Source-load-storage coordinated control method and system for off-grid operation of new energy micro-grid

Abstract

The present application relates to a kind of source load storage coordination control method of new energy microgrid off-grid operation, control object includes energy storage system, new energy unit and each area load switch, control framework includes equipment local control layer, microgrid coordination control layer and distribution network master control layer;The equipment local control layer adopts power balance strategy based on energy storage dynamic compensation, the power difference of new energy unit and load is dynamically compensated by energy storage converter, realize instantaneous power balance;The microgrid coordination control layer adopts short-term power balance strategy based on source storage collaborative control, the output of new energy unit is adjusted by microgrid controller, realize short-term power balance;The distribution network master control layer adopts long-time power balance strategy based on load adjustment, load is adjusted by distribution master station, realize long-time power balance.The method and system are conducive to the off-grid stable operation of microgrid.

Description

Technical Field

[0001] This invention belongs to the field of new energy microgrid control technology, specifically relating to a source-load-storage coordinated control method and system for off-grid operation of a new energy microgrid. Background Technology

[0002] In the process of building a new power system with new energy sources as the mainstay, the power grid development mode is shifting from being dominated by large power grids to a development model integrating large power grids, microgrids, and local DC power grids. In-depth exploration and widespread practice of microgrid construction is a crucial part of power system development. A microgrid includes distributed new energy generating units, energy storage systems, load systems, and control, monitoring, and protection devices. It can operate in parallel with the external power grid or independently. When a microgrid operates in grid-connected mode, its voltage and frequency depend on the external power grid. The power difference between the source and load within the microgrid is balanced by the power of the tie lines, and fluctuations in new energy sources and loads do not affect the system's stability. When the external power grid is abnormal or the tie lines fail, the microgrid needs to operate independently to ensure reliable power supply to the loads within the region. In this case, the source-load-storage coordination control strategy becomes extremely important, especially under conditions of limited energy storage capacity and the randomness and volatility of new energy unit power. Achieving long-term stable operation of the microgrid off-grid becomes a key issue in microgrid operation and control.

[0003] Existing off-grid operation control methods for microgrids require the construction of a microgrid master station or local energy management system, and require coordinated off-grid operation control based on ultra-short-term power output forecast data from renewable energy sources. Considering factors such as large investment in control systems and the difficulty in accurately predicting ultra-short-term power output from renewable energy sources, existing methods have shortcomings in terms of replicability, scalability, and control accuracy. There is an urgent need to research and optimize off-grid operation control technologies for renewable energy microgrids. Summary of the Invention

[0004] The purpose of this invention is to provide a source-load-storage coordinated control method and system for off-grid operation of new energy microgrids, which is beneficial to achieving stable off-grid operation of microgrids.

[0005] To achieve the above objectives, the technical solution adopted by this invention is: a source-load-storage coordinated control method for off-grid operation of a new energy microgrid. The controlled objects include energy storage systems, new energy generating units, and load switches in various distribution areas. The control architecture includes a local equipment control layer, a microgrid coordination control layer, and a distribution network master station control layer. The local equipment control layer adopts a power balance strategy based on dynamic compensation of energy storage, dynamically compensating for the power difference between new energy generating units and loads through energy storage converters to achieve instantaneous power balance. The microgrid coordination control layer adopts a short-term power balance strategy based on source-storage collaborative control, adjusting the output of new energy generating units through the microgrid controller to achieve short-term power balance. The distribution network master station control layer adopts a long-term power balance strategy based on load regulation, adjusting the load through the distribution network master station to achieve long-term power balance.

[0006] Furthermore, in the power balancing strategy, the energy storage system includes multiple bidirectional energy storage converters, each with two control modes: current source and voltage source. When the converter operates in current source mode, it generates or absorbs a set active or reactive power according to a given value. When the converter operates in voltage source mode, it acts as a balance node in the microgrid to compensate for the power difference between other devices and outputs a voltage with a set amplitude and frequency according to the built-in droop characteristic curve.

[0007] Furthermore, in the power balancing strategy, the first type of control mode setting for multiple converters is: all converters operate in voltage source mode, that is, all converters simultaneously respond to power fluctuations from new energy sources and loads, and the calculation formula for the output power of each converter is:

[0008]

[0009] In the formula, N is the total number of converters, and P BU (i) represents the active power output of the i-th voltage source mode converter, Q. BU (i) represents the reactive power output of the i-th voltage source mode converter, P L For the total active power of the microgrid load, P S Q is the total active power of the power supply within the microgrid. L Q represents the total reactive power of the microgrid load. S The total reactive power of the power supply within the microgrid.

[0010] Furthermore, in the power balancing strategy, the second type of control mode setting for multiple converters is: N U The converter operates in voltage source mode, N I The converter operates in current source mode. In voltage source mode, the converter responds in real-time to power fluctuations from renewable energy sources and loads. The formula for calculating the converter's output power at the current time t is:

[0011]

[0012] In the formula, P BI (i2,t) and Q BI (i2, t) represent the active and reactive power outputs of the i2th current source mode converter at the current time; the calculation formula for adjusting the active and reactive power of the current source mode converter at the next time (t+1) is as follows:

[0013]

[0014] Furthermore, in the short-term power balance strategy, the remaining battery capacity (SOC) of the energy storage system and the average power (P) of the energy storage system during the adjustment cycle are used as the basis. BS Whether the renewable energy units have the capacity to increase output is used as the basis for calculating the renewable energy unit output adjustment value △Ps for the next cycle, in order to avoid control deviations introduced by inaccurate ultra-short-term renewable energy output forecasts and ultra-short-term load power forecasts; specifically, it includes the following 7 operating conditions:

[0015] Operating condition ①: SOC is lower than the set ideal charge threshold S Bd Furthermore, the output of the new energy units could not be increased, and the ΔPs generated by the microgrid controller was zero;

[0016] Operating Condition ②: SOC is lower than the set ideal charge threshold S Bd Furthermore, the new energy units have room for increased output, allowing P Br Given the rated total charging power of the energy storage system and k1 as the maximum charging power coefficient, the ΔPs generated by the microgrid controller is: k1*P Br +P BS ;

[0017] Operating condition ③: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu The output of the new energy units cannot be increased, and the ΔPs generated by the microgrid controller is zero;

[0018] Operating condition 4: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu The new energy unit has room for power output improvement. Let k2 be the slow charging power coefficient, and the ΔPs generated by the microgrid controller is: P Br +k2*(S Bu -SOC);

[0019] Operating condition ⑤: SOC is lower than the set ideal charge threshold SBu And higher than S Bd P BS Less than P BSu And it is greater than the lower limit of the average power P of the energy storage system's regulation cycle. BSd The ΔPs generated by the microgrid controller is zero;

[0020] Operating condition ⑥: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Less than the lower limit of average power P during the energy storage system's regulation cycle BSd The ΔPs generated by the microgrid controller is: P Br +k2*(S Bu -SOC);

[0021] Operating condition ⑦: SOC is higher than the set ideal charge threshold S Bu The ΔPs generated by the microgrid controller is equal to P. Br .

[0022] Furthermore, in the aforementioned short-term power balance strategy, the output of new energy generating units is adjusted using a variable step size method; on a time scale of seconds, the microgrid controller adjusts the output at small intervals T. b Periodically read the SOC of the energy storage system and calculate the average power P of the energy storage system within the short cycle. bs When SOC exceeds the limit or P BS When the limit is exceeded, the output of the new energy units is adjusted, and the average power P of the new energy units is adjusted within a single cycle. BS The formula for calculation is:

[0023]

[0024] In the formula, N B For P within a single new energy output adjustment cycle BS The small cycle T experienced before exceeding the limit b quantity.

[0025] Furthermore, in the long-term power balancing strategy, the distribution network master station sorts and classifies the power supply importance of each distribution area load in the microgrid according to user characteristics, and then predicts the hourly power demand of each load level based on historical data; the distribution network master station periodically reads the SOC and output power of the energy storage system, and combines the hourly predicted value of available renewable energy and the hourly power demand value of each load level, and issues a plan in advance when renewable energy output is insufficient and the SOC of the energy storage system is insufficient, limiting the power of adjustable loads or cutting off some non-critical loads.

[0026] This invention also provides a source-load-storage coordinated control system for off-grid operation of a new energy microgrid to implement the above method, comprising:

[0027] The local control layer of the equipment is used to adopt a power balance strategy based on dynamic compensation of energy storage, and to achieve instantaneous power balance by dynamically compensating the power difference between the new energy unit and the load through the energy storage converter.

[0028] The microgrid coordination control layer is used to implement a short-term power balance strategy based on source-storage coordinated control, adjusting the output of renewable energy units through the microgrid controller to achieve short-term power balance; and

[0029] The distribution network master station control layer is used to adopt a long-term power balance strategy based on load regulation, and to achieve long-term power balance by regulating the load through the distribution master station.

[0030] The present invention also provides a computer-readable storage medium having stored thereon computer program instructions that can be executed by a processor, wherein when the processor executes the computer program instructions, it can implement the above-described method steps.

[0031] The present invention also provides a source-load-storage coordinated control device for off-grid operation of a new energy microgrid, including a memory, a processor, and computer program instructions stored in the memory and executable by the processor. When the processor executes the computer program instructions, it can implement the above-mentioned method steps.

[0032] Compared with the prior art, the present invention has the following beneficial effects: It provides a source-load-storage coordinated control method and system for off-grid operation of new energy microgrids. Through the implementation of corresponding control strategies in the local control layer of equipment, the microgrid coordinated control layer and the distribution network master station control layer, the method can achieve dynamic balance between new energy units, energy storage systems and loads in the microgrid when the microgrid grid connection point switch is disconnected or the interconnection line between the microgrid and the external power grid fails, thereby realizing the stable off-grid operation of the microgrid. It has strong technical feasibility and good promotion and application value. Attached Figure Description

[0033] Figure 1 This is a schematic diagram illustrating the implementation principle of the source-load-storage coordinated control method for off-grid operation of a new energy microgrid according to an embodiment of the present invention.

[0034] Figure 2 This is a schematic diagram of the microgrid system structure in an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram illustrating the implementation process of the short-term power balance strategy of the microgrid coordination control layer in this embodiment of the invention. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0038] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0039] like Figure 1 As shown, this embodiment provides a source-load-storage coordinated control method for off-grid operation of a new energy microgrid. The controlled objects of this method include energy storage systems, new energy generating units, and load switches in each distribution area. The control architecture includes a local equipment control layer, a microgrid coordination control layer, and a distribution network master station control layer. The local equipment control layer adopts a power balance strategy based on dynamic compensation of energy storage, which dynamically compensates for the power difference between new energy generating units and loads through energy storage converters to achieve instantaneous power balance. The microgrid coordination control layer adopts a short-term power balance strategy based on source-storage collaborative control, which adjusts the output of new energy generating units through the microgrid controller to achieve short-term power balance. The distribution network master station control layer adopts a long-term power balance strategy based on load regulation, which adjusts the load through the distribution network master station to achieve long-term power balance.

[0040] In the power balancing strategy, the energy storage system includes multiple bidirectional energy storage converters, each with two control modes: current source and voltage source. When the converter operates in current source mode, it generates or absorbs a set active or reactive power according to a given value. When the converter operates in voltage source mode, it acts as a balance node in the microgrid to compensate for the power difference between other devices and outputs a voltage with a set amplitude and frequency according to the built-in droop characteristic curve.

[0041] In the power balancing strategy, the first type of control mode setting for multiple converters is: all converters operate in voltage source mode, that is, all converters simultaneously respond to power fluctuations from both new energy sources and loads, and the calculation formula for the output power of each converter is:

[0042]

[0043] In the formula, N is the total number of converters, and P BU (i) represents the active power output of the i-th voltage source mode converter, Q. BU (i) represents the reactive power output of the i-th voltage source mode converter, P LFor the total active power of the microgrid load, P S Q is the total active power of the power supply within the microgrid. L Q represents the total reactive power of the microgrid load. S The total reactive power of the power supply within the microgrid.

[0044] In the power balancing strategy, the second type of control mode setting for multiple converters is: N U The converter operates in voltage source mode, N I The converter operates in current source mode. In voltage source mode, the converter responds in real-time to power fluctuations from renewable energy sources and loads. The formula for calculating the converter's output power at the current time t is:

[0045]

[0046] In the formula, P BI (i2,t) and Q BI (i2, t) represent the active and reactive power outputs of the i2th current source mode converter at the current time; the calculation formula for adjusting the active and reactive power of the current source mode converter at the next time (t+1) is as follows:

[0047]

[0048] In the aforementioned short-term power balance strategy, the remaining battery capacity (SOC) of the energy storage system and the average power (P) of the energy storage system during the adjustment cycle are used as the basis for calculation. BS Whether the new energy generating units have the capacity to increase output is used as the basis for calculating the output adjustment value △Ps of the new energy generating units in the next cycle, in order to avoid control deviations introduced by inaccurate ultra-short-term forecasts of new energy output and load power; specifically, it includes the following 7 operating conditions:

[0049] Operating condition ①: SOC is lower than the set ideal charge threshold S Bd Furthermore, the output of the new energy units could not be increased, and the ΔPs generated by the microgrid controller was zero;

[0050] Operating Condition ②: SOC is lower than the set ideal charge threshold S Bd Furthermore, the new energy units have room for increased output, allowing P Br Given the rated total charging power of the energy storage system and k1 as the maximum charging power coefficient, the ΔPs generated by the microgrid controller is: k1*P Br +P BS ;

[0051] Operating condition ③: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Greater than the upper limit of average power P during the energy storage system's regulation cycleBSu The output of the new energy units cannot be increased, and the ΔPs generated by the microgrid controller is zero;

[0052] Operating condition 4: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu The new energy unit has room for power output improvement. Let k2 be the slow charging power coefficient, and the ΔPs generated by the microgrid controller is: P Br +k2*(S Bu -SOC);

[0053] Operating condition ⑤: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Less than P BSu And it is greater than the lower limit of the average power P of the energy storage system's regulation cycle. BSd The ΔPs generated by the microgrid controller is zero;

[0054] Operating condition ⑥: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Less than the lower limit of average power P during the energy storage system's regulation cycle BSd The ΔPs generated by the microgrid controller is: P Br +k2*(S Bu -SOC);

[0055] Operating condition ⑦: SOC is higher than the set ideal charge threshold S Bu The ΔPs generated by the microgrid controller is equal to P. Br .

[0056] In the aforementioned short-term power balance strategy, the output of new energy generating units is adjusted using a variable step size method; on a time scale of seconds, the microgrid controller adjusts the output at small intervals T. b Periodically read the SOC of the energy storage system and calculate the average power P of the energy storage system within the short cycle. bs When SOC exceeds the limit or P BS When the limit is exceeded, the output of the new energy units is adjusted, and the average power P of the new energy units is adjusted within a single cycle. BS The formula for calculation is:

[0057]

[0058] In the formula, N B For P within a single new energy output adjustment cycle BS The small cycle T experienced before exceeding the limit b quantity.

[0059] In the long-term power balancing strategy, the distribution network master station sorts and classifies the power supply importance of each distribution area load in the microgrid according to user characteristics, and then predicts the hourly power demand of each load level based on historical data. The distribution network master station periodically reads the SOC and output power of the energy storage system, and combines the hourly predicted value of available renewable energy and the hourly power demand value of each load level. In the event of insufficient renewable energy output and insufficient SOC of the energy storage system, the master station issues a plan in advance to limit the power of adjustable loads or cut off some non-critical loads.

[0060] This embodiment also provides a source-load-storage coordinated control system for off-grid operation of a new energy microgrid to implement the above method, including:

[0061] The local control layer of the equipment is used to adopt a power balance strategy based on dynamic compensation of energy storage, and to achieve instantaneous power balance by dynamically compensating the power difference between the new energy unit and the load through the energy storage converter.

[0062] The microgrid coordination control layer is used to implement a short-term power balance strategy based on source-storage coordinated control, adjusting the output of renewable energy units through the microgrid controller to achieve short-term power balance; and

[0063] The distribution network master station control layer is used to adopt a long-term power balance strategy based on load regulation, and to achieve long-term power balance by regulating the load through the distribution master station.

[0064] This embodiment also provides a computer-readable storage medium storing computer program instructions that can be executed by a processor. When the processor executes the computer program instructions, it can implement the above-described method steps.

[0065] This embodiment also provides a source-load-storage coordinated control device for off-grid operation of a new energy microgrid, including a memory, a processor, and computer program instructions stored in the memory and executable by the processor. When the processor executes the computer program instructions, it can implement the above-mentioned method steps.

[0066] In this embodiment, the system structure of a microgrid on an island is as follows: Figure 2 As shown, the microgrid's backbone is a 10kV busbar on the island, which is connected to the substation of the external power grid via a single-circuit 10kV submarine cable. In addition, the island's load includes public transformers for residents and dedicated transformers for industrial and commercial users. Both public and dedicated transformers have rated voltages of 10 / 0.4kV and rated capacities ranging from 50kVA to 800kVA. The island's annual peak load is approximately 2MW, and its annual valley load is approximately 0.4MW.

[0067] To fully utilize the island's superior wind power resources and avoid long-term power outages in the event of submarine cable failures, the island's microgrid construction project included a microgrid switchyard containing energy storage batteries, new energy generator sets, and a microgrid monitoring system. The core equipment consists of two sets of 0.5MW / 1MWh electrochemical energy storage batteries and three wind turbines with a rated power of 2.0MW. The energy storage subsystem is installed in a prefabricated module. After being combined on the AC side by two 630kW rated power energy storage converters, the current is connected to the 10kV busbar within the switchyard via a 2.5MVA rated capacity step-up transformer. The wind turbines use a "one turbine, one transformer" unit connection method. After the wind turbine is stepped up to 10kV by a box-type transformer, the voltage is transmitted to the 10kV switchyard busbar via collector lines. Meanwhile, the prefabricated cabin of the project is equipped with a microgrid local monitoring room, which includes station loads such as remote control devices, switches, fault recording devices, wind power prediction devices, workstations, and air conditioners connected in parallel to the 0.4kV bus in the station, and connected to the 10kV bus via a 100kVA station service transformer.

[0068] When the grid connection point of the island microgrid is tripped, the microgrid enters off-grid operation after a black start or planned grid connection to off-grid transition. Both energy storage PCS units operate in voltage source mode, dynamically compensating for the power difference between the island's power source and load through power sharing. The implementation process of the short-term power balance strategy of the microgrid coordination control layer is as follows: Figure 3 As shown, there are 7 operating conditions:

[0069] Operating condition ①: SOC is lower than the specified ideal charge threshold S Bd (70%) and the output of new energy units cannot be increased, the ΔPs generated by the microgrid controller is zero, and the power setpoint of the wind turbine unit remains unchanged;

[0070] Operating condition ②: SOC is lower than the specified ideal charge threshold S Bd (70%) and the new energy units have room for output improvement, and the rated total charging power P of the energy storage system Br For a capacity of 1MW, with a maximum charging power coefficient k1 of 0.5, the ΔPs generated by the microgrid controller is: 0.5 + P BS The output of wind turbine units has increased;

[0071] Operating condition ③: SOC is lower than the specified ideal charge threshold S Bu (85%) and higher than S Bd (70%), P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu (100kW) The output of the new energy unit cannot be increased, the ΔPs generated by the microgrid controller is zero, and the power setpoint of the wind turbine unit remains unchanged.

[0072] Operating condition 4: SOC is lower than the specified ideal charge threshold S Bu (85%) and higher than S Bd (70%), P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu (100kW) The new energy unit has room for output improvement, making the slow charging power coefficient k2 0, and the ΔPs generated by the microgrid controller is P. Br The output of wind turbine units has increased;

[0073] Operating condition ⑤: SOC is lower than the specified ideal charge threshold S Bu (85%) and higher than S Bd (70%), P BS Less than P BSu (100kW) and greater than the lower limit of the average power P during the energy storage system's regulation cycle. BSd (-100kW), the ΔPs generated by the microgrid controller is zero, and the power setpoint of the wind turbine remains unchanged;

[0074] Operating condition ⑥: SOC is lower than the specified ideal charge threshold S Bu (85%) and higher than S Bd (70%), P BS Less than the lower limit of average power P during the energy storage system's regulation cycle BSd (-100kW), the ΔPs generated by the microgrid controller is equal to P. Br The output of wind turbine units decreased;

[0075] Operating condition ⑦: SOC is higher than the specified ideal charge threshold S Bu (85%), let the ΔPs generated by the microgrid controller be equal to P. Br The output of the wind turbine may decrease or increase depending on the energy storage charging / discharging status.

[0076] Based on the above short-term power balance strategy, autonomous dynamic coordination of source and storage under specific energy storage charge states has been achieved in the source-load-storage coordinated control. Furthermore, the strategy shown in the table below is needed to achieve load participation in coordinated control in order to achieve long-term power balance across the island.

[0077]

[0078] After on-site debugging of the microgrid project, the islands where this method was deployed had the ability to operate offline, verifying the effectiveness of the above strategy.

[0079] This invention provides a source-load-storage coordinated control method (system) for off-grid operation of a renewable energy microgrid. Aiming at multi-timescale microgrid power balance, it divides time into millisecond, minute, and hourly scales and proposes a hierarchical microgrid control architecture for distribution-microgrid coordination. At the local equipment control layer, millisecond-level power balance is achieved by dynamically compensating for the power difference between renewable energy generators and loads through energy storage converters. At the microgrid coordinated control layer, minute-level power balance is achieved through source-storage coordinated control strategies within the microgrid controller. At the distribution master station control layer, hourly-level power balance is achieved through load regulation based on source-load forecast data. The source-load-storage coordinated control method for off-grid operation of a renewable energy microgrid proposed in this invention does not require real-time forecasting of distributed renewable energy unit output or the configuration of a local master station within the microgrid. It is technically feasible and has significant potential for widespread application.

[0080] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0081] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0082] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0083] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0084] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A source-load-storage coordinated control method for off-grid operation of a new energy microgrid, characterized in that, The controlled objects include energy storage systems, new energy generating units, and load switches in various distribution areas. The control architecture includes a local equipment control layer, a microgrid coordination control layer, and a distribution network master station control layer. The local equipment control layer adopts a power balance strategy based on dynamic compensation of energy storage, which dynamically compensates for the power difference between new energy generating units and loads through energy storage converters to achieve instantaneous power balance. The microgrid coordination control layer adopts a short-term power balance strategy based on source-storage collaborative control, which adjusts the output of new energy generating units through microgrid controllers to achieve short-term power balance. The distribution network master station control layer adopts a long-term power balance strategy based on load regulation, which adjusts the load through the distribution network master station to achieve long-term power balance. In the power balance strategy, the energy storage system includes multiple bidirectional energy storage converters, each of which has two control modes: current source and voltage source. When the converter operates in current source mode, it outputs or absorbs a set active or reactive power according to a given value. When the converter operates in voltage source mode, it acts as a balance node of the microgrid to compensate for the power difference between other devices and outputs a voltage with a set amplitude and frequency according to the built-in droop characteristic curve. In the long-term power balancing strategy, the distribution network master station sorts and classifies the power supply importance of each distribution area load in the microgrid according to user characteristics, and then predicts the hourly power demand of each load level based on historical data. The distribution network master station periodically reads the SOC and output power of the energy storage system, and combines the hourly predicted value of available renewable energy and the hourly power demand value of each load level. In the event of insufficient renewable energy output and insufficient SOC of the energy storage system, the master station issues a plan in advance to limit the power of adjustable loads or cut off some non-critical loads.

2. The source-load-storage coordinated control method for off-grid operation of a new energy microgrid according to claim 1, characterized in that, In the power balancing strategy, the first type of control mode setting for multiple converters is: all converters operate in voltage source mode, that is, all converters simultaneously respond to power fluctuations from both new energy sources and loads, and the calculation formula for the output power of each converter is: In the formula, N is the total number of converters, and P BU (i) represents the active power output of the i-th voltage source mode converter, Q. BU (i) represents the reactive power output of the i-th voltage source mode converter, P L For the total active power of the microgrid load, P S Q is the total active power of the power supply within the microgrid. L Q represents the total reactive power of the microgrid load. S The total reactive power of the power supply within the microgrid.

3. The source-load-storage coordinated control method for off-grid operation of a new energy microgrid according to claim 1, characterized in that, In the power balancing strategy, the second type of control mode setting for multiple converters is: N U The converter operates in voltage source mode, N I The converter operates in current source mode. In voltage source mode, the converter responds in real time to power fluctuations from renewable energy sources and loads. The formula for calculating the converter's output power at the current time t is: In the formula, P BI (i2,t) and Q BI (i2, t) represent the active and reactive power outputs of the i2th current source mode converter at the current time; the calculation formula for adjusting the active and reactive power of the current source mode converter at the next time (t+1) is as follows:

4. The source-load-storage coordinated control method for off-grid operation of a new energy microgrid according to claim 1, characterized in that, In the aforementioned short-term power balance strategy, the remaining battery capacity (SOC) of the energy storage system and the average power (P) of the energy storage system during the adjustment cycle are used as the basis. BS Whether the renewable energy units have the capacity to increase output is used as the basis for calculating the renewable energy unit output adjustment value △Ps for the next cycle, in order to avoid control deviations introduced by inaccurate ultra-short-term renewable energy output forecasts and ultra-short-term load power forecasts; specifically, it includes the following 7 operating conditions: Operating condition ①: SOC is lower than the set ideal charge threshold S Bd Furthermore, the output of the new energy units could not be increased, and the ΔPs generated by the microgrid controller was zero; Operating Condition ②: SOC is lower than the set ideal charge threshold S Bd Furthermore, the new energy units have room for increased output, allowing P Br Given the rated total charging power of the energy storage system and k1 as the maximum charging power coefficient, the ΔPs generated by the microgrid controller is: k1×P Br +P BS ; Operating condition ③: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu The output of the new energy units cannot be increased, and the ΔPs generated by the microgrid controller is zero; Operating condition 4: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Greater than the upper limit of average power P during the energy storage system's regulation cycle BSu The new energy unit has room for power output improvement. Let k2 be the slow charging power coefficient, and the ΔPs generated by the microgrid controller is: P Br +k2×(S Bu -SOC); Operating condition ⑤: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Less than P BSu And it is greater than the lower limit of the average power P of the energy storage system's regulation cycle. BSd The ΔPs generated by the microgrid controller is zero; Operating condition ⑥: SOC is lower than the set ideal charge threshold S Bu And higher than S Bd P BS Less than the lower limit of average power P during the energy storage system's regulation cycle BSd The ΔPs generated by the microgrid controller is: P Br +k2×(S Bu -SOC); Operating condition ⑦: SOC is higher than the set ideal charge threshold S Bu The ΔPs generated by the microgrid controller is equal to P. Br .

5. The source-load-storage coordinated control method for off-grid operation of a new energy microgrid according to claim 4, characterized in that, In the aforementioned short-term power balance strategy, the output of new energy generating units is adjusted using a variable step size method; on a time scale of seconds, the microgrid controller adjusts the output at small intervals T. b Periodically read the SOC of the energy storage system and calculate the average power P of the energy storage system within the short cycle. bs When SOC exceeds the limit or P BS When the limit is exceeded, the output of the new energy units is adjusted, and the average power P of the new energy units is adjusted within a single cycle. BS The formula for calculation is: In the formula, N B For P within a single new energy output adjustment cycle BS The small cycle T experienced before exceeding the limit b quantity.

6. A source-load-storage coordinated control system for implementing the off-grid operation of a new energy microgrid as described in any one of claims 1-5, characterized in that, include: The local control layer of the equipment is used to adopt a power balance strategy based on dynamic compensation of energy storage, and to achieve instantaneous power balance by dynamically compensating the power difference between the new energy unit and the load through the energy storage converter. The microgrid coordination control layer is used to adopt a short-term power balance strategy based on source-storage coordinated control, and adjust the output of new energy units through the microgrid controller to achieve short-term power balance; as well as The distribution network master station control layer is used to adopt a long-term power balance strategy based on load regulation, and to achieve long-term power balance by regulating the load through the distribution master station.

7. A computer-readable storage medium having stored thereon computer program instructions executable by a processor, wherein when the processor executes the computer program instructions, it is able to implement the method as described in any one of claims 1-5.

8. A source-load-storage coordinated control device for off-grid operation of a new energy microgrid, characterized in that, It includes a memory, a processor, and computer program instructions stored in the memory and executable by the processor, wherein when the processor executes the computer program instructions, it can implement the method as described in any one of claims 1-5.

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