Power interaction active management-oriented AC / DC power distribution network control method and system

Abstract

The invention relates to the technical field of power supply or power distribution circuits, in particular to a power interaction active management-oriented AC / DC power distribution network control method and system, and the method comprises the following steps: building an instantaneous power limited typical operation scene and model; establishing a modular multilevel converter interactive active management condition constrained by a projection operator; a gradient descent method is adopted to convert the power generation cost optimization operation problem of the AC / DC power distribution network into an iterative solution scheme, and a controller iterative solution scheme considering the power active management constraint is obtained; an integration process in a gradient descent method is converted into an integration link of a controller, a proportional link is added, variables are obtained through iterative control of the proportional-integral link of the modular multilevel converter, and alternating-current and direct-current power distribution network control oriented to power interaction active management is achieved. The method and the system provided by the invention can realize the real-time minimization of the power generation cost and the safe and stable operation of the system.

Description

Technical Field

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

[0002] The existing multi-terminal interconnected AC / DC hybrid distribution network often ignores the instantaneous and transient interactive management of controller output power. The traditional scheduling plan formulation stage cannot take into account 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 operating requirements. 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, which realizes real-time active management of multiple control power interactions and real-time minimization of system power generation costs through distributed real-time coordinated control, thereby improving the system operation economy and safety and stability.

[0004] The present invention is achieved through the following technical solutions: The AC / DC distribution network control method for active power interaction management comprises the following steps: S1: Establish typical operation scenarios and models of instantaneous power limitation of multi-terminal AC / DC hybrid distribution systems under insufficient power supply capacity of AC distribution systems; S2: Under the established typical operation scenario and model of multi-terminal AC / DC hybrid distribution system with instantaneous power limitation, the interactive active management conditions of modular multilevel converters using projection operator constraints are established; S3: The gradient descent method is used to transform the problem of optimizing the operation of the AC / DC distribution network generation cost considering the interactive active management constraints of modular multilevel converters into an iterative solution, and an iterative solution of the controller considering the active power management constraints is obtained; 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, so as to realize the AC / DC distribution network control for active power interactive management.

[0005] Specifically, the typical operation scenario and model of instantaneous power limitation of a multi-terminal AC / DC hybrid distribution system under insufficient power supply capacity of an 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 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 of the modular multilevel converters is locally configured with a corresponding controller, and the multiple AC distribution units are connected to the DC distribution unit through the AC ports of the modular multilevel converter.

[0006] Preferably, the rated voltage of the DC bus is .

[0007] Preferably, the modular multi-level converter adopts a hybrid topology structure in which half-bridge sub-modules and full-bridge sub-modules are mixed.

[0008] Furthermore, the interactive active management condition of the modular multilevel converter using the projection operator constraint in step S2 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 collection 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 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. represents the set of power supply constraints for the modular multilevel converter, Represents the projection operator.

[0009] Furthermore, 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 power distribution system is limited, the output power of the modular multilevel converter connected to the AC power distribution system is actively managed according to the constraint condition of formula (2): (2); in: Indicates interactive power management requirements, Indicates The interaction management needs to manage the limited power, Indicates A modular multilevel converter supplies the required power. Indicates 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 node of the modular multilevel converter and the adjacent The conductance between nodes of a modular multilevel converter, Indicates The node voltages of the modular multilevel converters, Indicates The node voltages of the modular multilevel converters, Indicates participation in A modular multilevel converter set with interactive power management requirements, Indicates The nodes of the modular multilevel converters adjacent to the nodes of the modular multilevel converters A collection of Indicates The power required by the node of a modular multilevel converter; S22: Introducing Lagrange multipliers into equation (2), we get equation (3): (3); in: Indicates The Lagrange multiplier for interactive power management demand matching, Indicates Lagrange multipliers for matching power supply constraints of modular multilevel converters; S23: Introducing the projection operator into equation (3) for , we get formula (1), Represents a projection operator variable.

[0010] Furthermore, in step S3, the specific process of using the gradient descent method to transform the AC / DC distribution network optimization operation problem considering the active power management constraint into an iterative solution is as follows: S31: Set the operation 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 Lagrangian 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 of 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: Defining operators for , define Voltage transition value of a node in a modular multilevel converter =Equation (6), the transition value of the Lagrange multiplier in the qth interactive power management requirement Formula (7) is obtained, and the iterative value of the variable is determined according to the projected gradient descent direction of Formula (6) and Formula (7), and the iterative solution of the controller considering the power active management constraint is obtained as Formula (8): (6); (7); (8); in: Indicates The voltage transition value of a modular multilevel converter node, Indicates 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 The Lagrange multiplier for power supply matching of modular multilevel converter nodes, Indicates The power supply constraints of a modular multilevel converter node, 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 transition value of Lagrange multiplier in the power supply of modular multilevel converter nodes, represents the set of Lagrange multipliers that match the interactive power management requirements, represents a negative constant related to the model convergence speed, Indicates all A collection of Indicates all A collection of Indicates all A collection of .

[0011] 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 multi-level converter power interaction active management constraint module, a projection operator constraint processing module, an iterative algorithm conversion to controller collaborative control strategy formulation module, a controller proportion link addition and parameter determination module, the DC distribution unit comprises a DC bus and multiple modular multi-level converters, the DC distribution unit uses a DC bus as a backbone network, the DC ports of multiple modular multi-level converters are all connected to the DC bus, and each modular multi-level converter is locally configured with a corresponding controller, and multiple AC distribution units are connected to the DC distribution unit through the AC ports of the modular multi-level converter.

[0012] Furthermore, the instantaneous power-constrained 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 arranged in the dispatching and control center of the AC / DC distribution network.

[0013] Furthermore, the iterative algorithm is converted into a controller collaborative control strategy formulation module, a controller proportional link increase and a parameter determination module which are interconnected and arranged in the controller of the modular multi-level converter.

[0014] Beneficial effects of the invention: 1) Compared with the traditional AC / DC distribution network operation scenarios and dispatching schemes, the instantaneous power-limited typical operation model of the multi-terminal AC / DC hybrid distribution network proposed in the present invention takes into account the short-term sudden power-limited scenario of the system. Different from the predictive and planned power outages in the dispatching scheme formulation stage, the proposed scenario and model can reflect the actual operation of the system in real time, providing a more realistic and accurate system status for the control strategy; 2) Compared with the traditional droop control method, this paper adopts multiple modular multilevel converter power interaction active management conditions constrained by projection operator, which can embed the output power active management control of multiple converters into droop control, realize the active management of output power through coordinated control, and ensure the safe and stable operation of the system; 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, which can embed the iterative process into the control link of the controller and improve the dynamic tracking response capability of the iterative process to power changes; 4) Through real-time distributed coordinated control among multiple modular multilevel converters, real-time optimization control of AC / DC hybrid distribution network is carried out with the functional requirements of minimizing power generation cost and real-time management of power interaction, thus improving the economy of system operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention.

[0016] Figure 2 It is a schematic diagram of the system structure of the present invention.

[0017] In the figure: 1. Modular multilevel converter; 2. AC distribution unit; 3. New park 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

[0018] 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: S1: Establish typical operation scenarios and models of instantaneous power limitation of multi-terminal AC / DC hybrid distribution systems under insufficient power supply capacity of AC distribution systems; Specifically, the typical operation scenario and model of the instantaneous power limitation of the multi-terminal AC / DC hybrid distribution system under the condition of insufficient power supply capacity of the AC distribution system established 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.

[0019] The plurality of AC power distribution units are connected to the DC power distribution unit through the AC port of the modular multilevel converter, so that the AC power distribution unit can supply power to the DC power distribution unit and absorb power from the DC power distribution unit. Each modular multilevel converter is locally configured with a corresponding controller, which can control the output power of the modular multilevel converter in real time. Different modular multilevel converters have a communication network established between each other, which can communicate in real time.

[0020] The above-mentioned multi-terminal AC / DC hybrid power distribution system is used as the system operation topology, and it is assumed that the AC distribution unit has multiple modular multilevel converters connected to the DC distribution unit. Considering that the AC distribution unit may have a short-term power transfer capacity shortage 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 operation scenario.

[0021] 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 the insufficient power transfer capacity of the AC distribution unit, when the modular multilevel converter does not have the function of active power interaction management, the entire AC / DC distribution system is prone to equipment downtime and system instability. Therefore, the modular multilevel converter must have the function of active power interaction management.

[0022] Compared with traditional AC / DC distribution network operation scenarios and scheduling schemes, the typical operation model of instantaneous power limitation of multi-terminal AC / DC hybrid distribution network proposed in the present invention takes into account the short-term sudden power limitation scenario of the system. Different from 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, and provide a more realistic and accurate system status for the control strategy.

[0023] S2: Under the established typical operation scenario and model of multi-terminal AC / DC hybrid distribution system with instantaneous power limitation, the interactive active management conditions of modular multilevel converters using projection operator constraints are established; Specifically, the interactive active management condition of the modular multilevel converter 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 collection 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 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. represents the set of power supply constraints for the modular multilevel converter, Represents the projection operator.

[0024] 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 power distribution system is limited, the output power of the modular multilevel converter connected to the AC power distribution system is actively managed according to the constraint condition of formula (2): (2); in: Indicates interactive power management requirements, Indicates The interaction management needs to manage the limited power, Indicates 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 node of the modular multilevel converter and the adjacent The conductance between nodes of a modular multilevel converter, Indicates The node voltages of the modular multilevel converters, Indicates The node voltages of the modular multilevel converters, Indicates participation in A modular multilevel converter set with interactive power management requirements, Indicates The nodes of the modular multilevel converters adjacent to the nodes of the modular multilevel converters A collection of Indicates The power required by the node of a modular multilevel converter; 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 operating state. It is a constraint that changes in real time over time, which is a constraint that traditional scheduling schemes cannot achieve.

[0025] Indicates 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 set by the system operator according to the needs. The interactive power management requirements need to be strengthened When the management is strict, the larger the coefficient is, and vice versa.

[0026] S22: Introducing Lagrange multipliers into equation (2), we get equation (3): (3); in: Indicates The Lagrange multiplier for interactive power management demand matching, Indicates Lagrange multipliers for matching power supply constraints of modular multilevel converters; S23: Introducing the projection operator into equation (3) for , we get formula (1), Represents a projection operator variable.

[0027] Compared with the traditional droop control method, this paper adopts multiple modular multilevel converter power interaction active management conditions constrained by projection operator, which can embed the output power active management control of multiple converters into droop control, realize active management of output power through coordinated control, and ensure safe and stable operation of the system.

[0028] S3: The gradient descent method is used to transform the problem of optimizing the operation of the AC / DC distribution network generation cost considering the interactive active management constraints of modular multilevel converters into an iterative solution, and an iterative solution of the controller considering the active power management constraints is obtained; Specifically, the specific process of using the gradient descent method to transform the optimal operation problem of AC / DC distribution network considering active power management constraints into an iterative solution is as follows: S31: Set the operation 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 Lagrangian 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 of 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: Defining operators for , define Voltage transition value of a node in a modular multilevel converter =Equation (6), the transition value of the Lagrange multiplier in the qth interactive power management requirement Formula (7) is obtained, and the iterative value of the variable is determined according to the projected gradient descent direction of Formula (6) and Formula (7), and the iterative solution of the controller considering the power active management constraint is obtained as Formula (8): (6); (7); (8); in: Indicates The voltage transition value of a modular multilevel converter node, Indicates 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 The Lagrange multiplier for power supply matching of modular multilevel converter nodes, Indicates The power supply constraints of a modular multilevel converter node, 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 transition value of Lagrange multiplier in the power supply of modular multilevel converter nodes, represents the set of Lagrange multipliers that match the interactive power management requirements, represents a negative constant related to the model convergence speed, Indicates all A collection of Indicates all A collection of Indicates all A collection of .

[0029] Formula (8) describes how to find the optimal solution to the problem. With the help of Formula (8), an iterative solution to the controller considering the active power management constraint can be obtained.

[0030] Through real-time distributed coordinated control among multiple modular multilevel converters, real-time optimization control of the AC / DC hybrid distribution network is carried out with the functional requirements of minimizing power generation cost and real-time management of power interaction, thus improving the economy of system operation.

[0031] 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, so as to realize the AC / DC distribution network control for active power interactive management.

[0032] Compared with the traditional distributed gradient descent iteration strategy, the present invention converts the integral process in the gradient descent method into the integral link of the controller, and adds a proportional link. 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, so as to realize the AC / DC distribution network control for active power interactive management. The iterative process can be embedded in the control link of the controller, and the dynamic tracking and response capability of the iterative process to power changes is improved, further improving the safety and stability of the system operation.

[0033] The AC / DC distribution network control system for active power interaction management is shown in the following figure. Figure 2As shown, the AC / DC distribution network control method for executing any one of the above-mentioned active power interaction management comprises a DC distribution unit 6, multiple AC distribution units 2, and a multi-terminal AC / DC hybrid distribution system operation topology and typical scenario construction module 8 with instantaneous power limitation, a modular multi-level converter power interaction 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 proportion link addition and parameter determination module 12. The DC distribution unit comprises a DC bus 13 and multiple modular multi-level converters 1, and the DC distribution unit adopts a DC bus as a backbone network. The DC ports of the multiple modular multi-level converters are all connected to the DC bus, and each modular multi-level converter is locally configured with a corresponding controller, and the multiple AC distribution units are connected to the DC distribution unit through the AC ports of the modular multi-level converter.

[0034] The DC distribution unit here can provide power for new park loads 3, industrial sensitive loads 4 and residential loads 5.

[0035] The instantaneous power-limited multi-terminal AC / DC hybrid power distribution system operating topology and typical scenario construction module is used to determine the operating topology of the multi-terminal AC / DC hybrid power distribution system and to construct relevant typical scenarios taking into account requirements such as instantaneous power limitation.

[0036] 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 constraints 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 that is subject to active power management and the power value that needs to be actively managed.

[0037] 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 the allowable range, and combines them into the optimization iterative calculation scheme of the gradient descent method to ensure the implementation of all power interaction active management and the node voltage of the whole system does not exceed the limit.

[0038] Specifically, the instantaneous power-constrained 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.

[0039] The iterative algorithm is converted into a controller collaborative control strategy formulation module for incorporating a distributed iterative scheme based on projected gradient descent method conversion into the controller.

[0040] 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.

[0041] 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 interconnected and can be set in the controller of the modular multi-level converter.

[0042] 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. The output power active management control of multiple modular multi-level converters can be embedded into the control, and real-time active management of output power can be achieved through coordinated control, while achieving real-time minimization of power generation costs and safe and stable operation of the system.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An AC / DC distribution network control method for active power interaction management, characterized by: The steps include: S1: Establish typical operation scenarios and models of instantaneous power limitation of multi-terminal AC / DC hybrid distribution systems under insufficient power supply capacity of AC distribution systems; S2: Under the established typical operation scenario and model of multi-terminal AC / DC hybrid distribution system with instantaneous power limitation, the interactive active management conditions of modular multilevel converters using projection operator constraints are established; S3: The gradient descent method is used to transform the problem of optimizing the operation of the AC / DC distribution network generation cost considering the interactive active management constraints of modular multilevel converters into an iterative solution, and an iterative solution of the controller considering the active power management constraints is obtained; 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, so as to realize the 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 instantaneous power limitation of a 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 a DC bus as a backbone network, the DC ports of the multiple modular multilevel converters are connected to the DC bus, and each of the modular multilevel converters is locally configured with a corresponding controller, and the multiple AC distribution units are 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. The AC / DC distribution network control method for active power interactive management according to claim 2, characterized in that: The interactive active management condition of the modular multilevel converter using the projection operator constraint in step S2 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 collection 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 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. represents the set of power supply constraints for the modular multilevel converter, Represents the projection operator.

6. The AC / DC distribution network control method for active power interactive management according to claim 5, characterized in that: 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 power distribution system is limited, the output power of the modular multilevel converter connected to the AC power distribution system is actively managed according to the constraint condition of formula (2): (2)； in: Indicates interactive power management requirements, Indicates The interaction management needs to manage the limited power, Indicates A modular multilevel converter supplies the required power. Indicates 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 node of the modular multilevel converter and the adjacent The conductance between nodes of a modular multilevel converter, Indicates The node voltages of the modular multilevel converters, Indicates The node voltages of the modular multilevel converters, Indicates participation in A modular multilevel converter set with interactive power management requirements, Indicates The nodes of the modular multilevel converters adjacent to the nodes of the modular multilevel converters A collection of Indicates The power required by the node of a modular multilevel converter; S22: Introducing Lagrange multipliers into equation (2), we get equation (3): （3）； in: Indicates The Lagrange multiplier for matching the interactive power management requirements, Indicates Lagrange multipliers for matching power supply constraints of modular multilevel converters; S23: Introducing the projection operator into equation (3) for , we get formula (1), Represents a projection operator variable.

7. The AC / DC distribution network control method for active power interactive management according to claim 6, characterized in that: The specific process of using the gradient descent method in step S3 to transform the AC / DC distribution network optimization operation problem considering active power management constraints into an iterative solution is as follows: S31: Set the operation 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 Lagrangian 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 of 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: Defining operators for , define Voltage transition value of a node in a modular multilevel converter =Equation (6), the transition value of the Lagrange multiplier in the qth interactive power management requirement Formula (7) is obtained, and the iterative value of the variable is determined according to the projected gradient descent direction of Formula (6) and Formula (7), and the iterative solution of the controller considering the power active management constraint is obtained as Formula (8): （6）； （7）； （8）； in: Indicates The voltage transition value of a modular multilevel converter node, Indicates 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 The Lagrange multiplier for power supply matching of modular multilevel converter nodes, Indicates The power supply constraints of a modular multilevel converter node, 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 transition value of Lagrange multiplier in the power supply of modular multilevel converter nodes, represents the set of Lagrange multipliers that match the interactive power management requirements, represents a negative constant related to the model convergence speed, Indicates all A collection of Indicates all A collection of Indicates all A collection of .

8. An AC / DC distribution network control system for active power interaction management, used to execute the AC / DC distribution network control method for active power interaction management according to any one of claims 1 to 7, characterized in that: It includes a DC distribution unit, multiple AC distribution units, and an operation topology and typical scenario building module for a multi-terminal AC / DC hybrid distribution system with instantaneous power constraints, a modular multi-level 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 proportion link addition and parameter determination module. The DC distribution unit includes a DC bus and multiple modular multi-level converters. The DC distribution unit uses a DC bus as a backbone network. The DC ports of multiple modular multi-level converters are all connected to the DC bus, and each modular multi-level converter is locally configured with a corresponding controller. Multiple AC distribution units are connected to the DC distribution unit through the AC ports of the modular multi-level converter.

9. The AC / DC power distribution network control system for active power interactive management according to claim 8, 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 interaction 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.

10. The AC / DC power distribution network control system for active power interactive management according to claim 8, 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.

Images