Micro-grid system and control method thereof

Abstract

The invention provides a micro-grid system and a control method thereof, and the method is suitable for a coordination controller of the micro-grid system, and comprises the steps: determining whether a to-be-detected node is subjected to countercurrent or not based on node operation data uploaded by a collection module disposed on the to-be-detected node of the micro-grid system; and if the countercurrent occurs, generating a switch control instruction and sending the switch control instruction to a sub-controller corresponding to the node to be detected so as to disconnect a power distribution switch arranged between power generation equipment corresponding to the node to be detected and the microgrid bus. The method and the device are used for avoiding the phenomena of energy loss and even equipment damage caused by reverse current of a micro-grid system, maintaining system stability and reducing equipment damage.

Description

Technical Field

[0001] The present application relates to the field of electric power technology, and in particular to a microgrid system and a control method thereof. Background Art

[0002] As a distributed energy system, the microgrid system aims to improve energy utilization efficiency and reliability. It usually includes components such as renewable energy power generation equipment, energy storage devices and loads. During the operation of the microgrid, in order to ensure the stability and safety of the system, it is necessary to strictly control the direction of power flow to avoid the occurrence of current reverse flow. However, in actual operation, due to various reasons, the problem of current reverse flow still occurs from time to time, which poses a threat to the safe operation of the microgrid. The reverse flow phenomenon not only causes energy loss, but also may damage equipment and affect the stability and economy of the microgrid. Therefore, how to effectively prevent current reverse flow in the microgrid system has become an urgent problem to be solved. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a microgrid system and a control method thereof, so as to avoid energy loss or even equipment damage in the microgrid system due to current reverse flow, maintain system stability, and reduce equipment damage.

[0004] In a first aspect, the present invention provides a control method for a microgrid system, which is applicable to a coordination controller of the microgrid system. The microgrid system further includes a collection module and a power module. The power module includes a power generation device, a sub-controller and a distribution switch. The method includes:

[0005] Based on the node operation data uploaded by the acquisition module set on the node to be detected in the microgrid system, it is determined whether reverse flow occurs at the node to be detected; if reverse flow occurs, a switch control instruction is generated and sent to the sub-controller corresponding to the node to be detected to disconnect the distribution switch set between the power generation equipment corresponding to the node to be detected and the microgrid bus.

[0006] In an optional embodiment, the microgrid system further includes an energy storage module and a load module, the node operation data includes a first voltage value of the node to be detected between each energy storage module and the microgrid bus, and a second voltage value of the node to be detected between each power module and the microgrid bus. For each node to be detected, whether the current direction of the node to be detected is abnormal is determined in the following manner:

[0007] Determine whether the first voltage value corresponding to the node to be detected is greater than the second voltage value corresponding to the node to be detected; if so, determine that a reverse current occurs at the node to be detected.

[0008] In an optional implementation, the node operation data includes a first current value of a node to be detected between each energy storage block and the microgrid bus, and also includes:

[0009] For each node to be detected, based on the first current value and the first voltage value corresponding to the detection node, determine the detection power value of the detection node within a preset time length; calculate the detection ratio between the detection power value and the rated power value; determine whether the detection ratio is greater than the target ratio; if so, determine that reverse current occurs at the node to be detected.

[0010] In an optional implementation, the preset time length is from the time point when it is determined that the first voltage value corresponding to the node to be detected is greater than the second voltage value corresponding to the node to be detected to the current time point.

[0011] In an optional embodiment, the energy storage module includes an energy storage device, a power distribution switch and an energy storage inverter, and the method further includes:

[0012] For each energy storage device, based on the difference between the real-time power at the node to be detected and the target power, the corresponding energy storage inverter is controlled to reduce the output voltage value.

[0013] In a second aspect, the present invention provides a microgrid system, the system includes a coordination controller, a collection module, a power module, an energy storage module, and a load module. The power module includes a power generation device, a sub-controller, and a distribution point switch. The energy storage module includes an energy storage device, a distribution switch, and an energy storage inverter.

[0014] Among them, the coordination controller is used to determine whether reverse flow occurs at the node to be detected based on the node operation data uploaded by the acquisition module set on the node to be detected of the microgrid system. If reverse flow occurs, a switch control instruction is generated and sent to the sub-controller corresponding to the node to be detected to disconnect the distribution switch set between the power generation equipment corresponding to the node to be detected and the microgrid bus.

[0015] In an optional embodiment, the node operation data includes a first voltage value of a node to be detected between each energy storage module and the microgrid bus, and a second voltage value of a node to be detected between each power module and the microgrid bus. For each node to be detected, the coordination controller determines whether the current direction of the node to be detected is abnormal in the following manner:

[0016] Determine whether the first voltage value corresponding to the node to be detected is greater than the second voltage value corresponding to the node to be detected; if so, determine that a reverse current occurs at the node to be detected.

[0017] In an optional embodiment, the node operation data includes a first current value of a node to be detected between each energy storage block and the microgrid bus, and the coordination controller is also used to determine, for each node to be detected, a detection power value of the detection node within a preset time length based on the first current value and the first voltage value corresponding to the detection node; calculate a detection ratio between the detection power value and the rated power value; determine whether the detection ratio is greater than a target ratio; and if so, determine that reverse current occurs at the node to be detected.

[0018] In an optional implementation, the coordination controller is also used to obtain the measured voltage value of the AC power uploaded by the acquisition module, and determine the operating mode of the energy storage inverter based on the relationship between the measured voltage value and the off-grid voltage value, and the operating mode includes an off-grid mode and a grid-connected mode; wherein, when the measured voltage value is greater than the off-grid voltage value, the energy storage inverter is determined to be in the grid-connected mode; when the measured voltage value is less than the off-grid voltage value, the energy storage inverter is determined to be in the off-grid mode.

[0019] In an optional embodiment, when it is determined that the energy storage inverter is in off-grid mode, the coordination controller generates a shutdown command and sends it to the energy storage inverter, so that the energy storage inverter disconnects the incoming circuit breaker and shuts down; the coordination controller generates an off-grid operation command and sends it to the energy storage inverter, so that the energy storage inverter starts and supplies power to the load module according to the specified power. In a third aspect, the present invention provides an electronic device, comprising: a processor, a memory and a bus, the memory storing machine-readable instructions executable by the processor, when the electronic device is running, the processor and the memory communicate through the bus, and the processor executes the machine-readable instructions to perform the steps of the control method of any microgrid system in the aforementioned embodiment.

[0020] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of a control method for a microgrid system in any of the aforementioned embodiments are executed.

[0021] The present application provides a control method for a microgrid system, which is applicable to a coordination controller of a microgrid system. The microgrid system also includes an acquisition module and a power module. The power module includes a power generation device, a sub-controller and a distribution switch. The method includes determining whether a reverse flow occurs at a node to be detected based on the node operation data uploaded by the acquisition module set on the node to be detected of the microgrid system; if a reverse flow occurs, a switch control instruction is generated and sent to the sub-controller corresponding to the node to be detected to disconnect the distribution switch between the power generation device corresponding to the node to be detected and the microgrid bus. By detecting the current of the node and cutting off the power generation device in time, the phenomenon of energy loss or even damage to the equipment due to the reverse flow of the current in the microgrid system can be avoided, the system stability can be maintained, and the equipment damage can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 A schematic diagram of the structure of a microgrid system provided in an embodiment of the present application;

[0024] Figure 2 A flow chart of a control method for a microgrid system provided in an embodiment of the present application;

[0025] Figure 3 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] First, the application scenario of the present application is explained. The technical solution of the present application can be applied to a meshed microgrid. The active support microgrid utilizes meshed technology to simulate the amplitude and phase angle of the potential inside a conventional generator (controlling active power by changing the phase angle and controlling reactive power by changing the voltage amplitude). It does not require a phase-locked loop to achieve synchronous operation of multiple power sources, and provides inertia support for the system after a system disturbance. At the same time, by adding primary frequency modulation control, voltage regulation control and other links, its external characteristics are closer to conventional synchronous machines.

[0027] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0028] Figure 1 A schematic diagram of the structure of a microgrid system provided in an embodiment of the present application. Figure 2 A flow chart of a control method for a microgrid system provided in an embodiment of the present application.

[0029] In one embodiment of the present application, Figure 1 As shown, the system includes at least one coordination controller, multiple acquisition modules, multiple power modules, multiple energy storage modules, multiple load modules and a microgrid bus.

[0030] The power module includes a power generation device, a sub-controller and a distribution switch. The power generation device is used to generate electrical energy to provide the energy required by the system. The power generation device here can be a photovoltaic power generation device, a wind power generation device or other new power generation equipment.

[0031] The energy storage module includes energy storage equipment, power distribution switches and energy storage inverters. The energy storage equipment here is used to absorb and store excess electrical energy and provide power when the power module is insufficient. The energy storage equipment here can be lithium battery energy storage equipment, flywheel energy storage equipment, etc.

[0032] The load module includes load devices and distribution point switches. The load devices here consume the power of the system, and the load devices can be charging piles or other charging load devices, etc.

[0033] The acquisition module can be set at the energy storage module, the load module, and the node to be detected between the power module and the main line of the microgrid. The acquisition module is used to collect the current value, voltage value and other operating data of the line, and can be a reverse current meter, etc.

[0034] The microgrid bus is connected to a certain power of the mains through a distribution switch. The distribution switch here can be a distribution box, which is used to distribute power to each branch. When the mains is normal, it can be used as a power source to provide power to all load devices. When the mains is insufficient, a power module or even an energy storage module is required to provide power.

[0035] In a microgrid system, the forward direction of the current is generally from the mains, power module or energy storage module to the load module for power transmission. In order to prevent the reverse flow of current in the microgrid system, a coordination controller (EMS, energy management system) can be set up in the microgrid system. The coordination controller here can communicate with each sub-device (mainly each PCS, such as energy storage converter, bidirectional inverter and inverter, etc.) through 485 lines and twisted pair cables using the modbus protocol. In actual application, the EMS can send a message, and each sub-device can reply with a compliant message to confirm that the communication is normal.

[0036] The coordination controller is used to determine the removal of power generation equipment when current reverse flow (reverse power) occurs in the system, such as Figure 2 As shown, the coordination controller can be used to perform the following steps:

[0037] S1, node operation data uploaded by the acquisition module set on the node to be detected based on the microgrid system.

[0038] S2. Determine whether a reverse flow occurs at the node to be detected.

[0039] Specifically, the node operation data includes a first voltage value of a node to be detected between each energy storage module and the microgrid bus, and a second voltage value of a node to be detected between each power module and the microgrid bus. For each node to be detected, whether the current direction of the node to be detected is abnormal can be determined in the following manner:

[0040] Determine whether the first voltage value corresponding to the node to be detected is greater than the second voltage value corresponding to the node to be detected. If so, determine that a reverse current occurs at the node to be detected.

[0041] Furthermore, the node operation data includes a first current value of a node to be detected between each energy storage block and the microgrid bus, and also includes:

[0042] For each node to be detected, based on the first current value and the first voltage value corresponding to the detection node, determine the detection power value of the detection node within a preset time length. Calculate the detection ratio between the detection power value and the rated power value to determine whether the detection ratio is greater than the target ratio. If so, it is determined that the node to be detected has reverse current.

[0043] The preset time length is from the time point when it is determined that the first voltage value corresponding to the node to be detected is greater than the second voltage value corresponding to the node to be detected to the current time point.

[0044] Here, in order to avoid reverse current detection errors, after detecting that the first voltage value is greater than the second voltage value corresponding to the node to be detected, the output power can be monitored. If the detected power value exceeds 5% of the rated power value, the corresponding power generation equipment and / or energy storage equipment can be cut off.

[0045] S2. If reverse flow occurs, a switch control instruction is generated and sent to the sub-controller corresponding to the node to be detected, so as to disconnect the distribution switch arranged between the power generation equipment corresponding to the node to be detected and the microgrid bus.

[0046] The control method of the microgrid system provided in the present application can avoid the phenomenon of energy loss or even equipment damage caused by current reverse flow in the microgrid system by detecting the current of the node and cutting off the power generation equipment in time, thereby maintaining system stability and reducing equipment damage.

[0047] In one embodiment of the present application, in order to prevent the microgrid system from causing damage to the equipment within the system due to reverse power, the voltage value, current value and real-time power of the inverter at the incoming switch can be collected in real time. When it is detected that current is flowing to the grid, the inverter will receive a signal and reduce the output power, so that the current flowing from the photovoltaic power station to the grid is close to 0, thereby achieving reverse flow prevention.

[0048] Specifically, the coordination controller can be used to control the corresponding energy storage inverter to reduce the output voltage value for each energy storage device based on the difference between the real-time power at the node to be detected of the mains and the target power.

[0049] In one embodiment of the present application, in order to avoid power failure after the mains is cut off, a network-building PCS is added to the energy storage module of the system, which can temporarily maintain the operation of the load module when the mains is abnormal.

[0050] Specifically, the coordination controller can obtain the measured voltage value of the mains power uploaded by the acquisition module, and determine the operation mode of the energy storage inverter according to the size relationship between the measured voltage value and the off-grid voltage value. The operation mode includes off-grid mode and grid-connected mode. When the measured voltage value is greater than the off-grid voltage value, the energy storage inverter is determined to be in grid-connected mode. When the measured voltage value is less than the off-grid voltage value, the energy storage inverter is determined to be in off-grid mode.

[0051] The off-grid voltage value here may be 75% of the rated voltage value of the mains electricity.

[0052] Specifically, when it is determined that the energy storage inverter is in off-grid mode, the coordination controller generates a shutdown command and sends it to the energy storage inverter, causing the energy storage inverter to disconnect the incoming circuit breaker and shut down; the coordination controller generates an off-grid operation command and sends it to the energy storage inverter, causing the energy storage inverter to start and supply power to the load module according to the specified power.

[0053] The specified power here can be determined according to the required power of the load. After the power grid is restored, the coordination controller sends a shutdown command to the energy storage inverter. After the energy storage inverter is shut down, the coordination controller sends a grid-connected operation command to the energy storage inverter. The energy storage inverter enters the grid-connected operation mode. The coordination controller remotely closes the external incoming circuit breaker of the energy storage inverter. The coordination controller sends a start command to the energy storage inverter. The coordination controller sends a power command to the energy storage inverter according to the load power.

[0054] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 3 As shown in , the electronic device 300 includes a processor 310 , a memory 320 and a bus 330 .

[0055] The memory 320 stores machine-readable instructions executable by the processor 310. When the electronic device 300 is running, the processor 310 communicates with the memory 320 through the bus 330. When the machine-readable instructions are executed by the processor 310, the steps of a microgrid system and a control method thereof in the above-mentioned method embodiment can be executed. The specific implementation method can be found in the method embodiment, which will not be repeated here.

[0056] An embodiment of the present application also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of a microgrid system and a control method thereof in the above-mentioned method embodiment can be executed. The specific implementation method can be found in the method embodiment and will not be repeated here.

[0057] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0058] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0059] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0060] Furthermore, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0061] It should be noted that if the function is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can essentially be embodied in the form of a software product, or the part that contributes to the prior art or the part of the technical solution. The computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM) random access memory (RAM), disk or optical disk, and other media that can store program codes.

[0062] In this document, relational terms such as first and second, etc. are used merely to distinguish one entity or operation from another entity or operation, but do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0063] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A control method for a microgrid system, characterized in that: A coordination controller applicable to a microgrid system, wherein the microgrid system further comprises a collection module and a power supply module, wherein the power supply module comprises a power generation device, a sub-controller and a distribution switch, and the method comprises: Based on the node operation data uploaded by the acquisition module set on the node to be detected in the microgrid system, determine whether reverse flow occurs at the node to be detected; If reverse flow occurs, a switch control instruction is generated and sent to the sub-controller corresponding to the node to be detected, so as to disconnect the distribution switch arranged between the power generation equipment corresponding to the node to be detected and the microgrid bus.

2. The method according to claim 1, characterized in that The microgrid system also includes an energy storage module and a load module. The node operation data includes a first voltage value of a node to be detected between each energy storage module and the microgrid bus, and a second voltage value of a node to be detected between each power module and the microgrid bus. For each node to be detected, whether the current direction of the node to be detected is abnormal is determined in the following manner: Determine whether a first voltage value corresponding to the node to be detected is greater than a second voltage value corresponding to the node to be detected; If yes, it is determined that a reverse flow occurs at the node to be detected.

3. The method according to claim 2, characterized in that The node operation data includes a first current value of a node to be detected between each energy storage block and the microgrid bus, and also includes: For each node to be detected, based on the first current value and the first voltage value corresponding to the detection node, determine the detection power value of the detection node within a preset time length; Calculating a detection ratio between the detected power value and the rated power value; determining whether the detection ratio is greater than a target ratio; If yes, it is determined that a reverse flow occurs at the node to be detected.

4. The method according to claim 3, characterized in that The preset time length is from the time point when it is determined that the first voltage value corresponding to the node to be detected is greater than the second voltage value corresponding to the node to be detected to the current time point.

5. The method according to claim 2, characterized in that: The energy storage module includes an energy storage device, a power distribution switch and an energy storage inverter, and the method further includes: For each energy storage device, based on the difference between the real-time power at the node to be detected and the target power, the corresponding energy storage inverter is controlled to reduce the output voltage value.

6. A microgrid system, characterized in that: The system includes a coordination controller, a collection module, a power module, an energy storage module, and a load module. The power module includes a power generation device, a sub-controller, and a distribution point switch. The energy storage module includes an energy storage device, a distribution switch, and an energy storage inverter. Among them, the coordination controller is used to determine whether reverse flow occurs at the node to be detected based on the node operation data uploaded by the acquisition module set on the node to be detected of the microgrid system. If reverse flow occurs, a switch control instruction is generated and sent to the sub-controller corresponding to the node to be detected to disconnect the distribution switch set between the power generation equipment corresponding to the node to be detected and the microgrid bus.

7. The system according to claim 6, characterized in that The node operation data includes a first voltage value of a node to be detected between each energy storage module and the microgrid bus, and a second voltage value of a node to be detected between each power module and the microgrid bus. For each node to be detected, the coordination controller determines whether the current direction of the node to be detected is abnormal in the following manner: Determine whether a first voltage value corresponding to the node to be detected is greater than a second voltage value corresponding to the node to be detected; If yes, it is determined that a reverse flow occurs at the node to be detected.

8. The system according to claim 6, characterized in that The node operation data includes a first current value of a node to be detected between each energy storage block and the microgrid bus, and the coordination controller is further used to determine, for each node to be detected, a detection power value of the detection node within a preset time period based on the first current value and the first voltage value corresponding to the detection node; and calculate a detection ratio between the detection power value and the rated power value; Determine whether the detection ratio is greater than the target ratio; if so, determine that a reverse flow occurs at the node to be detected.

9. The system according to claim 6, characterized in that The coordination controller is also used to obtain the measured voltage value of the mains power uploaded by the acquisition module, and determine the operation mode of the energy storage inverter according to the magnitude relationship between the measured voltage value and the off-grid voltage value, wherein the operation mode includes an off-grid mode and a grid-connected mode; When the measured voltage value is greater than the off-grid voltage value, the energy storage inverter is determined to be in grid-connected mode; When the measured voltage value is less than the off-grid voltage value, it is determined that the energy storage inverter is in off-grid mode.

10. The system according to claim 9, characterized in that When it is determined that the energy storage inverter is in off-grid mode, the coordination controller generates a shutdown command and sends it to the energy storage inverter, so that the energy storage inverter disconnects the incoming circuit breaker and shuts down; The coordination controller generates an off-grid operation instruction and sends it to the energy storage inverter, so that the energy storage inverter starts and supplies power to the load module according to the specified power.

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