A large-scale source-storage distributed collaborative control system and method for a multi-DC microgrid

Abstract

The present disclosure belongs to the technical field of microgrid control, and specifically relates to a large-scale source-storage distributed collaborative control system and method for a DC microgrid, including: a DC microgrid module, including at least two DC microgrids, each of the DC microgrids internally provided with a large-scale distributed power source and an electrical load; a distributed power source converter collaborative control module within the microgrid, including a voltage and current consistency control unit and a droop control unit, eliminating the voltage static error and power distribution error generated by the droop control unit through the voltage and current consistency control unit; a multi-port interconnection converter module between microgrids, connecting the plurality of DC microgrid modules, increasing the number of ports according to the number of the DC microgrids, and controlling the power flow between the DC microgrids based on a symmetric phase-shifted control strategy to achieve balanced power output of the DC microgrids and non-error control of the bus voltage.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of microgrid control, and particularly relates to a large-scale source-storage distributed collaborative control system and method for multiple DC microgrids. Background Art

[0002] The statements in this part only provide background technical information related to the present disclosure and do not necessarily constitute prior art.

[0003] With the continuous advancement of energy transformation, DC microgrids have received extensive attention in the fields of new energy power generation and power consumption due to the absence of problems such as frequency synchronization and reactive power compensation. Since a DC microgrid needs to maintain the stability of the DC bus voltage, it is necessary to control the power output of each distributed power source within the DC microgrid; at the same time, multiple DC microgrids form a DC microgrid cluster, and mutual support of power output is required between each sub-grid to support the bus voltage; to achieve balanced power output of each distributed power source, and stable and error-free bus voltages of each DC microgrid.

[0004] According to the inventor's understanding, the traditional control methods for distributed power sources within a DC microgrid include centralized control and decentralized control; among them, the controller for centralized control needs to obtain the parameters of all distributed power sources and loads, and centrally calculate the power that each distributed power source needs to output; decentralized control is mainly based on droop control, and each distributed power source calculates the output voltage reference according to its own droop characteristics and output power. Distributed control based on the consensus algorithm is a control method between centralized control and decentralized control, which reaches an agreement on the control objectives of the circuit under a sparse communication network.

[0005] However, due to the existence of droop characteristics and line impedance in droop control, droop control cannot achieve error-free control of the bus voltage and precise balanced power output of distributed power sources. Distributed control based on the consensus algorithm can reach an agreement on the average value of the DC bus voltage under a sparse communication network, and at the same time achieve balanced power output of distributed power sources. However, traditional distributed control only considers the control of distributed power sources within a single DC microgrid, does not involve the control of interconnection converters between DC microgrids, and does not achieve mutual support and mutual assistance of power output among multiple DC microgrids under a sparse communication network.

[0006] Existing control schemes for multi-port interconnection converters between DC microgrids need to obtain the droop control parameters of all converters within each DC microgrid and parameters such as converter voltage and current; this control scheme highly depends on the parameters of each distributed power source and the communication network, and has low reliability and accuracy; only power control is performed on the multi-port interconnection converter, and the problem of DC bus voltage error is not considered. Summary of the Invention

[0007] To solve the above problems, the present disclosure proposes a large-scale source-storage distributed collaborative control system and method for a multi-DC microgrid. Through the designed large-scale source-storage distributed collaborative control system for the DC microgrid, the average value of the DC bus voltage can be stably and error-free under a sparse communication network, the power output among microgrids can be mutually supplemented and supported, and the power output of each distributed power source can be balanced. Furthermore, it solves the problems of voltage static error and power output balance caused by droop control and line impedance of distributed power sources in the DC microgrid, as well as the problem that the control of the interconnected converters for power output mutual supplementation among DC microgrids highly depends on the parameters and communication of each distributed power source.

[0008] According to some embodiments, the first solution of the present disclosure provides a large-scale source-storage distributed collaborative control system for a DC microgrid, adopting the following technical solutions:

[0009] A large-scale source-storage distributed collaborative control system for a DC microgrid, comprising:

[0010] A DC microgrid module, including at least two DC microgrids, each of the DC microgrids internally provided with a large-scale distributed power source (i.e., an energy storage unit and a distributed generation unit) and an electrical load;

[0011] A distributed power source converter collaborative control module within the microgrid, including a voltage and current consistency control unit and a droop control unit, eliminating the voltage static error and power distribution error generated by the droop control unit through the voltage and current consistency control unit;

[0012] A multi-port interconnected converter module among microgrids, connecting the multiple DC microgrid modules, increasing the number of ports according to the number of the DC microgrids, and controlling the power flow between the DC microgrids based on a symmetric phase-shift control strategy to achieve balanced power output of the DC microgrids and error-free control of the bus voltage.

[0013] As a further technical limitation, the large-scale source-storage distributed collaborative control system for the DC microgrid further includes a DC bus average voltage observer, estimating the average value of the current bus voltage based on a consistency algorithm when each DC bus average voltage observer only communicates with the DC bus average voltage observers of neighboring nodes.

[0014] As a further technical limitation, the DC microgrids are DC microgrids with different voltage levels or DC microgrids with the same voltage level.

[0015] As a further technical limitation, the distributed power source converter collaborative control module within the microgrid further includes a network communication unit with neighboring nodes.

[0016] According to some embodiments, the second solution of the present disclosure provides a DC microgrid large-scale source-storage distributed coordinated control method, which adopts the DC microgrid large-scale source-storage distributed coordinated control system provided in the first solution and adopts the following technical solutions:

[0017] A large-scale distributed source-storage cooperative control method for a DC microgrid is proposed. Based on the coordinated control module of the distributed power converter within a single microgrid, a multi-port interconnected converter module between microgrids is introduced to connect multiple DC microgrids. Based on the consistency algorithm and droop control, the voltage static difference and power distribution error are eliminated, and the symmetrical phase-shift control is adopted to achieve the balanced output of the DC microgrid and the error-free control of the bus voltage.

[0018] As a further technical limitation, when there is current on the DC bus, the voltages at different points on the DC bus are not exactly the same due to the existence of the DC bus impedance. It is necessary to use a consistency algorithm to estimate the average value of the current bus voltage when each DC bus average voltage observer only communicates with the DC bus average voltage observer of the neighboring node; the specific process is:

[0019] Get the estimated average voltage of the node's neighboring nodes;

[0020] Obtaining a local voltage sampling value of the node and using the obtained local voltage sampling value as an initial value of the bus average voltage estimation value;

[0021] Calculate the voltage error between the estimated value of the bus average voltage of the node and the estimated value of the neighboring nodes;

[0022] The obtained voltage error is input into the error controller, and the output value of the error controller is compensated to the acquired local voltage sampling value to obtain the estimated value of the average bus voltage of the node.

[0023] Furthermore, the specific process of eliminating voltage static error and power distribution error based on consistency algorithm and droop control is as follows:

[0024] Obtaining an estimated average voltage and a per-unit current value of a neighboring node based on communication with the neighboring node;

[0025] According to the obtained average voltage estimation value and current per unit value, combined with the DC bus average voltage observer, the current DC bus average voltage is estimated;

[0026] The DC bus voltage error is obtained by subtracting the obtained DC bus average voltage from the DC bus voltage reference value;

[0027] Subtract the obtained neighbor node current per unit value from the local current per unit value to obtain the current per unit value error;

[0028] The obtained DC bus voltage error and per-unit current error are respectively input into the bus voltage controller and the current controller;

[0029] The DC bus voltage reference values respectively output by the voltage controller and the current controller are added together and then output to the droop controller;

[0030] The droop controller obtains the local current value and calculates the reference value of the output voltage of the converter port, and controls the output of the distributed power converter;

[0031] The local per-unit current value and the average value of the bus voltage estimated by the voltage observer are sent to the neighbor nodes.

[0032] As a further technical limitation, the power flow between the microgrids is controlled based on the multi-port interconnected converter module, enabling the multi-microgrids to mutually support their power outputs, and finally achieving balanced power outputs of each microgrid, stable and zero-error voltages of each microgrid. The specific process is as follows:

[0033] The interconnected converter communicates with the neighbor nodes in the connected DC microgrid to obtain the per-unit current values and average voltage estimation values of all neighbor nodes;

[0034] The average voltage estimation values of each microgrid are respectively obtained through the DC bus average voltage observer, and the average value of the per-unit current values of two neighbor nodes in each calculated microgrid is used as the per-unit current value reflecting the overall power output of each microgrid;

[0035] Based on the multi-port interconnected converter module, the difference between the average voltage estimation value of each microgrid and the voltage reference value of each microgrid is calculated to obtain the voltage error of each microgrid;

[0036] The obtained voltage error and current error are respectively sent into the corresponding bus voltage controller and current controller;

[0037] The outputs of the bus voltage controller and the current controller of the same microgrid are added together to obtain the phase shift signal of the port of the interconnected converter connected to the current microgrid;

[0038] All the phase shift signals are sent into the square wave phase shift modulator to obtain the switch control signals of all ports of the multi-port interconnected converter;

[0039] The average voltage of each microgrid bus estimated by the interconnected converter and the per-unit current value of each microgrid are sent to the neighbor nodes in the corresponding microgrid, and the per-unit current value obtained by the corresponding neighbor node at the interconnected converter is the per-unit current value of the neighbor microgrid of the overall power output of the microgrid.

[0040] According to some embodiments, the third solution of the present disclosure provides a computer-readable storage medium, adopting the following technical solution:

[0041] A computer-readable storage medium stores a program thereon, and when the program is executed by a processor, the steps in the DC microgrid large-scale source-storage distributed collaborative control method described in the second aspect of the present disclosure are implemented.

[0042] According to some embodiments, the fourth aspect of the present disclosure provides an electronic device, adopting the following technical solution:

[0043] An electronic device includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, the steps in the DC microgrid large-scale source-storage distributed collaborative control method described in the second aspect of the present disclosure are implemented.

[0044] Compared with the prior art, the beneficial effects of the present disclosure are as follows:

[0045] The present disclosure adopts a sparse communication network design, which can simultaneously implement control within and between microgrids, has high system stability and certain fault tolerance; considering the problems of DC bus voltage error and power distribution error caused by bus impedance and droop control, it can achieve zero DC bus voltage error and balanced output of each distributed power source; the multi-port interconnected converter adopts symmetric control, reduces the DC bias of the inductor current, can quickly achieve mutual support and mutual assistance in power output between microgrids, and can also achieve zero microgrid voltage control; it has strong scalability, and distributed power sources and interconnected converters within the DC microgrid can achieve plug-and-play. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The specification drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The schematic embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation to the present disclosure.

[0047] Figure 1 is the structural diagram of the DC microgrid module in the embodiment of the present disclosure;

[0048] Figure 2 is the internal communication topology diagram of the DC microgrid in the embodiment of the present disclosure;

[0049] Figure 3 is the structural diagram of the DC bus average voltage observer in the embodiment of the present disclosure;

[0050] Figure 4 is the structural diagram of the distributed power source converter collaborative control module within the microgrid in the embodiment of the present disclosure;

[0051] Figure 5 is the circuit topology diagram of the multi-port interconnected converter module in the embodiment of the present disclosure;

[0052] Figure 6 is the communication and control block diagram of the multi-port interconnected converter in the embodiment of the present disclosure. Detailed implementation manners

[0053] The present disclosure will be further described below in conjunction with the accompanying drawings and embodiments.

[0054] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further descriptions of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present disclosure belongs.

[0055] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary implementation manners according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that when the terms "include" and / or "comprise" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0056] Without conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other.

[0057] Embodiment 1

[0058] Embodiment 1 of the present disclosure introduces a large-scale source-storage distributed collaborative control system for DC microgrids.

[0059] The power mutual assistance between DC microgrids with different voltage levels is carried out through interconnected multi-port converters. Traditional interconnected converter control needs to calculate the transmission power of the converter according to the output power of distributed power sources between different microgrids after obtaining the parameters of each distributed power source inside the DC microgrid. For this reason, this embodiment provides a large-scale source-storage distributed collaborative control system for DC microgrids, which realizes the collaborative control of multi-port interconnected converters between distributed power sources within multiple microgrids and the microgrids under sparse communication network conditions, thereby realizing the power mutual assistance and mutual support between multiple DC microgrids with different voltage levels or that cannot be directly connected, and finally realizing the balanced output of the converters in each DC microgrid and the stable and error-free bus voltage of each DC microgrid.

[0060] As Figure 1 shown in the power mutual assistance structure topology of the multi-DC microgrid module, the multi-DC microgrid module is composed of three or more DC microgrids with different voltage levels or the same voltage level. This embodiment takes three DC microgrids as an example to give a schematic structure diagram. Equivalent each converter in Figure 1 to a node, and design the node communication topology shown in Figure 2 . Among them, the multi-port interconnected converter connected to the DC microgrid is also equivalent to a node inside the microgrid.

[0061] In each microgrid, any node communicates only with its adjacent nodes. The interconnected converter acts as a bridge for communication between DC microgrids, and communicates with its two adjacent nodes in each DC microgrid. Figure 2 The three ports of the multi-port interconnected converter are connected to three microgrids respectively, so there are six nodes communicating with the multi-port interconnected converter. Inside the three microgrids, the nodes of the multi-port interconnected converter are numbered t, a, and b, respectively, indicating that the interconnected converter is connected to node t, node a, and node b of the DC microgrid respectively. In different DC microgrids, the interconnected converter can be connected to any node of the microgrid, and it only needs to be numbered in sequence according to the node position.

[0062] like Figure 3 The DC bus average voltage observer shown in the figure, when there is current on the DC bus, the voltage at each point on the DC bus is not exactly the same due to the existence of the DC bus impedance. The role of the average bus voltage observer is to estimate the average value of the current bus voltage based on the consistency algorithm when each DC bus average voltage observer only communicates with neighboring nodes.

[0063] like Figure 4 The distributed power converter cooperative control module in the microgrid shown includes a voltage and current consistency control part, a droop control part, and network communication with neighboring nodes. Since traditional droop control has voltage static error and power distribution error, this error needs to be eliminated through the consistency control part.

[0064] like Figure 5 The topology of the multi-port interconnected converter module shown in FIG. 1 can increase the number of ports according to the number of DC microgrids. This embodiment is described by taking a three-port interconnected converter as an example.

[0065] like Figure 6 As shown in the communication and control block diagram of the multi-port interconnected converter, the traditional phase-shift control uses the square wave control signal of one port of the multi-port converter as the reference, and the other ports are phase-shifted relative to the reference signal. The phase-shifting method adopted in this embodiment is symmetrical phase-shifting control, and the square wave signals of all ports can be phase-shifted. This ensures the symmetry of the control of multiple DC microgrids. When the phase-shifted signal fluctuates rapidly, the DC bias of the converter inductor current can also be reduced. The main function of the symmetrical controller of the multi-port interconnected converter between microgrids is to control the power flow between microgrids, so that multiple microgrids can assist each other in output, and finally achieve balanced output of each microgrid and stable voltage of each microgrid.

[0066] A DC microgrid large-scale source-storage distributed coordinated control system, comprising:

[0067] A DC microgrid module, comprising at least two DC microgrids, each of which is equipped with a large-scale distributed power source (i.e., an energy storage unit and a distributed power generation unit) and a power load;

[0068] DC bus average voltage observer, which estimates the average value of the current bus voltage based on the consensus algorithm when each DC bus average voltage observer communicates only with the DC bus average voltage observers of neighboring nodes.

[0069] Distributed power converter cooperative control module in the microgrid, including a voltage and current consensus control unit and a droop control unit, which eliminates the voltage static error and power distribution error generated by the droop control unit through the voltage and current consensus control unit.

[0070] Multi-port interconnected converter module between microgrids, which connects the multiple DC microgrid modules, increases the number of ports according to the number of the DC microgrids, and controls the power flow between the DC microgrids based on the symmetric phase-shifted control strategy to achieve the balanced output of the DC microgrids and the non-error control of the bus voltage.

[0071] Existing microgrid control technologies only consider the control of a single microgrid, and can achieve the non-error control of the bus voltage of a single microgrid and the balanced output of distributed power sources; existing multi-microgrid control technologies require a complex centralized communication network, and the system stability is poor; the bus voltage offset caused by the bus impedance is not considered, and the non-error control of the bus voltage cannot be achieved; moreover, the control between multiple DC microgrids is asymmetric, which will cause a DC bias in the inductor current of the interconnected converter and reduce the service life.

[0072] The DC microgrid large-scale source-storage distributed cooperative control system introduced in this embodiment can achieve the mutual support and mutual assistance of the outputs of multiple DC microgrids with different voltage levels or that cannot be directly connected. Finally, the converters in each DC microgrid output evenly, and the bus voltages of each DC microgrid are stable and error-free.

[0073] Embodiment 2

[0074] Based on the DC microgrid large-scale source-storage distributed cooperative control system introduced in Embodiment 1, Embodiment 2 of the present disclosure introduces a DC microgrid large-scale source-storage distributed cooperative control method.

[0075] Based on the distributed power converter cooperative control module in a single microgrid in this embodiment, a multi-port interconnected converter module between microgrids is introduced to connect multiple DC microgrids. Based on the consensus algorithm and droop control, the voltage static error and power distribution error are eliminated, and the symmetric phase-shifted control is adopted to achieve the balanced output of the DC microgrids and the non-error control of the bus voltage.

[0076] As Figure 3 shown, the DC bus average voltage observer estimates the average value of the current bus voltage based on the consensus algorithm when each DC bus average voltage observer communicates with neighboring nodes. Among them, in the figure, V est.i 、Vspl.i respectively represent the sampled value of the DC bus voltage at node i locally and the estimated value of the average DC bus voltage, V est.(i-1) and V est.(i+1) respectively represent the estimated values of the average DC bus voltages of the neighbor nodes obtained by node i communicating with two neighbor nodes. The specific process is as follows:

[0077] (1) Obtain the estimated values of the average voltages of the neighbor nodes of node i, V est.(i-1) 、V est.(i+1) ;

[0078] (2) Obtain the locally sampled voltage value V spl.i of node i and use it as the initial value of the estimated value V est.i of the bus average voltage;

[0079] (3) Calculate the error between the estimated value of the bus average voltage of node i and the estimated values of the neighbor nodes;

[0080] (4) Send the voltage error obtained in step (3) to the error controller;

[0081] (5) Compensate the output of the error controller to the locally sampled voltage value obtained in step (2) to obtain the estimated value V est.i of the bus average voltage of node i;

[0082] Among them, the error controller can adopt various control methods including but not limited to proportional control, integral control, proportional-integral control, predictive control, etc.; when node i is the last node in the communication network, its neighbor nodes are i - 1 and 1.

[0083] Such as Figure 4 shown in the coordinated control module of the distributed power converter in the microgrid. In the figure is the per-unit value of the current, indicating the output of the converter at node i; i i represents the actual output current of the current converter; represents the reference value of the port output voltage of the current converter calculated by droop control; the specific process is as follows:

[0084] (1) Communicate with neighbor nodes to obtain the estimated values of the average voltages and per-unit values of the currents of the neighbor nodes;

[0085] (2) Send the information obtained by communication and the local sampling information into the DC bus average voltage observer to estimate the average voltage of the current DC bus;

[0086] (3) Subtract the average value of the DC bus voltage obtained in step (2) from the reference value of the DC bus voltage to obtain the DC bus voltage error;

[0087] (4) Subtract the per-unit value of the neighbor node current obtained from communication from the per-unit value of the local current to obtain the per-unit value error of the current;

[0088] It can be understood that here, since there are two neighbor nodes, after obtaining the per-unit value errors of the two neighbor nodes respectively, the two obtained per-unit value errors of the current are added together as the per-unit value error of the current of the current node;

[0089] (5) Input the voltage error and current error obtained in steps (3) and (4) into the bus voltage controller and current controller respectively;

[0090] (6) Add the outputs of the voltage controller and current controller to the voltage reference of the DC bus, and then output to the droop controller;

[0091] (7) The droop controller obtains the local current value and calculates the reference value of the output voltage of the converter port to control the output of the converter;

[0092] (8) Send the per-unit value of the local current and the average value of the bus voltage estimated by the voltage observer to the neighbor nodes;

[0093] Among them, the voltage and current controllers can adopt various control methods including but not limited to proportional control, integral control, proportional-integral control, predictive control, etc.; when node i is the last node of the communication network, its neighbor nodes are i - 1 and 1. When the neighbor node is an interconnected converter, the information obtained is based on the information sent by the interconnected converter. The calculation method is exactly the same as the previous steps.

[0094] Such as Figure 5 shown in the multi-port interconnected converter module, which adopts symmetric phase-shifted control. The specific process is as follows:

[0095] (1) The interconnected converter communicates with the neighbor nodes in the connected DC microgrid to obtain the per-unit values of the currents and the estimated average voltage values of all neighbor nodes;

[0096] (2) The average voltage observer estimates the average voltages V est.t 、V est.a 、V est.b ……V est.k of each microgrid respectively; Calculate the average value of the per-unit values of the currents of two neighbor nodes in each microgrid as the per-unit value of the current of each microgrid reflecting the overall output of each microgrid;

[0097] (3) Subtract the estimated average voltage value of each microgrid of the interconnected converter from the voltage reference value of each microgrid to obtain the voltage error of each microgrid;

[0098] Current error calculation method 1: The per-unit value of the current of Microgrid 2 minus the per-unit value of the current of Microgrid 1 is used as the current error of Microgrid 1, and the per-unit value of the current of Microgrid 3 minus the per-unit value of the current of Microgrid 2 is used as the current error of Microgrid 2. And so on, the per-unit value of the current of Microgrid 1 minus the per-unit value of the current of Microgrid N is used as the current error of Microgrid N;

[0099] Current error calculation method 2: For a system with N microgrids, the current error of the i-th microgrid is the sum of the per-unit values of the microgrid currents of the i-1-th and i+1-th microgrids minus the per-unit value of the current of the i-th microgrid respectively. When i is 1, the parameters of the N-th microgrid are used to replace the i-1-th microgrid. When i is N, the parameters of the 1st microgrid are used to replace the i+1-th microgrid.

[0100] Taking a 3-microgrid system as an example, the expression of the current error of Microgrid 1 is as follows:

[0101]

[0102] (4) Send the obtained voltage error and current error into the corresponding bus voltage controller and current controller respectively;

[0103] (5) Add the outputs of the bus voltage controller and current controller of the same microgrid to obtain the phase shift signal of the interconnection converter port connected to the current microgrid;

[0104] (6) Send all the phase shift signals D1, D2... D N into the square wave phase shift modulator to obtain the switch control signals of all ports of the multi-port interconnection converter;

[0105] (7) Send the average bus voltage of each microgrid estimated by the interconnection converter and the per-unit value of the current of each microgrid to the neighbor nodes in the corresponding microgrid; the per-unit value of the current obtained by the corresponding neighbor nodes at the interconnection converter is the per-unit value of the microgrid current representing the overall output of the neighbor microgrid;

[0106] Among them, the voltage and current controllers can adopt various control methods including but not limited to proportional control, integral control, proportional-integral control, predictive control, etc.

[0107] Embodiment 3

[0108] Embodiment 3 of the present disclosure provides a computer-readable storage medium.

[0109] A computer-readable storage medium, on which a program is stored, and when the program is executed by a processor, it implements the steps in the DC microgrid large-scale source-storage distributed cooperative control method as described in Embodiment 2 of the present disclosure.

[0110] The detailed steps are the same as those of the DC microgrid large-scale source-storage distributed cooperative control method provided in Embodiment 2, and will not be repeated here.

[0111] Embodiment 4

[0112] Embodiment 4 of the present disclosure provides an electronic device.

[0113] An electronic device includes a memory, a processor, and a program stored on the memory and executable on the processor. When the processor executes the program, it implements the steps in the DC microgrid large-scale source-storage distributed collaborative control method described in Embodiment 2 of the present disclosure.

[0114] The detailed steps are the same as those of the DC microgrid large-scale source-storage distributed collaborative control method provided in Embodiment 2 and will not be elaborated here.

[0115] The above are only the preferred embodiments of the present disclosure and are not used to limit the present disclosure. For those skilled in the art, the present disclosure may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A large-scale source-storage distributed collaborative control system for a DC microgrid, characterized in that, include: A DC microgrid module includes at least two DC microgrids, each of which is equipped with a large-scale distributed power supply and power load; the DC microgrids are DC microgrids of different voltage levels or DC microgrids of the same voltage level; The distributed power converter cooperative control module in the microgrid includes a voltage and current consistency control unit and a droop control unit, and the voltage static difference and power distribution error generated by the droop control unit are eliminated by the voltage and current consistency control unit; the distributed power converter cooperative control module in the microgrid also includes a network communication unit with neighboring nodes; The multi-port interconnected converter module between microgrids is connected to multiple DC microgrid modules, the number of ports is increased according to the number of the DC microgrids, and the power flow between the DC microgrids is controlled based on a symmetrical phase-shift control strategy to achieve balanced output of the DC microgrid and zero-difference control of the bus voltage; The DC bus average voltage observer estimates the average value of the current bus voltage based on the consistency algorithm when each DC bus average voltage observer only communicates with the DC bus average voltage observer of the neighboring node.

2. A large-scale source-storage distributed cooperative control method for a DC microgrid, which adopts the large-scale source-storage distributed cooperative control system for a DC microgrid as described in claim 1, and is characterized in that, On the basis of the coordinated control module of distributed power converter within a single microgrid, a multi-port interconnected converter module is introduced between microgrids to connect multiple DC microgrids. Based on the consistency algorithm and droop control, the voltage static difference and power distribution error are eliminated, and the symmetrical phase-shift control is adopted to achieve balanced output of the DC microgrid and error-free control of the bus voltage.

3. A large-scale source-storage distributed cooperative control method for a DC microgrid as described in claim 2, characterized in that, When there is current on the DC bus, the voltage at each point on the DC bus is not exactly the same due to the existence of the DC bus impedance. It is necessary to use a consistency algorithm to estimate the average value of the current bus voltage when each DC bus average voltage observer only communicates with the DC bus average voltage observer of the neighboring node; the specific process is: Get the estimated average voltage of the node's neighboring nodes; Obtaining a local voltage sampling value of the node and using the obtained local voltage sampling value as an initial value of the bus average voltage estimation value; Calculate the voltage error between the estimated value of the bus average voltage of the node and the estimated value of the neighboring nodes; The obtained voltage error is input into the error controller, and the output value of the error controller is compensated to the acquired local voltage sampling value to obtain the estimated value of the average bus voltage of the node.

4. A large-scale source-storage distributed collaborative control method for a DC microgrid as described in claim 3, characterized in that, The specific process of eliminating voltage static error and power distribution error based on consistency algorithm and droop control is as follows: Obtaining an estimated average voltage and a per-unit current value of a neighboring node based on communication with the neighboring node; According to the obtained average voltage estimation value and current per unit value, combined with the DC bus average voltage observer, the current DC bus average voltage is estimated; The DC bus voltage error is obtained by subtracting the obtained DC bus average voltage from the DC bus voltage reference value; Subtract the obtained neighbor node current per unit value from the local current per unit value to obtain the current per unit value error; The obtained DC bus voltage error and current per unit value error are input into the bus voltage controller and the current controller respectively; The DC bus voltage reference values ​​respectively outputted by the voltage controller and the current controller are added together and outputted to the droop controller; The droop controller obtains the local current value and calculates the reference value of the output voltage of the converter port to control the output of the distributed power converter. Send the per-unit value of the local current and the average value of the bus voltage estimated by the voltage observer to the neighbor nodes.

5. A large-scale source-storage distributed collaborative control method for a DC microgrid as described in claim 2, characterized in that, Based on the multi-port interconnected converter module, control the power flow between microgrids, enabling the mutual support of the outputs of multiple microgrids, and ultimately achieving the balanced output of each microgrid, with the voltage of each microgrid stable and without error. The specific process is as follows: The interconnected converter communicates with the neighbor nodes in the connected DC microgrid to obtain the per-unit values of the currents and the estimated average voltage values of all neighbor nodes. The average voltage estimates of each microgrid are obtained through the DC bus average voltage observer, and the average value of the per-unit values of the currents of two neighbor nodes in each microgrid is used as the per-unit value of the current reflecting the overall output of each microgrid. Based on the multi-port interconnected converter module, the difference between the average voltage estimate of each microgrid and the voltage reference value of each microgrid is calculated to obtain the voltage error of each microgrid. The obtained voltage error and current error are respectively sent to the corresponding bus voltage controller and current controller. The outputs of the bus voltage controller and the current controller of the same microgrid bus are added together to obtain the phase shift signal of the port of the interconnected converter connected to the current microgrid. All the phase shift signals are sent to the square wave phase shift modulator to obtain the switch control signals of all ports of the multi-port interconnected converter. The average voltage of each microgrid bus estimated by the interconnected converter and the per-unit value of the current of each microgrid are sent to the neighbor nodes in the corresponding microgrid. The per-unit value of the current obtained by the corresponding neighbor node at the interconnected converter is the per-unit value of the current of the neighbor microgrid of the overall output of the said microgrid.

6. A computer-readable storage medium having a program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the large-scale source-storage distributed cooperative control method for DC microgrids described in any one of claims 2-5.

7. An electronic device, comprising a memory, a processor, and a program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps in the large-scale source-storage distributed cooperative control method for DC microgrids described in any one of claims 2-5.

Images