A microgrid group coordinated control method and system based on shared energy storage

Abstract

The present invention relates to the field of power grid control technology, and discloses a coordinated control method and system for a microgrid group based on shared energy storage. According to the DC side output voltage value of the first distributed power source in the shared energy storage and the constant power distributed coordinated control strategy, a coordinated controlled DC voltage value is obtained; according to the active power measurement value of the second distributed power source in the microgrid group and the distributed secondary frequency control strategy, a droop control frequency is obtained; according to the distributed peer coordinated control strategy obtained by processing the coordinated controlled DC voltage value and the droop control frequency based on the finite time consistency algorithm, the DC side voltage change of each flexible interconnected converter is determined, and according to the DC side bus rated voltage value and the DC side voltage change, a DC side voltage reference value is obtained; the DC side voltage reference value is transformed, and the obtained voltage control signal is sent to the corresponding flexible interconnected converter. The method provided in the present application effectively improves the stability of the microgrid group based on shared energy storage.

Description

Technical Field

[0001] The present invention relates to the field of power grid control technology, and in particular to a microgrid group coordinated control method and system based on shared energy storage. Background Art

[0002] As a power supply system that can integrate multiple distributed power sources, energy storage devices and loads, microgrid plays a key role in absorbing new energy and reducing carbon emissions.

[0003] In recent years, microgrid structures based on shared energy storage have emerged. In this new architecture, one or more energy storage devices are connected to serve multiple microgrid systems together, realizing a more flexible microgrid interconnection form, forming a microgrid cluster, and creating favorable conditions for maximizing the utilization of distributed energy. Shared energy storage and microgrids are connected with the help of voltage source converters, realizing flexible interconnection between microgrids across feeders, substations and even voltage levels, greatly improving the convenience of DC microgrids accessing the DC distribution network.

[0004] However, with the continuous addition of a large number of distributed energy resources to microgrid systems and the widespread access of shared energy storage in microgrids, the connections between microgrids are becoming increasingly close. This close connection inevitably leads to more significant electrical interactions. At present, the control targets of existing microgrids are concentrated within the microgrid, and the control objects are single, resulting in poor voltage and frequency stability in flexible interconnected microgrid groups containing shared energy storage.

[0005] It can be seen that how to improve the stability of voltage and frequency of a flexible interconnected microgrid group containing shared energy storage has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] The present invention provides a microgrid group coordinated control method and system based on shared energy storage to solve the technical problem of how to improve the stability of voltage and frequency of a flexible interconnected microgrid group containing shared energy storage, thereby realizing the interconnected coordinated control of a flexible interconnected microgrid group containing shared energy storage and improving the stability of its voltage and frequency.

[0007] In a first aspect, the present invention provides a method for coordinated control of a microgrid cluster based on shared energy storage. The method is applied to a scenario where each microgrid in the microgrid cluster is connected to the shared energy storage using a one-to-one flexible interconnected converter. The method comprises:

[0008] obtaining a coordinated controlled DC voltage value of the shared energy storage based on the currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and a constant power distributed coordinated control strategy designed for the shared energy storage, wherein the constant power distributed coordinated control strategy is configured to perform droop control on the DC side output voltage value, obtain an output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio;

[0009] Obtaining a droop control frequency of each second distributed power source according to the currently acquired active power measurement value of each second distributed power source in the microgrid group and a distributed secondary frequency control strategy designed for the second distributed power source;

[0010] The collaboratively controlled DC voltage value and the droop control frequency are processed based on a finite-time consistency algorithm to obtain a distributed peer-to-peer coordinated control strategy for the flexible interconnected converter, and a DC side voltage variation of each of the flexible interconnected converters is determined based on the distributed peer-to-peer coordinated control strategy, and a DC side voltage reference value of each of the flexible interconnected converters is obtained according to the rated voltage value of the DC side busbar of the shared energy storage and the DC side voltage variation;

[0011] The DC side voltage reference value is transformed by adopting a DC voltage-quadrature axis current control method and a current inner loop control method, and the voltage control signal of each flexible interconnected converter obtained by the transformation is sent to the corresponding flexible interconnected converter.

[0012] Preferably, obtaining the collaborative control DC voltage value of the shared energy storage based on the currently acquired DC side output voltage value of each first distributed power supply in the shared energy storage and the constant power distributed collaborative control strategy designed for the shared energy storage includes:

[0013] Obtaining a DC side output voltage value of each first distributed power source in the shared energy storage, and designing a constant power distributed collaborative control strategy for the shared energy storage based on the DC side output voltage value and a preset ratio;

[0014] Based on the constant power distributed collaborative control strategy, obtaining an output active power reference value of each of the first distributed power sources;

[0015] Adjusting the DC side output active power of each of the first distributed power sources according to the output active power reference value and the preset ratio;

[0016] According to the active power output on the DC side of each first distributed power source, the collaboratively controlled DC voltage value of each first distributed power source is obtained, and the sum of the collaboratively controlled DC voltage values ​​of all the first distributed power sources is calculated to obtain the collaboratively controlled DC voltage value of the shared energy storage.

[0017] Preferably, the relational expression of the constant power distributed collaborative control strategy is expressed as:

[0018]

[0019] in, Indicates the first distributed power source The output active power reference value, Indicates the reference value of the DC bus voltage of the shared energy storage. Indicates the first distributed power source The DC side output voltage value, Indicates the first distributed power source The droop coefficient, Indicates the first distributed power source The droop coefficient, Indicates the first distributed power source The coordinated control DC voltage value, represents the preset ratio of the constant power distributed cooperative control strategy, represents the integral parameter of the constant power distributed cooperative control strategy, represents the Laplace operator, represents the control parameters of the constant power distributed cooperative control strategy, Indicates the first distributed power source With the first distributed power supply The communication gain is 1 if there is communication and 0 if there is no communication. Indicates the first distributed power source neighborhood.

[0020] Preferably, obtaining the droop control frequency of each second distributed power source in the microgrid group based on the currently acquired active power measurement value of each second distributed power source and the distributed secondary frequency control strategy designed for the second distributed power source includes:

[0021] Obtaining an active power measurement value of each second distributed power source in the microgrid group;

[0022] Based on the distributed consensus algorithm and the frequency adjustment item of the second distributed power source introduced, a distributed secondary frequency control strategy based on active power / frequency droop control is designed for the second distributed power source;

[0023] Based on each of the active power measurement values ​​and the distributed secondary frequency control strategy, frequency non-difference adjustment is performed on each of the second distributed power sources to obtain a droop control frequency of each of the second distributed power sources.

[0024] Preferably, the method further comprises:

[0025] Designing a distributed secondary voltage control strategy based on reactive power / voltage droop control for the second distributed power source according to the distributed consensus algorithm and the introduced voltage regulation term of the second distributed power source;

[0026] Based on the distributed secondary voltage control strategy, voltage control is performed on each of the second distributed power supplies so that an average value of the droop controlled output voltages of all the second distributed power supplies is equal to a rated reference voltage value;

[0027] Based on the distributed secondary voltage control strategy, reactive power control is performed on each of the second distributed power sources so that the reactive power of each of the second distributed power sources is evenly divided according to the coefficient of the reactive power / voltage droop control.

[0028] Preferably, the finite-time consensus algorithm is used to process the coordinated control DC voltage value and the droop control frequency to obtain a distributed peer-to-peer coordinated control strategy for the flexible interconnected converters, and the DC side voltage change of each flexible interconnected converter is determined based on the distributed peer-to-peer coordinated control strategy, including:

[0029] Normalizing the coordinated control DC voltage value based on an upper limit of a DC side bus voltage and a lower limit of a DC side bus voltage of the first distributed power supply to obtain a normalized coordinated control DC voltage value;

[0030] Normalizing the droop control frequency based on an upper limit and a lower limit of an AC side frequency of the second distributed power source to obtain a normalized droop control frequency;

[0031] Calculating a difference between the normalized coordinated control DC voltage value and the normalized droop control frequency, and constructing a distributed peer-to-peer coordinated control strategy based on the difference using a finite-time consensus algorithm;

[0032] Based on the distributed peer-to-peer coordinated control strategy, a DC side voltage change of each of the flexible interconnected converters is obtained.

[0033] Preferably, the distributed peer-to-peer coordination control strategy is constructed based on the difference using a finite time consensus algorithm, including:

[0034] Based on the difference, a finite time consistency algorithm is used to construct a DC side voltage change relationship of each flexible interconnected converter;

[0035] A finite-time protocol is constructed based on a Lyapunov-Krasovsky candidate function, and a relationship equation for a DC side voltage change is solved based on the finite-time protocol to obtain a DC side voltage change of each of the flexible interconnected converters;

[0036] Based on the DC side voltage variation, a distributed peer-to-peer coordinated control strategy is constructed.

[0037] Preferably, the relationship of the distributed peer-to-peer coordinated control strategy is expressed as:

[0038]

[0039] in, Flexible Interconnected Converter The DC side voltage change, Flexible Interconnected Converter The time consistency control parameters of , represents the symbolic function, represents the normalized coordinated control DC voltage value of the shared energy storage, Flexible Interconnected Converter The corresponding normalized droop control frequency of the second distributed power supply is, represents the control parameter of the convergence speed, and , represents the Laplace operator.

[0040] Preferably, the DC voltage-quadrature axis current control method and the current inner loop control method are used to transform the DC side voltage reference value, and the voltage control signal of each flexible interconnected converter obtained by the transformation is sent to the corresponding flexible interconnected converter, including:

[0041] Adopting a DC voltage-quadrature axis current control method to convert the DC side voltage reference value to obtain a current inner loop d-axis reference value of each flexible interconnected converter;

[0042] Based on the current inner loop d-axis reference value, a current inner loop control method is used to perform coordinate transformation on the d-axis voltage value of each of the flexible interconnected converters to obtain a d-axis voltage control signal of each of the flexible interconnected converters;

[0043] Based on a preset current inner loop q-axis reference value, the current inner loop control method is used to perform coordinate transformation on the q-axis voltage value of each of the flexible interconnected converters to obtain a q-axis voltage control signal of each of the flexible interconnected converters;

[0044] The d-axis voltage control signal and the q-axis voltage control signal are sent to the corresponding flexible interconnected converter.

[0045] In a second aspect, the present invention further provides a microgrid group coordinated control system based on shared energy storage, which implements the above-mentioned microgrid group coordinated control method based on shared energy storage. The system is applied to a scenario where each microgrid in the microgrid group and the shared energy storage are connected by a one-to-one flexible interconnected converter. The system includes: a shared energy storage collaborative control unit, a microgrid group frequency control unit, a distributed peer-to-peer coordination control unit, and a control signal generation unit.

[0046] The shared energy storage collaborative control unit is configured to obtain a collaboratively controlled DC voltage value of the shared energy storage based on a currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and a constant power distributed collaborative control strategy designed for the shared energy storage, wherein the constant power distributed collaborative control strategy is configured to perform droop control on the DC side output voltage value, obtain an output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio;

[0047] The microgrid frequency control unit is configured to obtain a droop control frequency of each second distributed power source in the microgrid according to a currently acquired active power measurement value of each second distributed power source in the microgrid and a distributed secondary frequency control strategy designed for the second distributed power source;

[0048] The distributed peer-to-peer coordination control unit is used to process the collaboratively controlled DC voltage value and the droop control frequency based on a finite-time consistency algorithm to obtain a distributed peer-to-peer coordination control strategy for the flexible interconnected converter, and determine a DC side voltage variation of each of the flexible interconnected converters based on the distributed peer-to-peer coordination control strategy, and obtain a DC side voltage reference value of each of the flexible interconnected converters according to the rated voltage value of the DC side busbar of the shared energy storage and the DC side voltage variation;

[0049] The control signal generating unit is used to transform the DC side voltage reference value by adopting a DC voltage-quadrature axis current control method and a current inner loop control method, and send the voltage control signal of each flexible interconnected converter obtained by the transformation to the corresponding flexible interconnected converter.

[0050] The present invention provides a method and system for coordinated control of a microgrid group based on shared energy storage. Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0051] The present application provides a coordinated control method for a microgrid group based on shared energy storage, designs a constant power distributed collaborative control strategy for the shared energy storage, achieves the control target of distributing the active power output on the DC side of each first distributed power supply in the shared energy storage according to a preset ratio, designs a distributed secondary frequency control strategy for the second distributed power supply of the microgrid, performs frequency differential adjustment on each second distributed power supply, so that the active power output by each second distributed power supply is evenly distributed in proportion, designs a distributed secondary voltage control strategy for the second distributed power supply of the microgrid, performs reactive power control on each second distributed power supply, so that the reactive power of each second distributed power supply is evenly distributed according to the coefficient of reactive power / voltage droop control, designs a distributed peer-to-peer coordinated control strategy for the flexible interconnected converter, achieves the target of distributing the total power output of the shared energy storage and the second distributed energy storage in the microgrid in proportion to their respective rated capacities, and improves the stability of the microgrid group based on shared energy storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a schematic diagram of the steps of a microgrid group coordinated control method based on shared energy storage provided by a preferred embodiment of the present invention;

[0053] Figure 2 Schematic diagram of the topological structure of a microgrid group coordinated control based on shared energy storage provided by a preferred embodiment of the present invention;

[0054] Figure 3 This is a structural diagram of a microgrid coordinated control system based on shared energy storage provided by a preferred embodiment of the present invention;

[0055] Reference numerals:

[0056] 1-Shared energy storage collaborative control unit, 2-Microgrid frequency control unit, 3-Distributed peer coordination control unit, 4-Control signal generation unit. DETAILED DESCRIPTION

[0057] The following is a detailed explanation of the embodiments of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limitations on the present invention. The accompanying drawings are for reference and illustration purposes only and do not constitute a limitation on the scope of patent protection of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0058] In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the two components. The terms "vertical", "horizontal", "left", "right", "up", "down" and similar expressions used herein are for illustrative purposes only, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In describing the present invention, it should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0060] See also Figure 1 In an embodiment of the present invention, a method for coordinated control of a microgrid cluster based on shared energy storage is provided. The method is applied to a scenario where each microgrid in the microgrid cluster is connected to the shared energy storage using a one-to-one flexible interconnected converter. The method includes:

[0061] S1. According to the currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and the constant power distributed collaborative control strategy designed for the shared energy storage, a collaborative control DC voltage value of the shared energy storage is obtained, wherein the constant power distributed collaborative control strategy is set to perform droop control on the DC side output voltage value, obtain an output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio; Figure 2 The figure shows a topological structure diagram of coordinated control of a microgrid group based on shared energy storage. The system is shown as an example in which the shared energy storage includes three first distributed power sources, the microgrid group includes three microgrids, and three flexible interconnected converters are used to connect the microgrid and the shared energy storage. Figure 2In the figure, ACMG1 represents microgrid 1, ACMG2 represents microgrid 2, ACMG3 represents microgrid 3, DG1 represents second distributed generation 1, DG2 represents second distributed generation 2, DG3 represents second distributed generation 3, DG4 represents second distributed generation 4, DG5 represents second distributed generation 5, and DG6 represents second distributed generation 6. IVSC1 represents flexible interconnected converter 1, IVSC2 represents flexible interconnected converter 2, and IVSC3 represents flexible interconnected converter 3. Load1 represents load 1, Load2 represents load 2, Load3 represents load 3, and Load4 represents load 4. DC / DC1 represents DC-DC converter 1, DC / DC2 represents DC-DC converter 2, and DC / DC3 represents DC-DC converter 3. For shared energy storage, a constant-power distributed collaborative control strategy is designed to ensure that each first distributed generation in the shared energy storage can operate at constant power under different operating conditions. Through the collaborative work of the first distributed generation, efficient and stable operation of the entire shared energy storage is achieved. In a preferred embodiment of the present application, the constant power distributed collaborative control strategy is set to perform droop control on the DC side output voltage value, obtain the output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio. Specifically, the DC side output voltage value of each first distributed power source in the shared energy storage is collected in real time, and a constant power distributed collaborative control strategy is designed for the shared energy storage based on each DC side output voltage value and a preset ratio; based on the constant power distributed collaborative control strategy, the output active power reference value of each first distributed power source is obtained, and constant power control is performed based on the output active power reference value, and the DC side output active power of each first distributed power source in the shared energy storage is adjusted to be distributed according to the preset ratio to obtain the DC side output active power of each first distributed power source, and then the collaborative control DC voltage value of each first distributed power source is obtained based on the DC side output active power of each first distributed power source, and the sum of the collaborative control DC voltage values ​​of all first distributed power sources is calculated to obtain the collaborative control DC voltage value of the shared energy storage.

[0062] In a preferred embodiment of the present application, the constant power distributed cooperative control strategy is expressed as:

[0063]

[0064] in, Indicates the first distributed power source The output active power reference value, Indicates the reference value of the DC bus voltage of the shared energy storage. Indicates the first distributed power source The DC side output voltage value, Indicates the first distributed power source The droop coefficient, Indicates the first distributed power source The droop coefficient, Indicates the first distributed power source The coordinated control DC voltage value, represents the preset ratio of the constant power distributed cooperative control strategy, represents the integral parameter of the constant power distributed cooperative control strategy, represents the Laplace operator, represents the control parameters of the constant power distributed cooperative control strategy, Indicates the first distributed power source With the first distributed power supply The communication gain is 1 if there is communication and 0 if there is no communication. Indicates the first distributed power source neighborhood.

[0065] According to the above-mentioned constant power distributed collaborative control strategy, a collaborative controller is designed to collaboratively control each first distributed power source in the shared energy storage, so as to achieve the control target of distributing the active power output on the DC side of each first distributed power source in the shared energy storage according to a preset ratio.

[0066] S2. Obtain a droop control frequency of each second distributed power source in the microgrid group based on the currently acquired active power measurement value of each second distributed power source and the distributed secondary frequency control strategy designed for the second distributed power source. Each microgrid in the microgrid group includes multiple distributed power sources, which are set as second distributed power sources. Based on a distributed consistency algorithm, a distributed secondary frequency control strategy based on active power / frequency droop control is designed for each second distributed power source in the microgrid group. In the design of the distributed secondary frequency control strategy based on active power / frequency droop control, a frequency adjustment item of the second distributed power source needs to be introduced. The relationship equation of the designed distributed secondary frequency control strategy based on active power / frequency droop control is expressed as:

[0067]

[0068] in, Indicates the second distributed power supply The droop control frequency, represents the rated frequency of the second distributed power source, Indicates the second distributed power supply Active power / frequency droop control coefficient, Indicates the second distributed power supply Active power / frequency droop control coefficient, Indicates the second distributed power supply The droop control active power, Indicates the second distributed power supply The droop control active power, Indicates the second distributed power supply The rated active power, Indicates the second distributed power supply Frequency adjustment item, Indicates the second distributed power supply The differential of the frequency adjustment term, and Indicates the second distributed power supply The frequency control parameters, Indicates the second distributed power supply With the second distributed power supply The communication gain is 1 if there is communication and 0 if there is no communication. Indicates the second distributed power supply Neighborhood, Indicates the second distributed power supply The droop control frequency.

[0069] According to the above-mentioned distributed secondary frequency control strategy, a frequency controller is designed. Based on the acquired active power measurement value of each second distributed power source in the microgrid group and the distributed secondary frequency control strategy, the frequency of each second distributed power source is adjusted without difference to obtain the droop control frequency of each second distributed power source.

[0070] In order to achieve differential regulation of the voltage of the second distributed power source of the microgrid, a distributed secondary voltage control strategy based on reactive power / voltage droop control is designed for the second distributed power source. In the design process of the distributed secondary voltage control strategy based on reactive power / voltage droop control, it is necessary to introduce the voltage regulation term of the second distributed power source. The relationship between the designed distributed secondary voltage control strategy based on reactive power / voltage droop control is expressed as follows:

[0071]

[0072] in, Indicates the second distributed power supply The droop control output voltage value, Indicates the rated reference voltage value, Indicates the second distributed power supply Reactive power / voltage droop control coefficient, Indicates the second distributed power supply The coefficient of reactive power / voltage droop control, Indicates the second distributed power supply The droop control reactive power, Indicates the second distributed power supply The droop control reactive power, Indicates the second distributed power supply The rated reactive power, Indicates the second distributed power supply Voltage regulation item, Indicates the second distributed power supply The differential of the voltage regulation term, and Indicates the second distributed power supply The voltage control parameters, Indicates the second distributed power supply The estimated voltage value, Indicates the second distributed power supply The estimated voltage value, Indicates the second distributed power supply The differential of the output voltage value of the droop control, Represents the control parameters of the distributed secondary voltage control strategy.

[0073] Furthermore, based on the distributed secondary voltage control strategy, voltage control is performed on each second distributed power source so that the average of the droop-controlled output voltages of all second distributed power sources is equal to the rated reference voltage. Based on the distributed secondary voltage control strategy, reactive power control is performed on each second distributed power source so that the reactive power of each second distributed power source is evenly distributed according to the reactive power / voltage droop control coefficient.

[0074] According to the above-mentioned distributed secondary voltage control strategy, a voltage controller is designed to perform voltage control on each second distributed power supply, so that the average value of the droop control output voltage of all second distributed power supplies is controlled at the rated reference voltage value, and the reactive power output by all second distributed power supplies is evenly divided according to the coefficient of reactive power / voltage droop control to obtain the droop control output voltage value of each second distributed power supply.

[0075] S3. Process the collaborative control DC voltage value and the droop control frequency based on a finite time consistency algorithm to obtain a distributed peer-to-peer coordinated control strategy for the flexible interconnected converter, and determine the DC side voltage variation of each flexible interconnected converter based on the distributed peer-to-peer coordinated control strategy. According to the rated voltage value of the DC side bus of the shared energy storage and the DC side voltage variation, obtain the DC side voltage reference value of each flexible interconnected converter. In a preferred embodiment of the present application, based on the DC side bus voltage upper limit and the DC side bus voltage lower limit of the first distributed power source, and according to the requirement that the maximum voltage value offset is 5% of the rated voltage value, the collaborative control DC voltage value is normalized to obtain a normalized collaborative control DC voltage value. Based on the AC side frequency upper limit and the AC side frequency lower limit of the second distributed power source, and according to the requirement that the maximum frequency offset is 1% of the rated frequency, the droop control frequency is normalized to obtain a normalized droop control frequency. The relationship between the normalization process of the collaborative control DC voltage value and the droop control frequency is expressed as follows:

[0076]

[0077] in, represents the normalized collaborative control DC voltage value of the shared energy storage, Flexible Interconnected Converter The corresponding normalized droop control frequency of the second distributed power supply is, Flexible Interconnected Converter The corresponding coordinated control DC voltage value of the first distributed power supply, and They represent the upper limit and lower limit of the DC bus voltage of the first distributed power supply, Flexible Interconnected Converter The corresponding droop control frequency of the second distributed power supply, and They represent the upper limit and lower limit of the AC side frequency of the second distributed power source respectively.

[0078] The flexible interconnected converters are controlled based on the normalized coordinated control DC voltage and the normalized droop control frequency. At the steady-state operating point, when the normalized coordinated control DC voltage and the normalized droop control frequency are equal, the active power output by the shared energy storage and the second distributed power source in the microgrid is proportionally distributed according to their respective rated capacities. Therefore, a finite-time consistency algorithm is used to calculate the time consistency of the difference between the normalized coordinated control DC voltage and the normalized droop control frequency, resulting in the DC side voltage change of each flexible interconnected converter.

[0079] The relationship of the time consistency algorithm is:

[0080]

[0081] in, represents the output of the finite-time consensus algorithm, represents the time consistency control parameter, and , Representation object with objects The communication gain is 1 if there is communication and 0 if there is no communication. represents the control parameter of the convergence speed, and , represents the symbolic function, Represents the input independent variable.

[0082] In a preferred embodiment of the present application, a distributed peer-to-peer coordinated control strategy is constructed based on the difference between the normalized collaborative control DC voltage value and the normalized droop control frequency. Specifically, the difference is used as the input independent variable of the finite-time consensus algorithm to construct a relationship between the DC side voltage change of each flexible interconnected converter, so that the normalized collaborative control DC voltage value and the normalized droop control frequency remain consistent. Based on the Lyapunov-Krasovsky candidate function, a finite-time protocol is constructed, and the finite-time protocol is expressed as:

[0083]

[0084] in, Indicates time, represents the Lyapunov-Krasovskii candidate function.

[0085] Based on the finite time protocol, the DC side voltage variation relationship is solved to obtain the DC side voltage variation of each flexible interconnected converter. Based on the DC side voltage variation, a distributed peer-to-peer coordinated control strategy is constructed. The relationship of the distributed peer-to-peer coordinated control strategy is expressed as:

[0086]

[0087] in, Flexible Interconnected Converter The DC side voltage change, Flexible Interconnected Converter The time consistency control parameters of , represents the symbolic function, represents the normalized coordinated control DC voltage value of the shared energy storage, Flexible Interconnected Converter The corresponding normalized droop control frequency of the second distributed power supply is, represents the Laplace operator.

[0088] Compared with the progressive time protocol, the finite time protocol adopted in this application accelerates the convergence speed and adds a certain level of disturbance suppression to improve the stability of the microgrid group based on shared energy storage.

[0089] The DC side voltage variation of each flexible interconnected converter is added to the rated voltage of the DC side busbar of each flexible interconnected converter to obtain the DC side voltage reference value transmitted by each flexible interconnected converter. The calculation formula of the DC side voltage reference value is:

[0090]

[0091] in, Flexible Interconnected Converter The DC side voltage reference value, Indicates the rated voltage of the DC busbar of the flexible interconnected converter.

[0092] S4. Using a DC voltage-quadrature-axis current control method and a current inner-loop control method, transform the DC side voltage reference value, and send the voltage control signal of each flexible interconnected converter obtained by the transformation to the corresponding flexible interconnected converter. In a preferred embodiment of the present application, based on the obtained DC side voltage reference value of each flexible interconnected converter, a DC voltage-quadrature-axis current (Vdciq) control method is used to transform the DC side voltage reference value to obtain a current inner-loop d-axis reference value of each flexible interconnected converter. Furthermore, based on the current inner-loop d-axis reference value, the current inner-loop control method is used to perform coordinate transformation on the d-axis voltage value of the flexible interconnected converter to obtain a d-axis voltage control signal. Furthermore, based on a preset current inner-loop q-axis reference value, the current inner-loop control method is used to perform coordinate transformation on the q-axis voltage value of the flexible interconnected converter to obtain a q-axis voltage control signal. The current inner-loop q-axis reference value is generally preset to 0.

[0093] The calculation formula of the current inner loop d-axis reference value is:

[0094]

[0095] in, Flexible Interconnected Converter The current inner loop d-axis reference value, Flexible Interconnected Converter The DC side voltage reference value, Flexible Interconnected Converter The corresponding droop control output voltage value of the second distributed power supply, Represents the proportional parameter of the current inner loop control, Indicates the integral parameter of the current inner loop control.

[0096] The d-axis voltage control signal and the q-axis voltage control signal are expressed as:

[0097]

[0098] in, represents the d-axis voltage control signal, represents the q-axis voltage control signal, Flexible Interconnected Converter The d-axis voltage value, Flexible Interconnected Converter The q-axis voltage value, Indicates the filter inductance value, Flexible Interconnected Converter The q-axis output current value, Flexible Interconnected Converter The d-axis output current value, Indicates the angular frequency of the second distributed power source, which is generally 314 rad / s.

[0099] A DC voltage-quadrature-axis current control method is adopted, and the DC side voltage reference value of each flexible interconnected converter is transformed through the current inner loop control method and coordinate transformation to obtain the d-axis voltage control signal and q-axis voltage control signal of each flexible interconnected converter. The total power output of the shared energy storage and the second distributed energy storage in the microgrid is proportionally distributed according to their respective rated capacities, thereby improving the stability of the microgrid group based on shared energy storage.

[0100] In a preferred embodiment of the present invention, based on the currently obtained DC side output voltage value of each first distributed power source in the shared energy storage and the constant power distributed collaborative control strategy designed for the shared energy storage, the collaborative control DC voltage value of the shared energy storage is obtained, the constant power distributed collaborative control strategy is set to perform droop control on the DC side output voltage value, and the output active power reference value of each first distributed power source is obtained, and based on the output active power reference value and the preset ratio, the DC side output active power of each first distributed power source is adjusted; based on the currently obtained active power measurement value of each second distributed power source in the microgrid group and the distributed secondary frequency control strategy designed for the second distributed power source, the The droop control frequency of each second distributed power source; based on the finite time consistency algorithm, the collaborative control DC voltage value and the droop control frequency are processed to obtain the distributed peer-to-peer coordinated control strategy of the flexible interconnected converter, and the DC side voltage change of each flexible interconnected converter is determined based on the distributed peer-to-peer coordinated control strategy, and the DC side voltage reference value of each flexible interconnected converter is obtained according to the rated voltage value of the DC side busbar of the shared energy storage and the DC side voltage change; the DC side voltage reference value is transformed by using the DC voltage-cross-axis current control method and the current inner loop control method, and the voltage control signal of each flexible interconnected converter obtained by the transformation is sent to the corresponding flexible interconnected converter. The present application provides a coordinated control method for a microgrid group based on shared energy storage, designs a constant power distributed collaborative control strategy for the shared energy storage, achieves the control target of distributing the active power output on the DC side of each first distributed power supply in the shared energy storage according to a preset ratio, designs a distributed secondary frequency control strategy for the second distributed power supply of the microgrid, performs frequency differential adjustment on each second distributed power supply, so that the active power output by each second distributed power supply is evenly distributed in proportion, designs a distributed secondary voltage control strategy for the second distributed power supply of the microgrid, performs reactive power control on each second distributed power supply, so that the reactive power of each second distributed power supply is evenly distributed according to the coefficient of reactive power / voltage droop control, designs a distributed peer-to-peer coordinated control strategy for the flexible interconnected converter, achieves the target of distributing the total power output of the shared energy storage and the second distributed energy storage in the microgrid in proportion to their respective rated capacities, and improves the stability of the microgrid group based on shared energy storage.

[0101] Accordingly, if Figure 3 As shown, based on a microgrid group coordinated control method based on shared energy storage, an embodiment of the present invention further provides a microgrid group coordinated control system based on shared energy storage, which implements the microgrid group coordinated control method based on shared energy storage disclosed in an embodiment of the present invention. The system is applied to a scenario where each microgrid in the microgrid group and the shared energy storage are connected by a one-to-one flexible interconnected converter, including: a shared energy storage collaborative control unit 1, a microgrid group frequency control unit 2, a distributed peer-to-peer coordination control unit 3 and a control signal generation unit 4;

[0102] The shared energy storage collaborative control unit 1 is configured to obtain a collaboratively controlled DC voltage value of the shared energy storage based on a currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and a constant power distributed collaborative control strategy designed for the shared energy storage, wherein the constant power distributed collaborative control strategy is configured to perform droop control on the DC side output voltage value, obtain an output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio;

[0103] The microgrid frequency control unit 2 is configured to obtain a droop control frequency of each second distributed power source in the microgrid according to a currently acquired active power measurement value of each second distributed power source and a distributed secondary frequency control strategy designed for the second distributed power source;

[0104] The distributed peer-to-peer coordination control unit 3 is used to process the collaborative control DC voltage value and the droop control frequency based on a finite-time consistency algorithm to obtain a distributed peer-to-peer coordination control strategy for the flexible interconnected converter, and determine a DC side voltage variation of each of the flexible interconnected converters based on the distributed peer-to-peer coordination control strategy, and obtain a DC side voltage reference value of each of the flexible interconnected converters according to the DC side bus rated voltage value of the shared energy storage and the DC side voltage variation;

[0105] The control signal generating unit 4 is used to transform the DC side voltage reference value by adopting a DC voltage-quadrature axis current control method and a current inner loop control method, and send the transformed voltage control signal of each of the flexible interconnected converters to the corresponding flexible interconnected converter.

[0106] For the specific definition of a microgrid group coordinated control system based on shared energy storage, please refer to the above-mentioned definition of a microgrid group coordinated control method based on shared energy storage, which will not be repeated here. A person of ordinary skill in the art will appreciate that each module and step described in conjunction with the embodiments disclosed in the present invention can be implemented in hardware, software, or a combination of both. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0107] A microgrid group coordinated control method and system based on shared energy storage provided in this embodiment is used to solve the technical problem of how to improve the stability of voltage and frequency of a flexible interconnected microgrid group containing shared energy storage. According to the currently obtained DC side output voltage value of each first distributed power source in the shared energy storage and the constant power distributed collaborative control strategy designed for the shared energy storage, the collaborative control DC voltage value of the shared energy storage is obtained. The constant power distributed collaborative control strategy is set to perform droop control on the DC side output voltage value to obtain the output active power reference value of each first distributed power source, and based on the output active power reference value and the preset ratio, the DC side output active power of each first distributed power source is adjusted; according to the currently obtained active power measurement value of each second distributed power source in the microgrid group and the distributed secondary frequency control strategy designed for the second distributed power source, the DC side output active power of each second distributed power source is obtained. The droop control frequency of the distributed power supply is determined; the collaborative control DC voltage value and the droop control frequency are processed based on the finite time consistency algorithm to obtain the distributed peer-to-peer coordinated control strategy of the flexible interconnected converter, and the DC side voltage change of each flexible interconnected converter is determined based on the distributed peer-to-peer coordinated control strategy, and the DC side voltage reference value of each flexible interconnected converter is obtained according to the rated voltage value of the DC side bus of the shared energy storage and the DC side voltage change; the DC side voltage reference value is transformed by using the DC voltage-cross-axis current control method and the current inner loop control method, and the voltage control signal of each flexible interconnected converter obtained by the transformation is sent to the corresponding flexible interconnected converter. The present application provides a coordinated control method for a microgrid group based on shared energy storage, designs a constant power distributed collaborative control strategy for the shared energy storage, achieves the control target of distributing the active power output on the DC side of each first distributed power supply in the shared energy storage according to a preset ratio, designs a distributed secondary frequency control strategy for the second distributed power supply of the microgrid, performs frequency differential adjustment on each second distributed power supply, so that the active power output by each second distributed power supply is evenly distributed in proportion, designs a distributed secondary voltage control strategy for the second distributed power supply of the microgrid, performs reactive power control on each second distributed power supply, so that the reactive power of each second distributed power supply is evenly distributed according to the coefficient of reactive power / voltage droop control, designs a distributed peer-to-peer coordinated control strategy for the flexible interconnected converter, achieves the target of distributing the total power output of the shared energy storage and the second distributed energy storage in the microgrid in proportion to their respective rated capacities, and improves the stability of the microgrid group based on shared energy storage.

[0108] Each embodiment in this specification is described in a progressive manner, and the parts that are directly the same or similar in each embodiment can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment. It should be noted that the various technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of each technical feature in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0109] The above-described embodiments merely represent several preferred implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and such improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be based on the scope of protection of the claims.

Claims

1. A coordinated control method for a microgrid group based on shared energy storage, characterized in that: The method is applied to a scenario where each microgrid in a microgrid group is connected to a shared energy storage using a one-to-one flexible interconnected converter. The method includes: obtaining a coordinated controlled DC voltage value of the shared energy storage based on the currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and a constant power distributed coordinated control strategy designed for the shared energy storage, wherein the constant power distributed coordinated control strategy is configured to perform droop control on the DC side output voltage value, obtain an output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio; Obtaining a droop control frequency of each second distributed power source according to the currently acquired active power measurement value of each second distributed power source in the microgrid group and a distributed secondary frequency control strategy designed for the second distributed power source; The collaboratively controlled DC voltage value and the droop control frequency are processed based on a finite-time consistency algorithm to obtain a distributed peer-to-peer coordinated control strategy for the flexible interconnected converter, and a DC side voltage variation of each of the flexible interconnected converters is determined based on the distributed peer-to-peer coordinated control strategy, and a DC side voltage reference value of each of the flexible interconnected converters is obtained according to the rated voltage value of the DC side busbar of the shared energy storage and the DC side voltage variation; The DC side voltage reference value is transformed by adopting a DC voltage-quadrature axis current control method and a current inner loop control method, and the voltage control signal of each flexible interconnected converter obtained by the transformation is sent to the corresponding flexible interconnected converter.

2. The method for coordinated control of a microgrid group based on shared energy storage according to claim 1, characterized in that: The step of obtaining the collaborative control DC voltage value of the shared energy storage according to the currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and the constant power distributed collaborative control strategy designed for the shared energy storage includes: Obtaining a DC side output voltage value of each first distributed power source in the shared energy storage, and designing a constant power distributed collaborative control strategy for the shared energy storage based on the DC side output voltage value and a preset ratio; Based on the constant power distributed collaborative control strategy, obtaining an output active power reference value of each of the first distributed power sources; Adjusting the DC side output active power of each of the first distributed power sources according to the output active power reference value and the preset ratio; According to the active power output on the DC side of each first distributed power source, the collaboratively controlled DC voltage value of each first distributed power source is obtained, and the sum of the collaboratively controlled DC voltage values ​​of all the first distributed power sources is calculated to obtain the collaboratively controlled DC voltage value of the shared energy storage.

3. The coordinated control method for a microgrid group based on shared energy storage according to claim 2, characterized in that: The relationship of the constant power distributed cooperative control strategy is expressed as: in, Indicates the first distributed power source The output active power reference value, Indicates the reference value of the DC bus voltage of the shared energy storage. Indicates the first distributed power source The DC side output voltage value, Indicates the first distributed power source The droop coefficient, Indicates the first distributed power source The droop coefficient, Indicates the first distributed power source The coordinated control DC voltage value, represents the preset ratio of the constant power distributed cooperative control strategy, represents the integral parameter of the constant power distributed cooperative control strategy, represents the Laplace operator, represents the control parameters of the constant power distributed cooperative control strategy, Indicates the first distributed power source With the first distributed power supply The communication gain is 1 if there is communication and 0 if there is no communication. Indicates the first distributed power source neighborhood.

4. The method for coordinated control of a microgrid group based on shared energy storage according to claim 1, characterized in that: The step of obtaining the droop control frequency of each second distributed power source in the microgrid group according to the currently acquired active power measurement value of each second distributed power source and the distributed secondary frequency control strategy designed for the second distributed power source includes: Obtaining an active power measurement value of each second distributed power source in the microgrid group; Based on the distributed consensus algorithm and the frequency adjustment item of the second distributed power source introduced, a distributed secondary frequency control strategy based on active power / frequency droop control is designed for the second distributed power source; Based on each of the active power measurement values ​​and the distributed secondary frequency control strategy, frequency non-difference adjustment is performed on each of the second distributed power sources to obtain a droop control frequency of each of the second distributed power sources.

5. The method for coordinated control of a microgrid group based on shared energy storage according to claim 4, characterized in that: The method further comprises: Designing a distributed secondary voltage control strategy based on reactive power / voltage droop control for the second distributed power source according to the distributed consensus algorithm and the introduced voltage regulation term of the second distributed power source; Based on the distributed secondary voltage control strategy, voltage control is performed on each of the second distributed power supplies so that an average value of the droop controlled output voltages of all the second distributed power supplies is equal to a rated reference voltage value; Based on the distributed secondary voltage control strategy, reactive power control is performed on each of the second distributed power sources so that the reactive power of each of the second distributed power sources is evenly divided according to the coefficient of the reactive power / voltage droop control.

6. The method for coordinated control of a microgrid group based on shared energy storage according to claim 1, characterized in that: The method of processing the collaboratively controlled DC voltage value and the droop control frequency based on a finite-time consensus algorithm to obtain a distributed peer-to-peer coordinated control strategy for the flexible interconnected converters, and determining a DC side voltage change of each of the flexible interconnected converters based on the distributed peer-to-peer coordinated control strategy, includes: Normalizing the coordinated control DC voltage value based on an upper limit of a DC side bus voltage and a lower limit of a DC side bus voltage of the first distributed power supply to obtain a normalized coordinated control DC voltage value; Normalizing the droop control frequency based on an upper limit and a lower limit of an AC side frequency of the second distributed power source to obtain a normalized droop control frequency; Calculating a difference between the normalized coordinated control DC voltage value and the normalized droop control frequency, and constructing a distributed peer-to-peer coordinated control strategy based on the difference using a finite-time consensus algorithm; Based on the distributed peer-to-peer coordinated control strategy, a DC side voltage change of each of the flexible interconnected converters is obtained.

7. The method for coordinated control of a microgrid group based on shared energy storage according to claim 6, characterized in that: The method of constructing a distributed peer-to-peer coordinated control strategy based on the difference using a finite time consensus algorithm includes: Based on the difference, a finite time consistency algorithm is used to construct a DC side voltage change relationship of each flexible interconnected converter; A finite-time protocol is constructed based on a Lyapunov-Krasovsky candidate function, and a relationship equation for a DC side voltage change is solved based on the finite-time protocol to obtain a DC side voltage change of each of the flexible interconnected converters; Based on the DC side voltage variation, a distributed peer-to-peer coordinated control strategy is constructed.

8. The method for coordinated control of a microgrid group based on shared energy storage according to claim 7, characterized in that: The relationship between the distributed peer-to-peer coordination control strategy is expressed as: in, Flexible Interconnected Converter The DC side voltage change, Flexible Interconnected Converter The time consistency control parameters of , represents the symbolic function, represents the normalized coordinated control DC voltage value of the shared energy storage, Flexible Interconnected Converter The corresponding normalized droop control frequency of the second distributed power supply is, represents the control parameter of the convergence speed, and , represents the Laplace operator.

9. The method for coordinated control of a microgrid group based on shared energy storage according to claim 1, characterized in that: The method adopts the DC voltage-quadrature axis current control method and the current inner loop control method to transform the DC side voltage reference value, and sends the transformed voltage control signal of each flexible interconnected converter to the corresponding flexible interconnected converter, including: Adopting a DC voltage-quadrature axis current control method to convert the DC side voltage reference value to obtain a current inner loop d-axis reference value of each flexible interconnected converter; Based on the current inner loop d-axis reference value, a current inner loop control method is used to perform coordinate transformation on the d-axis voltage value of each of the flexible interconnected converters to obtain a d-axis voltage control signal of each of the flexible interconnected converters; Based on a preset current inner loop q-axis reference value, the current inner loop control method is used to perform coordinate transformation on the q-axis voltage value of each of the flexible interconnected converters to obtain a q-axis voltage control signal of each of the flexible interconnected converters; The d-axis voltage control signal and the q-axis voltage control signal are sent to the corresponding flexible interconnected converter.

10. A microgrid group coordinated control system based on shared energy storage, implementing the microgrid group coordinated control method based on shared energy storage according to any one of claims 1 to 9, characterized in that: The system is applied to scenarios where each microgrid in a microgrid group is connected to the shared energy storage using a one-to-one flexible interconnected converter. The system includes: a shared energy storage collaborative control unit, a microgrid group frequency control unit, a distributed peer coordination control unit, and a control signal generation unit. The shared energy storage collaborative control unit is configured to obtain a collaboratively controlled DC voltage value of the shared energy storage based on a currently acquired DC side output voltage value of each first distributed power source in the shared energy storage and a constant power distributed collaborative control strategy designed for the shared energy storage, wherein the constant power distributed collaborative control strategy is configured to perform droop control on the DC side output voltage value, obtain an output active power reference value of each first distributed power source, and adjust the DC side output active power of each first distributed power source based on the output active power reference value and a preset ratio; The microgrid frequency control unit is configured to obtain a droop control frequency of each second distributed power source in the microgrid according to a currently acquired active power measurement value of each second distributed power source in the microgrid and a distributed secondary frequency control strategy designed for the second distributed power source; The distributed peer-to-peer coordination control unit is used to process the collaboratively controlled DC voltage value and the droop control frequency based on a finite-time consistency algorithm to obtain a distributed peer-to-peer coordination control strategy for the flexible interconnected converter, and determine a DC side voltage variation of each of the flexible interconnected converters based on the distributed peer-to-peer coordination control strategy, and obtain a DC side voltage reference value of each of the flexible interconnected converters according to the rated voltage value of the DC side busbar of the shared energy storage and the DC side voltage variation; The control signal generating unit is used to transform the DC side voltage reference value by adopting a DC voltage-quadrature axis current control method and a current inner loop control method, and send the voltage control signal of each flexible interconnected converter obtained by the transformation to the corresponding flexible interconnected converter.

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