Microgrid control method and microgrid control system

Abstract

The application provides a microgrid control method and a microgrid control system, and the method comprises the following steps: collecting state data of the microgrid when the microgrid is in a connection mode; calculating a dynamic model of the microgrid according to the state data of the microgrid in the connection mode; collecting state data of the microgrid in an island mode after the microgrid is switched to the island mode, and calculating a control command of the microgrid according to the state data of the microgrid in the island mode and the dynamic model. The application can realize stable operation of the microgrid with multiple distributed energy equipment in the island mode, so that the microgrid can be smoothly switched between the access mode and the island mode, and the embodiment of the application supports multiple distributed energy equipment, such as three-phase and single-phase equipment.

Description

Technical Field

[0001] This invention relates to the field of power electronics microgrid technology, specifically to a microgrid control method and a microgrid control system. Background Technology

[0002] A microgrid, also known as a micro-grid, is a concept relative to a traditional large power grid. It refers to a network composed of multiple distributed power sources and their associated loads arranged in a specific topology and connected to the conventional power grid through static switches. Developing and extending microgrids can fully promote the large-scale integration of distributed power sources and renewable energy, achieving a highly reliable supply of multiple energy forms to loads, and is an effective way to realize an active distribution network.

[0003] A microgrid is an autonomous system capable of self-control, protection, and management. It can operate in connected mode, meaning it is connected to the external power grid (such as the main grid), or in islanded mode, meaning it operates independently of the external power grid. Maintaining the stable function of the microgrid after it transitions from connected mode to islanded mode (e.g., during a natural disaster) is a pressing technical challenge.

[0004] A prior art technology (see European Patent Office patent application publication EP2715904B1) proposes a system integrating a generator that adjusts the connection between the load and the generator by regulating the DC voltage, with each load or generator having a specific control voltage range. This system can only be used in DC grids, not the more common AC grids. Furthermore, while it uses different voltages to manage different loads to avoid power peaks, it requires setting precise voltage values ​​for each load and necessitates line voltage control by a grid dispatch center.

[0005] Another existing technology (see European Patent Office patent application EP2973940B1 and US patent applications US 2018 / 0366978A1, US2016 / 0239006A1, and US2040 / 0004212A1, etc.) provides a centralized control and management scheme to maintain voltage or frequency stability by monitoring the real-time status of loads and generators. These schemes mostly control the load through a central communication system, but require real-time and precise control of all loads and generators, placing high demands on communication capabilities and exhibiting weak robustness. Furthermore, these schemes cannot handle uncertain load disturbances; users cannot control the load independently.

[0006] There are also some existing technologies (see Chinese patent application CN103683323 and US patent applications US 7116010B2 and US 7687937B2, etc.) that maintain voltage or frequency stability by controlling loads and generators in islanded mode. These solutions control each island individually, do not require a communication system, but cannot guarantee stability. Furthermore, these solutions typically require remote real-time monitoring of all loads and generators, and the microgrid structure cannot be reconfigured. Summary of the Invention

[0007] The technical problem to be solved by the embodiments of the present invention is to provide a microgrid control method and a microgrid control system that can realize the stable operation of a microgrid with multiple distributed energy devices in islanded mode.

[0008] To address the aforementioned technical problems, this invention provides a microgrid control method, comprising:

[0009] When the microgrid is in connected mode, the status data of the microgrid is collected;

[0010] Calculate the dynamic model of the microgrid based on its state data in the connection mode;

[0011] After the microgrid switches to island mode, the status data of the microgrid in island mode is collected, and the control command of the microgrid is calculated based on the status data of the microgrid in island mode and the dynamic model.

[0012] Optionally, when the microgrid is in connected mode, collecting the status data of the microgrid includes: collecting the status data of multiple distributed energy devices in the microgrid and the status data at the access point where the microgrid connects to the main network when the microgrid is in connected mode;

[0013] After calculating the control commands for the microgrid, the method further includes sending the calculated control commands to the corresponding distributed energy devices.

[0014] Optionally, before calculating the dynamic model of the microgrid based on its state data in the connected mode, the method further includes:

[0015] When the state data is three-phase data, the state data is converted into a three-phase symmetrical vector. The three-phase data is three-phase voltage, three-phase current or three-phase power, and the three-phase symmetrical vector is a three-phase voltage symmetrical vector, a three-phase current symmetrical vector or a three-phase power symmetrical vector.

[0016] When the state data is single-phase data, the state data is converted into a single-phase vector. The single-phase data is single-phase voltage, single-phase current, or single-phase power, and the single-phase vector is a single-phase voltage vector, a single-phase current vector, or a single-phase power vector.

[0017] Optionally, if the calculated control command is the three-phase symmetrical vector, the control command is converted into the three-phase data before sending the calculated control command to the corresponding distributed energy device;

[0018] If the calculated control command is a single-phase vector, the control command is converted into single-phase data before being sent to the corresponding distributed energy device.

[0019] Optionally, calculating the control commands for the microgrid based on its state data in islanded mode and the dynamic model includes:

[0020] Based on the microgrid's status data in islanded mode, the dynamic model, and the hardware capacity of the multiple distributed energy devices, the control commands for the multiple distributed energy devices in islanded mode are calculated.

[0021] Optionally, the plurality of distributed energy devices are selected from all distributed energy devices in the microgrid in descending order of hardware capacity.

[0022] Optionally, the status data of the plurality of distributed energy devices includes the status data of the plurality of distributed energy devices at both the input and output ends of their respective output filters.

[0023] Optionally, the distributed energy device includes a single physical device and / or a virtual device, wherein the virtual device is the sum of multiple physical devices under unified control.

[0024] According to another aspect of the present invention, at least one embodiment provides a microgrid control system, comprising:

[0025] The data acquisition module is used to collect the status data of the microgrid when the microgrid is in connected mode;

[0026] The model recognition module is used to calculate the dynamic model of the microgrid based on the state data of the microgrid in the connection mode.

[0027] An optimal controller is used to collect the state data of the microgrid in islanded mode after the microgrid switches to islanded mode, and to calculate the control command of the microgrid based on the state data of the microgrid in islanded mode and the dynamic model.

[0028] Optionally, the data acquisition module is also used to collect status data of multiple distributed energy devices in the microgrid and status data at the access point of the microgrid to the main network when the microgrid is in connected mode;

[0029] The optimal controller is also used to send the calculated control commands to the corresponding distributed energy devices.

[0030] Optionally, the optimal controller is further configured to calculate control commands for the multiple distributed energy devices in islanded mode based on the microgrid's state data in islanded mode, the dynamic model, and the hardware capacity of the multiple distributed energy devices.

[0031] Optionally, the status data of the plurality of distributed energy devices includes the status data of the plurality of distributed energy devices at both the input and output ends of their respective output filters.

[0032] According to another aspect of the present invention, at least one embodiment provides a computer-readable storage medium on which a program is stored, which, when executed by a processor, implements the steps of the method described above.

[0033] Compared with the prior art, the microgrid control method and microgrid control system provided in this embodiment of the invention can simultaneously and securely isolate data on the client and server sides without increasing development and maintenance costs.

[0034] As can be seen from the above, the microgrid control system provided by the embodiments of the present invention can realize the stable operation of a microgrid with multiple distributed energy devices in islanded mode, enabling the microgrid to switch smoothly between access mode and islanded mode. Furthermore, the embodiments of the present invention support a variety of distributed energy devices, such as three-phase and single-phase devices. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a microgrid structure according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the hardware structure of the inverter and related data collection in an embodiment of the present invention;

[0038] Figure 3This is a schematic flowchart of a microgrid control method according to an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of a microgrid control system according to an embodiment of the present invention;

[0040] Figure 5 This is a schematic diagram of another structure of the microgrid control system according to an embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of the transfer function of the optimal controller and the system model in an embodiment of the present invention;

[0042] Figure 7 This is a general operation flow of the microgrid control system according to an embodiment of the present invention;

[0043] Figure 8 This is a schematic diagram of another structure of the microgrid control system according to an embodiment of the present invention;

[0044] Figure 9 This is a schematic diagram of another structure of the microgrid control system according to an embodiment of the present invention. Detailed Implementation

[0045] To make the technical problems, technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments. In the following description, specific details such as particular configurations and components are provided merely to aid in a comprehensive understanding of the embodiments of this invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this invention. Furthermore, for clarity and brevity, descriptions of known functions and structures have been omitted.

[0046] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0047] In various embodiments of the present invention, it should be understood that the sequence number of each process described below does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0048] Please refer to Figure 1This invention provides a hardware structure diagram of a microgrid 116, which includes multiple distributed energy resource (DER) devices. The microgrid 116 is connected to the main power grid 114 through an access point 115. Wherein:

[0049] 101 and 108 represent transformers; 102, 103, and 109 represent active loads; 105 represents a distributed generator or energy storage unit, typically with medium or small capacity (capacity can specifically be power). 104 represents the inverter of the distributed generator or energy storage unit 105, which is capable of autonomous operation without remote communication with the control center 112. Specifically, this inverter can be controlled using conventional control logic, such as droop control in an independent power system, or maximum power point tracking (MPPT) technology.

[0050] 106 and 110 represent inverters or distributed generators connected to control center 112. These inverters or distributed generators are capable of remote communication with control center 112. The status data 113 exchanged during communication can specifically be the real-time voltage, current, or power at the location where the inverter or distributed generator is connected to the grid. All inverters connected to control center 112 need to exchange the above information. A more detailed description of the process for collecting status data 113 can be found later.

[0051] 107 and 111 represent distributed generators or energy storage devices, typically with large capacities. 114 represents the main power grid (or main grid, large power grid, etc.). 115 represents the access point between the microgrid and the main power grid 114, where real-time voltage, current, or power is measured and collected to obtain status data 113. In this embodiment of the invention, the microgrid 116 can be connected to the main power grid 114 through one or more access points 115.

[0052] Microgrids typically operate in two modes: access mode and islanding mode. In access mode, the microgrid connects to the main grid through one or more access points similar to access point 115, while in islanding mode, the microgrid disconnects from all access points to the main grid 114, thus operating independently from the main grid.

[0053] 117 and 112 represent uninterrupted power supplies (UPS), which can be connected to microgrid 116 and charged through microgrid 116. Additionally, the UPS will provide power to control center 112 when necessary.

[0054] In this embodiment of the invention, inverters of large distributed energy generators and energy storage devices can be connected to the control center 112 according to capacity, while the remaining inverters operate autonomously. The proportion of inverters connected to the control center 112 in the microgrid among all distributed energy generator and energy storage device inverters can be determined through offline dynamic simulation of the target power grid. For example, this proportion can be gradually increased until the target power grid meets the standard for stable power quality.

[0055] Figure 1 In the microgrid 116, there are multiple DER devices, such as 111, 105, and 107. These DER devices can be distributed generators and / or energy storage devices. Typically, each DER device converts DC to AC through an inverter (such as 110 / 104 / 106) and then connects to the main grid through a transformer (such as 101 / 108). Figure 1 In this context, a DER can be a physical device or a virtual device (sometimes called a virtual power plant, VPP). A virtual device can be the sum of multiple physical devices that are close to each other and under unified control.

[0056] Figure 2 The hardware structure of inverter 200 and related data collection diagrams are shown. Inverter 200 can convert the energy generated by DER device 201 into AC power 205 for microgrid transmission. DER device 201 can be a photovoltaic panel, energy storage device (such as a battery energy storage unit), or other types of DC generator. Figure 2 The DER device 201 in the text is specifically equivalent to Figure 1 Equipment such as 111 or 107 in the middle, Figure 2 The inverter 200 in the middle is equivalent to Figure 1 Equipment such as 110 or 106 in the system. Figure 2 As shown, the inverter 200 of the DER device 201 includes:

[0057] In some scenarios, the DC-to-DC converter 202 may not be necessary.

[0058] The DC-to-AC converter 203 converts the DC energy generated by the DER device 201 into AC energy.

[0059] The output filter 204 has its input terminal connected to the output terminal of the DC / AC converter. The output terminal of the output filter 204 is a microgrid, and the frequency of the AC power transmitted can be 50 or 60 Hz, etc.

[0060] Controller 206 is used to determine the voltage signal at the output terminal of output filter 204 (e.g., ...) Figure 2The Va, Vb, and Vc values ​​in the DC / AC converter generate control commands and send them to the DC / AC converter 203.

[0061] In this embodiment of the invention, Figure 1 The collected state data 113 includes data 207 from the input terminal and data 208 from the output terminal of the DC / AC converter 203. Specifically, this data may be the measurement result of the original voltage (such as real-time voltage), or other parameters derived from the original voltage measurement result, such as a three-phase symmetrical vector, a single-phase vector, or a dq component.

[0062] Please refer to Figure 3 This invention provides a microgrid control method, comprising:

[0063] S21, when the microgrid is in connected mode, collect the status data of the microgrid.

[0064] Here, in this embodiment of the invention, when the microgrid is in connected mode, the status data of multiple distributed energy devices in the microgrid and the status data at the access point where the microgrid connects to the main network are collected. The status data of the multiple distributed energy devices includes the status data of each distributed energy device at both the input and output ends of its respective output filter. Here, the output filter of each distributed energy device refers to the output filter of the inverter of the distributed energy resource device, such as... Figure 2 The output filter 204 is included. Additionally, the distributed energy device may include a single physical device and / or a virtual device, where the virtual device is the sum of multiple physical devices under unified control.

[0065] In this embodiment of the invention, multiple distributed energy devices can be selected from all distributed energy devices in the microgrid according to their hardware capacity (e.g., power) in descending order. The specific number of selected devices can be determined by performing offline simulation on the target microgrid, for example, by gradually increasing the number of the devices until the target microgrid meets the standard of stable power quality.

[0066] S22, Calculate the dynamic model of the microgrid based on the state data of the microgrid in the connection mode.

[0067] Here, this embodiment of the invention can utilize the state data of the microgrid in connected mode to calculate the dynamic model of the microgrid. The above calculation process can be continuously performed in connected mode; that is, based on the latest collected state data of the microgrid in connected mode, the dynamic model of the microgrid is calculated and updated, thereby obtaining the latest dynamic model. Furthermore, after the microgrid enters a stable state, this embodiment of the invention can use the above steps to obtain the dynamic model of the microgrid in a stable state in access mode.

[0068] Additionally, it should be noted that when the state data is three-phase data, the state data is converted into a three-phase symmetrical vector before the model calculation process in step S22 is executed. The three-phase data is three-phase voltage, three-phase current, or three-phase power, and the three-phase symmetrical vector is a three-phase voltage symmetrical vector, a three-phase current symmetrical vector, or a three-phase power symmetrical vector. When the state data is single-phase data, the state data is converted into a single-phase vector before the model calculation process in step S22 is executed. The single-phase data is single-phase voltage, single-phase current, or single-phase power, and the single-phase vector is a single-phase voltage vector, a single-phase current vector, or a single-phase power vector.

[0069] S23, after the microgrid switches to island mode, collect the status data of the microgrid in island mode, and calculate the control command of the microgrid based on the status data of the microgrid in island mode and the dynamic model.

[0070] Here, after the microgrid switches from connected mode to islanded mode, that is, after the microgrid disconnects from the main grid, the present invention embodiment can calculate the control command of the microgrid through the above S23, so that the control command can be calculated using the dynamic model of the microgrid in connected mode, which enables the microgrid to maintain stability when entering islanded mode.

[0071] Furthermore, in embodiment S23 of the present invention, the hardware capacity of the devices can also be considered. In this case, control commands for the multiple distributed energy devices in islanded mode can be calculated based on the state data of the microgrid in islanded mode, the dynamic model, and the hardware capacity of the multiple distributed energy devices. This allows each distributed energy device to output energy approximately according to the proportion of its hardware capacity.

[0072] Following S23 above, the embodiments of the present invention may also send the calculated control commands to the corresponding distributed energy devices, which will receive and execute the control commands.

[0073] In addition, if the calculated control command is a three-phase symmetrical vector, the control command needs to be converted into the three-phase data before sending the control command to the corresponding distributed energy device; if the calculated control command is a single-phase vector, the control command needs to be converted into the single-phase data before sending the control command to the corresponding distributed energy device.

[0074] Through the above steps, this embodiment of the invention can send control commands to distributed energy devices, for example, to the controller 206 of the inverter of the distributed energy device, thereby controlling each distributed energy device. Since the state data of the microgrid in access mode is considered when identifying the dynamic model, and a dynamic model is generated based on the aforementioned state data, the microgrid can maintain stability when entering islanded mode and achieve smooth switching between access mode and islanded mode. Furthermore, this embodiment of the invention can accommodate various types of distributed energy devices, such as single-phase or multi-phase devices, and supports three-phase and single-phase devices.

[0075] Figure 4 This invention provides a system function and data processing structure for a microgrid control system according to an embodiment of the invention. Figure 5 This invention provides another system function and data processing structure for a microgrid control system, compared to... Figure 4 , Figure 5 The database has been reduced by 305 errors. The following is in conjunction with... Figure 4 and Figure 5 The following provides a further explanation of the model recognition and control command calculation in the embodiments of the present invention.

[0076] Figure 4 and Figure 5 middle:

[0077] 301 indicates distributed energy devices (DERs) whose status data are collected, and these devices are remotely controlled by computing system 304. These devices are typically located far apart from each other; specifically, these devices can be... Figure 1 111 / 107 or Figure 2 The 301 redirect. It should be noted that a 301 redirect for one or more devices may not be a single physical device, but rather an access point between the micronet and the main network, such as... Figure 1 115 in the middle.

[0078] Status data 302 represents status data collected from device 301. These status data are sorted according to a preset inter-device order to form specific status data numbers (1, 2, ..., n). This status data 302 corresponds to... Figure 2 State 208 is defined. This state data needs to be collected in real time, and its sampling frequency should typically be higher than the microgrid's system frequency (e.g., 50Hz or 60Hz). Here, n represents the number of distributed energy devices whose state data is being collected.

[0079] Status data 303 is similar to 302, but the difference is that 303 includes... Figure 2 207 and Figure 1The data is from access point 115. Following the same device order and a preset access point order, these status data are sorted to form specific status data numbers (n+1, n+2, ..., n+m). Here, m represents the sum of the number of distributed energy devices whose status data is collected and the number of access points whose status data is collected.

[0080] Note that status data 302 and 303 can be found in... Figure 1 The data is collected when the microgrid 116 is connected to the main grid 114 and when it is disconnected from the main grid 114.

[0081] 304 represents a computing system used to process status data and communicate with device 301, corresponding to... Figure 1 112.305 represents a database or other data storage device. 306 represents a data transformation module that converts state data into other types of data. Note that this state data is all time-series data. The processing procedure is as follows:

[0082] a) If the original collected state data is three-phase real-time voltage (va0, vb0, vc0) (or current or power), then it is converted into three-phase symmetrical components (v1∠θ1, v2∠θ2, v0∠θ0) using standard formulas known in the art. Note that these data are time series.

[0083] b) If the original collected state data is a symmetric component similar to the above, then keep the data unchanged.

[0084] c) If the original collected state data is single-phase voltage (va0) (or current or power), then convert it to a single-phase quantity (va∠θa).

[0085] 307 represents the model recognition module, which uses the state data obtained by the data conversion module 306 to identify the dynamic model of the microgrid using the following formula:

[0086]

[0087] C = (E n 0);

[0088] x dd =(v1) 1t0 x1 1t0 v2 1t1 ,θ2 1t0 v0 1t0 ,θ0 1t0 v1 2t0 ,θ1 2t0 ,…,θ0 nt0 )

[0089] xd =(x dd ,0,0,…,0) T

[0090] ud =

[0091] ((f((v1 (n+1)t0 θ1 (n+1)t0 v2 (n+1)t0 θ2 (n+1)t0 v0 (n+1)t0 θ0 (n+1)t0 v1 (n+2)t0 θ1 (n+2) t 0, ..., θ0 (n+m)t0 ) T )) T ,0,0,...,0) T

[0092] Among them, v1 itj ∠θ1 itj v2 itj ∠θ2 itj and v0 itj ∠θ0 itj , respectively represent the positive-sequence component, negative-sequence component, and zero-sequence component of the three-phase symmetrical components at time tj of the output filter of the distributed energy device numbered i. Here, the value of i ranges from 1 to n, and n represents the number of distributed energy devices whose state data are collected. These devices are numbered in a preset order.

[0093] v1 (n+s)tj ∠θ1 (n+s)tj v2 (n+s)tj ∠θ2 (n+s)tj and v0 (n+s)tj ∠θ0 (n+s)tj , represent the positive-sequence component, negative-sequence component, and zero-sequence component of the three-phase symmetrical components of the target location point s at time tj, respectively. The target location point includes the input terminal of the output filter of the distributed energy device collecting state data and the access point of the collected state data. The value range of s is 1 to m, where the value range of s corresponding to the input terminal of the output filter of the distributed energy device numbered i is 1 to n, and the value range of s corresponding to the access point of the collected state data is n+1 to m, where mn represents the number of access points of the collected state data.

[0094] In this embodiment of the invention, status data is collected in real time during the transition of the microgrid from access mode to island mode. Here, t0 represents the moment when status data was most recently collected in the microgrid access mode, and td represents a moment when status data was collected in the microgrid access mode, with td preceding t0; thus, (td, t0) represents the most recent period in which the microgrid is in access mode. Here, the following constraint must be met: the number of status data collection times within the time interval (td, t0) is greater than or equal to the number of status data items contained in (n+m) devices, that is, the length of the time series of status data obtained within the time interval (td, t0) is greater than or equal to the number of status data items contained in (n+m) devices. The (n+m) devices may include the distributed energy devices and access points mentioned above. Here, the microgrid is already in a stable state when operating in access mode.

[0095] pinv represents the pseudo-inverse operation. n or m are quantities defined in 302 and 303.

[0096] E n It is an identity matrix of dimension n. Matrix A0 has a dimension of L*L, and matrix B0 has a dimension of L*W.

[0097] Where L represents a matrix The number of rows, W represents the matrix. number of rows.

[0098] The data in the above formulas are defined in 306 as either three-phase symmetrical components or single-phase quantities.

[0099] The function f(B0) is defined as follows: the discard matrix B0 corresponds to the connection point between the microgrid and the main grid (e.g., ...). Figure 1 The columns of state data (such as current or power) measured at node 115 are used to retain the remaining columns in the original order in matrix B0, where the dimension of f(B0) is L*r.

[0100] x dd This indicates the stable state of microgrid 116 when it is connected to the main power grid.

[0101] vector x d The dimension is (2*L)*1, and the vector u d The dimension is (2*r)*1.

[0102] The standard (state-space) system model is as follows:

[0103] y = Cx

[0104] x is the real-time state vector, u is the input of the system model, and y is the output of the system model.

[0105] Based on the above standard (state-space) system model, an augmented state-space model is provided as follows:

[0106] y = E n x rt

[0107] x rt =(v1) 1t ,θ1 1t v2 1t ,θ2 1t v0 1t ,θ0 1t v1 2t ,θ1 2t ,…,θ0 nt )

[0108] x=(x rt ,∫(x dd -x rt )dt) T

[0109] Among them, v1 it ∠θ1 it v2 it ∠θ2 it and v0 it ∠θ0 it , respectively, represent the positive-sequence component, negative-sequence component, and zero-sequence component of the three-phase symmetrical components at time t of the output filter of the distributed energy device numbered i, where time t is the current time (corresponding to the above x). dd In the calculation formula, t0), i ranges from 1 to n, where n represents the number of distributed energy devices whose status data are collected. These devices are numbered in a preset order.

[0110] The optimal controller 308, specifically based on a linear quadratic regulator (LQR), calculates the optimal control command for device 301. The flowchart of the optimal controller 308 is as follows: Figure 6 As shown, Figure 6 The transfer function of the optimal controller and the augmented system model are shown.

[0111] K = LQR(A,B,C,Q,R,0)

[0112] Q = E

[0113] R = diag(cp1, cp2, ..., cp r )

[0114] Where 401 represents the integral operator 1 / s of the transfer function, 402 represents the gain matrix K, E represents the identity matrix, diag represents the diagonal matrix operator, and cp i This represents the hardware capacity, such as power, of the DER device numbered i. 403 represents the augmented system model described above. Thus, the output of the optimal controller is:

[0115] u=-K(xx d )+u d

[0116] The data recovery module 309, following the reverse process of the data conversion module 306, restores the control commands output by the optimal controller into three-phase or single-phase data, thereby obtaining the final control commands 310 for the DER devices in the microgrid. The final control commands 310 include commands arranged in the same numerical order as when the status data of these DER devices was collected. These commands are sent to the remote DER devices and executed by them in real time, thus ensuring smooth switching and stable operation of the microgrid in islanded mode.

[0117] As can be seen from the above, in this embodiment of the invention, when calculating the dynamic model of the microgrid based on the state data of the microgrid in the connection mode, the specific steps include:

[0118] The state-space model of the microgrid is obtained according to the following formula: y = E n x rt ;

[0119] in, C = (E n 0);

[0120] x=(x rt ,∫(x dd -x rt )dt) T

[0121] When calculating the control commands for the microgrid based on its state data in islanded mode and the dynamic model, the specific steps include:

[0122] The control command is obtained according to the following formula: u = -K(xx) d )+u d .

[0123] Figure 7 The present invention provides an overall operation flow of the microgrid control system in an embodiment of the invention, including:

[0124] 501, Start, the microgrid begins operation and connects to the main power grid. At this time, the microgrid operates in connected mode.

[0125] 502, Collect status data of DER devices within the most recent time range.

[0126] 503, System calculation process, please refer to sections 305-309 above for details.

[0127] 504. Does the microgrid disconnect from the main grid and enter islanded mode? If yes, proceed to 506; otherwise, return to 503.

[0128] 505, Real-time data collected from DER devices in islanded mode

[0129] 506, The system outputs the calculated control command (310) to all DER devices, which execute the command.

[0130] 507, Manual shutdown command or fault signal.

[0131] 508. Determine if the shutdown command or fault signal from 507 has been received. If so, proceed to 509; otherwise, return to 503.

[0132] 509, Microgrid closed, process ended.

[0133] The microgrid control method of this invention can realize the stable operation of a microgrid with multiple distributed energy devices in islanded mode, enabling the microgrid to switch smoothly between access mode and islanded mode. Furthermore, this invention supports a variety of distributed energy devices, such as three-phase and single-phase devices.

[0134] Please refer to the following: Figure 8 The present invention also provides a microgrid control system, which is equivalent to Figure 1 112 in the middle, such as Figure 8 As shown, the system includes:

[0135] The data acquisition module 801 is used to collect the status data of the microgrid when the microgrid is in connected mode;

[0136] The model recognition module 802 is used to calculate the dynamic model of the microgrid based on the state data of the microgrid in the connection mode.

[0137] The optimal controller 803 is used to collect the state data of the microgrid in island mode after the microgrid switches to island mode, and calculate the control command of the microgrid based on the state data of the microgrid in island mode and the dynamic model.

[0138] Optionally, the data acquisition module is also used to collect status data of multiple distributed energy devices in the microgrid and status data at the access point of the microgrid to the main network when the microgrid is in connected mode;

[0139] The optimal controller is also used to send the calculated control commands to the corresponding distributed energy devices.

[0140] Optionally, a data conversion module is used before the model recognition module calculates the dynamic model of the microgrid: if the state data is three-phase data, then the state data is converted into a three-phase symmetrical vector, wherein the three-phase data is three-phase voltage, three-phase current, or three-phase power, and the three-phase symmetrical vector is a three-phase voltage symmetrical vector, a three-phase current symmetrical vector, or a three-phase power symmetrical vector; if the state data is single-phase data, then the state data is converted into a single-phase vector, wherein the single-phase data is single-phase voltage, single-phase current, or single-phase power, and the single-phase vector is a single-phase voltage vector, a single-phase current vector, or a single-phase power vector.

[0141] Optionally, the above system may also include

[0142] The data recovery module is configured to convert the calculated control command into three-phase data before sending the calculated control command to the corresponding distributed energy device when the calculated control command is the three-phase symmetrical vector; and to convert the calculated control command into single-phase data before sending the calculated control command to the corresponding distributed energy device when the calculated control command is the single-phase vector.

[0143] Optionally, the optimal controller is further configured to calculate control commands for the multiple distributed energy devices in islanded mode based on the microgrid's state data in islanded mode, the dynamic model, and the hardware capacity of the multiple distributed energy devices.

[0144] Optionally, the plurality of distributed energy devices are selected from all distributed energy devices in the microgrid in descending order of hardware capacity.

[0145] Optionally, the status data of the plurality of distributed energy devices includes the status data of the plurality of distributed energy devices at both the input and output ends of their respective output filters.

[0146] Optionally, the distributed energy device includes a single physical device and / or a virtual device, wherein the virtual device is the sum of multiple physical devices under unified control.

[0147] Please refer to Figure 9 This invention provides another structural schematic diagram of a microgrid control system 900, including: a processor 901, a transceiver 902, a memory 903, and a bus interface, wherein:

[0148] In this embodiment of the invention, the microgrid control system 900 further includes: a program stored in a memory 903 and executable on a processor 901, wherein the program, when executed by the processor 901, performs the following steps:

[0149] When the microgrid is in connected mode, the status data of the microgrid is collected;

[0150] Calculate the dynamic model of the microgrid based on its state data in the connection mode;

[0151] After the microgrid switches to island mode, the status data of the microgrid in island mode is collected, and the control command of the microgrid is calculated based on the status data of the microgrid in island mode and the dynamic model.

[0152] Understandably, in this embodiment of the invention, when the computer program is executed by the processor 901, it can implement the processes of the various embodiments of the microgrid control method described above and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0153] exist Figure 9 In this context, the bus architecture can include any number of interconnected buses and bridges, specifically linking various circuits together, represented by one or more processors (processor 901) and memory (memory 903). The bus architecture can also link various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further herein. The bus interface provides an interface. The transceiver 902 can be multiple elements, including transmitters and receivers, providing a unit for communicating with various other devices over a transmission medium.

[0154] The processor 901 is responsible for managing the bus architecture and general processing, while the memory 903 can store the data used by the processor 901 when performing operations.

[0155] It should be noted that the terminal in this embodiment is the same as the one described above. Figure 3 The device corresponding to the method shown above, and the implementation methods in each embodiment, are all applicable to the embodiments of this terminal, and can achieve the same technical effect. In this device, the transceiver 902 and the memory 903, as well as the transceiver 902 and the processor 901, can be connected for communication via a bus interface. The function of the processor 901 can also be implemented by the transceiver 902, and the function of the transceiver 902 can also be implemented by the processor 901. It should be noted that the device provided by the embodiments of the present invention can implement all the method steps implemented in the above method embodiments and can achieve the same technical effect. Therefore, the parts that are the same as those in the method embodiments and the beneficial effects will not be described in detail here.

[0156] In some embodiments of the present invention, a computer-readable storage medium is also provided, on which a program is stored, which, when executed by a processor, performs the following steps:

[0157] When the microgrid is in connected mode, the status data of the microgrid is collected;

[0158] Calculate the dynamic model of the microgrid based on its state data in the connection mode;

[0159] After the microgrid switches to island mode, the status data of the microgrid in island mode is collected, and the control command of the microgrid is calculated based on the status data of the microgrid in island mode and the dynamic model.

[0160] When executed by the processor, this program can implement all the above-mentioned microgrid control methods and achieve the same technical effect. To avoid repetition, it will not be described again here.

[0161] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0162] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0163] In the embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0164] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention, depending on actual needs.

[0165] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0166] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0167] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A microgrid control method, characterized in that, include: When the microgrid is in connected mode, the status data of the microgrid is collected; Calculate the dynamic model of the microgrid based on its state data in connection mode; After the microgrid switches to island mode, the status data of the microgrid in island mode is collected, and the control command of the microgrid is calculated based on the status data of the microgrid in island mode and the dynamic model. The dynamic model of the microgrid is identified using the collected state data of the microgrid through the following formula: in, ∠ , ∠ and ∠ , respectively represent the positive-sequence component, negative-sequence component, and zero-sequence component of the output of the output filter of the distributed energy device in the microgrid numbered i at time tj. The value of i ranges from 1 to n, where n represents the number of distributed energy devices whose state data are collected. ∠ , ∠ and ∠ , , respectively represent the positive-sequence component, negative-sequence component, and zero-sequence component of the three-phase symmetrical components of the target location point s at time tj; the value range of s is 1 ~ m, where the value range of s corresponding to the input terminal of the output filter of the distributed energy device numbered i is 1 ~ n, and the value range of s corresponding to the access point of the collected state data is n+1 ~ m, where mn represents the number of access points of the collected state data.

2. The method as described in claim 1, characterized in that, The step of collecting the status data of the microgrid when it is in connected mode includes: collecting the status data of multiple distributed energy devices in the microgrid and the status data of the access point of the microgrid to the main network when it is in connected mode; After calculating the control commands for the microgrid, the method further includes sending the calculated control commands to the corresponding distributed energy devices.

3. The method as described in claim 2, characterized in that, Before calculating the dynamic model of the microgrid based on its state data in connectivity mode, the method further includes: When the state data is three-phase data, the state data is converted into a three-phase symmetrical vector. The three-phase data is three-phase voltage, three-phase current or three-phase power, and the three-phase symmetrical vector is a three-phase voltage symmetrical vector, a three-phase current symmetrical vector or a three-phase power symmetrical vector. When the state data is single-phase data, the state data is converted into a single-phase vector. The single-phase data is single-phase voltage, single-phase current, or single-phase power, and the single-phase vector is a single-phase voltage vector, a single-phase current vector, or a single-phase power vector.

4. The method as described in claim 3, characterized in that, If the calculated control command is the three-phase symmetrical vector, the control command is converted into the three-phase data before being sent to the corresponding distributed energy device. If the calculated control command is a single-phase vector, the control command is converted into single-phase data before being sent to the corresponding distributed energy device.

5. The method as described in claim 2, characterized in that, The step of calculating the control commands for the microgrid based on the microgrid's state data in islanded mode and the dynamic model includes: Based on the microgrid's status data in islanded mode, the dynamic model, and the hardware capacity of the multiple distributed energy devices, the control commands for the multiple distributed energy devices in islanded mode are calculated.

6. The method as described in claim 2, characterized in that, The plurality of distributed energy devices are selected from all distributed energy devices in the microgrid in descending order of hardware capacity.

7. The method as described in claim 2, characterized in that, The status data of the multiple distributed energy devices includes the status data of the multiple distributed energy devices at both the input and output ends of their respective output filters.

8. The method as described in claim 1, characterized in that, The distributed energy equipment includes a single physical device and / or a virtual device, wherein the virtual device is the sum of multiple physical devices under unified control.

9. A microgrid control system, characterized in that, include: The data acquisition module is used to collect the status data of the microgrid when the microgrid is in connected mode; The model recognition module is used to calculate the dynamic model of the microgrid based on the state data of the microgrid in the connection mode. An optimal controller is used to collect the state data of the microgrid in island mode after the microgrid switches to island mode, and calculate the control command of the microgrid based on the state data of the microgrid in island mode and the dynamic model. The dynamic model of the microgrid is identified using the collected state data of the microgrid through the following formula: in, ∠ , ∠ and ∠ , respectively represent the positive-sequence component, negative-sequence component, and zero-sequence component of the output of the output filter of the distributed energy device in the microgrid numbered i at time tj. The value of i ranges from 1 to n, where n represents the number of distributed energy devices whose state data are collected. ∠ , ∠ and ∠ , , respectively represent the positive-sequence component, negative-sequence component, and zero-sequence component of the three-phase symmetrical components of the target location point s at time tj; the value range of s is 1 ~ m, where the value range of s corresponding to the input terminal of the output filter of the distributed energy device numbered i is 1 ~ n, and the value range of s corresponding to the access point of the collected state data is n+1 ~ m, where mn represents the number of access points of the collected state data.

10. The system as described in claim 9, characterized in that, The data acquisition module is also used to collect status data of multiple distributed energy devices in the microgrid and status data at the access point of the microgrid to the main network when the microgrid is in connected mode. The optimal controller is also used to send the calculated control commands to the corresponding distributed energy devices.

11. The system as claimed in claim 10, characterized in that, The optimal controller is further configured to calculate the control commands for the multiple distributed energy devices in the islanded mode based on the state data of the microgrid in islanded mode, the dynamic model, and the hardware capacity of the multiple distributed energy devices.

12. The system as described in claim 10, characterized in that, The status data of the multiple distributed energy devices includes the status data of the multiple distributed energy devices at both the input and output ends of their respective output filters.

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