New energy power generation grid-connected control method and control device

Abstract

The invention provides a new energy power generation grid-connected control method and device, and relates to the technical field of grid-connected control. The new energy power generation grid-connected control method is applied to a new energy power generation-energy storage sending-out system. The control method comprises the steps that power grid frequency information is acquired; obtaining inertia response data and frequency modulation data in response to the power grid frequency information; and in response to the inertia response data and the frequency modulation data, controlling the new energy power generation-stored energy delivery system to provide an inertia response and frequency modulation strategy for a power grid, and the new energy power generation-stored energy delivery system coupling stored energy with a preset capacity to a DC bus through a preset circuit. According to the control method, the autonomous support power grid of the new energy power generation-stored energy delivery system can be realized, and real-time and reliable active frequency support is provided for the power grid.

Description

Technical Field

[0001] The present application relates to the technical field of grid-connected control, and in particular to a new energy power generation grid-connected control method and control device. Background Art

[0002] At present, with the increasingly urgent global response to climate change, energy shortages and energy supply security becoming increasingly severe, the world's energy development has entered a new round of strategic adjustment. Large-scale development and utilization of offshore wind power is a powerful means to solve energy shortages and is also a major demand at present.

[0003] Generally, when AC transmission is adopted, the charging effect caused by long-distance submarine cables will greatly increase the transmission cost of offshore wind power. Therefore, flexible DC transmission technology with fast power decoupling control characteristics and island grid access capability, and without reactive power compensation equipment, is an important technical means for large-scale offshore wind power access to the grid in the future;

[0004] Different from the voltage source characteristics of synchronous generators, the current conventional wind power-flexible DC system has current source characteristics, has no inertia to the power grid, and cannot participate in frequency regulation. As a result, the offshore wind flexible DC grid-connected system cannot support the power grid autonomously like synchronous generators, and cannot provide real-time and reliable active frequency support for the power grid. Summary of the invention

[0005] The purpose of this application is to provide a new energy power generation grid-connected control method, control device, electronic equipment and computer-readable storage medium, which can realize an autonomously supported power grid of a new energy power generation-energy storage delivery system and provide real-time and reliable active frequency support for the power grid.

[0006] In a first aspect, the present application provides a new energy power generation grid connection control method, which is applied to a new energy power generation-energy storage delivery system, and the control method includes:

[0007] Obtain grid frequency information;

[0008] In response to the power grid frequency information, obtaining inertia response data and frequency modulation data;

[0009] In response to the inertia response data and the frequency modulation data, the renewable energy power generation-energy storage delivery system is controlled to provide inertia response and frequency modulation strategies to the power grid, and the renewable energy power generation-energy storage delivery system couples the energy storage of a preset capacity to the DC bus through a preset circuit.

[0010] In the above implementation process, in response to the grid frequency response requirements of the renewable energy power generation-energy storage delivery system, the preset capacity of energy storage is coupled to the DC bus through a preset circuit, and the renewable energy power generation-energy storage delivery system is controlled based on the inertia response data and frequency modulation data to provide inertia response and frequency modulation strategies to the grid. The coordinated energy storage control makes the renewable energy power generation-energy storage delivery system look like a large synchronous generator from the shore grid connection point, which can autonomously release the inertia of the wind turbine and autonomously mobilize energy storage to participate in the primary frequency modulation of the grid, which is reflected in the voltage source characteristics, thereby realizing the autonomous support of the renewable energy power generation-energy storage delivery system for the grid, and providing real-time and reliable active frequency support for the grid.

[0011] Furthermore, the control method further includes:

[0012] In response to the grid frequency information, the receiving-end converter of the renewable energy power generation-energy storage transmission system is controlled by a self-synchronous voltage source type, and the grid frequency information and the DC bus voltage satisfy a preset relationship.

[0013] In the above implementation process, self-synchronous voltage source control is adopted in the receiving-end converter, and the grid frequency information and the DC bus voltage satisfy a preset relationship, that is, a one-to-one correspondence is established between the grid frequency information and the DC bus voltage, thereby mapping the grid frequency to the DC voltage to provide inertia response and primary frequency regulation strategy for the grid.

[0014] Furthermore, the control method further includes:

[0015] Controlling the sending-end converter of the new energy power generation-energy storage delivery system to obtain the grid frequency information from the DC bus;

[0016] The grid frequency information is transmitted to the wind farm side of the new energy power generation and energy storage delivery system. The wind turbines on the wind farm side detect AC frequency information based on the grid frequency information and a phase-locked loop, and provide inertia response to the grid through the AC frequency information.

[0017] In the above implementation process, the sending-end converter extracts the grid frequency information from the DC bus and transmits the grid frequency to the wind farm side of the offshore wind farm. The wind turbines in the offshore wind farm detect the AC frequency through a phase-locked loop, thereby providing inertia response for the grid.

[0018] Furthermore, the receiving-end converter of the new energy power generation-energy storage delivery system is provided with a module group, the module group includes a plurality of submodules, and the control method further includes:

[0019] Based on the synchronous generator rotor simulation performed on the capacitors of multiple submodules in the module group at the receiving-end converter, the phase-locked loop-free self-synchronization of the receiving-end converter to the power grid is controlled.

[0020] In the above implementation process, the capacitor of the submodule is analogized to the rotor of a synchronous generator and simulated at the receiving end converter to achieve self-synchronization of the power grid without a phase-locked loop, so that the DC voltage on the DC bus can automatically reflect the change of the power grid frequency.

[0021] Furthermore, the control method further includes:

[0022] Obtaining information on the number of submodules in the module group;

[0023] In response to the quantity information of the submodules, the grid frequency information is matched to the capacitance energy corresponding to the submodules according to a preset DC side control mode of the receiving-end converter.

[0024] In the above implementation process, the corresponding DC side control mode is selected according to the number of sub-modules put into operation on the DC side, so as to automatically map the grid frequency onto the DC bus voltage.

[0025] Furthermore, the preset DC side control mode includes a coupling control mode and a decoupling control mode, and in response to the quantity information of the submodules, the grid frequency information is matched with the capacitance energy corresponding to the submodule according to the preset DC side control mode of the receiving end converter, including:

[0026] If the quantity information of the submodule is a constant, matching the grid frequency information with the capacitance energy corresponding to the submodule according to the coupling control method;

[0027] If the quantity information of the submodules is not a constant, the grid frequency information is matched to the capacitor energy corresponding to the submodules according to a decoupling control method.

[0028] In the above implementation process, whether it is coupled or decoupled control, the grid frequency can be automatically mapped to the DC bus voltage. Based on this feature, the energy storage device and the sending-end converter can obtain grid frequency information by detecting the DC voltage. The energy storage device can respond directly to provide inertia support and primary frequency modulation. The sending-end converter can transmit the grid frequency change to each wind turbine in the offshore wind farm by changing the AC frequency of the wind farm. The wind turbine provides a fast frequency response to the grid. Ultimately, the self-synchronous voltage source control of the new energy power generation-energy storage delivery system is realized to provide active frequency support for the grid.

[0029] Furthermore, the control method further includes:

[0030] In response to the DC current and DC voltage on the DC side of the receiving-end converter, the DC bus voltage is controlled according to a preset double closed-loop control strategy.

[0031] In the above implementation process, the DC bus voltage can be quickly controlled through the dual closed-loop control of the DC voltage and DC current on the DC side of the receiving-end converter.

[0032] Furthermore, the control method further includes:

[0033] In response to the grid frequency information, the output AC voltage of the receiving-end converter of the renewable energy power generation and energy storage transmission system is controlled.

[0034] In the above implementation process, by controlling the output AC voltage of the receiving-end converter, damping can be increased, thereby shortening the process time of the receiving-end converter synchronizing the grid frequency and improving stability.

[0035] Furthermore, the preset capacity has a value range of 15% to 20%.

[0036] Furthermore, the preset circuit includes a plurality of submodules connected in series; wherein the submodule includes a commutation unit connected in parallel with an energy storage unit.

[0037] In a second aspect, the present application provides a new energy power generation grid-connected control device, which is applied to a new energy power generation-energy storage delivery system, and the control device includes:

[0038] A power grid frequency unit, used for obtaining power grid frequency information;

[0039] A response unit, configured to obtain inertia response data and frequency modulation data in response to the power grid frequency information;

[0040] A control unit is used to control the new energy power generation-energy storage delivery system to provide inertia response and frequency modulation strategy to the power grid in response to the inertia response data and the frequency modulation data, and the new energy power generation-energy storage delivery system couples the energy storage of a preset capacity to the DC bus through a preset circuit.

[0041] Furthermore, the control unit is also used to: respond to the grid frequency information, control the receiving-end converter of the renewable energy power generation and energy storage transmission system through a self-synchronous voltage source type, and the grid frequency information and the DC bus voltage satisfy a preset relationship.

[0042] Furthermore, the control unit is also used to: control the sending-end converter of the renewable energy power generation-energy storage delivery system to obtain the grid frequency information from the DC bus; transmit the grid frequency information to the wind farm side of the renewable energy power generation-energy storage delivery system, and the wind turbines on the wind farm side detect the AC frequency information based on the grid frequency information and the phase-locked loop, and provide inertia response to the grid through the AC frequency information.

[0043] Furthermore, the receiving-end converter of the new energy power generation and energy storage transmission system is provided with a module group, and the module group includes multiple sub-modules. The control unit is also used to: based on the synchronous generator rotor simulation of the capacitance of multiple sub-modules in the module group at the receiving-end converter, control the phase-locked loop-free self-synchronization of the receiving-end converter to the power grid.

[0044] Furthermore, the control unit is also used to: obtain the quantity information of sub-modules in the module group; in response to the quantity information of the sub-modules, match the grid frequency information with the capacitor energy corresponding to the sub-module according to the preset DC side control method of the receiving-end converter.

[0045] Furthermore, the preset DC side control mode includes a coupling control mode and a decoupling control mode, and the control unit is also used to: if the quantity information of the submodule is a constant, match the grid frequency information to the capacitor energy corresponding to the submodule according to the coupling control mode; if the quantity information of the submodule is not a constant, match the grid frequency information to the capacitor energy corresponding to the submodule according to the decoupling control mode.

[0046] In a third aspect, the present application provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in any one of the first aspects when executing the computer program.

[0047] In a fourth aspect, the present application provides a computer-readable storage medium, on which instructions are stored. When the instructions are executed on a computer, the computer executes the method as described in any one of the first aspects.

[0048] In a fifth aspect, the present application provides a computer program product, which, when running on a computer, enables the computer to execute the method as described in any one of the first aspects.

[0049] Other features and advantages disclosed in the present application will be described in the following description, or some features and advantages can be inferred or determined without doubt from the description, or can be learned by implementing the above-mentioned technology disclosed in the present application.

[0050] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] 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.

[0052] Figure 1 A topological diagram of a new energy power generation-energy storage and delivery system provided in an embodiment of the present application;

[0053] Figure 2 A schematic diagram of a process flow of a new energy power generation grid connection control method provided in an embodiment of the present application;

[0054] Figure 3 A schematic diagram of an equivalent circuit of the DC side of the receiving-end MMC under decoupling control provided in an embodiment of the present application;

[0055] Figure 4 A schematic diagram of a DC voltage-DC current dual closed-loop control provided in an embodiment of the present application;

[0056] Figure 5 A topological diagram of a self-synchronous voltage source control system for a new energy power generation-energy storage delivery system provided in an embodiment of the present application;

[0057] Figure 6 A structural block diagram of a new energy power generation grid-connected control device provided in an embodiment of the present application;

[0058] Figure 7 A structural block diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0059] 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.

[0060] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0061] As the global response to climate change becomes increasingly urgent, energy shortages and energy supply security become increasingly severe, the world's energy development has entered a new round of strategic adjustment period; relatively speaking, large-scale development and utilization of offshore wind power energy is a powerful means to achieve the goal of solving energy shortages and improving energy supply security, and it is also a major demand of my country at present;

[0062] Generally speaking, for offshore wind power systems, when AC transmission is adopted, the charging effect brought by long-distance submarine cables will greatly increase the transmission cost of offshore wind power; therefore, flexible DC transmission technology with fast power decoupling control characteristics and island grid access capability, without reactive compensation equipment, is an important technical means for large-scale offshore wind power access to the grid in the future; different from the voltage source characteristics of synchronous generators, the current conventional wind power-flexible DC system has current source characteristics, has no inertia for the grid, and cannot participate in frequency regulation. In the context of capacity reaching GW level, how to make the offshore wind flexible DC grid-connected system support the grid autonomously like synchronous generators and have the characteristics of supporting power supply is of great significance. In addition, how to achieve this characteristic transformation at low cost and high reliability is particularly important. Through the coordination of flexible DC, energy storage and wind power, real-time and reliable active frequency support can be provided to the grid.

[0063] For example, for the flexible DC system commonly used in the market, by connecting the DC side high voltage and large capacity of the energy storage battery to the grid, it can provide frequency response for the grid, but it does not involve how the energy storage device measures the grid frequency. Generally, it needs to be communicated, and the technology does not involve wind farms. The ability to provide frequency response by relying solely on energy storage is limited, and the cost is higher than the inertia response of wind farms.

[0064] Alternatively, the grid frequency can be transmitted to the wind farm through a flexible DC system to help the wind farm sense the grid frequency in real time and provide inertia response. However, this technology does not involve an energy storage system and relies solely on the wind farm to provide inertia response, which has a weak support capacity for the grid.

[0065] In order to solve the technical problems raised above, the embodiment of the present application provides a new energy power generation grid connection control method. According to the grid frequency response requirements of the new energy power generation-energy storage delivery system, by coupling the preset capacity of energy storage to the DC bus through a preset circuit, the new energy power generation-energy storage delivery system is controlled based on the inertia response data and the frequency modulation data to provide inertia response and frequency modulation strategies to the grid, and the energy storage control is coordinated. From the perspective of the onshore grid connection point, the new energy power generation-energy storage delivery system is similar to a large synchronous generator, which can autonomously release the inertia of the wind turbine and autonomously mobilize the energy storage to participate in the primary frequency modulation of the grid, which is reflected in the voltage source characteristics, thereby realizing the autonomous support of the new energy power generation-energy storage delivery system to the grid, and providing real-time and reliable active frequency support for the grid.

[0066] Illustratively, an embodiment of the present application provides a new energy power generation grid-connected control method, which can change the current source characteristics of a conventional wind power flexible grid-connected system that needs to rely on the grid for operation, cannot damp grid frequency fluctuations, and cannot participate in the primary frequency modulation of the grid.

[0067] The new energy power generation grid-connected control method, system, electronic device and computer-readable storage medium disclosed in the embodiments of the present application can be applied to a controller to realize the self-synchronous voltage source control of the new energy power generation-energy storage delivery system. The controller includes a server, which can be an independent server or a server cluster composed of multiple servers, and can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence sampling point devices.

[0068] Exemplarily, the new energy power generation - energy storage and delivery system described in the embodiment of the present application can be a new energy power generation system such as wind energy, solar energy, tidal energy, etc.; optionally, the new energy power generation - energy storage and delivery system hereinafter is described using the sea wind - flexible direct current - energy storage and delivery system as an example, which is only for the convenience of description and does not limit the application scope of the new energy power generation - energy storage and delivery system.

[0069] According to some embodiments of this application, see Figure 1 , Figure 1 A topological diagram of a renewable energy power generation-energy storage delivery system provided in an embodiment of the present application; the renewable energy power generation-energy storage delivery system comprises an offshore wind farm 101, an AC submarine cable 102, a sending-end converter 103, a DC submarine cable 104, a receiving-end converter 105, a power grid 106, and an energy storage device 107;

[0070] Among them, an offshore wind farm 101, an AC submarine cable 102, a sending-end converter 103, a DC submarine cable 104, a receiving-end converter 105, and a power grid 106 are connected in sequence; generally, the power grid 106 refers to an onshore AC power grid;

[0071] The energy storage device 107 is installed on the DC side of the receiving end converter 105. Figure 1 As shown, the capacity of the energy storage device 107 is configured according to the preset capacity of energy storage; in some embodiments, 15% to 20% of the system rated capacity of energy storage can be directly coupled to the high-voltage DC bus (i.e., DC submarine cable 104) of the new energy power generation-energy storage transmission system through a preset circuit, thereby forming high-voltage DC direct-hanging energy storage.

[0072] Exemplarily, the preset circuit described in the embodiments of the present application may be an electric power network wiring circuit, for example: the preset circuit may be a radial trunk type, chain type, double-loop radial type, main line type, chain ring type, or other electric power network wiring circuits, which are limited here.

[0073] Exemplarily, the preset circuit includes a plurality of submodules connected in series; wherein the submodule includes a commutation unit connected in parallel with an energy storage unit.

[0074] In some embodiments, the commutation unit is a power module, which includes a capacitor and a half-bridge or full-bridge circuit composed of power devices such as IGBTs.

[0075] See also Figure 2 , Figure 2 The flowchart of the new energy power generation grid connection control method provided in the embodiment of the present application is as follows. The new energy power generation grid connection control method is applied to the new energy power generation-energy storage delivery system. The control method includes the following steps:

[0076] S100: Obtaining grid frequency information;

[0077] S200: In response to the power grid frequency information, obtaining inertia response data and frequency modulation data;

[0078] S300: In response to the inertia response data and the frequency modulation data, the renewable energy power generation-energy storage transmission system is controlled to provide the inertia response and frequency modulation strategy to the power grid, and the renewable energy power generation-energy storage transmission system couples the energy storage of the preset capacity to the DC bus through the preset circuit.

[0079] Exemplarily, the grid frequency information is the grid frequency of the grid 106; by directly coupling the energy storage of a preset capacity to the high-voltage DC bus (i.e., the DC submarine cable 104) of the new energy power generation-energy storage transmission system through a preset circuit, thereby forming a high-voltage DC direct-hanging energy storage, and adopting a self-synchronous voltage source control at the receiving-end converter, the grid frequency of the grid 106 can be mapped to the DC voltage of the DC submarine cable 104;

[0080] On the basis of the above, after the energy storage device 107 extracts the grid frequency information from the DC submarine cable 104, it obtains inertia response data and frequency modulation data in response to the grid frequency information, and then provides inertia response and frequency modulation strategy to the grid based on the inertia response data and frequency modulation data; optionally, the frequency modulation strategy of the new energy power generation grid-connected control method in the embodiment of the present application is a primary frequency modulation strategy.

[0081] Exemplarily, the renewable energy power generation grid-connected control method provided in the present application is targeted at the grid frequency response requirements of the renewable energy power generation-energy storage delivery system. By coupling the energy storage of a preset capacity to the DC bus through a preset circuit, the renewable energy power generation-energy storage delivery system is controlled based on the inertia response data and the frequency modulation data to provide the inertia response and frequency modulation strategy to the grid, and the energy storage is coordinated to control the renewable energy power generation-energy storage delivery system. From the perspective of the onshore grid connection point, the renewable energy power generation-energy storage delivery system is similar to a large synchronous generator, which can autonomously release the inertia of the wind turbine and autonomously mobilize the energy storage to participate in the primary frequency modulation of the grid, which is reflected in the voltage source characteristics, thereby realizing the autonomous support of the renewable energy power generation-energy storage delivery system for the grid, and providing real-time and reliable active frequency support for the grid.

[0082] In some embodiments, the new energy power generation grid connection control method further includes:

[0083] In response to the grid frequency information, the receiving-end converter of the renewable energy power generation-energy storage transmission system is controlled by a self-synchronous voltage source type, and the grid frequency information and the DC bus voltage satisfy a preset relationship.

[0084] Exemplarily, a self-synchronous voltage source control is adopted at the receiving-end converter, and the grid frequency information and the DC bus voltage satisfy a preset relationship, that is, a one-to-one correspondence is established between the grid frequency information and the DC bus voltage, thereby mapping the grid frequency to the DC voltage to provide inertia response and primary frequency regulation strategy for the grid.

[0085] In some embodiments, the new energy power generation grid connection control method further includes:

[0086] Control the sending-end converter of the renewable energy power generation and energy storage delivery system to obtain grid frequency information from the DC bus;

[0087] The grid frequency information is transmitted to the wind farm side of the renewable energy power generation and energy storage delivery system. The wind turbines on the wind farm side detect the AC frequency information based on the grid frequency information and the phase-locked loop, and provide inertia response to the grid through the AC frequency information.

[0088] Exemplarily, after the sending-end converter extracts the grid frequency information from the DC bus, it transmits the grid frequency to the wind farm side of the offshore wind farm. The wind turbines in the offshore wind farm detect the AC frequency through a phase-locked loop, thereby providing inertia response for the grid.

[0089] In some embodiments, the receiving-end converter of the new energy power generation-energy storage delivery system is provided with a module group, the module group includes a plurality of sub-modules, and the control method further includes:

[0090] Based on the capacitors of multiple submodules in the module group of the receiving-end converter, the synchronous generator rotor simulation is performed to control the phase-locked loop-free self-synchronization of the receiving-end converter to the power grid.

[0091] For example, at the receiving-end converter, the capacitor of the submodule is analogized to the rotor of a synchronous generator and simulated to achieve self-synchronization of the power grid without a phase-locked loop, so that the DC voltage on the DC bus can automatically reflect the change of the power grid frequency.

[0092] In some embodiments, the new energy power generation grid connection control method further includes:

[0093] Get the number of submodules in the module group;

[0094] In response to the quantity information of the submodules, the grid frequency information is matched to the capacitance energy corresponding to the submodules according to a preset DC side control mode of the receiving-end converter.

[0095] Exemplarily, according to the number of submodules put into operation on the DC side, a corresponding DC side control mode is selected to automatically map the grid frequency onto the DC bus voltage.

[0096] In some embodiments, the preset DC side control mode includes a coupling control mode and a decoupling control mode, and in response to the quantity information of the submodules, the grid frequency information is matched to the capacitance energy corresponding to the submodule according to the preset DC side control mode of the receiving end converter, including:

[0097] If the number information of the submodules is a constant, the grid frequency information is matched to the capacitance energy corresponding to the submodules according to the coupling control method;

[0098] If the number information of the submodules is not a constant, the grid frequency information is matched to the capacitor energy corresponding to the submodules according to the decoupling control method.

[0099] For example, whether it is coupled or decoupled control, the grid frequency can be automatically mapped to the DC bus voltage. Based on this feature, the energy storage device and the sending-end converter can obtain grid frequency information by detecting the DC voltage. The energy storage device can respond directly to provide inertia support and primary frequency modulation. The sending-end converter can transmit the grid frequency change to each wind turbine in the offshore wind farm by changing the AC frequency of the wind farm. The wind turbine provides a fast frequency response to the grid. Ultimately, the self-synchronous voltage source control of the new energy power generation-energy storage delivery system is realized to provide active frequency support for the grid.

[0100] In some embodiments, the new energy power generation grid connection control method further includes:

[0101] In response to the DC current and DC voltage on the DC side of the receiving-end converter, the DC bus voltage is controlled according to a preset double closed-loop control strategy.

[0102] By way of example, the DC bus voltage can be quickly controlled by dual closed-loop control of the DC voltage and DC current on the DC side of the receiving-end converter. For details on the dual closed-loop control, see the following Figure 3 , Figure 4 .

[0103] In some embodiments, the preset capacity ranges from 15% to 20%.

[0104] In some embodiments, the new energy power generation grid connection control method further includes:

[0105] In response to the grid frequency information, the output AC voltage of the receiving-end converter of the renewable energy power generation and energy storage transmission system is controlled.

[0106] For example, by controlling the output AC voltage of the receiving-end converter, damping can be increased, thereby shortening the process time of the receiving-end converter synchronizing the grid frequency and improving stability.

[0107] In one possible implementation, combining Figure 1 and Figure 2 The control method for grid-connected renewable energy power generation provided in the embodiment of the present application can directly couple 15% to 20% of the system rated capacity of energy storage to the high-voltage DC bus of the renewable energy power generation-energy storage delivery system through a preset circuit, thereby forming a high-voltage DC direct-connected energy storage device;

[0108] At the same time, the receiving-end converter adopts self-synchronous voltage source control to map the grid frequency onto the DC voltage; on this basis, the energy storage device extracts the grid frequency information from the DC bus and provides inertia response and primary frequency modulation strategy to the grid; in addition, the sending-end converter extracts the grid frequency information from the DC bus and transmits the grid frequency to the wind farm side of the offshore wind farm, and the wind turbine detects the AC frequency through a phase-locked loop, thereby providing inertia response to the grid.

[0109] Optionally, the receiving-end converter can realize self-synchronization of the power grid without a phase-locked loop by analogizing the capacitor of the submodule to the rotor of a synchronous generator. The DC voltage can automatically map the change of the power grid frequency, and can be divided into coupling type and decoupling type according to whether the number of submodules put into operation on the DC side is constant. The advantage of the coupling type is that the control loop is simple and easy to implement. The advantage of the decoupling type is that the DC voltage has good dynamic control performance.

[0110] Exemplarily, a modular multilevel converter (MMC), also known as an MMC converter, is composed of a plurality of cascaded sub-modules (SM) with the same structure.

[0111] In some implementation scenarios, the new energy power generation grid connection control method provided in the embodiments of the present application has a specific solution example as follows:

[0112] First, calculate the total energy W of the submodules of the receiving-end MMC converter total :

[0113]

[0114] Where N is the total number of bridge arm submodules, C SM is the submodule capacitance value (assuming that all submodule capacitances are equal), C SMK is the submodule voltage, W total Will be affected by the MMC DC side power P dc and AC side power P ac Effects of swapping:

[0115]

[0116] In order to simulate the rotor equation of the synchronous generator, the total energy W total and the receiving MMC output frequency ω rec The following relationship is established:

[0117]

[0118] The horizontal line above the symbol in the text indicates its per unit value. In formula (3), H v is the virtual inertia time constant. Since the inertia provided by the MMC converter submodule capacitor is limited, H v The value should not be too large (for common projects, it is generally 30 to 100ms);

[0119] At this time, the receiving-end converter will have a self-synchronization capability similar to that of a synchronous generator. For example: when the grid frequency decreases, the receiving-end converter power angle becomes larger, the output active power increases, resulting in less total energy of the submodule, and the output AC frequency of the receiving-end converter will decrease accordingly until it is the same as the grid frequency. However, the above characteristics only simulate the motion terms of the synchronous generator rotor motion equation. Due to the lack of damping terms, the process of the receiving-end MMC synchronizing the grid frequency takes a long time and has poor stability. Therefore, it is possible to further use the receiving-end MMC output AC voltage to adjust To increase damping:

[0120]

[0121] In the formula, is the steady-state operating point of the output AC power, D v is the virtual damping coefficient, The introduction of will result in an additional damping term in the output power on the AC side:

[0122]

[0123] In the formula, is the per unit value of the grid voltage at the receiving converter connection point, is the per unit value of the reactance between the receiving converter and the equivalent synchronous machine port of the grid. is the per-unit AC power output of the receiving MMC after the damping term is introduced. Replace with You can get:

[0124]

[0125] Right now:

[0126]

[0127] This is similar to the rotor equation for a synchronous generator, where the AC side power It can be written as:

[0128]

[0129] Through the above control, the receiving-end converter can achieve phase-locked loop-free self-synchronization with the grid, and the energy of its submodule capacitors will spontaneously synchronize with the grid frequency:

[0130]

[0131] Therefore, the grid frequency is mapped to the submodule capacitor energy. Next, according to the different control methods of the DC side of the receiving converter, it can be divided into two types: coupling type and decoupling type:

[0132] 1) Coupling type

[0133] Under the currently commonly used direct modulation method, the total number of sub-modules put into the upper and lower bridge arms of the MMC is a constant N, so the DC voltage will be coupled with the sub-module voltage, that is:

[0134] ΔU dc =NΔUS Mav (10);

[0135] There are also:

[0136]

[0137] U SMav is the average voltage of the submodule capacitor (U SMavN is its rated value), N is the number of submodules in each bridge arm (excluding redundancy), T MMC is the MMC submodule capacitance time constant, which is generally 30-50ms in engineering. Substituting equations (10), (11) and (3) into equation (9), we can get:

[0138]

[0139] As mentioned above, the bandwidth of G(s) is generally greater than the grid frequency ω g The DC voltage will keep pace with the grid frequency, and since the grid frequency generally does not deviate too far from the rated value, the DC voltage can also remain stable, thus taking into account both DC voltage control and grid self-synchronization control. dc , W total and rec Mutual coupling, changes in grid frequency Will be able to be naturally mapped onto DC voltage without the need for additional control.

[0140] 2) Decoupling type

[0141] Under the decoupling strategy, the total number of submodules put into use in each phase upper and lower bridge arms is no longer a constant, but an adjustable quantity N insert .like Figure 3 As shown, Figure 3 A schematic diagram of an equivalent circuit of the DC side of the receiving-end MMC under decoupling control provided in an embodiment of the present application;

[0142] Figure 3 Medium 0.5C line is the capacitance of the π-type DC transmission line equivalent to the DC side of the receiving converter, L eq E is the equivalent inductance of the MMC DC side, which generally includes the bridge arm inductance and the DC current limiting inductance. dc It is the sum of the submodule voltages of the upper and lower bridge arms of each phase of the receiving MMC:

[0143] E dc =N insert U SMav (12);

[0144] based on Figure 3 The equivalent circuit shown in FIG. Figure 4 The DC voltage and DC current dual closed-loop control shown in the figure is achieved by adjusting N insert and E dc , it can realize the DC bus voltage U dc Rapid control of

[0145] like Figure 4 As shown in the figure, by decoupling the DC bus voltage from the receiving-end MMC submodule voltage, the dynamic control performance of the DC bus voltage can be enhanced. Although compared with the coupled control, the DC bus voltage loses the automatic mapping of the grid frequency change, but considering that the grid frequency changes slowly in general, a low-pass filter can be used to filter the DC bus voltage from ω rec (or W total ) to extract the low-frequency part, and then add it to the given DC voltage U dcref Compared with the coupling control, it not only does not reduce the tracking speed of the grid frequency, but also can filter out the influence of wind power change and grid voltage change on the DC voltage;

[0146] It should be noted that both coupling and decoupling control can automatically map the grid frequency to the DC bus voltage. Based on this feature, the energy storage device and the sending-end converter can obtain grid frequency information by detecting the DC voltage. The energy storage device can respond directly to provide inertia support and primary frequency modulation. The sending-end converter can transmit the grid frequency change to each wind turbine by changing the AC frequency of the wind farm, and the wind turbine provides a fast frequency response to the grid. Ultimately, the self-synchronous voltage source control of the renewable energy power generation-energy storage delivery system is realized to provide active frequency support for the grid, such as Figure 5 As shown, Figure 5 A topological diagram of the self-synchronous voltage source control of the renewable energy power generation and energy storage transmission system provided in an embodiment of the present application.

[0147] See also Figure 6 , Figure 6 This is a structural block diagram of a new energy power generation grid-connected control device provided in an embodiment of the present application. The new energy power generation grid-connected control device is applied to a new energy power generation-energy storage delivery system. The control device includes:

[0148] A power grid frequency unit 100, used to obtain power grid frequency information;

[0149] The response unit 200 is used to obtain inertia response data and frequency modulation data in response to the power grid frequency information;

[0150] The control unit 300 is used to control the renewable energy power generation-energy storage delivery system to provide inertia response and frequency modulation strategy to the power grid in response to inertia response data and frequency modulation data, and the renewable energy power generation-energy storage delivery system couples the energy storage of preset capacity to the DC bus through a preset circuit.

[0151] In some embodiments, the control unit 300 is also used to: respond to grid frequency information, control the receiving-end converter of the renewable energy power generation and energy storage transmission system through self-synchronous voltage source type control, and the grid frequency information and the DC bus voltage satisfy a preset relationship.

[0152] In some embodiments, the control unit 300 is also used to: control the sending-end converter of the renewable energy power generation-energy storage delivery system to obtain grid frequency information from the DC bus; transmit the grid frequency information to the wind farm side of the renewable energy power generation-energy storage delivery system, and the wind turbines on the wind farm side detect the AC frequency information based on the grid frequency information and the phase-locked loop, and provide inertia response to the grid through the AC frequency information.

[0153] In some embodiments, the receiving-end converter of the new energy power generation and energy storage transmission system is provided with a module group, which includes multiple sub-modules. The control unit 300 is also used to: simulate the synchronous generator rotor based on the capacitance of multiple sub-modules in the module group by the receiving-end converter, and control the phase-locked loop-free self-synchronization of the receiving-end converter to the power grid.

[0154] In some embodiments, the control unit 300 is also used to: obtain the quantity information of sub-modules in the module group; in response to the quantity information of the sub-modules, match the grid frequency information with the capacitance energy corresponding to the sub-module according to the preset DC side control method of the receiving-end converter.

[0155] In some embodiments, the preset DC side control mode includes a coupling control mode and a decoupling control mode, and the control unit 300 is also used to: if the quantity information of the submodules is a constant, match the grid frequency information to the capacitor energy corresponding to the submodule according to the coupling control mode; if the quantity information of the submodules is not a constant, match the grid frequency information to the capacitor energy corresponding to the submodule according to the decoupling control mode.

[0156] It should be noted that the new energy power generation grid-connected control device provided in the embodiment of the present application is Figures 1 to 5 The method embodiments shown correspond to each other and will not be described again here to avoid repetition.

[0157] This application also provides an electronic device, see Figure 7 , Figure 7 A block diagram of an electronic device provided in an embodiment of the present application. The electronic device may include a processor 510, a communication interface 520, a memory 530, and at least one communication bus 540. The communication bus 540 is used to realize direct connection and communication between these components. The communication interface 520 of the electronic device in the embodiment of the present application is used to communicate signaling or data with other node devices. The processor 510 may be an integrated circuit chip with signal processing capabilities.

[0158] The processor 510 mentioned above can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general-purpose processor can be a microprocessor or the processor 510 can also be any conventional processor, etc.

[0159] The memory 530 may be, but is not limited to, a random access memory (RAM), a read only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electric erasable programmable read-only memory (EEPROM), etc. The memory 530 stores computer-readable instructions. When the computer-readable instructions are executed by the processor 510, the electronic device can execute the above-mentioned Figures 1 to 5 The method embodiment involves various steps.

[0160] Optionally, the electronic device may further include a storage controller and an input / output unit.

[0161] The memory 530, storage controller, processor 510, peripheral interface, input and output unit components are directly or indirectly electrically connected to each other to achieve data transmission or interaction. For example, these components can be electrically connected to each other via one or more communication buses 540. The processor 510 is used to execute executable modules stored in the memory 530, such as software function modules or computer programs included in the electronic device.

[0162] The input and output unit is used to provide users with the task creation and to create a start optional time period or preset execution time for the task to realize the interaction between the user and the server. The input and output unit can be, but is not limited to, a mouse and a keyboard.

[0163] Understandably, Figure 7 The structure shown is for illustration only, and the electronic device may also include Figure 7 More or fewer components as shown, or with Figure 7 Different configurations are shown. Figure 7 Each component shown in the figure can be implemented by hardware, software or a combination thereof.

[0164] An embodiment of the present application further provides a storage medium having instructions stored thereon. When the instructions are run on a computer, the computer program is executed by a processor to implement the method described in the method embodiment. To avoid repetition, the method will not be described here.

[0165] The present application also provides a computer program product, which, when executed on a computer, enables the computer to execute the method described in the method embodiment.

[0166] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0167] In addition, 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 separately, or two or more modules may be integrated to form an independent part.

[0168] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several 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 methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0169] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0170] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0171] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A new energy power generation grid connection control method, characterized in that: Applied to a new energy power generation-energy storage delivery system, the control method includes: Obtain grid frequency information; In response to the power grid frequency information, obtaining inertia response data and frequency modulation data; In response to the inertia response data and the frequency modulation data, the renewable energy power generation-energy storage delivery system is controlled to provide inertia response and frequency modulation strategies to the power grid, and the renewable energy power generation-energy storage delivery system couples the energy storage of a preset capacity to the DC bus through a preset circuit.

2. The new energy power generation grid connection control method according to claim 1, characterized in that: The control method further comprises: In response to the grid frequency information, the receiving-end converter of the renewable energy power generation-energy storage transmission system is controlled by a self-synchronous voltage source type, and the grid frequency information and the DC bus voltage satisfy a preset relationship.

3. The new energy power generation grid connection control method according to claim 1 or 2, characterized in that: The control method further comprises: Controlling the sending-end converter of the new energy power generation-energy storage delivery system to obtain the grid frequency information from the DC bus; The grid frequency information is transmitted to the wind farm side of the new energy power generation and energy storage delivery system. The wind turbines on the wind farm side detect AC frequency information based on the grid frequency information and a phase-locked loop, and provide inertia response to the grid through the AC frequency information.

4. The new energy power generation grid connection control method according to claim 2, characterized in that: The receiving-end converter of the new energy power generation-energy storage delivery system is provided with a module group, and the module group includes a plurality of sub-modules. The control method further includes: Based on the receiving-end converter simulating the synchronous generator rotor of the capacitors of the multiple submodules in the module group, the receiving-end converter is controlled to self-synchronize with the power grid without a phase-locked loop.

5. The new energy power generation grid connection control method according to claim 4, characterized in that: The control method further comprises: Obtaining information on the number of submodules in the module group; In response to the quantity information of the submodules, the grid frequency information is matched to the capacitance energy corresponding to the submodules according to a preset DC side control mode of the receiving-end converter.

6. The new energy power generation grid connection control method according to claim 5, characterized in that: The preset DC side control mode includes a coupling control mode and a decoupling control mode. In response to the quantity information of the submodules, the grid frequency information is matched with the capacitance energy corresponding to the submodule according to the preset DC side control mode of the receiving end converter, including: If the quantity information of the submodule is a constant, matching the grid frequency information with the capacitance energy corresponding to the submodule according to the coupling control method; If the quantity information of the submodules is not a constant, the grid frequency information is matched to the capacitor energy corresponding to the submodules according to a decoupling control method.

7. The new energy power generation grid connection control method according to claim 2, characterized in that: The control method further comprises: In response to the DC current and DC voltage on the DC side of the receiving-end converter, the DC bus voltage is controlled according to a preset double closed-loop control strategy.

8. The new energy power generation grid connection control method according to claim 1, characterized in that: The preset capacity has a value range of 15% to 20%.

9. The new energy power generation grid connection control method according to claim 1, characterized in that: The control method further comprises: In response to the grid frequency information, the output AC voltage of the receiving-end converter of the renewable energy power generation and energy storage transmission system is controlled.

10. The new energy power generation grid connection control method according to claim 1, characterized in that: The preset circuit includes a plurality of submodules connected in series; wherein the submodule includes a commutation unit connected in parallel with an energy storage unit.

11. A new energy power generation grid-connected control device, characterized in that: Applied to a new energy power generation-energy storage and delivery system, the control device includes: A power grid frequency unit, used for obtaining power grid frequency information; A response unit, configured to obtain inertia response data and frequency modulation data in response to the power grid frequency information; A control unit is used to control the new energy power generation-energy storage delivery system to provide inertia response and frequency modulation strategy to the power grid in response to the inertia response data and the frequency modulation data, and the new energy power generation-energy storage delivery system couples the energy storage of a preset capacity to the DC bus through a preset circuit.

12. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the new energy power generation grid-connected control method as described in any one of claims 1 to 10 are implemented.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the computer executes the new energy power generation grid-connected control method according to any one of claims 1 to 10.

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