3);

[0022] in: Indicates the Lagrange multipliers for interactive power management demand matching, Indicates the Lagrange multipliers for power supply constraint matching of a modular multilevel converter;

[0023] S23: Introducing the projection operator into Equation (3) for , we get formula (1), Represents a projection operator variable.

[0024] Furthermore, in step S3, the specific process of converting the AC / DC distribution network optimization operation problem considering active power management constraints into an iterative solution using the gradient descent method is as follows:

[0025] S31: Set the operating target of the AC / DC distribution network to the power generation cost of the AC distribution system corresponding to all hybrid modular multilevel converters Minimize and use the Lagrange multiplier method to integrate the constraints into the objective function to form the Lagrange form of the objective function Formula (4):

[0026] (4);

[0027] in: represents the number of constraints for active management of power interaction, Indicates the number of constraints on node power supply;

[0028] S32: Introduce the gradient descent method to make the Lagrange multiplier satisfy equation (5) and obtain the optimality condition;

[0029] (5);

[0030] in: represents the node voltage set of the modular multilevel converter, represents the node voltage set of the modular multilevel converter when the problem is optimally solved, The power generation cost of the AC distribution system when the problem is optimally solved is The gradient, represents the set of interactive power management requirements when the problem is optimally solved, represents the gradient of the set of interactive power management requirements when the problem is optimally solved, represents the set of power supply constraints of the modular multilevel converter when the problem is optimally solved, represents the gradient of the set of power supply constraints of the modular multilevel converter when the problem is optimally solved, Represents matrix transpose;

[0031] S33: Define operators for , define Voltage transition value of a modular multilevel converter node =Equation (6), the transition value of the Lagrange multiplier in the qth interactive power management demand The iterative solution of the controller considering the power active management constraint is obtained as Equation (8):

[0032] (6);

[0033] (7);

[0034] (8);

[0035] in: Indicates the The voltage transition value of a modular multilevel converter node, Indicates the A modular multilevel converter supplies the required power, Indicates the The modular multilevel converter node is connected to the The modular multilevel converter nodes transmit values, Indicates the Lagrange multiplier for power supply matching of modular multilevel converter nodes, Indicates the Power supply constraints for modular multilevel converter nodes, represents the maximum value of the node voltage of the modular multilevel converter, represents the minimum value of the node voltage of the modular multilevel converter, represents the transition value of the Lagrange multiplier in the qth interactive power management requirement, Indicates all A collection of Indicates the The Lagrange multiplier transition value in the power supply of a modular multilevel converter node, represents the set of Lagrange multipliers that match the interactive power management requirements, represents a negative constant related to the convergence speed of the model, Indicates all A collection of Indicates all A collection of Indicates all A collection of .

[0036] An AC / DC distribution network control system for active power interaction management, used to execute any of the above-mentioned AC / DC distribution network control methods for active power interaction management, comprising a DC distribution unit, multiple AC distribution units, and a multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module with instantaneous power limitation, a modular multilevel converter power interaction active management constraint module, a projection operator constraint processing module, an iterative algorithm conversion to controller collaborative control strategy formulation module, and a controller proportional link addition and parameter determination module. The DC distribution unit comprises a DC bus and multiple modular multilevel converters. The DC distribution unit uses a DC bus as a backbone network. The DC ports of the multiple modular multilevel converters are all connected to the DC bus, and each modular multilevel converter is locally configured with a corresponding controller. The multiple AC distribution units are all connected to the DC distribution unit through the AC ports of the modular multilevel converter.

[0037] Furthermore, the instantaneous power-limited multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module, the modular multi-level converter power interaction active management constraint module, and the projection operator constraint processing module are sequentially connected and set in the dispatching control center of the AC / DC distribution network.

[0038] Furthermore, the iterative algorithm is converted into a controller collaborative control strategy formulation module, a controller proportional link increase and parameter determination module which are interconnected and arranged in the controller of the modular multi-level converter.

[0039] Beneficial effects of the invention:

[0040] 1) Compared with traditional AC / DC distribution network operation scenarios and scheduling schemes, the proposed model for instantaneous power limitation in a multi-terminal AC / DC hybrid distribution network takes into account short-term, sudden power limitation scenarios. Unlike the predictive and planned power outages in the scheduling scheme formulation phase, the proposed scenario and model can reflect the actual system operation in real time, providing a more realistic and accurate system status for the control strategy.

[0041] 2) Compared with traditional droop control methods, this paper adopts multiple modular multilevel converters' interactive active power management conditions constrained by projection operators. This can embed the active management control of the output power of multiple converters into the droop control. Through coordinated control, active management of output power is achieved, ensuring safe and stable operation of the system.

[0042] 3) Compared with the traditional distributed gradient descent iterative strategy, the present invention transforms the integral process in the gradient descent method into the integral link of the controller and adds a proportional link. This can embed the iterative process into the control link of the controller and improve the dynamic tracking and response capability of the iterative process to power changes.

[0043] 4) Through real-time distributed coordinated control among multiple modular multilevel converters, real-time optimization control of the AC / DC hybrid distribution network is performed with the functional requirements of minimizing power generation costs and real-time management of power interaction, thereby improving the economic efficiency of system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic flow chart of the present invention.

[0045] Figure 2 It is a schematic diagram of the system structure of the present invention.

[0046] In the figure: 1. Modular multilevel converter; 2. AC distribution unit; 3. New campus load; 4. Industrial sensitive load; 5. Residential load; 6. DC distribution unit; 7. Dispatching control center; 8. Multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module with instantaneous power limitation; 9. Modular multilevel converter power interaction active management constraint module; 10. Projection operator constraint processing module; 11. Iterative algorithm conversion to controller collaborative control strategy formulation module; 12. Controller proportional link addition and parameter determination module; 13. DC bus. DETAILED DESCRIPTION

[0047] AC / DC distribution network control method and system for active power interactive management, the flow chart of which is as follows Figure 1 As shown, the specific steps include:

[0048] S1: Establish a typical operation scenario and model for a multi-terminal AC / DC hybrid distribution system with instantaneous power limitation when the AC distribution system has insufficient power supply capacity;

[0049] Specifically, the typical operation scenario and model of the instantaneous power limitation of the multi-terminal AC / DC hybrid distribution system under the insufficient power supply capacity of the AC distribution system is established, which includes a DC distribution unit and multiple AC distribution units. The DC distribution unit includes a DC bus and multiple modular multi-level converters. The DC distribution unit uses the DC bus as the backbone network. The rated voltage of the DC bus can be preferentially The DC ports of multiple modular multilevel converters are all connected to the DC bus. The modular multilevel converter can adopt a hybrid topology structure that mixes half-bridge sub-modules with full-bridge sub-modules, so that a single modular multilevel converter has DC fault ride-through capability.

[0050] The multiple AC power distribution units are connected to the DC power distribution units via the AC ports of the modular multilevel converters, enabling the AC power distribution units to both supply power to and absorb power from the DC power distribution units. Each modular multilevel converter is locally configured with a corresponding controller capable of real-time control of the output power of the modular multilevel converter. A communication network is established between the different modular multilevel converters, enabling real-time communication.

[0051] The aforementioned multi-terminal AC / DC hybrid power distribution system is adopted as the system operating topology, assuming that the AC distribution unit has multiple modular multilevel converters connected to the DC distribution unit. Considering that the AC distribution unit may experience short-term power transfer capacity shortages due to insufficient transformer capacity, line capacity, and renewable energy generation capacity, that is, the power supply from the AC distribution unit to the DC distribution unit is limited, the output power of multiple modular multilevel converters needs to be limited in a typical operating scenario.

[0052] Since the DC distribution unit contains various types of loads, including industrial loads, residential loads, and new park loads, and due to the short-term and sudden nature of insufficient power transfer capacity of the AC distribution unit, if the modular multilevel converter does not have the function of active power interaction management, the entire AC / DC distribution system is very likely to experience equipment downtime and system instability. Therefore, the modular multilevel converter must have the function of active power interaction management.

[0053] Compared with traditional AC / DC distribution network operating scenarios and scheduling schemes, the typical operating model of instantaneous power limitation of multi-terminal AC / DC hybrid distribution networks proposed in this invention takes into account the system's short-term sudden power limitation scenarios. Unlike the predictive and planned power outages in the scheduling scheme formulation stage, the proposed scenario and model can reflect the actual operation status of the system in real time, providing a more realistic and accurate system status for the control strategy.

[0054] S2: Under the established typical operating scenario and model of a multi-terminal AC / DC hybrid distribution system with instantaneous power limitation, establish the interactive active management conditions of modular multilevel converters using projection operator constraints;

[0055] Specifically, the interactive active management condition of the modular multilevel converter using projection operator constraint is formula (1):

[0056] (1);

[0057] in: express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the interactive power management requirements. express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the interactive power management requirements. represents a set of interactive power management requirements, express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the power supply constraints of the modular multilevel converter. express The set of Lagrange multipliers that matches the power supply constraints of the modular multilevel converter is obtained when the solution to minimize the total system power generation cost is obtained at any time. represents the set of power supply constraints for the modular multilevel converter, Represents the projection operator.

[0058] The specific process of interactive active management conditions of modular multilevel converters using projection operator constraints is as follows:

[0059] S21: When the power transfer capacity of an AC distribution system is limited, the output power of the modular multilevel converter connected to the AC distribution system is actively managed according to the constraint of formula (2):

[0060] (2);

[0061] in: Indicates the interactive power management requirements, Indicates the The interaction management needs to manage the limited power, Indicates the A modular multilevel converter supplies the required power, Indicates the management of the qth interaction management requirement The coefficient corresponding to the power of a modular multilevel converter is, Indicates the Power supply constraints of a modular multilevel converter, Indicates the The node of the modular multilevel converter and the adjacent The conductance between nodes of a modular multilevel converter, Indicates the The node voltages of the modular multilevel converters, Indicates the The node voltages of the modular multilevel converters, Indicates participation in A modular multilevel converter set with interactive power management requirements, Indicates the The nodes of the modular multilevel converter are adjacent to the nodes of the modular multilevel converter A collection of Indicates the The power required by the node of a modular multilevel converter;

[0062] The limited power supplied by the AC power distribution unit to the DC power distribution unit may change as the AC power distribution unit recovers from the operation state. It is a constraint that changes in real time over time, which is a constraint that traditional scheduling solutions cannot achieve.

[0063] Indicates the The first interaction management requirement The coefficient corresponding to the power of the modular multilevel converter is a non-negative number. When the value is 1, it indicates the linear sum of the output powers of multiple modular multilevel converters. When the value is not 1, it indicates the weighted sum of the output powers of multiple modular multilevel converters. The coefficient is determined by the system operator according to the needs. The interactive power management needs to be strengthened When the management is in place, the larger the coefficient is, and vice versa.

[0064] S22: Introducing Lagrange multipliers into equation (2) yields equation (3):

[0065] (3);

[0066] in: Indicates the Lagrange multipliers for interactive power management demand matching, Indicates the Lagrange multipliers for power supply constraint matching of a modular multilevel converter;

[0067] S23: Introducing the projection operator into Equation (3) for , we get formula (1), Represents a projection operator variable.

[0068] Compared with the traditional droop control method, this paper adopts multiple modular multilevel converter power interaction active management conditions constrained by projection operators, which can embed the output power active management control of multiple converters into the droop control, realize the active management of output power through coordinated control, and ensure the safe and stable operation of the system.

[0069] S3: Using the gradient descent method, the problem of optimizing the generation cost of AC / DC distribution networks with consideration of the interactive active management constraints of modular multilevel converters is transformed into an iterative solution. This results in an iterative solution for the controller with consideration of the active power management constraints.

[0070] Specifically, the specific process of using the gradient descent method to transform the AC / DC distribution network optimization operation problem considering active power management constraints into an iterative solution is as follows:

[0071] S31: Set the operating target of the AC / DC distribution network to the power generation cost of the AC distribution system corresponding to all hybrid modular multilevel converters Minimize and use the Lagrange multiplier method to integrate the constraints into the objective function to form the Lagrange form of the objective function Formula (4):

[0072] (4);

[0073] in: represents the number of constraints for active management of power interaction, Indicates the number of constraints on node power supply;

[0074] S32: Introduce the gradient descent method to make the Lagrange multiplier satisfy equation (5) and obtain the optimality condition;

[0075] (5);

[0076] in: represents the node voltage set of the modular multilevel converter, represents the node voltage set of the modular multilevel converter when the problem is optimally solved, The power generation cost of the AC distribution system when the problem is optimally solved is The gradient, represents the set of interactive power management requirements when the problem is optimally solved, represents the gradient of the set of interactive power management requirements when the problem is optimally solved, represents the set of power supply constraints of the modular multilevel converter when the problem is optimally solved, represents the gradient of the set of power supply constraints of the modular multilevel converter when the problem is optimally solved, Represents matrix transpose;

[0077] S33: Define operators for , define Voltage transition value of a modular multilevel converter node =Equation (6), the transition value of the Lagrange multiplier in the qth interactive power management demand The iterative solution of the controller considering the power active management constraint is obtained as Equation (8):

[0078] (6);

[0079] (7);

[0080] (8);

[0081] in: Indicates the The voltage transition value of a modular multilevel converter node, Indicates the A modular multilevel converter supplies the required power, Indicates The modular multilevel converter node is connected to the The modular multilevel converter nodes transmit values, Indicates Lagrange multiplier for power supply matching of modular multilevel converter nodes, Indicates the Power supply constraints for modular multilevel converter nodes, represents the maximum value of the node voltage of the modular multilevel converter, represents the minimum value of the node voltage of the modular multilevel converter, represents the transition value of the Lagrange multiplier in the qth interactive power management requirement, Indicates all A collection of Indicates the The Lagrange multiplier transition value in the power supply of a modular multilevel converter node, represents the set of Lagrange multipliers that match the interactive power management requirements, represents a negative constant related to the convergence speed of the model, Indicates all A collection of Indicates all A collection of Indicates all A collection of .

[0082] Equation (8) describes how to find the optimal solution to the problem. With the help of Equation (8), an iterative solution to the controller considering the active power management constraint can be obtained.

[0083] Through real-time distributed coordinated control among multiple modular multilevel converters, real-time optimization control of the AC / DC hybrid distribution network is performed with the functional requirements of minimizing power generation cost and real-time management of power interaction, thereby improving the economic efficiency of system operation.

[0084] S4: The integral process in the gradient descent method is converted into the integral link of the controller, and a proportional link is added. Then, through the iterative control of the proportional integral link of the modular multilevel converter, the node voltage of the modular multilevel converter, the Lagrange multiplier matching the interactive power management requirements, and the iterative value of the Lagrange multiplier matching the power supply constraint of the modular multilevel converter are obtained, thereby realizing AC / DC distribution network control for active power interactive management.

[0085] Compared to traditional distributed gradient descent iterative strategies, this invention transforms the integral process in the gradient descent method into an integral link in the controller and adds a proportional link. Through iterative control of the modular multilevel converter's proportional-integral link, iterative values ​​of the Lagrange multiplier matching the interactive power management requirements and the power supply constraints of the modular multilevel converter are obtained, thus achieving AC / DC distribution network control for interactive active power management. The iterative process can be embedded into the controller's control link, improving its ability to dynamically track and respond to power changes, further enhancing the safety and stability of system operation.

[0086] The AC / DC distribution network control system for active power interaction management is shown in the following diagram: Figure 2 As shown, the AC / DC distribution network control method for power interactive active management described in any of the above items includes a DC distribution unit 6, multiple AC distribution units 2, and an instantaneous power-constrained multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module 8, a modular multilevel converter power interactive active management constraint module 9, a projection operator constraint processing module 10, an iterative algorithm conversion to controller collaborative control strategy formulation module 11, and a controller proportional link addition and parameter determination module 12. The DC distribution unit includes a DC bus 13 and multiple modular multilevel converters 1. The DC distribution unit uses a DC bus as a backbone network. The DC ports of the multiple modular multilevel converters are all connected to the DC bus, and each modular multilevel converter is locally configured with a corresponding controller. The multiple AC distribution units are all connected to the DC distribution unit through the AC ports of the modular multilevel converter.

[0087] The DC distribution unit here can provide power for new park loads 3, industrial sensitive loads 4, and residential loads 5.

[0088] The instantaneous power-limited multi-terminal AC / DC hybrid distribution system operating topology and typical scenario construction module is used to determine the operating topology of the multi-terminal AC / DC hybrid distribution system and construct relevant typical scenarios considering requirements such as instantaneous power limitation.

[0089] The modular multilevel converter power interactive active management constraint module is used to accept the operating topology of the multi-terminal AC / DC hybrid distribution system with instantaneous power limitation and the topology and scenario constructed by the typical scenario construction module, determine whether the system AC power supply is limited, and determine the modular multilevel converter body subject to active power management and the power value that needs to be actively managed.

[0090] The projection operator constraint processing module accepts the constraints constructed by the multi-level converter power interaction active management constraint module, takes voltage and Lagrange multipliers as key system variables, uses the projection operator to clamp all node voltages, Lagrange multipliers of power interaction active management, and Lagrange multipliers of node power within an allowable range, and combines it with the optimization iterative calculation scheme of the gradient descent method to ensure the implementation of all power interaction active management and the non-excessive limit of the node voltage of the entire system.

[0091] Specifically, the instantaneous power-limited multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module, the modular multi-level converter power interaction active management constraint module, and the projection operator constraint processing module are connected in sequence and can be set in the dispatching control center 7.

[0092] The iterative algorithm is converted into a controller collaborative control strategy formulation module for incorporating a distributed iterative scheme based on the projected gradient descent method conversion into the controller.

[0093] The controller proportional link addition and parameter determination module is used to add a proportional link in the preliminary distributed iterative controller and select appropriate proportional control parameters to achieve AC / DC distribution network control for active power interaction management.

[0094] Specifically, the iterative algorithm is converted into a controller collaborative control strategy formulation module, and the controller proportional link addition and parameter determination module are connected to each other and can be set in the controller of the modular multi-level converter.

[0095] In summary, the present invention provides an AC / DC distribution network control method and system for active power interaction management. The system's active power interaction management capability can be applied to power-limited scenarios that take into account short-term bursts of the system. It can embed the output power active management control of multiple modular multi-level converters into the control, and realize real-time active management of output power through coordinated control, while achieving real-time minimization of power generation costs and safe and stable operation of the system.

[0096] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An AC / DC distribution network control method for active power interactive management, characterized by: The steps include: S1: Establish a typical operation scenario and model for a multi-terminal AC / DC hybrid distribution system with instantaneous power limitation when the AC distribution system has insufficient power supply capacity; S2: Under the established typical operating scenario and model of a multi-terminal AC / DC hybrid distribution system with instantaneous power limitation, establish the interactive active management conditions of modular multilevel converters using projection operator constraints; The interactive active management condition of modular multilevel converters using projection operator constraints is formula (1): （1）； in: express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the interactive power management requirements. express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the interactive power management requirements. represents a set of interactive power management requirements, express The solution to minimize the total system power generation cost at any given moment is the set of Lagrange multipliers that matches the power supply constraints of the modular multilevel converter. express The set of Lagrange multipliers that matches the power supply constraints of the modular multilevel converter is obtained when the solution to minimize the total system power generation cost is obtained at any time. represents the set of power supply constraints for the modular multilevel converter, represents the projection operator; The specific process of interactive active management conditions of modular multilevel converters using projection operator constraints is as follows: S21: When the power transfer capacity of an AC distribution system is limited, the output power of the modular multilevel converter connected to the AC distribution system is actively managed according to the constraint of formula (2): (2)； in: Indicates the interactive power management requirements, Indicates the The interaction management needs to manage the limited power, Indicates the A modular multilevel converter supplies the required power, Indicates the The first interaction management requirement The coefficient corresponding to the power of a modular multilevel converter is, Indicates the Power supply constraints of a modular multilevel converter, Indicates the The node of the modular multilevel converter and the adjacent The conductance between nodes of a modular multilevel converter, Indicates the The node voltages of the modular multilevel converters, Indicates the The node voltages of the modular multilevel converters, Indicates participation in A modular multilevel converter set with interactive power management requirements, Indicates the The nodes of the modular multilevel converter are adjacent to the nodes of the modular multilevel converter A collection of Indicates the The power required by the node of a modular multilevel converter; S22: Introducing Lagrange multipliers into equation (2) yields equation (3): （3）； in: Indicates the Lagrange multipliers for interactive power management demand matching, Indicates the Lagrange multipliers for power supply constraint matching of a modular multilevel converter; S23: Introducing the projection operator into Equation (3) for , we get formula (1), represents the projection operator variable; S3: Using the gradient descent method, the problem of optimizing the generation cost of AC / DC distribution networks with consideration of the interactive active management constraints of modular multilevel converters is transformed into an iterative solution. This results in an iterative solution for the controller with consideration of the active power management constraints. The specific process of using the gradient descent method to transform the optimal operation problem of AC / DC distribution networks with active power management constraints into an iterative solution is as follows: S31: Set the operating target of the AC / DC distribution network to the power generation cost of the AC distribution system corresponding to all hybrid modular multilevel converters Minimize and use the Lagrange multiplier method to integrate the constraints into the objective function to form the Lagrange form of the objective function Formula (4): （4）； in: represents the number of constraints for active management of power interaction, Indicates the number of constraints on node power supply; S32: Introduce the gradient descent method to make the Lagrange multiplier satisfy equation (5) and obtain the optimality condition; (5)； in: represents the node voltage set of the modular multilevel converter, represents the node voltage set of the modular multilevel converter when the problem is optimally solved, The power generation cost of the AC distribution system when the problem is optimally solved is The gradient, represents the set of interactive power management requirements when the problem is optimally solved, represents the gradient of the set of interactive power management requirements when the problem is optimally solved, represents the set of power supply constraints of the modular multilevel converter when the problem is optimally solved, represents the gradient of the set of power supply constraints of the modular multilevel converter when the problem is optimally solved, Represents matrix transpose; S33: Define operators for , define Voltage transition value of a modular multilevel converter node =Equation (6), the transition value of the Lagrange multiplier in the qth interactive power management demand The iterative solution of the controller considering the power active management constraint is obtained as Equation (8): （6）； （7）； （8）； in: Indicates the The voltage transition value of a modular multilevel converter node, Indicates the A modular multilevel converter supplies the required power, Indicates The modular multilevel converter node is connected to the The modular multilevel converter nodes transmit values, Indicates Lagrange multiplier for power supply matching of modular multilevel converter nodes, Indicates the Power supply constraints for modular multilevel converter nodes, represents the maximum value of the node voltage of the modular multilevel converter, represents the minimum value of the node voltage of the modular multilevel converter, represents the transition value of the Lagrange multiplier in the qth interactive power management requirement, Indicates all A collection of Indicates the The Lagrange multiplier transition value in the power supply of a modular multilevel converter node, represents the set of Lagrange multipliers that match the interactive power management requirements, represents a negative constant related to the convergence speed of the model, Indicates all A collection of Indicates all A collection of Indicates all A collection of S4: The integral process in the gradient descent method is converted into the integral link of the controller, and a proportional link is added. Then, through the iterative control of the proportional integral link of the modular multilevel converter, the node voltage of the modular multilevel converter, the Lagrange multiplier matching the interactive power management requirements, and the iterative value of the Lagrange multiplier matching the power supply constraint of the modular multilevel converter are obtained, thereby realizing AC / DC distribution network control for active power interactive management.

2. The AC / DC distribution network control method for active power interactive management according to claim 1, characterized in that: The typical operation scenario and model of the instantaneous power limitation of the multi-terminal AC / DC hybrid distribution system under insufficient power supply capacity of the AC distribution system established in step S1 include a DC distribution unit and multiple AC distribution units, the DC distribution unit includes a DC bus and multiple modular multilevel converters, the DC distribution unit uses the DC bus as a backbone network, the DC ports of the multiple modular multilevel converters are all connected to the DC bus, and each modular multilevel converter is locally configured with a corresponding controller, and the multiple AC distribution units are all connected to the DC distribution unit through the AC ports of the modular multilevel converter.

3. The AC / DC distribution network control method for active power interactive management according to claim 2, characterized in that: The rated voltage of the DC bus is .

4. The AC / DC distribution network control method for active power interactive management according to claim 2, characterized in that: The modular multi-level converter adopts a hybrid topology structure in which half-bridge submodules and full-bridge submodules are mixed.

5. An AC / DC power distribution network control system for active power interaction management, configured to execute the AC / DC power distribution network control method for active power interaction management according to any one of claims 1 to 4, characterized in that: It includes a DC distribution unit, multiple AC distribution units, and a multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module with instantaneous power limitation, a modular multilevel converter power interaction active management constraint module, a projection operator constraint processing module, an iterative algorithm conversion to controller collaborative control strategy formulation module, and a controller proportional link addition and parameter determination module. The DC distribution unit includes a DC bus and multiple modular multilevel converters. The DC distribution unit uses a DC bus as the backbone network. The DC ports of the multiple modular multilevel converters are all connected to the DC bus, and each modular multilevel converter is locally configured with a corresponding controller. The multiple AC distribution units are all connected to the DC distribution unit through the AC ports of the modular multilevel converter.

6. The AC / DC distribution network control system for active power interactive management according to claim 5, characterized in that: The instantaneous power-limited multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module, the modular multi-level converter power interactive active management constraint module, and the projection operator constraint processing module are sequentially connected and arranged in the dispatching control center of the AC / DC distribution network.

7. The AC / DC distribution network control system for active power interactive management according to claim 5, characterized in that: The iterative algorithm is converted into a controller collaborative control strategy formulation module, a controller proportional link increase and parameter determination module, which are interconnected and arranged in the controller of the modular multi-level converter.

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