A distributed collaborative control method and system for an AC / DC hybrid microgrid of heterogeneous distributed renewable energy

Abstract

The application discloses a kind of AC / DC hybrid microgrid distributed collaborative control method and system for heterogeneous distributed renewable energy, belong to microgrid distributed control and energy internet technical field. Including the operation quantity of collection, communication graph is established;Respectively to AC subnetwork and DC subnetwork executes local primary control based on droop characteristic;It is constructed as collaborative control state;Based on consistency error design AC subnetwork distributed secondary control quantity;Based on voltage consistency error and proportional integral compensation design DC subnetwork distributed secondary control quantity;And through interconnection transformer adjustment bidirectional active power exchange between AC / DC subnetwork.This application can realize frequency / voltage recovery, power / current sharing and cross-subnet power coordination in AC / DC hybrid microgrid simultaneously, reduce centralized control dependence, improve collaborative operation performance and engineering applicability under heterogeneous distributed energy access condition.

Description

Technical Field

[0001] This invention relates to the fields of distributed control of microgrids and energy internet technology, and in particular to a distributed collaborative control method and system for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy. Background Technology

[0002] With a high proportion of distributed renewable energy being integrated into the distribution-side system, microgrids are gradually becoming the basic operating units in the energy internet. Distributed photovoltaic (PV), energy storage, electric vehicle charging facilities, and DC loads typically exhibit significant DC-side integration characteristics, while traditional AC loads and existing AC distribution infrastructure still hold a crucial position. Therefore, hybrid AC / DC microgrids, by simultaneously retaining both AC and DC buses, can accommodate both existing AC infrastructure and the integration needs of DC-type renewable energy / loads, making them an effective structure for improving energy conversion efficiency and enhancing system flexibility.

[0003] In AC / DC hybrid microgrids, bidirectional energy exchange between the AC and DC subgrids is typically achieved through interconnecting converters. These interconnecting converters not only perform power conversion but also directly impact power balance, frequency / voltage recovery, and dynamic power redistribution after disturbances between the AC and DC subgrids. If the interconnecting converter merely functions as a local power interface and is not integrated into a unified collaborative control framework, it becomes difficult to simultaneously ensure coordination of AC-side frequency, DC-side voltage, and the output ratios of various distributed energy sources under conditions such as load fluctuations, changes in distributed energy output, and cross-subgrid energy exchange.

[0004] Existing control methods for AC / DC hybrid microgrids mainly include centralized control, decentralized control, and partially distributed control. Centralized control relies on a central controller and global communication, which suffers from problems such as high communication burden, high risk of single-point failure, and insufficient engineering scalability. Decentralized control is usually based only on local measurement information, making it difficult to guarantee global power sharing and cross-subgrid power coordination. Existing distributed methods mostly focus on single AC microgrids or single DC microgrids, and the unified characterization of heterogeneous distributed renewable energy, interconnected converters, and AC / DC coupled operation objectives is still insufficient.

[0005] Furthermore, while traditional droop-based primary control can quickly achieve power balance at the local level, it introduces AC frequency deviation and DC bus voltage deviation. When the system contains heterogeneous distributed energy sources with different capacities, interface types, and droop coefficients, relying solely on primary control makes it difficult to accurately achieve frequency recovery, voltage recovery, and proportional power / current distribution. Therefore, it is necessary to propose a distributed cooperative control method suitable for AC / DC hybrid microgrids, enabling heterogeneous distributed energy sources and interconnected converters to participate in secondary coordinated control within a unified framework. Summary of the Invention

[0006] In view of this, the present invention provides a distributed collaborative control method and system for AC / DC hybrid microgrids with heterogeneous distributed renewable energy, addressing the problems of insufficient participation of interconnecting converters in the coordinated control of AC / DC subgrids, difficulty in unifying control objectives between AC and DC subgrids, strong dependence of centralized control on the central controller and global communication, and difficulty in achieving coordinated power allocation among distributed renewable energy units of different capacities and interface types in existing AC / DC hybrid microgrid control methods. The present invention can simultaneously achieve AC frequency recovery, DC bus voltage recovery, active power ratio sharing, DC output current ratio sharing, and power coordination between AC and DC subgrids, thereby improving the operational stability and coordinated control performance of AC / DC hybrid microgrids under load disturbances and cross-subgrid power exchange conditions.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, this invention provides a distributed collaborative control method for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy, comprising: The system collects operational data from an AC / DC hybrid microgrid and establishes a communication graph based on the information interaction relationships between control nodes. The operational data includes the output frequency, output voltage, active power, and reactive power of the AC distributed renewable energy units, the DC bus voltage and output current of the DC distributed renewable energy units, and the active power of the interconnected converters. The construction process of the communication graph includes: abstracting the local controllers corresponding to the AC distributed renewable energy units, DC distributed renewable energy units, and interconnected converters as control nodes; determining communication edges based on the existence of information transmission links and information reception directions between control nodes, and establishing an adjacency matrix accordingly; and determining the node degree matrix and Laplace matrix based on the adjacency matrix to characterize the information interaction relationships between control nodes. Local power balancing is performed on the AC and DC subnets based on primary control with droop characteristics. Based on the aforementioned operating quantities, a cross-subnet collaborative control state is constructed, which includes an AC frequency normalization state, a DC bus voltage normalization state, an active power sharing ratio, and a DC output current sharing ratio. Based on the AC frequency normalization state and the neighbor information of the AC subnet in the communication graph, an AC distributed secondary control quantity is generated. The neighbor information of the AC subnet includes the AC output frequency or AC frequency normalization state of the neighbor node, and the droop-weighted active power state of the neighbor node. Based on the normalized state of the DC bus voltage and the neighbor information of the DC subnet, a DC distributed secondary control quantity is generated by combining integral compensation. The neighbor information of the DC subnet includes the secondary voltage compensation quantity of the neighbor nodes. The secondary voltage compensation quantity is sent to the adjacent control nodes via the communication link to construct the voltage consistency error between adjacent nodes. Based on the AC frequency normalization state and the DC bus voltage normalization state, the cross-subgrid power exchange requirement is determined, and the interconnect converter power command is generated. The AC distributed secondary control quantity, the DC distributed secondary control quantity, and the interconnected converter power command are sent to the corresponding local control loops, and distributed cooperative control is executed in a closed loop.

[0008] Preferably, the communication diagram is represented as follows: ,in For the set of control nodes, Let be the set of communication edges; for the th The neighbor set of each control node is represented as The adjacency matrix is ​​represented as When the first The first control node can receive the first When information about each control node is received. ,otherwise .

[0009] Preferably, the primary control of the AC subnet satisfies , ; The primary control of the DC subnet satisfies , ; in, For the frequency of distributed renewable energy units; and These are the corresponding rated settings; and These are the droop coefficients; For alternating current to the voltage of distributed renewable energy units; To exchange the active power of distributed renewable energy units; For the reactive power of distributed renewable energy units; This is the voltage reference value. This is the rated voltage of the DC bus. This is the DC droop factor; This is the DC bus voltage. The output current for the DC distributed renewable energy unit. This is the equivalent resistance of a DC line.

[0010] Preferably, after constructing the cross-subnet cooperative control state based on the operating quantities, the method further includes: performing quantization dimension normalization processing on the AC frequency state quantities collected from the AC subnet and the DC bus voltage state quantities collected from the DC subnet.

[0011]

[0012] In the formula, To provide the output frequency of distributed renewable energy units for AC transmission. The upper limit of the allowed frequency for the communication subnet. This is the lower limit of the allowed frequency for the communication subnet. This is the DC bus voltage. This is the upper limit of the allowable bus voltage for the DC subnetwork. This is the lower limit of the allowable bus voltage for the DC subnetwork.

[0013] Preferably, based on the AC frequency normalization state and the neighbor information of the AC subnet in the communication graph, an AC distributed secondary control quantity is generated, specifically including: The auxiliary frequency control quantity is determined based on the difference between the node's AC frequency state quantity and the rated frequency, and the difference between the normalized AC frequency state quantities of neighboring nodes in the communication graph model. The auxiliary active power control quantity is determined based on the difference in the droop-weighted active power state quantities of neighboring nodes in the communication graph model. The auxiliary frequency control quantity and the auxiliary active power control quantity are integrated to generate the corrected AC subnet rated frequency setting value. AC distributed secondary control quantities are generated based on the corrected AC subnet rated frequency setting.

[0014] Preferably, the formula for calculating the auxiliary frequency control quantity is:

[0015] In the formula, For frequency control gain, The reference node access gain; when the node When the reference frequency can be obtained directly, Take a positive value, otherwise Set to 0; For AC rated frequency, For the output frequency of distributed renewable energy units; For the first The set of neighbors of a node. Let a be the output frequency of the j-th neighbor communication control node at time t; ij Let be the element in the i-th row and j-th column of the adjacency matrix; The formula for calculating the auxiliary active power control quantity is:

[0016] In the formula, For active power control gain, and The droop coefficient is... and To output active power.

[0017] Preferably, based on the normalized state of the DC bus voltage and the neighbor information of the DC subnet, the DC distributed secondary control quantity is generated by combining integral compensation, specifically including: The voltage error is determined based on the difference between the node DC bus voltage and the rated DC bus voltage, and the difference between the secondary voltage compensation amounts of neighboring nodes in the communication diagram. The voltage error is subjected to proportional-integral calculation to generate a secondary voltage compensation quantity, which is the distributed secondary control quantity.

[0018] Preferably, the cross-subgrid power exchange requirement is determined based on the normalized AC frequency state and the normalized DC bus voltage state, specifically including: Determine the power deficit between the total load power of the AC subgrid and the total output active power of the AC distributed renewable energy units; Based on the power deficit, generate the interconnect converter power initialization command; A limiting circuit is applied to the initial power command of the interconnect converter to obtain the power command of the interconnect converter within the capacity range of the interconnect converter.

[0019] On the other hand, the present invention provides a distributed collaborative control system for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy, comprising: The measurement and acquisition module is used to collect the operating data of AC distributed renewable energy units, DC distributed renewable energy units, and interconnected converters. The communication network module is used to establish the communication diagram of the control nodes; The primary control module is used to perform droop primary control of the AC subnet and the DC subnet; The state normalization module is used to generate AC frequency normalized state, DC bus voltage normalized state, active power sharing ratio, and DC output current sharing ratio. The AC collaborative control module is used to generate AC distributed secondary control quantities; The DC collaborative control module is used to generate DC distributed secondary control quantities; The interconnect converter power exchange module is used to generate bidirectional power exchange commands for the interconnect converter. The reference output module is used to send the AC distributed secondary control quantity, the DC distributed secondary control quantity, and the interconnected converter power command to the corresponding local control loop.

[0020] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a distributed collaborative control method and system for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy, which has the following beneficial effects: (1) This invention unifies AC frequency recovery, DC bus voltage recovery, active power ratio sharing, DC output current ratio sharing and bidirectional power exchange of interconnected converters into the same distributed collaborative control framework, avoiding the problem of the AC sub-network, DC sub-network and interconnected converter control objectives being separated in the traditional method, and improving the overall coordinated operation capability of AC-DC hybrid microgrid.

[0021] (2) The present invention constructs a distributed secondary control quantity based on neighbor node information and reference node information. Each distributed renewable energy unit does not need to rely on the central controller to obtain global state information, which reduces the burden on the communication network and improves the scalability and robustness of the system.

[0022] (3) The present invention fully considers the active adjustment role of the interconnection converter in the energy exchange between the AC subnet and the DC subnet, so that the interconnection converter not only serves as a power electronic interface, but also as an adjustment node for the coordinated operation of the AC and DC subnets, thereby improving the dynamic response capability under cross-subnet power disturbance.

[0023] (4) This invention is applicable to heterogeneous distributed renewable energy units with different capacities, different droop coefficients and different interface forms. It can maintain the stability of frequency, voltage and power distribution in operation scenarios such as load step, DC load access and AC / DC subgrid power exchange, and has strong engineering applicability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 A flowchart of the distributed collaborative control method for AC / DC hybrid microgrids provided by the present invention; Figure 2 A schematic diagram of the module structure of the AC / DC hybrid microgrid distributed collaborative control system provided by the present invention; Figure 3 This is a schematic diagram of the AC / DC hybrid microgrid test structure in an embodiment of the present invention; Figure 4 This is a schematic diagram of the AC / DC hybrid microgrid communication topology in an embodiment of the present invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1: Distributed cooperative control method.

[0028] See Figure 1 This embodiment provides a distributed collaborative control method for a hybrid AC / DC microgrid oriented towards heterogeneous distributed renewable energy. The hybrid microgrid includes an AC subgrid, a DC subgrid, and an interconnecting converter connecting the two. The AC subgrid contains several AC distributed renewable energy units, and the DC subgrid contains several DC distributed renewable energy units. Each distributed energy unit is connected to its corresponding bus via a local power electronic converter, and the interconnecting converter enables bidirectional power exchange between the AC and DC subgrids.

[0029] Step S1: Establish the communication graph model. Assume the AC / DC hybrid microgrid includes... There are 10 nodes participating in the collaborative control, among which Each node is located in the communication subnet. Each node is located in the DC subnet, and interconnected converter nodes are set up for cross-subnet power coordination. The communication network is represented as follows: , For a set of nodes, Let be the set of edges; the first... The neighbor set of each node is The adjacency matrix is If node Able to receive nodes The information, ,otherwise Laplace matrix The definition is as follows:

[0030] Equation (1) can be used to uniformly represent the communication relationship between the AC subnet, DC subnet and interconnecting converter, providing a structural basis for subsequent distributed consensus control.

[0031] Step S2, perform droop control once. For the AC subnet, the first... Each AC distributed renewable energy unit employs frequency-active power droop and voltage-reactive power droop, expressed as follows:

[0032] In the formula, and These are the output frequency and output voltage of the AC distributed renewable energy unit, respectively. and These are the corresponding rated settings; and These are the droop coefficients; and These are the output active power and the output reactive power, respectively.

[0033] For the DC subnetwork, the first Each DC distributed renewable energy unit employs voltage-current droop control, and its voltage reference value and bus voltage can be expressed as:

[0034] In the formula, This is the rated voltage of the DC bus. This is the DC droop factor. This is the DC output current. This is the equivalent resistance of a DC line. Because in engineering, it is usually... The DC output current sharing relationship can be approximated as:

[0035] Step S3: Construct the cross-subnet coordinated control state. Since the key recovery quantity for the AC subnet is frequency, and the key recovery quantity for the DC subnet is bus voltage, their dimensions are different, and direct comparison would affect cross-subnet coordination. Therefore, this embodiment normalizes the AC frequency and DC bus voltage:

[0036] In the formula, and These are the upper and lower frequency limits allowed for the AC subnet, respectively. and These are the upper and lower limits of the allowable bus voltage for the DC subgrid, respectively. Through equations (6) and (7), the AC frequency state and DC voltage state are converted into dimensionless state quantities, which can then participate in control under a unified and coordinated framework.

[0037] The distributed secondary control objectives of this embodiment include:

[0038] In the formula, For AC rated frequency, For the first The rated capacity of each distributed energy unit, The active power command for the interconnect converter. For the active power of the AC side load, For interconnect converter capacity limits, This is the amplitude limiting function.

[0039] Step S4: Design the distributed secondary control variables for the AC subnet. For AC frequency control, construct the auxiliary frequency control variables:

[0040] In the formula, For frequency control gain, The reference node access gain; when the node When the reference frequency can be obtained directly, Take a positive value, otherwise Take 0.

[0041] To achieve active power sharing according to capacity ratio, an auxiliary active power control quantity is introduced:

[0042] In the formula, The active power control gain is given by applying equations (11) and (12) together to the frequency setpoint of the AC distributed energy source, resulting in:

[0043] Therefore, the AC subnet can eliminate frequency deviation through reference node entries and achieve power sharing according to capacity ratio through the droop-weighted active power difference of neighboring nodes.

[0044] Step S5: Design the distributed secondary control variables for the DC subgrid. To compensate for the bus voltage deviation caused by DC droop control, a secondary voltage compensation variable is introduced into the DC bus voltage model. :

[0045] The secondary voltage compensation amount is obtained through proportional-integral consistency control:

[0046] In the formula, and These are proportional gain and integral gain, respectively. This is the voltage control gain. The first term in equation (16) is used to ensure consistency in the secondary voltage compensation of adjacent nodes, and the second term is used to restore the DC bus voltage to its rated value. .

[0047] Step S6, power coordination of the interconnect converter. The power flow direction of the interconnect converter is defined as positive from the DC subgrid to the AC subgrid. When the AC load power is greater than the sum of the active power output of the AC distributed energy sources, the interconnect converter injects active power from the DC side to the AC side; when there is an active power surplus on the AC side, the interconnect converter transmits power in the reverse direction to the DC side or the energy storage side. The output power of the interconnect converter is preferably generated according to equation (10), and safe operation is ensured by capacity limiting and power change rate constraints.

[0048] Step S7, Reference Output and Closed-Loop Execution. Each distributed control node calculates the secondary control quantity based on local measurement information, neighbor communication information, and reference node information, and updates the output. , and The control signals are respectively sent to the local converter control loop and the interconnected converter control loop, ultimately realizing the distributed and coordinated operation of the AC / DC hybrid microgrid.

[0049] Example 2: Distributed collaborative control system.

[0050] See Figure 2 This embodiment provides a distributed collaborative control system for a hybrid AC / DC microgrid oriented towards heterogeneous distributed renewable energy. The measurement and acquisition module collects AC frequency, AC active power, AC reactive power, DC bus voltage, DC output current, and interconnect converter power. The communication network module generates an adjacency matrix and a Laplace matrix based on topology relationships. The primary control module executes AC and DC droop control. The state normalization module generates cross-subgrid collaborative states. The AC collaborative control module calculates frequency recovery control quantities and active power sharing control quantities. The DC collaborative control module calculates voltage recovery control quantities and current sharing control quantities. The interconnect converter power exchange module generates bidirectional power exchange commands. The reference output module outputs the control commands to each local control loop.

[0051] In one implementation, the above modules can be deployed in each distributed energy local controller and interconnected converter controller, and each node only needs to communicate with its neighboring nodes to complete the control quantity calculation. In another implementation, the communication network module and state normalization module can be deployed in the edge controller, while the AC collaborative control module, DC collaborative control module, and interconnected converter power exchange module are still deployed in the local controller. All of the above deployment methods fall within the protection scope of this invention.

[0052] Example 3: AC / DC hybrid microgrid test structure.

[0053] See Figure 3The test system includes four AC distributed renewable energy units, three DC distributed renewable energy units, and one interconnect converter. The AC subgrid includes an AC bus, AC loads, and an LC filter interface; the DC subgrid includes a DC bus, DC loads, and a DC-side LC filter interface; the interconnect converter is located between the AC and DC buses and is used to achieve bidirectional active power exchange.

[0054] See Figure 4 In the diagram, 0 represents the communication control node corresponding to the interconnect converter; reference numerals 1, 2, 3, and 4 in the AC subnet represent the local control nodes corresponding to the four AC distributed renewable energy units, with node 1 connected to the reference node and capable of receiving the rated frequency reference value; reference numerals 1, 2, and 3 in the DC subnet represent the local control nodes corresponding to the three DC distributed renewable energy units. The directed lines in the diagram indicate the information reception direction between nodes, and node 0 is used to achieve cross-subnet information coordination between the AC and DC subnets. This communication topology is only an example; those skilled in the art can make equivalent adjustments to the topology based on the actual line structure, communication constraints, and controller arrangement.

[0055] In the test conditions, the AC subnet first operates under droop control, and then the distributed collaborative control is initiated; the DC subnet can initiate the distributed collaborative control earlier; under the conditions of load step, DC subnet injecting active power into AC subnet through interconnection converter, and new load access on the DC side, the control method can restore the AC frequency to the rated frequency, restore the DC bus voltage to the rated voltage, and keep the AC active power sharing ratio and DC output current sharing ratio consistent.

[0056] Example 4: Stability description.

[0057] Under the conditions that the communication graph has a spanning tree or a reachable reference node, all control gains are positive, and the interconnect converter capacity constraints meet the operational requirements, the AC frequency error, droop-weighted active power error, DC bus voltage error, and DC current shared error can form a closed-loop error vector. For distributed consensus closed-loop systems, the Lyapunov function can be used. From equations (11) to (16), it can be seen that the error dynamics include positive semi-definite / positive definite terms composed of the Laplace matrix and the access gain of the reference node; when at least one reference node is reachable from the corresponding subnet, the closed-loop error system satisfies the following near the operating point. ,in It is a positive number related to the control gain and the communication topology. It can be seen that the closed-loop error converges to zero or a specified small neighborhood, thereby achieving the control objectives described in equations (8) and (9).

[0058] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0059] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A distributed collaborative control method for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy, characterized in that, include: The system collects operational data from an AC / DC hybrid microgrid and establishes a communication graph based on the information interaction relationships between control nodes. The operational data includes the output frequency, output voltage, active power, and reactive power of the AC distributed renewable energy units (DREEs), the DC bus voltage and output current of the DC DREEs, and the active power of the interconnected converters. The construction process of the communication graph includes: abstracting the local controllers corresponding to the AC DREEs, DC DREEs, and interconnected converters as control nodes; determining communication edges based on the existence of information transmission links and information reception directions between control nodes, and establishing an adjacency matrix accordingly; and determining the node degree matrix and Laplace matrix based on the adjacency matrix to characterize the information interaction relationships between control nodes. The communication graph is represented as follows: ,in For the set of control nodes, Let be the set of communication edges; for the th The neighbor set of each control node is represented as The adjacency matrix is ​​represented as When the first The first control node can receive the first When information about each control node is received. ,otherwise ; Local power balancing is performed on the AC and DC subnets based on primary control with droop characteristics. Based on the aforementioned operating quantities, a cross-subnet collaborative control state is constructed, which includes an AC frequency normalization state, a DC bus voltage normalization state, an active power sharing ratio, and a DC output current sharing ratio. Based on the AC frequency normalization state and the neighbor information of the AC subnet in the communication graph, a distributed secondary control quantity for AC is generated. The neighbor information of the AC subnet includes the AC output frequency or AC frequency normalization state of the neighbor nodes, and the droop-weighted active power state of the neighbor nodes. The specific process is as follows: The auxiliary frequency control quantity is determined based on the difference between the node's AC frequency state quantity and the rated frequency, and the difference between the normalized AC frequency state quantities of neighboring nodes in the communication graph model. The auxiliary active power control quantity is determined based on the difference in the droop-weighted active power state quantities of neighboring nodes in the communication graph model. The auxiliary frequency control quantity and the auxiliary active power control quantity are integrated to generate the corrected AC subnet rated frequency setting value. AC distributed secondary control quantities are generated based on the corrected AC subnet rated frequency setpoint. Based on the normalized state of the DC bus voltage and the neighbor information of the DC subnet, a DC distributed secondary control quantity is generated by combining integral compensation. The neighbor information of the DC subnet includes the secondary voltage compensation quantity of neighboring nodes. The secondary voltage compensation quantity is sent to adjacent control nodes via a communication link to construct the voltage consistency error between adjacent nodes. The specific process is as follows: The voltage error is determined based on the difference between the node DC bus voltage and the rated DC bus voltage, and the difference between the secondary voltage compensation amounts of neighboring nodes in the communication diagram. Perform proportional-integral calculations on the voltage error to generate a secondary voltage compensation quantity, which is the distributed secondary control quantity. Based on the AC frequency normalization state and the DC bus voltage normalization state, the cross-subgrid power exchange requirement is determined, and the interconnect converter power command is generated. The AC distributed secondary control quantity, the DC distributed secondary control quantity, and the interconnected converter power command are sent to the corresponding local control loops, and distributed cooperative control is executed in a closed loop.

2. The distributed collaborative control method for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy as described in claim 1, characterized in that, The primary control of the AC subnet satisfies , ; The primary control of the DC subnet satisfies , ; in, For the frequency of distributed renewable energy units; and These are the corresponding rated settings; and These are the droop coefficients; For alternating current to the voltage of distributed renewable energy units; To exchange the active power of distributed renewable energy units; For the reactive power of distributed renewable energy units; This is the voltage reference value. This is the rated voltage of the DC bus. This is the DC droop factor; This is the DC bus voltage. The output current for the DC distributed renewable energy unit. This is the equivalent resistance of a DC line.

3. The distributed collaborative control method for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy as described in claim 1, characterized in that, After constructing the cross-subnet cooperative control state based on the aforementioned operational quantities, the process further includes: performing quantization dimension normalization on the AC frequency state quantities collected from the AC subnet and the DC bus voltage state quantities collected from the DC subnet. In the formula, To provide the output frequency of distributed renewable energy units for AC transmission. The upper limit of the allowed frequency for the communication subnet. This is the lower limit of the allowed frequency for the communication subnet. This is the DC bus voltage. This is the upper limit of the allowable bus voltage for the DC subnetwork. This is the lower limit of the allowable bus voltage for the DC subnetwork.

4. The distributed collaborative control method for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy as described in claim 1, characterized in that, The formula for calculating the auxiliary frequency control quantity is: In the formula, For frequency control gain, The reference node access gain; when the node When the reference frequency can be obtained directly, Take a positive value, otherwise Set to 0; For AC rated frequency, For the output frequency of distributed renewable energy units; For the first The set of neighbors of a node. Let a be the output frequency of the j-th neighbor communication control node at time t; ij Let be the element in the i-th row and j-th column of the adjacency matrix; The formula for calculating the auxiliary active power control quantity is: In the formula, For active power control gain, and The droop coefficient is... and To output active power.

5. The distributed collaborative control method for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy as described in claim 1, characterized in that, Based on the normalized AC frequency state and the normalized DC bus voltage state, the cross-subgrid power exchange requirement is determined, specifically including: Determine the power deficit between the total load power of the AC subgrid and the total output active power of the AC distributed renewable energy units; Based on the power deficit, generate the interconnect converter power initialization command; A limiting circuit is applied to the initial power command of the interconnect converter to obtain the power command of the interconnect converter within the capacity range of the interconnect converter.

6. A distributed collaborative control system for AC / DC hybrid microgrids oriented towards heterogeneous distributed renewable energy, characterized in that, include: The measurement and acquisition module is used to collect the operating data of AC distributed renewable energy units, DC distributed renewable energy units, and interconnected converters. The communication network module is used to establish the communication diagram of the control nodes; The primary control module is used to perform droop primary control of the AC subnet and the DC subnet; The state normalization module is used to generate AC frequency normalized state, DC bus voltage normalized state, active power sharing ratio, and DC output current sharing ratio. The AC collaborative control module is used to generate AC distributed secondary control quantities; The DC collaborative control module is used to generate DC distributed secondary control quantities; The interconnect converter power exchange module is used to generate bidirectional power exchange commands for the interconnect converter. The reference output module is used to send the AC distributed secondary control quantity, the DC distributed secondary control quantity, and the interconnected converter power command to the corresponding local control loop.

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