A power control-based energy storage type ac-dc hybrid microgrid system and control method

Abstract

The present application belongs to the field of energy storage and new energy technology, and particularly relates to a power control-based energy storage AC-DC hybrid microgrid system control method for controlling a microgrid system, the microgrid system comprising a central controller, a converter, an AC load, a DC load, and a distributed energy unit, and the method comprising the following steps: obtaining the basic information of the devices of each distributed energy in the microgrid system to perform control in a first cycle; in each control cycle, collecting the operation information of each distributed energy, determining the active power reference value of all energy storage units, the reactive power reference value of all distributed energies, and the scalar coefficient of each distributed energy according to the operation information of each distributed energy. The present application combines the advantages of DC microgrid and AC microgrid, increases the reliability of power supply by using energy storage units, and further improves the consumption amount of new renewable energy.

Description

Technical Field

[0001] This invention relates to the fields of energy storage and new energy technologies, and in particular to an energy storage-type AC / DC hybrid microgrid system and control method based on power control. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] With the increasing integration of modern loads such as renewable energy sources (RESs), energy storage units (ESUs), and electric vehicles (EVs) into the distribution system, grid interconnection faces severe challenges in terms of efficiency, reliability, and power quality. Among these challenges, the main factors affecting power quality include overvoltage, conductor overload, and voltage imbalance. In this context, microgrids, as a novel energy supply system, can interconnect multiple RESs, ESUs, and loads within the same cluster, ensuring the dispatchability, reliability, and stability of the entire system. This helps improve the carrying capacity of the distribution network and, consequently, increases the number of distributed energy resources (DERs) integrated into the power system.

[0004] Microgrid systems are an effective way to reliably integrate new renewable energy sources. Based on different energy transmission methods, microgrid systems can be divided into two main categories: AC microgrids and DC microgrids. Microgrid systems typically operate in grid-connected mode. In grid-connected operation, both AC and DC microgrids require a suitable bidirectional interactive power converter installed at the Point of Common Coupling (PCC) to obtain voltage and power support from the external power grid, thereby ensuring the stable and reliable operation of the power supply system. Since most distribution systems are AC-based, AC microgrid systems have better compatibility with traditional equipment; however, DC microgrids require fewer energy conversion stages, making them more efficient than AC microgrids in integrating renewable energy and power supply. Combining the advantages of AC and DC microgrids is currently a key research focus. With ongoing research, a hybrid AC / DC microgrid system is gradually becoming an effective alternative to modern power systems. Hybrid AC / DC microgrid systems combine the advantages of both AC and DC microgrids. Their emergence and application have accelerated the integration of distributed renewable energy, achieved clean and reliable energy supply, and further improved my country's energy supply system. Adopting appropriate energy management strategies to address the coordinated scheduling of AC and DC subgrids is crucial for achieving fully dispatchable power flow, state of charge (SoC) balance, and stable and reliable operation.

[0005] Energy management in microgrid systems typically employs a hierarchical control approach. Proportional power sharing is achieved at the primary control level, while a centralized controller is used at the secondary control level to achieve precise energy management of the microgrid. However, this energy management system does not consider the role of energy storage units, resulting in power fluctuation issues in the system's islanded operation mode.

[0006] How to provide a control method for AC / DC hybrid microgrid systems that takes into account the role of energy storage units is an urgent problem to be solved. Summary of the Invention

[0007] This invention provides a power control-based energy storage AC / DC hybrid microgrid system and control method to address the problem that existing microgrid system control methods do not consider the role of energy storage units. To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its sole purpose is to present some concepts in a simple form as a prelude to the detailed description that follows.

[0008] According to a first aspect of the present invention, a control method for an energy storage-type AC / DC hybrid microgrid system based on power control is provided.

[0009] In one embodiment, a power control-based energy storage AC / DC hybrid microgrid system control method is provided for controlling a microgrid system, the microgrid system comprising: a central controller, a converter, AC loads, DC loads, and distributed energy resources, the method comprising the following steps:

[0010] Acquire basic information about the devices of each distributed energy source within the microgrid system and perform the first cycle of control;

[0011] In each control cycle, the operation information of each distributed energy source is collected. Based on the operation information of each distributed energy source, the active power reference value of all energy storage units and the reactive power reference value of all distributed energy sources are determined for the next control cycle.

[0012] Optionally, the basic equipment information includes one or more of the following: equipment type, equipment location, or rated capacity.

[0013] Optionally, the control of the first cycle includes the following steps:

[0014] The active power reference values ​​of all energy storage units and the reactive power reference values ​​of all distributed energy sources are calculated based on the rated capacity of distributed energy sources, the capacity of energy storage units, and the power factor of the power grid.

[0015] Optionally, the step of determining the active power reference value of all energy storage units in the next control cycle includes:

[0016] The active power reference values ​​for all energy storage units in the (k+1)th control cycle are shown in the following formula:

[0017]

[0018] in, P represents the reference value of active power for all energy storage units. L (k) represents the active power of the microgrid system in the kth control cycle. This represents the reference value of active power of the power grid in the (k+1)th control cycle.

[0019] Optionally, the step of determining the reactive power reference value for all distributed energy sources in the next control cycle includes:

[0020]

[0021] in, Q represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; L (k) represents the reactive power absorbed by the AC bus of the microgrid system in the kth control cycle; Q represents the reference value of reactive power in the power grid during the (k+1)th control cycle;IUI (k) represents the reactive power output of the converter in the kth control cycle.

[0022] Optionally, the method further includes: in each control cycle, determining the scalar coefficient of each distributed energy source for the next control cycle based on the operating information of each distributed energy source.

[0023] Optionally, in the first control cycle, the scalar coefficient of each distributed energy source is a set initial value.

[0024] Optionally, the step of determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0025] when

[0026]

[0027] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the minimum charging power of all energy storage units in the k-th control cycle. α represents the maximum discharge power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0028] Optionally, the step of determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0029] when

[0030] α ESU =-1

[0031] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. α represents the minimum charging power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0032] Optionally, the step of determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0033] when

[0034] α ESU =1

[0035] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. α represents the maximum discharge power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0036] Optionally, the step of determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0037] when

[0038]

[0039] in, This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; α represents the reference value of the maximum reactive power of all distributed energy sources in the k-th control cycle. Q This represents the reactive power scalar coefficient of distributed energy resources.

[0040] Optionally, the method further includes a step of controlling the state of charge balance of each energy storage unit, including:

[0041] The state of charge (SOC) value of the i-th energy storage unit is used as the SoC. i Average State of Charge (SOC) of Each Energy Storage Unit a We perform weighting to obtain the proportional coefficient weight α of the i-th energy storage unit. pi ;

[0042] In charging mode, the proportional gain weight α of the energy storage unit pi With State of Charge SoC i Inversely proportional;

[0043] In discharge mode, the proportional gain weight α of the energy storage unit pi With State of Charge SoC i Proportional.

[0044] Optionally, the step of controlling the state of charge balance of each energy storage unit further includes: limiting the active power scalar coefficient α of the energy storage unit. ESU The value is lower than the average state of charge of each energy storage unit in the SoC. a .

[0045] Optionally, the active power reference value of the energy storage unit is shown in the following formula:

[0046] (1) Charging mode

[0047]

[0048] (2) Discharge Mode

[0049]

[0050] Where the superscript p is the convergence factor for adjusting the SoC equalization speed. This represents the reference value of the active power of energy storage unit i. This represents the minimum charging power of energy storage unit i. This represents the maximum discharge power of energy storage unit i.

[0051] According to a second aspect of the present invention, a power control-based energy storage AC / DC hybrid microgrid system is provided.

[0052] In one embodiment, the system includes: a central controller, a converter, an AC load, a DC load, and a distributed energy source;

[0053] The central controller acquires basic information about the devices of each distributed energy source in the microgrid system and performs the first cycle of control.

[0054] In each control cycle, the central controller collects the operating information of each distributed energy source and determines the active power reference value of all energy storage units and the reactive power reference value of all distributed energy sources for the next control cycle based on the operating information of each distributed energy source.

[0055] Optionally, the basic equipment information includes one or more of the following: equipment type, equipment location, or rated capacity.

[0056] Optionally, the central controller is further configured to: in the first cycle of control, calculate and obtain the active power reference value of all energy storage units and the reactive power reference value of all distributed energy sources based on the rated capacity of distributed energy sources, the capacity of energy storage units and the power factor of the grid.

[0057] Optionally, determining the active power reference value of all energy storage units in the next control cycle includes:

[0058] The active power reference values ​​for all energy storage units in the (k+1)th control cycle are shown in the following formula:

[0059]

[0060] in, P represents the reference value of active power for all energy storage units. L (k) represents the active power of the microgrid system in the kth control cycle. This represents the reference value of active power of the power grid in the (k+1)th control cycle.

[0061] Optionally, determining the reactive power reference value for all distributed energy sources in the next control cycle includes:

[0062]

[0063] in, Q represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; L (k) represents the reactive power absorbed by the AC bus of the microgrid system in the kth control cycle; Q represents the reference value of reactive power in the power grid during the (k+1)th control cycle; IUI (k) represents the reactive power output of the converter in the kth control cycle.

[0064] Optionally, the central controller is further configured to: determine the scalar coefficients of each distributed energy source for the next control cycle based on the operating information of each distributed energy source in each control cycle.

[0065] Optionally, the central controller is further configured to: set the initial value of the scalar coefficient of each distributed energy source during the first control cycle.

[0066] Optionally, determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0067] when

[0068]

[0069] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the minimum charging power of all energy storage units in the k-th control cycle. α represents the maximum discharge power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0070] Optionally, determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0071] when

[0072] α ESU =-1

[0073] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. α represents the minimum charging power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0074] Optionally, determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0075] when

[0076] α ESU =1

[0077] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. α represents the maximum discharge power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0078] Optionally, determining the scalar coefficients of each distributed energy source in the next control cycle includes:

[0079] when

[0080]

[0081] in, This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; α represents the reference value of the maximum reactive power of all distributed energy sources in the k-th control cycle. Q This represents the reactive power scalar coefficient of distributed energy resources.

[0082] Optionally, the central controller is further configured to: control the state of charge balance of each energy storage unit, including:

[0083] The state of charge (SOC) value of the i-th energy storage unit is used as the SoC. i Average State of Charge (SOC) of Each Energy Storage Unit a We perform weighting to obtain the proportional coefficient weight α of the i-th energy storage unit. pi ;

[0084] In charging mode, the proportional gain weight α of the energy storage unit pi With State of Charge SoC i Inversely proportional;

[0085] In discharge mode, the proportional gain weight α of the energy storage unit pi With State of Charge SoC i Proportional.

[0086] Optionally, the central controller is further configured to: limit the active power scalar coefficient α of the energy storage unit. ESU The value is lower than the average state of charge of each energy storage unit in the SoC. a .

[0087] Optionally, the active power reference value of the energy storage unit is shown in the following formula:

[0088] (1) Charging mode

[0089]

[0090] (2) Discharge Mode

[0091]

[0092] Where the superscript p is the convergence factor for adjusting the SoC equalization speed. This represents the reference value of the active power of energy storage unit i. This represents the minimum charging power of energy storage unit i. This represents the maximum discharge power of energy storage unit i.

[0093] According to a third aspect of the present invention, a computer device is provided.

[0094] In some embodiments, the computer device includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the steps of the method described above.

[0095] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0096] (1) A hybrid AC / DC microgrid system with energy storage is disclosed. The hybrid AC / DC microgrid system with energy storage is a single controllable entity. The system includes distributed energy, DC microgrid subsystem and AC microgrid subsystem. The system combines the advantages of DC microgrid and AC microgrid and uses energy storage units to increase the reliability of energy supply, thereby further improving the absorption of new renewable energy.

[0097] (2) It simplifies the calculation and complexity of system regulation parameters. At the same time, the control strategy has the function of realizing power flow control and energy storage SoC balance of the two sub-microgrids, making the collaborative optimization scheduling process of the microgrid system more convenient.

[0098] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description

[0099] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0100] Figure 1 This is a schematic diagram of an energy storage AC / DC hybrid microgrid system according to an exemplary embodiment;

[0101] Figure 2This is a schematic diagram of the structure of an interconnecting multi-functional interface converter according to an exemplary embodiment;

[0102] Figure 3 This is a flowchart illustrating a power control-based control method for an energy storage-type AC / DC hybrid microgrid system according to an exemplary embodiment;

[0103] Figure 4 This is a schematic diagram of the structure of a computer device according to an exemplary embodiment. Detailed Implementation

[0104] The following description and accompanying drawings fully illustrate specific embodiments described herein to enable those skilled in the art to practice them. Some embodiments may include or substitute parts and features of other embodiments. The scope of the embodiments herein encompasses the entire scope of the claims and all available equivalents thereof. Throughout this document, the terms “first,” “second,” etc., are used only to distinguish one element from another without requiring or implying any actual relationship or order between the elements. Indeed, a first element can also be referred to as a second element, and vice versa. Furthermore, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a structure, apparatus, or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a structure, apparatus, or device. Without further limitation, an element defined by the phrase “comprising one…” does not exclude the presence of other identical elements in the structure, apparatus, or device that includes said element. The various embodiments described herein are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments; similar or identical parts between embodiments can be referred to interchangeably.

[0105] The terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" used in this document to indicate orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings. They are used solely for the convenience of describing the document and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In the description herein, unless otherwise specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two elements; they can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0106] In this document, unless otherwise stated, the term "multiple" means two or more.

[0107] In this article, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0108] In this article, the term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0109] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0110] This invention discloses a power control-based control method for a power storage-type AC / DC hybrid microgrid system, used to control a microgrid system. The microgrid system includes a central controller, a converter, AC loads, DC loads, and multiple distributed energy sources. The converter connects both the AC and DC buses, connecting the microgrid system to the external power grid; for example, the converter is an Interlinking Utility Interface (IUI) converter. Distributed energy sources include renewable energy units and energy storage units (ESUs), with one or more renewable energy units and one or more energy storage units. For example, renewable energy units can be photovoltaic (PV) units, wind power units, or tidal power units, etc. Of course, distributed energy sources can also include other types of renewable energy units; this invention uses PV units as an example. Energy storage units are an important component of the AC / DC hybrid microgrid system. On the one hand, they provide optimized scheduling capabilities for the microgrid system, enabling ancillary services to be provided in grid-connected operation mode; on the other hand, energy storage units can provide the electrical energy required by the microgrid system in islanded operation mode, supporting the operation of the microgrid system in islanded mode.

[0111] Figure 1 An embodiment of a microgrid system is provided, including an interconnecting multi-function interface (IUI) converter, AC loads, DC loads, photovoltaic (PV) power generation units, multiple energy storage units (ESU1, ESU2, and ESU3), and related communication lines. The two DC-side ESUs (ESU1 and ESU2) are both implemented through a DC / DC bridge converter and its connected battery pack. The AC-side ESU3 is implemented through a DC / AC inverter and its connected battery pack. One end of the converter is connected to the AC bus, and the other end is connected to the power grid through a transformer. Each converter is controlled using the method disclosed in this embodiment.

[0112] Figure 2An embodiment of an interconnect multifunction interface converter is shown, which employs a two-order topology. This two-order topology allows for the decoupling of the control loops on the AC and DC sides and allows for the accommodation of higher voltage fluctuations in the DC loop without affecting the IUI output voltage waveform. Of course, Figure 2 The embodiments shown are merely illustrative. Those skilled in the art can select appropriate interconnect multi-functional interface converter implementation methods according to design requirements.

[0113] Figure 3 An embodiment of a control method for an energy storage-type AC / DC hybrid microgrid system based on power control is shown.

[0114] In this embodiment, the method disclosed in this invention includes the following steps:

[0115] Step S1: Obtain basic information about the distributed energy devices in the microgrid system, including one or more of the device type, device location, or rated capacity, and perform control for the first control cycle.

[0116] Specifically, the central controller detects each distributed energy source connected to the communication network and records its type (e.g., photovoltaic power generation unit PV or energy storage unit ESU), location (DC bus or AC bus), and rated capacity. Then, the central controller begins the first cycle of control.

[0117] In the first control cycle, the active power reference values ​​of all energy storage units and the reactive power reference values ​​of all distributed energy sources are calculated from the rated capacity of distributed energy sources, the capacity of energy storage units, and the power factor of the power grid.

[0118] The active power reference values ​​for all energy storage units and the reactive power reference values ​​for all distributed energy sources are shown in the following formulas:

[0119]

[0120]

[0121] P ESU Q represents the reference value of active power for all energy storage units during the first control cycle. D This represents the reference value of reactive power for all distributed energy sources during the first control cycle, S. D ,S ESU These represent the rated capacity of distributed energy resources and the capacity of energy storage units, respectively. This represents the power factor of the power grid.

[0122] Step S2: In each control cycle, for example at the beginning of each control cycle, collect the operating information of each distributed energy source, including operating status, available capacity, power and other information. Based on the operating information of each distributed energy source, obtain the operating status of the microgrid system, and determine the active power reference value of all energy storage units and the reactive power reference value of all distributed energy sources in the next control cycle, so as to realize the control of the microgrid system in the next control cycle.

[0123] At the beginning of each control cycle (denoted as the kth control cycle), the central controller communicates with all recorded distributed energy sources to collect information such as the operating status, available capacity, and power of the distributed energy sources.

[0124] For example, in the k-th control cycle, the central controller collects the operating information of the j-th PV. Assuming it's on the AC side, the operating information includes: active power output P. PVj (k) and reactive power output Q PVj (k) and the rated power A of the converter of the PV PVj (k).

[0125] For example, in the k-th control cycle, the central controller collects the operating information of the i-th ESU, including: the output active power P. ESUi (k) and reactive power Q ESUi (k) Maximum power capacity and minimum power capacity (i.e., maximum discharge power and minimum charging power), State of Charge (SoC) i (k) and the converter rated power A of the ESU ESUi (k).

[0126] The central controller also collects the operating information of the IUI converter. For example, in the k-th control cycle, the central controller collects the operating information of the IUI converter, including: the output active power P of the IUI converter. IUI (k) and reactive power Q IUI (k) and the rated power A of the IUI converter IUI (k).

[0127] The central controller also collects grid operation information. For example, for the grid side of the PCC, in the k-th control cycle, the central controller collects the active power P of the grid. GRID (k) and reactive power Q GRID (k).

[0128] In the kth control cycle, the total active power P on the AC side is... D (k) and reactive power Q D (k) is calculated using formulas (1) and (2) respectively:

[0129]

[0130]

[0131] The total number of photovoltaic power generation units (PV) is denoted as J, and the total number of energy storage units is denoted as I.

[0132] In the kth control cycle, the maximum reactive power output of all distributed energy sources can be calculated using formula (3):

[0133]

[0134] A represents the reference value of the maximum reactive power of all distributed energy sources in the k-th control cycle; D (k) represents the rated power of all distributed energy converters in the k-th control cycle.

[0135] Optionally, the step of obtaining the operating status of the entire microgrid system based on the operating information of each of the aforementioned distributed energy sources includes:

[0136] The active power of the entire microgrid system is calculated by the central controller according to formula (4), and the total reactive power absorbed by the AC bus of the microgrid system in the kth control cycle is calculated by formula (5).

[0137] P L (k)=P GRID (k)+P D (k) (4)

[0138] Q L (k)=Q GRID (k)+Q D (k)+Q IUI (k) (5)

[0139] Optionally, the step of determining the active power reference values ​​for all energy storage units and the reactive power reference values ​​for all distributed energy sources in the next control cycle includes:

[0140] The active power reference values ​​of all energy storage units and the reactive power reference values ​​of all distributed energy sources in the (k+1)th control cycle are calculated according to formulas (6) and (7):

[0141]

[0142]

[0143] in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle; This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; and Q represents the active power reference value and reactive power reference value of the power grid in the (k+1)th control cycle, respectively; IUI (k) represents the reactive power output of the converter in the kth control cycle; Q L (k) represents the total reactive power absorbed by the AC bus of the microgrid system in the kth control cycle.

[0144] To prevent overcharging or over-discharging of energy storage units, the active power reference values ​​for all energy storage units are... Cannot exceed the minimum charging power and maximum discharge power

[0145]

[0146]

[0147] Optionally, the method further includes: collecting operational information of each distributed energy source in each control cycle, including operating status, available capacity, power, etc., and determining the scalar coefficient of each distributed energy source in the next control cycle. The scalar coefficient includes the proportion of active power and reactive power exchanged between each distributed energy source and the microgrid system. The scalar coefficient is dimensionless and, considering the available capacity of the distributed energy sources, serves as a factor for providing proportional power sharing.

[0148] Optionally, in the first control cycle, the scalar coefficient of each distributed energy source is set to an initial value. For example, in the first control cycle, the scalar coefficient of each distributed energy source is set to 1.

[0149] Optionally, the steps for determining the scalar coefficients of each distributed energy source in the next control cycle are described in the table below, showing the correspondence between the power reference conditions and the scalar coefficients:

[0150] Table 1

[0151]

[0152] P represents the reference value of active power for all energy storage units in the (k+1)th control cycle. L (k) represents the active power of the microgrid system in the kth control cycle. This represents the reference value of active power of the power grid in the (k+1)th control cycle; This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; α represents the reference value of the maximum reactive power of all distributed energy sources in the k-th control cycle. QQ represents the reactive power scalar coefficient of distributed energy resources; L (k) represents the reactive power absorbed by the AC bus of the microgrid system in the kth control cycle; Q represents the reference value of reactive power in the power grid during the (k+1)th control cycle; IUI (k) represents the reactive power output of the converter in the kth control cycle; This represents the minimum charging power of all energy storage units in the k-th control cycle. α represents the maximum discharge power of all energy storage units in the k-th control cycle. ESU This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

[0153] The central controller calculates a scalar coefficient and transmits it to the local controllers of the distributed energy sources. This process provides a power reference for each distributed energy source. The reactive power of the AC distributed energy sources is determined by the scalar coefficient α. Q Control, the active power of the energy storage unit is controlled by the scalar coefficient α ESU Control. Regardless of whether the reactive power reference value is negative or positive, the distributed energy source is used to handle the reactive power generated by capacitors or inductors respectively. Similarly, regardless of whether the active power reference value of the energy storage unit is negative, positive, or zero, the energy storage unit operates in charging mode, discharging mode, or non-operating mode respectively. The above-mentioned AC distributed energy source is a distributed energy source connected to an AC microgrid through a DC / AC converter.

[0154] Optionally, the method in this embodiment of the invention further includes a step of controlling the state of charge (SBC) balance of each energy storage unit, wherein the step of controlling the SBC balance of each energy storage unit further includes:

[0155] The local controller of the energy storage unit will associate the i-th energy storage unit SoC with it. i Average SoC of microgrid systems a We perform weighting to obtain the proportional coefficient weight α of the i-th energy storage unit. pi Then the central controller assigns the proportional coefficient weight α pi The energy is transmitted to the corresponding energy storage unit. During charging mode, the proportional gain weight α of the energy storage unit is... pi Its state of charge value SoC i The scaling factor is inversely proportional; that is, the energy storage unit with the lowest SoC value will have the highest scaling factor weight, while the energy storage unit with the highest SoC value will have the lowest scaling factor weight. Therefore, energy storage units with lower energy storage capacity can absorb more microgrid power, causing the SoC value to increase rapidly. When the SoC value of an energy storage unit approaches the average SoC value of the microgrid system, its scaling factor weight decreases, thus reducing power imbalance caused by the SoC equalization process. Conversely, in discharge mode, the scaling factor weight α of the energy storage unit... piIts state of charge value SoC i The weighting of a scaling factor is directly proportional to the SoC value: the higher the SoC of an energy storage unit, the greater its weighting, and vice versa. Therefore, energy storage units with larger storage capacities contribute more to the microgrid's demand, and their SoC decreases more rapidly. Conversely, when the SoC of an energy storage unit approaches the average SoC of the microgrid system, its scaling factor weighting is reduced. In both cases, the SoC value of each energy storage unit gradually converges to the average SoC of the microgrid system over time.

[0156] Average State of Charge (SoC) of Each Energy Storage Unit a Calculated according to formula (8):

[0157]

[0158] Among them, the SoC of the i-th energy storage unit is a SoC i To express.

[0159] The SoC equalization process of energy storage units can lead to power imbalances between units, potentially exceeding the rated power of their inverters. To ensure that the inverters of the energy storage units achieve SoC equalization and operate within their power limits, the central controller limits the active power scalar coefficient α of the energy storage units. ESU The value is lower than the average state of charge of each energy storage unit in the SoC. a By analyzing α ESU The limitation ensures that the power absorbed or released by the energy storage unit is lower than its maximum charge / discharge power, while maintaining the power required to achieve SoC equalization. Optionally, a saturation limiter is used at the beginning of the SoC equalization process of the energy storage unit to avoid generating excessively high SoC values, thereby preventing IUI converter overload problems.

[0160] Optionally, during the SoC equalization process of the energy storage unit, α ESU The restrictions specifically include:

[0161] (1) Charging mode (α) ESU <0)

[0162] If |α ESU |>SoC a ,but

[0163] α ESU =-SoC a (9)

[0164] (2) Discharge mode (α) ESU >0)

[0165] If |α ESU |>SoC a ,but

[0166] α ESU =SoC a (10)

[0167] When the central controller calculates α ESU Value, then α ESU The value is passed to the local controller of each energy storage unit, and the local controller is based on α. ESU The value is used to calculate the power reference for this energy storage unit.

[0168] The proportional gain weight α received by the energy storage unit from the central controller pi Then, it is compared with the received scalar coefficient α of the active power of the energy storage unit. ESU The active power reference value of the energy storage unit is obtained by combining the above methods. The control method of this invention corrects the output active power of the energy storage unit based on its System-on-Chip (SoC) state, thereby solving the SoC balance problem of the energy storage unit. Optionally, this invention uses a power function to calculate the SoC-based proportional coefficient weight α. pi In charging mode, the active power reference value of energy storage unit i is calculated according to equation (11), and in discharging mode, the active power reference value of energy storage unit i is calculated according to equation (12).

[0169] (1) Charging mode

[0170]

[0171] (2) Discharge Mode

[0172]

[0173] The superscript p is the convergence factor that adjusts the SoC equalization speed. The larger the p value, the faster the SoC equalization process.

[0174] In islanded mode, the DC-side energy storage units act as a controlled voltage source to regulate the DC bus voltage. Simultaneously, as a dispatchable distributed energy source, the DC-side energy storage units can be controlled via an external control loop. To maintain coordination between energy storage units.

[0175] The method disclosed in this invention aims to manage the entire hybrid AC / DC microgrid system as a single controllable entity, achieve proportional power sharing between AC-side or DC-side energy storage units through SoC equalization, and control the reactive power injection of AC-side distributed energy sources and grid power flow.

[0176] Optionally, in the method disclosed in this embodiment of the invention, the photovoltaic power generation unit (PV) operates at its maximum power point to obtain more photovoltaic output, while the power of the energy storage unit is determined by a scalar coefficient transmitted by the central controller. In the AC sub-microgrid, the required reactive power is provided by each distributed energy source (i.e., a renewable energy unit or energy storage unit, ESU).

[0177] In another embodiment, a power control-based energy storage AC / DC hybrid microgrid system is also provided, including: a central controller, a converter, AC loads, DC loads, and distributed energy sources; the central controller acquires basic equipment information of each distributed energy source within the microgrid system and performs control for the first cycle; in each control cycle, the central controller collects operating information of each distributed energy source, and determines the active power reference value of all energy storage units and the reactive power reference value of all distributed energy sources for the next control cycle based on the operating information of each distributed energy source, so as to realize the control of the microgrid system in the next control cycle.

[0178] The working principle of the power control-based energy storage AC / DC hybrid microgrid system disclosed in this embodiment is the same as the working principle of the power control-based energy storage AC / DC hybrid microgrid system control method in the above embodiments, and will not be repeated here.

[0179] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 4 As shown, the computer device includes a processor, memory, and a network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores static and dynamic information data. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements the steps in the above method embodiments.

[0180] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the computer device to which the present invention is applied. A specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0181] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0182] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon that, when executed by a processor, implements the steps in the method embodiments described above.

[0183] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical storage, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0184] This invention is not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this invention is limited only by the appended claims.

Claims

1. A control method for an energy storage-type AC / DC hybrid microgrid system based on power control, characterized in that, For controlling a microgrid system, the microgrid system including: a central controller, converters, AC loads, DC loads, and distributed energy sources, the method includes the following steps: Acquire basic information about the devices of each distributed energy source within the microgrid system and perform the first cycle of control; In each control cycle, operational information from each distributed energy source is collected. Based on this information, reference values ​​for the active power of all energy storage units and the reactive power of all distributed energy sources are determined for the next control cycle. The steps for determining the reference values ​​for the active power of all energy storage units for the next control cycle include: The active power reference values ​​for all energy storage units in the (k+1)th control cycle are shown in the following formula: in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the active power of the microgrid system in the k-th control cycle. This represents the reference value of active power of the power grid in the (k+1)th control cycle; The steps for determining the reactive power reference values ​​for all distributed energy sources in the next control cycle include: in, This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; This represents the reactive power absorbed by the AC bus of the microgrid system during the k-th control cycle. This represents the reference value of reactive power of the power grid in the (k+1)th control cycle; This represents the reactive power output of the converter in the kth control cycle.

2. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 1, characterized in that, The control of the first cycle includes the following steps: The active power reference values ​​of all energy storage units and the reactive power reference values ​​of all distributed energy sources are calculated based on the rated capacity of distributed energy sources, the capacity of energy storage units, and the power factor of the power grid.

3. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 1, characterized in that, The method further includes: in each control cycle, determining the scalar coefficient of each distributed energy source in the next control cycle based on the operation information of each distributed energy source, wherein the scalar coefficient includes the proportion of active power and reactive power exchanged between each distributed energy source and the microgrid system.

4. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 3, characterized in that, The step of determining the scalar coefficients of each distributed energy source in the next control cycle includes: when , in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the minimum charging power of all energy storage units in the k-th control cycle. This represents the maximum discharge power of all energy storage units in the k-th control cycle. This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

5. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 3, characterized in that, The step of determining the scalar coefficients of each distributed energy source in the next control cycle includes: when , in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the minimum charging power of all energy storage units in the k-th control cycle. This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

6. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 3, characterized in that, The step of determining the scalar coefficients of each distributed energy source in the next control cycle includes: when , in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the maximum discharge power of all energy storage units in the k-th control cycle. This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

7. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 3, characterized in that, The step of determining the scalar coefficients of each distributed energy source in the next control cycle includes: when , in, This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; This represents the reference value of the maximum reactive power of all distributed energy sources in the k-th control cycle; This represents the reactive power scalar coefficient of distributed energy resources.

8. A control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in any one of claims 3 to 7, characterized in that, The method also includes a step of controlling the state of charge balance of each energy storage unit, including: The state of charge value of the i-th energy storage unit Average state of charge of each energy storage unit Perform weighting to obtain the proportional coefficient weight of the i-th energy storage unit. ; In charging mode, the proportional gain weight of the energy storage unit With state of charge Inversely proportional; In discharge mode, the proportional gain weight of the energy storage unit With state of charge Proportional.

9. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 8, characterized in that, The step of controlling the state of charge balance of each energy storage unit further includes: limiting the active power scalar coefficient of the energy storage unit. The value is lower than the average state of charge of each energy storage unit. .

10. The control method for an energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 9, characterized in that, The active power reference value of the energy storage unit is shown in the following formula: (1) Charging mode (2) Discharge mode (12) Where the superscript p is the convergence factor for adjusting the SoC equalization speed. This represents the reference value of the active power of energy storage unit i. This represents the minimum charging power of energy storage unit i. This represents the maximum discharge power of energy storage unit i.

11. A power control-based energy storage AC / DC hybrid microgrid system, characterized in that, include: Central controller, converter, AC load, DC load, distributed energy source; The central controller acquires basic information about the devices of each distributed energy source in the microgrid system and performs the first cycle of control. In each control cycle, the central controller collects operational information from each distributed energy source. Based on this information, it determines the active power reference values ​​for all energy storage units and the reactive power reference values ​​for all distributed energy sources for the next control cycle. The steps for determining the active power reference values ​​for all energy storage units in the next control cycle include: The active power reference values ​​for all energy storage units in the (k+1)th control cycle are shown in the following formula: in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the active power of the microgrid system in the k-th control cycle. This represents the reference value of active power of the power grid in the (k+1)th control cycle; The steps for determining the reactive power reference values ​​for all distributed energy sources in the next control cycle include: in, This represents the reference value of reactive power for all distributed energy sources in the (k+1)th control cycle; This represents the reactive power absorbed by the AC bus of the microgrid system during the k-th control cycle. This represents the reference value of reactive power in the power grid during the (k+1)th control cycle; This represents the reactive power output of the converter in the kth control cycle.

12. The energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 11, characterized in that, The central controller is also used for: In the first cycle of control, the active power reference value of all energy storage units and the reactive power reference value of all distributed energy sources are calculated based on the rated capacity of distributed energy sources, the capacity of energy storage units and the power factor of the grid.

13. The energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 11, characterized in that, The central controller is also used to: determine the scalar coefficients of each distributed energy source in the next control cycle based on the operating information of each distributed energy source, wherein the scalar coefficients include the proportion of active power and reactive power exchanged between each distributed energy source and the microgrid system.

14. The energy storage-type AC / DC hybrid microgrid system based on power control as described in claim 13, characterized in that, The determination of the scalar coefficients for each distributed energy source in the next control cycle includes: when , in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the minimum charging power of all energy storage units in the k-th control cycle. This represents the maximum discharge power of all energy storage units in the k-th control cycle. This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

15. A power control-based energy storage AC / DC hybrid microgrid system as described in claim 13, characterized in that, The determination of the scalar coefficients for each distributed energy source in the next control cycle includes: when , in, This represents the reference value of active power for all energy storage units in the (k+1)th control cycle. This represents the minimum charging power of all energy storage units in the k-th control cycle. This represents the active power scalar coefficient of the energy storage unit in the (k+1)th control cycle.

16. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 10.

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