New energy transmission power grid intensity self-adaptive network following / network construction switchable system and new energy transmission power grid intensity self-adaptive network following / network construction switchable method

Abstract

The invention provides a new energy sending-out power grid intensity adaptive network following / network construction switchable method and system, and the method comprises the steps: obtaining the operation parameters of each new energy station and a power grid, and determining the operation state information of the new energy station and the power grid according to the obtained parameters; when the determined state information is oscillation, generating an operation mode switching instruction, and switching the operation mode of the network following / network construction switchable equipment to a network construction control mode; if the operation state of the power grid is still not recovered to be stable, controlling the operation mode of the grid following / grid construction type switchable energy storage equipment to be switched to a grid construction control mode; and if the operation state of the power grid is still not recovered to be stable, generating an operation mode switching instruction, and switching the operation mode of the following network / construction network switchable current converter to a construction network control mode. Reliable consumption of new energy under the weak power grid working condition is guaranteed through coordinated control of all the devices, and the reliability of transient and steady state operation of the whole system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of power control, and particularly relates to a method and system for adaptively switching between following the grid and forming the grid according to the strength of a new energy power grid for sending out power. Background Art

[0002] The statements in this part only provide background technical information related to the present invention, and do not necessarily constitute prior art.

[0003] Large-scale new energy replaces traditional generators and is connected to the power grid through a large number of power electronic converters with very little inertia. The cornerstone of power grid stability centered on rotational inertia in traditional power systems is severely weakened. The gradually emerging insufficient inertia and short-circuit capacity in a dual-high power system ( "high proportion of power electronic devices" and "high proportion of new energy") will make the system have poor anti-disturbance ability and is very likely to induce problems of power system frequency stability and voltage stability. The stable operation of a new power system with high-penetration new energy and the friendly consumption of new energy face challenges. Therefore, the grid-forming control technology has emerged, which controls the converter to simulate the characteristics of a synchronous generator and actively supports the power grid inertia, damping, etc. Although the grid-forming control technology can realize the dynamic behavior of the converter simulating a synchronous generator, its actual power support process must rely on the support of large-capacity energy storage devices and power electronic devices.

[0004] The new energy grid connection and power sending include a series of power electronic equipment such as energy storage, SVG, STATCOM, flexible DC converter, synchronous condenser, etc. To solve the problem of power oscillation caused by a weak power grid after large-scale new energy access to the power grid, the existing control methods cannot adapt to the change of power grid strength. It is necessary to adaptively match the grid-forming control methods such as grid-forming energy storage, grid-forming SVG, and STATCOM according to the power grid strength, actively identify and judge the strength of the power grid, and then automatically switch the following-the-grid / grid-forming equipment, following-the-grid / grid-forming energy storage, flexible DC converter station VSC, etc. to the grid-forming operation mode to improve the system damping and provide active support for the stable inertia, frequency, etc. of the AC power grid, and enhance the smoothness and stability of the new energy power station output.

[0005] The existing control methods for solving the problem of power oscillation caused by large-scale new energy access to a weak power grid cannot adapt to the change of power grid strength. Summary of the Invention

[0006] To solve the above problems, the present invention proposes a method and system for adaptively switching between following the grid and forming the grid according to the strength of a new energy power grid for sending out power. The present invention ensures the reliable consumption of new energy under weak power grid conditions through the coordinated control of each device, and improves the reliability of the whole system in transient and steady-state operation.

[0007] According to some embodiments, the present invention adopts the following technical solutions:

[0008] A new energy transmission grid strength adaptive grid-following / grid-forming switchable system, including at least two new energy power stations. At the AC collection first bus of the first new energy power station, there are multiple grid-following / grid-forming switchable devices; a energy storage system is also connected to the first bus. Multiple grid-following / grid-forming switchable energy storage devices and grid-following energy storage devices are respectively configured in the energy storage system, which are used for peak shaving and valley filling, suppressing the volatility of new energy power generation, and promoting the consumption of new energy.

[0009] The second new energy power station is connected to the second bus through a grid-following / grid-forming switchable converter.

[0010] Each grid-following / grid-forming switchable device, grid-following / grid-forming switchable energy storage device, and grid-following / grid-forming switchable converter are connected to the corresponding control device and are controlled by the control device to perform grid-following / grid-forming state switching. The control devices are all connected to the device coordination control system, and the device coordination control system is connected to the controller. The controller is configured to generate an operation mode switching instruction and send it to the device coordination control system when the operation parameters of the new energy power station or the grid are not within the set range, considering that the grid has an oscillation, so that the operation mode of the grid-following / grid-forming switchable device is switched to the grid-forming control mode; if the grid operation state still does not return to stability, an operation mode switching instruction is generated and sent to the device coordination control system to control the operation mode of the grid-following / grid-forming switchable energy storage device to be switched to the grid-forming control mode.

[0011] If the grid operation state still does not return to stability, an operation mode switching instruction is generated and sent to the device coordination control system to switch the operation mode of the grid-following / grid-forming switchable converter to the grid-forming control mode.

[0012] As an alternative implementation, the grid-following / grid-forming switchable devices are connected in parallel with each other.

[0013] As an alternative implementation, the grid-following / grid-forming switchable device is one of a grid-forming static var generator, a grid-forming static synchronous compensator, and a grid-forming power electronic synchronous condenser.

[0014] As an alternative implementation, the grid-following / grid-forming switchable energy storage devices are connected in parallel with each other.

[0015] As an alternative implementation, the grid-forming control mode is one of droop control, matching control, and virtual oscillator control.

[0016] A new energy transmission grid strength adaptive grid-following / grid-forming switchable method includes the following steps:

[0017] Obtain the operation parameters of each new energy power station and the grid, and determine the operation state information of the new energy power station and the grid according to the obtained parameters.

[0018] When the determined status information indicates oscillation, a running mode switching instruction is generated to switch the running mode of the grid-connected / network-forming switchable device to the network-forming control mode; if the grid operating status has not yet returned to stability, the running mode of the grid-connected / network-forming switchable energy storage device is controlled to switch to the network-forming control mode;

[0019] If the grid operating status has not yet returned to stability, a running mode switching instruction is generated to switch the running mode of the grid-connected / network-forming switchable converter to the network-forming control mode.

[0020] As an alternative implementation, when power oscillation occurs at the new energy power station or the voltage / frequency at the AC bus is unstable, it is determined that the grid has oscillations.

[0021] As an alternative implementation, when the output power of the new energy power station is stable or the voltage / frequency at the AC bus is in a stable state, it is determined that the grid strength is stable and the grid-connected control mode is switched to.

[0022] As an alternative implementation, after receiving the mode switching instruction, the grid-connected / network-forming switchable converter switches from the constant DC voltage mode to the network-forming control mode.

[0023] An electronic device includes a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the steps in the above method are completed.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The large-scale new energy transmission grid strength adaptive grid-connected / network-forming switchable device configuration and control method of the present invention automatically identifies and judges the strength of the grid according to the operating status of the new energy power station and the AC bus, and adaptively switches the operating status of the grid-connected / network-forming switchable energy storage device, the grid-connected / network-forming switchable device, and the grid-connected / network-forming switchable converter through the coordinated control system. The reliable consumption of new energy under weak grid conditions is ensured through the coordinated control of each device, improving the reliability of the transient and steady-state operation of the entire system.

[0026] (2) The large-scale new energy transmission grid strength adaptive grid-connected / network-forming switchable device configuration and control method proposed by the present invention is universal, different from the existing control methods that cannot adapt to the change of grid strength. When applied to large-scale new energy transmission systems with other topological structures, the present invention still holds.

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0028] The accompanying drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0029] Figure 1 It is a schematic diagram of the configuration of a switchable device and energy storage for large-scale new energy accommodation of the present invention;

[0030] Figure 2 It is a coordinated control logic diagram of the operation modes of the grid-following / grid-forming switchable device, grid-following / grid-forming energy storage, VSC1 and other devices of the present invention;

[0031] Figure 3 It is a grid-forming control block diagram of the present invention. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0033] It should be noted that the following detailed descriptions are all illustrative and are intended to provide a further description of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0034] It should be noted that the terms used herein are only for describing specific implementation manners and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, 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.

[0035] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0036] Embodiment 1

[0037] A large-scale new energy transmission grid strength adaptive grid-following / grid-forming switchable device and energy storage system, as Figure 1 shown, includes: grid-following / grid-forming switchable devices #1 to #N at the 35 kV AC collection bus of the new energy station 1; grid-following / grid-forming switchable energy storage devices #1 to #N and grid-following energy storage devices are respectively configured in the energy storage system for peak shaving and valley filling, suppressing the volatility of new energy power generation, and promoting new energy accommodation; a grid-following / grid-forming switchable converter for the new energy station 2 to be sent out through a flexible DC, that is, VSC1 in the figure;

[0038] Each grid-following / grid-forming switchable device, grid-following / grid-forming switchable energy storage device, and grid-following / grid-forming switchable converter are connected to the corresponding control device and are controlled by the control device to perform grid-following / grid-forming state switching. The control devices are all connected to the device coordination control system, and the device coordination control system is connected to the controller. The controller is configured to determine that the power grid has oscillations when the operating parameters of the new energy power station or the power grid are not within the set range, generate an operating mode switching instruction, and send it to the device coordination control system to switch the operating mode of the grid-following / grid-forming switchable device to the grid-forming control mode; if the operating state of the power grid still has not returned to stability, generate an operating mode switching instruction, send it to the device coordination control system, and control the operating mode of the grid-following / grid-forming switchable energy storage device to switch to the grid-forming control mode;

[0039] If the operating state of the power grid still has not returned to stability, generate an operating mode switching instruction, send it to the device coordination control system, and switch the operating mode of the grid-following / grid-forming switchable converter to the grid-forming control mode.

[0040] As Figure 1 shown, the grid-following / grid-forming switchable devices are connected in parallel; the grid-following / grid-forming switchable device is one of a grid-forming static var generator, a grid-forming static synchronous compensator, and a grid-forming power electronic synchronous condenser.

[0041] As Figure 1 shown, the grid-following / grid-forming switchable energy storage devices are connected in parallel.

[0042] In this embodiment, the grid-forming control mode is one of droop control, matching control, and virtual oscillator control.

[0043] Embodiment 2

[0044] To achieve the reliable and stable operation of a large-scale new energy grid-connected system, for the actual operating state of the system, a grid strength adaptive grid-following / grid-forming switchable device control method, as Figure 2 shown, includes the following steps:

[0045] Step 1: Judging the operating state information of the new energy power station and the power grid.

[0046] The specific analysis process is as follows: Obtain the output power parameters of the new energy power station 1 or electrical quantities such as the bus voltage / frequency of the 35kV / 110kV AC power grid, and analyze the oscillation conditions of the relevant electrical quantities to make an adaptive judgment and identify the strength of the power grid. When power oscillation occurs at the new energy power station 1 or the voltage / frequency at the AC bus is unstable, it is determined that the power grid strength becomes weak, and an operation mode switching instruction is sent to the device coordination control system. When the output power of the new energy power station is stable or the voltage / frequency at the AC bus is in a stable state, it is determined that the power grid strength is strong, and an instruction is sent to the device coordination control system, which can be switched to the grid-following control mode according to the system requirements to enhance the stability and controllability of new energy output such as power smoothing and peak shaving and valley filling.

[0047] Step 2: Configuration and operation mode switching control of grid-following / grid-forming devices, VSC1 converter station, energy storage, etc.

[0048] The coordinated control logic for the operation modes of grid-following / grid-forming switchable devices, grid-following / grid-forming energy storage, VSC1, etc., such as Figure 2 shown. After making a judgment on the operation state information of the new energy power station and the power grid, send operation mode switching instructions for each device to the device coordination control system, and then the device coordination control system sequentially sends specific operation mode switching instructions to grid-following / grid-forming switchable devices, grid-following / grid-forming switchable energy storage devices, VSC1, etc. The converter devices of each device specifically execute the operation mode switching instructions.

[0049] The specific analysis process is as follows: After receiving the device operation mode switching instruction, the device coordination control system sequentially sends operation mode switching instructions to grid-following / grid-forming switchable energy storage devices #1 to #N, grid-following / grid-forming switchable devices #1 to #N (such as static var generator SVG, static synchronous compensator STATCOM, power electronic phase shifter, etc.), and VSC1 converter station according to the real-time operation state of the power grid.

[0050] It should be noted that in this implementation scheme, the grid-following / grid-forming switchable devices include, but are not limited to, power quality devices such as grid-forming static var generator SVG, grid-forming static synchronous compensator STATCOM, and grid-forming power electronic synchronous phase shifter.

[0051] Step 3: The instructions of each device converter are executed and switched to a specific control mode.

[0052] When the grid strength weakens, after the DC / AC converters of each device such as the grid-connected / grid-forming switchable energy storage devices #1 to #N and the grid-connected / grid-forming switchable devices #1 to #N receive the operation mode switching instructions issued by the coordinated control system, the converter control device sequentially switches each device to the grid-forming control operation mode. After receiving the operation mode switching instruction issued by the coordinated control system, the VSC1 converter station switches the VSC1 converter station from the constant DC voltage mode to the grid-forming control mode. When the grid strength is strong enough, after the DC / AC converters of each device such as the grid-connected / grid-forming switchable energy storage devices #1 to #N, the grid-connected / grid-forming switchable devices #1 to #N, and VSC1 receive the instructions issued by the device coordinated control system, they can be switched to the grid-connected control mode by the converter control device according to the system requirements, enhancing the stability and controllability of new energy output such as power smoothing and peak shaving and valley filling.

[0053] As Figure 3 shown, in this embodiment, the grid-forming control method is a grid-forming control based on virtual synchronous machine control.

[0054] It should be noted that the grid-forming control methods include, but are not limited to, droop control, matching control, virtual oscillator control, and other grid-forming control methods that can provide active support for the grid such as frequency and voltage.

[0055] Embodiment III

[0056] An electronic device includes a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the following steps are completed:

[0057] Obtain the operation parameters of each new energy power station and the grid, and determine the operation state information of the new energy power station and the grid according to the obtained parameters;

[0058] When the determined state information indicates oscillation, generate an operation mode switching instruction to switch the operation mode of the grid-connected / grid-forming switchable device to the grid-forming control mode; if the grid operation state still has not returned to stability, control the operation mode of the grid-connected / grid-forming switchable energy storage device to switch to the grid-forming control mode;

[0059] If the grid operation state still has not returned to stability, generate an operation mode switching instruction to switch the operation mode of the grid-connected / grid-forming switchable converter to the grid-forming control mode;

[0060] When the output power of the new energy power station is stable or the voltage / frequency at the AC bus is in a stable state, it is determined that the grid strength is stable and switched to the grid-connected control mode.

[0061] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0062] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0063] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that realizes the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0064] These computer program instructions can also be loaded onto a computer or other programmable data processing devices, such that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process, so that the instructions executed on the computer or other programmable devices provide steps for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0065] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made by those skilled in the art without creative efforts within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A new energy transmission grid strength adaptive grid-following / grid-forming switchable system, characterized in that, It includes at least two new energy power stations. At the first AC collection first bus of the first new energy power station, there are multiple grid-following / grid-forming switchable devices; a energy storage system is also connected to the first bus. At the energy storage system, multiple grid-following / grid-forming switchable energy storage devices and grid-following energy storage devices are respectively configured, which are used for peak shaving and valley filling, suppressing the volatility of new energy power generation, and promoting the consumption of new energy; The second new energy power station is connected to the second bus through a grid-following / grid-forming switchable converter; Each grid-following / grid-forming switchable device, grid-following / grid-forming switchable energy storage device, grid-following / grid-forming switchable converter is connected to the corresponding control device and is controlled by the control device to perform grid-following / grid-forming state switching. The control devices are all connected to the device coordination control system, the device coordination control system is connected to the controller, and the controller is configured to consider that the power grid has an oscillation when the operating parameters of the new energy power station or the power grid are not within the set range, generate an operating mode switching instruction, and send it to the device coordination control system to switch the operating mode of the grid-following / grid-forming switchable device to the grid-forming control mode; if the operating state of the power grid still does not return to stability, generate an operating mode switching instruction, send it to the device coordination control system, and control the operating mode of the grid-following / grid-forming switchable energy storage device to switch to the grid-forming control mode; If the operating state of the power grid still does not return to stability, generate an operating mode switching instruction, send it to the device coordination control system, and switch the operating mode of the grid-following / grid-forming switchable converter to the grid-forming control mode.

2. The adaptive grid-following / grid-forming switchable system for the new energy transmission grid strength as claimed in claim 1, wherein The grid-following / grid-forming switchable devices are connected in parallel with each other.

3. The adaptive grid-following / grid-forming switchable system for the new energy transmission grid strength according to claim 1, characterized in that, The grid-following / grid-forming switchable device is one of a grid-forming static var generator, a grid-forming static synchronous compensator, and a grid-forming power electronic synchronous condenser.

4. The new energy transmission grid strength adaptive grid-following / grid-forming switchable system according to claim 1, characterized in that, The grid-following / grid-forming switchable energy storage devices are connected in parallel with each other.

5. The new energy transmission grid strength adaptive grid-following / grid-forming switchable system according to claim 1, characterized in that The grid-forming control mode is one of droop control, matching control, and virtual oscillator control.

6. A method for adaptively following / forming a power grid with adjustable grid strength for a new energy power transmission network, characterized in that, It includes the following steps: Obtain the operating parameters of each new energy power station and the power grid, and determine the operating state information of the new energy power station and the power grid according to the obtained parameters; When the determined state information indicates an oscillation, generate an operating mode switching instruction to switch the operating mode of the grid-following / grid-forming switchable device to the grid-forming control mode; If the operating state of the power grid still does not return to stability, control the operating mode of the grid-following / grid-forming switchable energy storage device to switch to the grid-forming control mode; If the operating state of the power grid still does not return to stability, generate an operating mode switching instruction to switch the operating mode of the grid-following / grid-forming switchable converter to the grid-forming control mode.

7. The adaptive grid-following / grid-forming switchable method for the strength of a new energy power transmission grid according to claim 6, wherein When there is a power oscillation in the new energy power station or the voltage / frequency at the AC bus is unstable, it is determined that the power grid has an oscillation.

8. The adaptive grid-following / grid-forming switchable method for new energy transmission grid strength according to claim 6, characterized in that, When the output power of the new energy power station is stable or the voltage / frequency at the AC bus is in a stable state, it is determined that the power grid strength is stable, and the grid-following control mode is switched.

9. The method for adaptively following / forming a network with switchable grid strength of a new energy power transmission network according to claim 6, wherein After receiving the mode switching instruction, the grid-following / grid-forming switchable converter switches from the constant DC voltage mode to the grid-forming control mode.

10. An electronic device, characterized in that, It includes a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the steps in the method according to any one of claims 6-9 are completed.

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