Control device, computer readable storage medium, photovoltaic power generation system, inverter system and power reservation method thereof

Abstract

The invention discloses a control device, a computer readable storage medium, a photovoltaic power generation system, an inverter system and a power reservation method thereof, and relates to the technical field of inverter control. In the inverter system, at least one inverter is used as main inverter equipment and works in a maximum power point tracking mode; meanwhile, at least one inverter is used as slave inversion equipment and works in a constant power mode; in other words, the inverter is used as a unit, and the whole device works in the maximum power point tracking mode or the constant power mode; therefore, the power reservation in the VSG function can be realized by the residual power of the slave inversion equipment in the constant power mode, and the problem of high system cost caused by using an energy storage battery to realize the power reservation can be avoided. A preset relation exists between the electrical parameter reference value in the constant power mode and the electrical parameter and the power reservation parameter of the main inversion equipment, and control complexity and electric energy quality fluctuation caused by mode switching can be avoided.

Description

Technical Field

[0001] This application relates to the field of inverter control technology, and in particular to a control device, a computer-readable storage medium, a photovoltaic power generation system, an inverter system, and a power reservation method thereof. Background Technology

[0002] Traditional grid-connected inverters typically employ droop control for grid-connected operation. However, due to their lack of rotational inertia and damping, they are prone to frequency and voltage fluctuations and struggle to meet the requirements of primary frequency and voltage regulation for grid connection. Therefore, VSG (Virtual Synchronous Generator) technology emerged based on droop control. VSG technology specifically controls the inverter by simulating the rotor motion equation and excitation current equation of a synchronous machine, giving the inverter inertia, primary frequency regulation, and primary voltage regulation characteristics to improve the grid-connected stability of the inverter.

[0003] To improve the stability of photovoltaic grid connection, current photovoltaic power generation systems have gradually adopted VSG technology; however, if energy storage batteries are used to reserve power to realize VSG function, the system cost will be too high. Summary of the Invention

[0004] In view of the above problems, this application provides a control device, a computer-readable storage medium, a photovoltaic power generation system, an inverter system, and a power reservation method thereof to reduce the system cost of implementing VSG functionality. The specific solution is as follows:

[0005] The first aspect of this application provides an inverter system, comprising: at least two inverters; wherein...

[0006] The DC side of the inverter is used to connect to the photovoltaic string; the AC side of the inverter is used to connect to the power grid.

[0007] There is at least one of the inverters, which serves as the main inverter and operates in maximum power point tracking mode;

[0008] There is at least one of the inverters, as a slave inverter device, operating in constant power mode.

[0009] In one possible implementation, there is a preset relationship between the electrical parameter reference values ​​in the constant power mode and the electrical parameters and power reserve parameters of the main inverter.

[0010] In one possible implementation, the electrical parameter reference value is a power reference value, the electrical parameter is power, and the power reserve parameter is the power that the inverter system needs to reserve.

[0011] The preset relationship is as follows: the power reference value is the product of the total reference power of all the slave inverter devices and the second coefficient; the total reference power is the difference between the sum of the power of all the master inverter devices and the power reserved parameter under the first coefficient.

[0012] In one possible implementation, the first coefficient is the ratio of the sum of the rated power of all the main inverters to the sum of the rated power of all the slave inverters; the second coefficient is the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all the main inverters.

[0013] Alternatively, when the rated power of each photovoltaic string connected to each inverter is the same, the first coefficient is: the ratio of the sum of the number of photovoltaic strings connected to all the main inverters to the sum of the number of photovoltaic strings connected to all the slave inverters; the second coefficient is: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all the main inverters.

[0014] In one possible implementation, the electrical parameter reference value is a power reference value, the electrical parameter is power, and the power reserve parameter is the power that the inverter system needs to reserve.

[0015] The preset relationship is as follows: the power reference value is the difference between the reference power and the reserved power allocation value; the reference power is the product of the sum of the power of all the main inverter devices and the second coefficient; the reserved power allocation value is the product of the power reserved parameter and the third coefficient.

[0016] In one possible implementation, the second coefficient is: the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all the master inverters; the third coefficient is: the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all the slave inverters;

[0017] Alternatively, when the rated power of each photovoltaic string connected to each inverter is the same, the second coefficient is: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all the main inverters; the third coefficient is: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all the slave inverters.

[0018] In one possible implementation, any of the inverters can be: a centralized inverter, a string inverter, or a distributed inverter;

[0019] The DC side of the centralized inverter is directly or via at least one combiner box connected to the photovoltaic string.

[0020] The DC side of the string inverter has at least one interface connected to the photovoltaic string;

[0021] The DC side of the distributed inverter is connected to the photovoltaic string via at least one DC / DC converter.

[0022] In one possible implementation, the controllers of each inverter are communicatively connected;

[0023] For the main inverter, the controller is used to determine and output the control signal for the conversion circuit in the main inverter when the main inverter is operated in maximum power point tracking mode;

[0024] For the slave inverter, the controller is used to determine and output the control signal for the conversion circuit in the slave inverter when the slave inverter is operated in constant power mode.

[0025] In one possible implementation, when the inverter is a centralized inverter, its controller includes: a power controller and a DC / AC controller;

[0026] For the main inverter device, the power controller is used to determine the maximum power point current and maximum power point voltage on the DC side of the main inverter device when the main inverter device is operated at the maximum power point, and the DC / AC controller is used to determine and output the control signal for the DC / AC conversion circuit in the main inverter device when the main inverter device is operated at the maximum power point.

[0027] For the slave inverter device, the power controller is used to determine the electrical parameter reference value in the constant power mode or to receive the electrical parameter reference value issued by the master controller that is communicatively connected to each of the controllers. The DC / AC controller is used to determine and output the control signal for the DC / AC conversion circuit when the slave inverter device operates in constant power mode according to the electrical parameter reference value.

[0028] In one possible implementation, when the inverter is a string inverter, it includes a DC / AC conversion circuit and at least one DC / DC conversion circuit connected to its DC side; the controller of the string inverter includes at least one power controller, at least one DC / DC controller, and a DC / AC controller.

[0029] For the main inverter: the power controller is used to determine the maximum power point current and maximum power point voltage on the input side of the corresponding DC / DC converter circuit when it operates at its maximum power point; the DC / DC controller is used to determine and output a control signal for stabilizing the output voltage of the corresponding DC / DC converter circuit at the bus voltage reference value based on its maximum power point voltage; the DC / AC controller is used to determine and output a control signal for the DC / AC converter circuit when the main inverter operates at its maximum power point under the bus voltage reference value.

[0030] For the slave inverter: the power controller is used to determine the electrical parameter reference value in the constant power mode or to receive the electrical parameter reference value issued by the main controller that is communicatively connected to each of the controllers; the DC / DC controller is used to determine and output the control signal for the corresponding DC / DC conversion circuit when the output side voltage of the corresponding DC / DC conversion circuit is stabilized at the bus voltage reference value; the DC / AC controller is used to determine and output the control signal for the DC / AC conversion circuit when the slave inverter operates in constant power mode according to the electrical parameter reference value.

[0031] In one possible implementation, when the inverter is a distributed inverter, at least one DC / DC converter is connected to its DC side, and its controller is communicatively connected to the branch controller corresponding to the DC / DC converter; the branch controller includes a power controller and a DC / DC controller, and the controller includes a DC / AC controller;

[0032] For the main inverter equipment: the power controller is used to determine the maximum power point current and maximum power point voltage on the input side of the corresponding DC / DC converter when it operates at its maximum power point; the DC / DC controller is used to determine and output a control signal for stabilizing the output voltage of the corresponding DC / DC converter at the bus voltage reference value based on its maximum power point voltage; the DC / AC controller is used to determine and output a control signal for the DC / AC conversion circuit in the main inverter equipment when it operates at its maximum power point under the bus voltage reference value.

[0033] For the slave inverter: the power controller is used to determine the electrical parameter reference value in the constant power mode or to receive the electrical parameter reference value issued by the main controller that is communicatively connected to each of the controllers; the DC / DC controller is used to determine and output the control signal for the corresponding DC / DC converter when the output side voltage of the corresponding DC / DC converter is stabilized at the bus voltage reference value; the DC / AC controller is used to determine and output the control signal for the DC / AC conversion circuit when the slave inverter operates in constant power mode according to the electrical parameter reference value.

[0034] A second aspect of this application provides a photovoltaic power generation system, comprising: at least two photovoltaic strings, and an inverter system as described in the first aspect or any implementation thereof; wherein...

[0035] Each inverter in the inverter system is connected to at least one photovoltaic string on its DC side.

[0036] In one possible implementation, each of the inverters and the photovoltaic strings connected to them belong to the same power station;

[0037] Alternatively, the main inverter and its connected photovoltaic strings in the inverter system, as well as the slave inverter and its connected photovoltaic strings in the inverter system, belong to different power plants.

[0038] A third aspect of this application provides a power reservation method for an inverter system, wherein the inverter system includes at least two inverters, the DC side of the inverters is used to connect to a photovoltaic string, and the AC side of the inverters is used to connect to the power grid; the power reservation method includes:

[0039] Control at least one of the inverters as the main inverter device, operating in maximum power point tracking mode;

[0040] Based on the electrical parameters and power reserve parameters of the main inverter equipment, the reference values ​​of electrical parameters in constant power mode are determined.

[0041] Based on the electrical parameter reference values, at least one of the inverters is controlled to operate as a slave inverter in constant power mode.

[0042] In one possible implementation, the electrical parameter reference value is a power reference value, the electrical parameter is power, and the power reserve parameter is the power that the inverter system needs to reserve.

[0043] In the power reservation method, the reference values ​​of electrical parameters in constant power mode are determined based on the electrical parameters and power reservation parameters of the main inverter equipment, including:

[0044] The sum of the power of all the main inverter devices is calculated, as well as the product of the first coefficient and the power reserved parameter;

[0045] The difference between the sum of the power and the product is calculated and used as the total reference power of all the inverter devices.

[0046] The total reference power is converted according to the second coefficient to obtain the reference value of the electrical parameters;

[0047] Alternatively, based on the electrical parameters and power reserve parameters of the main inverter equipment, reference values ​​for electrical parameters in constant power mode can be determined, including:

[0048] The sum of the power of all the main inverter devices is calculated and multiplied by the second coefficient, which is used as the reference power;

[0049] The product of the power reservation parameter and the third coefficient is calculated and used as the reserved power allocation value;

[0050] The difference between the reference power and the reserved power allocation value is calculated and used as the reference value for the electrical parameters.

[0051] In one possible implementation, the first coefficient is the ratio of the sum of the rated power of all the main inverters to the sum of the rated power of all the slave inverters; the second coefficient is the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all the main inverters; and the third coefficient is the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all the slave inverters.

[0052] Alternatively, when the rated power of each photovoltaic string connected to the inverters is the same, the first coefficient is: the ratio of the sum of the number of photovoltaic strings connected to all the main inverters to the sum of the number of photovoltaic strings connected to all the slave inverters; the second coefficient is: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all the main inverters; and the third coefficient is: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all the slave inverters.

[0053] In one possible implementation, controlling at least one of the inverters as a primary inverter operating in maximum power point tracking mode includes:

[0054] The control signal for the conversion circuit in the main inverter is determined and output when the main inverter is operated in maximum power point tracking mode.

[0055] In one possible implementation, determining and outputting control signals for the conversion circuitry in the main inverter when it operates in maximum power point tracking mode includes:

[0056] If the main inverter is a centralized inverter, then: determine the maximum power point current and maximum power point voltage on the DC side of the main inverter when it operates at the maximum power point; and determine and output the control signal for its DC / AC conversion circuit when it operates at the maximum power point.

[0057] If the main inverter is a string inverter, then: for each of its DC / DC conversion circuits, determine the maximum power point current and maximum power point voltage corresponding to its input side when it operates at the maximum power point; for each of its DC / DC conversion circuits, determine and output a control signal to stabilize its output voltage at the bus voltage reference value based on its maximum power point voltage; and determine and output a control signal for its DC / AC conversion circuit when the main inverter operates at the maximum power point based on the bus voltage reference value.

[0058] If the main inverter is a distributed inverter and at least one DC / DC converter is connected to the DC side, then: for each DC / DC converter, determine the maximum power point current and maximum power point voltage corresponding to its input side when it operates at the maximum power point; for each DC / DC converter, determine and output a control signal to stabilize its output voltage at the bus voltage reference value based on its maximum power point voltage; and determine and output a control signal for its DC / AC conversion circuit when the main inverter operates at the maximum power point based on the bus voltage reference value.

[0059] In one possible implementation, controlling at least one of the inverters as a slave inverter, operating in constant power mode, based on the electrical parameter reference value, includes:

[0060] Determine and output the control signal for the conversion circuit in the slave inverter when the slave inverter operates in constant power mode.

[0061] In one possible implementation, determining and outputting control signals for the conversion circuitry in the slave inverter when it operates in constant power mode includes:

[0062] If the slave inverter is a centralized inverter, then: determine or receive the electrical parameter reference value; and determine and output the control signal for the DC / AC conversion circuit of the slave inverter to operate in constant power mode according to the electrical parameter reference value.

[0063] If the slave inverter is a string inverter, then: determine or receive each of the electrical parameter reference values; determine and output control signals for the corresponding DC / DC conversion circuits when the output voltage of each DC / DC conversion circuit in the slave inverter is stabilized at the bus voltage reference value; and determine and output control signals for the DC / AC conversion circuits of the slave inverter when it operates in constant power mode according to the electrical parameter reference values.

[0064] If the slave inverter is a distributed inverter and has at least one DC / DC converter connected to its DC side, then: determine or receive the reference values ​​of each of the electrical parameters; determine and output control signals to the corresponding DC / DC converters when the output voltage of each DC / DC converter in the slave inverter is stabilized at the reference value of the bus voltage; and determine and output control signals to the DC / AC conversion circuit of the slave inverter when it operates in constant power mode according to the reference values ​​of the electrical parameters.

[0065] The fourth aspect of this application provides a control device including a processor and a memory, the memory being used to store programs, instructions or code, and the processor being used to execute the programs, instructions or code in the memory to perform the power reservation method for an inverter system as described in the third aspect or any implementation thereof.

[0066] The fifth aspect of this application provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute the power reservation method for an inverter system as described in the third aspect or any implementation thereof.

[0067] Using the above technical solution, the inverter system provided in this application includes at least one inverter as the main inverter device, operating in maximum power point tracking mode; and at least one inverter as the slave inverter device, operating in constant power mode. That is, the inverter as a unit operates in either maximum power point tracking mode or constant power mode. Therefore, the power reservation in the VSG function can be achieved by the slave inverter device using the remaining power in constant power mode, which avoids the problem of high system cost caused by using energy storage batteries to achieve power reservation. Attached Figure Description

[0068] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0069] Figure 1 This is a schematic diagram of a photovoltaic power generation system provided in an embodiment of this application;

[0070] Figure 2 This is another structural schematic diagram of the photovoltaic power generation system provided in the embodiments of this application;

[0071] Figure 3 This is another structural schematic diagram of the photovoltaic power generation system provided in the embodiments of this application;

[0072] Figure 4 A schematic diagram of the controller of a photovoltaic power generation system in which a centralized inverter is used as the main inverter device, as provided in the embodiments of this application;

[0073] Figure 5 A schematic diagram of the controller of a photovoltaic power generation system in which a centralized inverter is used as a slave inverter device, provided in an embodiment of this application;

[0074] Figure 6 A schematic diagram of the controller of a string inverter in a photovoltaic power generation system provided in this application embodiment when the string inverter is used as the main inverter device;

[0075] Figure 7 A schematic diagram of the controller of a string inverter in a photovoltaic power generation system provided in this application embodiment when it is used as a slave inverter device;

[0076] Figure 8 A flowchart illustrating a power reservation method for a photovoltaic power generation system provided in this application embodiment;

[0077] Figure 9 This is a schematic diagram of the control device provided in an embodiment of this application. Detailed Implementation

[0078] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0079] The embodiments of this application are described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Those skilled in the art will understand that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0080] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0081] In the field of photovoltaic power generation, additional energy is required to support the grid through VSG technology. Currently, most photovoltaic arrays adopt MPPT (Maximum Power Point Tracking) control, and their output power is volatile and uncertain. Therefore, energy storage batteries are required to reserve power, resulting in high system costs.

[0082] With the improvement of photovoltaic power generation efficiency, the power supply and demand relationship of high-penetration power grids no longer requires photovoltaic power generation systems to be in MPPT state at all times. Therefore, realizing VSG function through power reservation within the photovoltaic power generation system itself has good application prospects. This application provides an inverter system to reduce the system cost of implementing VSG function. The specific solution is as follows:

[0083] See Figure 1 The inverter system includes: at least two inverters 10; wherein:

[0084] The DC side of each inverter 10 is used to connect photovoltaic strings. In practical applications, the DC side of the inverter 10 can connect to multiple photovoltaic strings, and the number of photovoltaic strings in each string is unlimited. Specifically, it can be a single photovoltaic string or multiple photovoltaic strings connected in parallel. In addition, the number of photovoltaic strings connected to each inverter 10 is not limited, and the number of photovoltaic strings connected to each inverter 10 can be the same or different, depending on the specific application environment. All of these are within the protection scope of this application.

[0085] The AC side of inverter 10 is used to connect to the power grid. In practical applications, the AC side of each inverter 10 can be connected to the power grid through a corresponding transformer. Each inverter 10 can be connected to the power grid through different transformers, or at least two inverters 10 can be connected to the power grid through the same transformer, or all inverters 10 can be connected to the power grid through the same transformer. No limitation is made here.

[0086] For each inverter 10 in the inverter system: there is at least one inverter 10 that acts as the master inverter and operates in maximum power point tracking mode, i.e., MPPT mode; at the same time, there is also at least one inverter 10 that acts as the slave inverter and operates in constant power mode.

[0087] The specific working principle is as follows:

[0088] Under normal circumstances, such as when there is no power reserve or external power command, each inverter 10 connected to the grid will operate in MPPT mode, that is, it will operate at the MPP (Maximum Power Point) of the photovoltaic string it is connected to.

[0089] When power reservation is required, this embodiment sets at least one inverter 10 in the system as the main inverter device operating in MPPT mode to maintain its normal output power; simultaneously, at least one inverter 10 in the system is set as a slave inverter device operating in constant power mode. For the slave inverter device operating in constant power mode, it can only output a constant power, which is necessarily less than the MPP of the photovoltaic string it is connected to, thus generating a certain amount of surplus power; the sum of the surplus power of all slave inverter devices can be used as the power reserved for realizing the VSG function.

[0090] The inverter system provided in this embodiment operates in MPPT mode or constant power mode, with inverter 10 as the unit. Therefore, the power reservation in the VSG function can be realized by the remaining power of the inverter device in constant power mode. That is, this embodiment can realize the VSG function with the photovoltaic energy of the photovoltaic string connected to the inverter system, which can also be called PV-VSG (Photovoltaic-Virtual Synchronous Generator) function, thereby avoiding the problem of high system cost caused by using energy storage batteries to realize power reservation.

[0091] In practical applications, any inverter 10 can be a centralized inverter, a string inverter, or a distributed inverter. Figure 2 The document demonstrates three inverter structures. The DC side of the centralized inverter can be directly connected to a photovoltaic string (not shown), or it can be connected to the photovoltaic string through at least one combiner box 12 (e.g., ...). Figure 2 (as shown in the diagram); the DC side of the string inverter has at least one interface for connecting to the photovoltaic string; the DC side of the distributed inverter is connected to the photovoltaic string through at least one DC / DC converter 11.

[0092] See Figure 2When the inverter 10 is a centralized inverter or a distributed inverter, it specifically includes: a DC / AC conversion circuit 101; the AC side of the DC / AC conversion circuit 101 is used to connect to the AC side of the inverter 10; the DC side of the DC / AC conversion circuit 101 is used to connect to the DC side of the inverter 10. When the inverter 10 is a string inverter, in addition to the aforementioned DC / AC conversion circuit 101, it also includes: at least one DC / DC conversion circuit 102; the input side of the DC / DC conversion circuit 102 is used to connect to the corresponding DC side interface of the inverter 10; the output side of the DC / DC conversion circuit 102 is used to connect to the DC side of the DC / AC conversion circuit 101.

[0093] That is, the DC side of the DC / AC conversion circuit 101 in each inverter 10 can be directly connected to at least one photovoltaic string, or it can be connected to the corresponding photovoltaic strings through other devices, for example:

[0094] The DC side of the DC / AC conversion circuit 101 in the string inverter is connected to the corresponding photovoltaic string through the aforementioned DC / DC conversion circuit 102.

[0095] Alternatively, the inverter system may also include at least one combiner box 12 connected to at least one inverter 10; such as Figure 2 The centralized inverter shown has its input side connected to the combiner box 12 for connecting to the corresponding photovoltaic string; the output side of these combiner boxes 12 is used to connect to the DC side of the corresponding inverter 10.

[0096] Alternatively, the inverter system may also include at least one DC / DC converter 11 connected to at least one inverter 10; such as Figure 2 The distributed inverter shown has its input side connected to the DC / DC converter 11 for connecting to the corresponding photovoltaic string; the output side of these DC / DC converters 11 is connected to the DC side of the corresponding inverter 10. In practical applications, the DC / DC converter 11 can be a standalone device or integrated into the smart combiner box 12, depending on the specific application environment, and both are within the scope of protection of this application.

[0097] Specifically, when there is a large open space and the power is relatively large, a centralized inverter or a distributed inverter can be used; while when there is a small open space and the power is moderate, a string inverter can be used to make full use of solar resources.

[0098] Figure 3Taking an inverter system containing N centralized inverters and M string inverters as an example, where N and M are both positive integers, this architecture allows for the configuration of n string inverters (string inverters #1 to #n as shown in the figure) and m centralized inverters (centralized inverters #1 to #m as shown in the figure) as primary inverters, and the remaining Nn string inverters (string inverters #n+1 to #N) and Mm centralized inverters as secondary inverters (centralized inverters #m+1 to #M). Here, n is a natural number less than or equal to N, m is a natural number less than or equal to M, and n+m is a positive integer greater than or equal to 1 and less than N+M.

[0099] In practical applications, the inverter system may include only one of the inverters 10 with the above-mentioned structure, or may include any two of the inverters 10 with the above-mentioned structure, or may include three different inverters 10 with the above-mentioned structure, depending on the specific application environment; moreover, the optional structure of each inverter 10 is not limited to the above three, and other structures in the prior art can also be adopted, all of which are within the protection scope of this application.

[0100] Furthermore, each inverter 10 in this inverter system may belong to the same power station or different power stations; as long as these inverters 10 can complete the active power reserve required by the entire system, they are all within the protection scope of this application.

[0101] Based on the above embodiments, this embodiment provides illustrative examples of specific methods for completing the active power reserve required for the entire system, such as:

[0102] To ensure the slave inverters operate in constant power mode and achieve active power reserve control, the MPP of the photovoltaic strings connected to the slave inverters is first obtained through MPPT control. Then, based on the required reserved power and the number of slave inverters, the remaining power that each slave inverter needs to reserve is determined, thus determining its current constant output power. Furthermore, since external environmental factors such as sunlight and temperature are constantly changing, the slave inverters also need to periodically switch back to MPPT mode, change the power tracking point, and adjust their constant output power according to the current MPP changes. This ensures that the sum of the remaining power of all slave inverters equals the reserved power required for the system to achieve VSG functionality.

[0103] Alternatively, unlike the approach where the inverter periodically controls itself to switch back to MPPT mode, this embodiment also provides another approach: setting a preset relationship between the reference values ​​of the electrical parameters of the slave inverter in this constant power mode and the electrical parameters and power reserve parameters of the master inverter. That is, the reference values ​​of the electrical parameters can be calculated based on the electrical parameters and power reserve parameters of the master inverter.

[0104] Since the main inverter operates in MPPT mode, its electrical parameters are those in MPP mode. The reference values ​​of the electrical parameters of the slave inverter in constant power mode are obtained based on the electrical parameters of the main inverter in MPP mode. In other words, the slave inverter can roughly understand the PV (Power voltage) curve of the photovoltaic string under the current external environment by operating the main inverter in MPPT mode. This allows it to determine the constant power that the slave inverter can output after reserving a certain amount of surplus power for active power reserve, and to operate at that constant power for a period of time.

[0105] exist Figure 3 In the inverter system shown, the string inverters #1 to #n and the centralized inverters #1 to #m, which serve as the main inverter devices, all employ MPPT control, allowing them to determine the electrical parameters that enable them to operate in MPP mode. Furthermore, the reference values ​​for the electrical parameters of the slave inverters can be determined based on these electrical parameters and the power reserve parameters. Meanwhile, the string inverters #n+1 to #N and the centralized inverters #m+1 to #M, which serve as slave inverters, can output power based on these reference values, i.e., operate in constant power mode, thus providing power reserve for PV-VSG.

[0106] For example, the electrical parameter reference value can refer to the power reference value, the electrical parameter of the main inverter can refer to the power, and the power reserve parameter is the power that the inverter system needs to reserve. A preset relationship is established between the power reference value of the slave inverter and the power of the main inverter and the power that the inverter system needs to reserve. That is, the power reference value of the slave inverter is no longer directly calculated by reserving surplus power for active power reserve based on the MPP of its connected photovoltaic strings, resulting in a constant power output. Instead, it is calculated by reserving surplus power based on the MPP of the main inverter to obtain its constant output power.

[0107] Therefore, under this scheme, the slave inverter does not need to periodically switch back to MPPT mode to obtain the MPP electrical parameters under the current external environment, thus reducing its control complexity. Meanwhile, the scheme where the slave inverter periodically switches back to MPPT mode not only easily causes fluctuations in its DC bus voltage, affecting the quality of its output waveform, but also causes its output power to switch between MPP and constant power with a large fluctuation range of residual power. Therefore, this scheme can also improve the output waveform quality of the slave inverter and avoid frequent large fluctuations in its output power, reducing the possibility of power quality fluctuations. Moreover, under this scheme, even if the electrical parameters of the main inverter in MPP mode change according to the external environment, the impact on the reference values ​​of the slave inverter's electrical parameters in constant power mode is small and gradual, only a minor influence from changes in the external environment. Therefore, compared to the large fluctuations in output power caused by the slave inverter periodically switching back to MPPT mode, this is negligible, and the operation of the slave inverter in constant power mode is more stable in this scheme.

[0108] In other words, this solution does not require the inverter to frequently switch back to MPPT mode to determine the MPP electrical parameters under the current external environment. Instead, it can use the electrical parameters of the main inverter in MPP mode as a reference. Therefore, this solution can avoid the control complexity and power quality fluctuations caused by mode switching. Moreover, even if there are many inverters 10 as slave inverters, since they do not need to switch modes, large power fluctuations can be avoided, thereby improving the stability of the system.

[0109] Based on the above embodiments, this embodiment provides some specific examples of the process for determining electrical parameter reference values, such as:

[0110] Assuming the reference value of the electrical parameters of the slave inverter is the power reference value, and the electrical parameter of the master inverter is the power, and the power reserve parameter is the power that the inverter system needs to reserve; then the preset relationship can specifically be: the power reference value is the product of the total reference power of all slave inverters and the second coefficient; wherein, the total reference power is the difference between the sum of the power of all master inverters and the power reserve parameter under the first coefficient; that is, the power reference value can specifically be calculated according to the second coefficient based on the difference between the sum of the power of all master inverters and the power reserve parameter under the first coefficient.

[0111] The two coefficients mentioned above are for parameter conversion between master and slave inverter devices. In practical applications, the conversion can be based on their respective rated power or other data, such as the number of photovoltaic strings connected to each device. No specific limit is imposed here.

[0112] In one example, the first coefficient may be the ratio of the sum of the rated power of all primary inverters to the sum of the rated power of all secondary inverters; the second coefficient may be the ratio of the rated power of the corresponding secondary inverter to the sum of the rated power of all primary inverters.

[0113] by Figure 3 Taking the example shown, the two types of inverters 10 can perform power coordination together. Specifically, for string inverters #1 to #n, taking the x-th string inverter, i.e., string inverter #x, as an example, its MPP voltage is denoted as U. pv_dx Its MPP current is denoted as I. pv_dx Its MPP power is denoted as P. pv_dx Its rated power is denoted as P. N_dx Where x = 1, 2, ..., n; for centralized inverters #1 to #m, taking the i-th centralized inverter, i.e., centralized inverter #i, as an example, its MPP current is denoted as I. pv_ci Its MPP power is denoted as P. pv_ci Its rated power is denoted as P. N_ci Where i = 1, 2, ..., m; for string inverters #n+1 to #N, taking the y-th string inverter, i.e., string inverter #y, as an example, its power reference value is denoted as P. pv_dy_ref Its rated power is denoted as P. N_dy Where y = n+1, n+2, ..., N; for centralized inverters #m+1 to #M, taking the j-th centralized inverter, i.e., centralized inverter #j, as an example, its power reference value is denoted as P. pv_cj_ref Its rated power is denoted as P. N_cj , where j = m+1, m+2, ..., M; the power reserve parameter is denoted as ΔP.

[0114] The formula for calculating the power reference value of each inverter device is as follows:

[0115]

[0116] Among them, P ref The total reference power for all slave inverters is the sum of the power of all master inverters. The difference is obtained by subtracting the reserved power after the power reserved parameter ΔP is converted by the first coefficient K1.

[0117] The first coefficient K1 exists to convert the power that the inverter system needs to reserve, that is, the power that all the inverter equipment needs to reserve, into the power required if all the main inverter equipment were to reserve the power. The calculation formula is as follows:

[0118]

[0119] Additionally, K2 y K2 is the second coefficient corresponding to the y-th string inverter from string inverter #n+1 to string inverter #N. j Let be the second coefficient corresponding to the i-th centralized inverter from centralized inverter #m+1 to centralized inverter #M. The formulas for calculating both are:

[0120]

[0121] The second coefficient K2 corresponding to any slave inverter is taken as the ratio of the rated power of the slave inverter to the sum of the rated power of the master inverters. In an ideal state, its value is approximately equal to the ratio of the maximum output power of the slave inverter to the sum of the maximum output power of all master inverters. The maximum output power of any inverter 10 is also its MPP power. For each slave inverter that is used for active power reserve, if their rated power is the same, they will have the same proportion of power output; for example, each slave inverter outputs 90% of its maximum output power, with the remaining 10% reserved for reserve. This makes the power allocation among the slave inverters more reasonable.

[0122] In practical applications, the output power of a slave inverter should be equal to its MPP power minus the active power reserve allocated to it. Therefore, when calculating the power reference value of a slave inverter using the MPP electrical parameters of the master inverter as a reference, the calculation is not limited to the above formula. For example, assuming the reference value of the slave inverter's electrical parameters is the power reference value, the master inverter's electrical parameters are the power, and the power reserve parameter is the power that the inverter system needs to reserve, the preset relationship can also be: the power reference value is the difference between the reference power and the reserved power allocation value; where the reference power is the product of the sum of the power of all master inverters and the second coefficient; and the reserved power allocation value is the product of the power reserve parameter and the third coefficient.

[0123] The second coefficient is the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all master inverters; the third coefficient is the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all slave inverters.

[0124] Similarly Figure 3 The example shown illustrates this point. In practical applications, the sum of the power of all main inverter devices can also be used as an example. According to the second coefficient K2 mentioned above y Or K2 jThe corresponding reference power of the slave inverter is obtained by conversion; then, the power reservation parameter ΔP is allocated according to the third coefficient, that is, the rated power ratio of each slave inverter, to obtain the reserved power allocation value of each slave inverter; then, for each slave inverter, its power reference value is obtained by subtracting its reserved power allocation value from its reference power.

[0125] In practical applications, the calculation of the above coefficients can also be performed by using the number of photovoltaic strings connected to each master and slave inverter device instead of their rated power. That is, when the rated power of each individual photovoltaic string connected to each inverter 10 is the same, i.e., when the rated power of each photovoltaic string is the same, the first coefficient can be: the ratio of the sum of the number of photovoltaic strings connected to all master inverter devices to the sum of the number of photovoltaic strings connected to all slave inverter devices; the second coefficient can be: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter device to the sum of the number of photovoltaic strings connected to all master inverter devices; and the third coefficient is: the ratio of the number of photovoltaic strings connected to the corresponding slave inverter device to the sum of the number of photovoltaic strings connected to all slave inverter devices. Their respective calculation formulas are similar to those described above and will not be elaborated upon here.

[0126] In order to avoid switching the working mode of the slave inverter, this embodiment adopts any of the above calculation methods, refers to the MPP electrical parameters of the master inverter, and combines the power reserve parameters and various conversion coefficients to calculate the power reference value of each slave inverter, and then gives the reference power of each slave inverter in the active power reserve state for its control.

[0127] In practical applications, the above two calculation methods are not the only ones that can be used. As long as the electrical parameters of the main inverter can be used as a reference to calculate the reference values ​​of the electrical parameters of the slave inverter, they are all within the scope of protection of this application.

[0128] Based on the above embodiments, this embodiment provides some specific examples of the control structure of the inverter system. For example, see [link to relevant documentation]. Figure 2 and Figure 3 In order to achieve the operation control of each inverter 10, each inverter 10 needs to be equipped with a corresponding controller 100, and the controller 100 of each inverter 10 can be set inside the corresponding inverter 10 (e.g., Figure 2 or Figure 3 As shown in the figure, it can also be set independently outside the corresponding inverter 10 (not shown), both of which are within the protection scope of this application.

[0129] Furthermore, the communication connection of the controllers 100 of each inverter 10 can be wireless or bus connection, etc., which is not limited here; in addition, each controller 100 can communicate directly, or they can all communicate indirectly with each other by communicating with another master controller, or each controller 100 and the master controller can communicate directly, depending on the specific application environment, all of which are within the protection scope of this application.

[0130] For the primary inverter, its controller 100 determines and outputs control signals for the conversion circuits within the primary inverter when it operates in MPPT mode; for the secondary inverter, its controller 100 determines and outputs control signals for the conversion circuits within the secondary inverter when it operates in constant power mode. As described in the above embodiments, the specific conversion circuits that need to be controlled within the inverter 10 may differ depending on its structure. For example:

[0131] In one example, when the inverter 10 is a centralized inverter, that is, when it includes a DC / AC conversion circuit 101, its controller 100 is as follows: Figure 4 or Figure 5 As shown, it includes: a power controller 111 and a DC / AC controller 112.

[0132] In this configuration, for the main inverter equipment, see [link / reference]. Figure 4 The power controller 111 is used to determine the MPP current and MPP voltage on the DC side of the main inverter when it operates in MPP mode; the DC / AC controller 112 is used to determine and output the control signal from the controller 100 to the DC / AC conversion circuit 101 when the main inverter operates in MPP mode. Figure 3 Taking centralized inverter #i from #1 to #m as an example, its power controller 111 in controller #ci is as follows: Figure 4 The MPPT#ci shown herein, wherein the DC / AC controller 112 in the controller#ci is as follows Figure 4The DC / AC control #ci is shown in the figure. Specifically, the MPPT #ci can be used to position the centralized inverter #i at its MPP position through methods such as perturbation observation or incremental conductance, and the corresponding MPP current Ipv_ci and MPP voltage Udc_ref_ci on the DC side of the centralized inverter #i, as well as the MPP power Ppv_ci of the centralized inverter #i, can be obtained. The DC / AC control #ci is used to determine and output the control signal for the DC / AC conversion circuit 101 in the main inverter when the main inverter operates in MPP mode. This control signal controls the operation of the DC / AC conversion circuit 101 of the centralized inverter #i. Specifically, the DC / AC control #ci targets the MPP voltage Udc_ref_ci and adjusts the deviation between it and the corresponding DC-side voltage sampling value Udc_real_ci of the DC / AC conversion circuit 101 to obtain the AC-side current reference value of the DC / AC conversion circuit 101. Then, based on the AC-side current reference value and the AC-side current feedback value i... abc_ci Adjust the current loop; the AC side voltage feedback value u of the centralized inverter #i. abc_ci It can be used as a feedforward to superimpose the output of the current loop, ultimately obtaining the control signal of the DC / AC converter circuit 101 (such as...). Figure 4 The PWMci shown is used to control the operation of the DC / AC conversion circuit 101 of the centralized inverter #i.

[0133] In this configuration, for the inverter device, see [link / reference]. Figure 5 The power controller 111 is used to determine the electrical parameter reference value of the corresponding slave inverter in constant power mode, or to receive the electrical parameter reference value issued by the main controller that is communicatively connected to each controller 100; the DC / AC controller 112 is used to determine and output the control signal of the controller 100 to the DC / AC conversion circuit 101 when the slave inverter operates in constant power mode according to the electrical parameter reference value. Figure 3 Taking centralized inverter #j from #m+1 to #M as an example, the power controller 111 in its controller #cj can be described as follows: Figure 5 As shown, the corresponding electrical parameter reference value, such as the power reference value Ppv_cj_ref, is obtained by using any of the calculation methods described in the above embodiments. The calculation process of the power controller 111 for the electrical parameter reference value, such as the power reference value Ppv_cj_ref, can be found in the above embodiments and will not be repeated here. Figure 5The first calculation method in the above embodiment is used as an example for demonstration; alternatively, the power controller 111 can also directly receive electrical parameter reference values, such as the power reference value Ppv_cj_ref, calculated and issued by the main controller. The DC / AC controller 112 in the controller #cj of the centralized inverter #j is as follows... Figure 5 The DC / AC control #ci shown here; specifically, under the current power reference value Ppv_cj_ref, the DC / AC control #ci can find the corresponding DC-side voltage reference value of the DC / AC conversion circuit 101 based on the PV curve of the photovoltaic string under the current external environment; then, using this DC-side voltage reference value as the target, the deviation between it and the DC-side voltage sampling value Udc_real_cj of the corresponding DC / AC conversion circuit 101 is adjusted, thereby obtaining the AC-side current reference value of the DC / AC conversion circuit 101; then, based on this AC-side current reference value and the AC-side current feedback value i abc_cj Adjust the current loop; the AC side voltage feedback value u of the centralized inverter #j. abc_cj It can be used as a feedforward to superimpose the output of the current loop, ultimately obtaining the control signal of the DC / AC converter circuit 101 (such as...). Figure 5 The PWMcj shown is used to control the operation of the DC / AC conversion circuit 101 of the centralized inverter #j.

[0134] In another example, when the inverter 10 is a string inverter, that is, when it includes a DC / AC conversion circuit 101 and at least one DC / DC conversion circuit 102, its controller 100 is as follows: Figure 6 or Figure 7 As shown, it includes: at least one power controller 111, at least one DC / DC controller 113, and DC / AC controller 112.

[0135] In this structure, for the main inverter: the power controller 111 determines the corresponding MPP current and MPP voltage on the input side of the corresponding DC / DC converter circuit 102 when it operates in MPP mode; the DC / DC controller 113 determines and outputs a control signal for the corresponding DC / DC converter circuit 102 based on its MPP voltage, ensuring that its output voltage is stabilized at the bus voltage reference value; the DC / AC controller 112 determines and outputs a control signal for the DC / AC converter circuit 101 when the main inverter operates in MPP mode, under this bus voltage reference value. Figure 6 Taking string inverter #x as an example from string inverters #1 to #n shown in the diagram, the power controller 111 in its controller #dx is as follows: Figure 6Any one of MPPT#dx1 to MPPT#dxz shown, whose controller #dx contains DC / DC controller 113 as follows: Figure 6 Any one of the DC / DC controls #dx1 to #dxz shown, whose DC / AC controller 112 in controller #dx is as follows Figure 6 The DC / AC control #dx shown is as follows. Specifically, the MPPT#dx1 (or any one of MPPT#dx2 to MPPT#dxz) can be used to make the DC / DC converter circuit 102 in the string inverter #x at its MPP position through methods such as perturbation observation method or incremental conductance method, and obtain the corresponding MPP current Ipv_dx1 (or one of Ipv_dx2 to Ipv_dxz) and MPP voltage Upv_dx1 (or one of Upv_dx2 to Upv_dxz) on the DC side of the DC / DC converter circuit 102, as well as the MPP power Ppv_dx1 (or one of Ppv_dx2 to Ppv_dxz) of the DC / DC converter circuit 102. The DC / DC control #dx1 (or any one of DC / DC control #dx2 to DC / DC control #dxz) is used to determine and output the control signal PWMdx1 (or any one of PWMdx2 to PWMdxz) for the corresponding DC / DC converter circuit 102 based on its MPP voltage Upv_dx1 (or the corresponding one of Upv_dx2 to Upv_dxz), thereby achieving control over the corresponding DC / DC converter circuit 102. Under the bus voltage reference value Udc_ref_dx, the DC / AC control #dx uses the sum of the MPP powers Ppv_dx1 to Ppv_dxz of each DC / DC converter circuit 102 in the string inverter #x as the active power target, and the reactive power Q injected by the string inverter #x according to actual conditions. ref_dx (Its steady-state value is generally zero) is used as the reactive power target, and combined with the AC side voltage feedback value u of the string inverter #x. abc_dx and AC side current feedback value i abc_dx The control signal (such as) of the DC / AC converter circuit 101 is obtained. Figure 6 The PWMdx shown is used to control the operation of the DC / AC conversion circuit 101 of the string inverter #x.

[0136] In this structure, for the slave inverter: the power controller 111 is used to determine the corresponding electrical parameter reference value, or to receive the electrical parameter reference value issued by the main controller that is communicatively connected to each controller 100; the DC / DC controller 113 is used to determine when the output voltage of the corresponding DC / DC converter 102 is stabilized at the bus voltage reference value, and outputs the control signal of the corresponding DC / DC converter 102; the DC / AC controller 112 is used to determine when the slave inverter operates in constant power mode according to the electrical parameter reference value, and outputs the control signal of the DC / AC converter 101. Figure 7 Taking string inverter #y from #n+1 to #N as an example, the power controller 111 in its controller #dy can be described as follows: Figure 7 As shown, the corresponding electrical parameter reference value, such as the power reference value Ppv_dy_ref, is obtained by using any of the calculation methods described in the above embodiments. The calculation process of the power controller 111 for the electrical parameter reference value, such as the power reference value Ppv_dy_ref, can be found in the above embodiments and will not be repeated here. Figure 7 The first calculation method in the above embodiment is used as an example for demonstration; alternatively, the power controller 111 can also directly receive electrical parameter reference values, such as the power reference value Ppv_dy_ref, calculated and issued by the main controller. The DC / DC controller 113 in the controller #dy of the string inverter #y is as follows... Figure 7 The DC / DC controller #dy1 shown is, in practical applications, the number of DC / DC controllers 113 and DC / DC converter circuits 102 is the same. Figure 7 Not all are shown in detail; the DC / DC control #dy1 is used to determine the output voltage Udc_dy of the corresponding DC / DC converter circuit 102 so that it is stable at the bus voltage reference value Udc_ref_dy. Then, it sends a control signal PWMdy1 to the corresponding DC / DC converter circuit 102 and controls its operation using this PWMdy1. Specifically, the DC / DC control #dy1 can adjust the deviation between the bus voltage reference value Udc_ref_dy and the output voltage Udc_dy to obtain the input voltage reference value of the corresponding DC / DC converter circuit 102; then, it adjusts the deviation between the input voltage reference value and the input voltage feedback value Upv_dy1 to obtain the control signal PWMdy1. The DC / AC controller 112 in controller #dy is as follows... Figure 7 The DC / AC control #dy shown uses the power reference value Ppv_dy_ref as the active power target, and injects reactive power Q from the string inverter #y according to the actual situation.ref_dy (Its steady-state value is generally zero) is used as the reactive power target, and combined with the AC side voltage feedback value u of the string inverter #y. abc_dy and AC side current feedback value i abc_dy The control signal (such as) of the DC / AC converter circuit 101 is obtained. Figure 7 The PWMdy shown in the figure is used to control the operation of the DC / AC conversion circuit 101 of the string inverter #y.

[0137] In another example, when the inverter 10 is a distributed inverter, that is, when it includes a DC / AC conversion circuit 101 and at least one DC / DC converter 11 is connected to the DC side, its controller 100 is communicatively connected to the branch controller of the corresponding DC / DC converter 11, and its control architecture is similar to... Figure 6 or Figure 7 The two controllers are the same, except that each power controller 111, each DC / DC controller 113, and each DC / AC controller 112 are located in different devices; specifically, the controller 100 includes: Figure 6 or Figure 7 The DC / AC controller 112 shown is included, and the branch controller includes Figure 6 or Figure 7 The power controller 111 and DC / DC controller 113 are shown.

[0138] In this structure, for the main inverter equipment: the power controller 111 is used to determine the corresponding MPP current and MPP voltage on the input side of the corresponding DC / DC converter 11 when it is operating in MPP mode; the DC / DC controller 113 is used to determine and output the control signal for stabilizing the output voltage of the corresponding DC / DC converter 11 to the bus voltage reference value based on its MPP voltage; the DC / AC controller 112 is used to determine and output the control signal for the DC / AC conversion circuit 101 when the main inverter equipment is operating in MPP mode under the bus voltage reference value.

[0139] In this structure, for the slave inverter: the power controller 111 is used to determine the corresponding electrical parameter reference value, or to receive the electrical parameter reference value issued by the main controller that is communicatively connected to each controller 100; the DC / DC controller 113 is used to determine and output the control signal of the corresponding DC / DC converter 11 to the corresponding DC / DC converter 11 when the output side voltage of the corresponding DC / DC converter 11 is stabilized at the bus voltage reference value; the DC / AC controller 112 is used to determine and output the control signal of the DC / AC conversion circuit 101 to the slave inverter when it operates in constant power mode according to the electrical parameter reference value.

[0140] For details on the specific working principle, please refer to the above embodiments, which will not be repeated here.

[0141] In this embodiment, the power controller 111 can enable the corresponding main inverter to be in MPP mode and obtain MPP electrical parameters; or, it can enable the corresponding slave inverter to obtain corresponding electrical parameter reference values ​​by combining these electrical parameters and power reserve parameters. The DC / DC controller 113 can control the input voltage of the DC / DC converter 102 by controlling the DC-side voltage of the DC / AC converter 101, and then provide control signals for the DC / DC converter 102 or the DC / DC converter 11 through specific control strategies, thereby maintaining the power balance between the photovoltaic side and the inverter side, and thus ensuring the stability of the DC bus voltage. That is, for string inverters and distributed inverters, the DC-side voltage of their DC / AC converter 101, i.e., the DC bus voltage, is obtained by controlling the DC / DC converter to obtain a stable bus voltage value, so as to ensure that the inverter 10 can output a stable grid-connected current waveform. Compared to string inverters and distributed inverters, where the DC bus voltage is controlled by the DC / DC controller 113 to stabilize at the corresponding bus voltage reference value Udc_ref_dx or Udc_ref_dy, centralized inverters, due to their inherent negative feedback, do not require bus voltage control. The DC / AC controller 112 can then employ appropriate control strategies based on the type of inverter 10, thereby providing control signals to the DC / AC conversion circuit 101. The control of the DC / AC conversion circuit 101 from the inverter equipment employs a VSG control strategy, controlling the corresponding DC / AC conversion circuit 101 based on the aforementioned electrical parameter reference values ​​Ppv_dy_ref and Ppv_cj_ref. That is, the power controller 111 is responsible for generating relevant parameters that enable the corresponding inverter 10 to achieve MPP output or constant power output, and providing them to the DC / DC controller 113 or DC / AC controller 112 for PWM control; the DC / DC controller 113 outputs corresponding control signals to control the DC / DC conversion circuit 102 or DC / DC converter 11 to boost the voltage; the DC / AC controller 112 outputs corresponding control signals to control the DC / AC conversion circuit 101 to perform inverter output, so that the main inverter can output its maximum power, and the slave inverter can output constant power, thereby realizing the PV-VSG function, which can better cope with the impact of changes in external factors on system stability and output waveform quality.

[0142] Another embodiment of this application also provides a photovoltaic power generation system, such as Figures 1 to 3 The system shown includes: at least two photovoltaic strings, and an inverter system as described in any of the above embodiments; wherein, the DC side of each inverter 10 in the inverter system is connected to at least one photovoltaic string. The structure of each inverter 10 and the number of photovoltaic strings connected to its DC side can be found in the above embodiments, and will not be repeated here.

[0143] In practical applications, each inverter 10 and its connected photovoltaic string in this photovoltaic power generation system can belong to the same power station; in this case, power station-level PV-VSG control can be achieved through the above principle. Alternatively, the main inverter and its connected photovoltaic string in the inverter system, as well as the slave inverter and its connected photovoltaic string in the inverter system, can also belong to different power stations; for example, the photovoltaic power generation system includes A power stations, where the inverters in a power stations are all main inverters, and the inverters in the other Aa power stations are all slave inverters, where a is a natural number less than A.

[0144] In the above embodiments, with Figure 3 The relevant embodiments are all illustrated using the photovoltaic power generation system as a power station-level PV-VSG system. When the inverters 10 in the photovoltaic power generation system belong to different power stations, it is convenient to set the operating mode of each inverter 10 on a power station basis. That is, all inverters 10 in at least one power station can be set as main inverters and all inverters 10 in at least one power station can be set as slave inverters. Of course, the inverters 10 in the same power station can also be set to different operating modes. It depends on the specific application environment, and all of them are within the protection scope of this application.

[0145] By adopting the above-described inverter system, the photovoltaic power generation system provided in this embodiment can realize PV-VSG functionality, while reducing control complexity and the possibility of power quality fluctuations, and improving system stability.

[0146] Another embodiment of this application provides a power reservation method for an inverter system. The inverter system includes at least two inverters, with the DC side of the inverters used to connect to photovoltaic strings and the AC side of the inverters used to connect to the power grid. The structure and working principle of the inverter system can be found in the above embodiments, and will not be repeated here.

[0147] See Figure 8 The power reservation method includes:

[0148] S101. Control at least one inverter as the main inverter device and operate in MPPT mode.

[0149] The specific process of S101 may include: determining and outputting the control signal for the conversion circuit in the main inverter when it operates in MPPT mode. Depending on the structure of the main inverter, the specific steps of this process may vary, for example:

[0150] For a main inverter device that includes a DC / AC conversion circuit, such as the centralized inverter mentioned in the above embodiments, the process may specifically include: determining the MPP current and MPP voltage on the DC side of the main inverter device when the main inverter device is operating in MPP mode; and determining and outputting the control signal for the DC / AC conversion circuit of the main inverter device when it is operating in MPP mode based on the MPP current.

[0151] For a main inverter device that includes a DC / AC conversion circuit and at least one DC / DC conversion circuit, such as the string inverter mentioned in the above embodiments, the process may specifically include: for each DC / DC conversion circuit, determining the MPP current and MPP voltage corresponding to its input side when it operates in MPP mode; for each DC / DC conversion circuit, determining and outputting a control signal based on its MPP voltage to stabilize its output voltage at the bus voltage reference value; and determining and outputting a control signal for its DC / AC conversion circuit when the main inverter device operates in MPP mode based on the bus voltage reference value.

[0152] For a main inverter device that includes a DC / AC conversion circuit and has at least one DC / DC converter connected to the DC side, such as the centralized inverter mentioned in the above embodiments, the process may specifically include: for each DC / DC converter, determining the MPP current and MPP voltage corresponding to its input side when it is operating in MPP mode; for each DC / DC converter, determining and outputting a control signal for stabilizing its output voltage to the bus voltage reference value based on its MPP voltage; and determining and outputting a control signal for its DC / AC conversion circuit when the main inverter device is operating in MPP mode based on the bus voltage reference value.

[0153] For the specific process of S101 for inverters with different structures, please refer to the above embodiments regarding... Figure 4 or Figure 6 The explanation will not be repeated here.

[0154] S102. Based on the electrical parameters and power reserve parameters of the main inverter equipment, determine the reference values ​​of electrical parameters in constant power mode.

[0155] Assuming the reference value for this electrical parameter is the power reference value, this electrical parameter represents power, and this power reserve parameter is the power that the inverter system needs to reserve; then:

[0156] In one example, S102 may specifically include: calculating the sum of the power of all main inverter devices, and the product of a first coefficient and a power reserve parameter; calculating the difference between the sum of the power and the product as the total reference power of all said slave inverter devices; and converting the total reference power according to a second coefficient to obtain electrical parameter reference values.

[0157] In another example, S102 may specifically include: calculating the sum of the power of all main inverter devices and multiplying it by a second coefficient as a reference power; calculating the product of the power reservation parameter and a third coefficient as a reserved power allocation value; and calculating the difference between the reference power and the reserved power allocation value as the electrical parameter reference value.

[0158] In practical applications, the first coefficient can specifically be the ratio of the sum of the rated power of all main inverters to the sum of the rated power of all slave inverters; the second coefficient can specifically be the ratio of the rated power of the slave inverters to the sum of the rated power of all main inverters; and the third coefficient can be the ratio of the rated power of the corresponding slave inverter to the sum of the rated power of all slave inverters. Alternatively, when the rated power of each individual photovoltaic string connected to each inverter is the same, i.e., when the rated power of each photovoltaic string is the same, the first coefficient can also be the ratio of the sum of the number of photovoltaic strings connected to all main inverters to the sum of the number of photovoltaic strings connected to all slave inverters; the second coefficient can also be the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all main inverters; and the third coefficient can also be the ratio of the number of photovoltaic strings connected to the corresponding slave inverter to the sum of the number of photovoltaic strings connected to all slave inverters. Their respective calculation formulas are similar to the above cases and will not be elaborated upon here.

[0159] The specific calculation process and principles can be found in the above embodiments, and will not be repeated here.

[0160] In addition, S102 can be implemented by the main controller described in the above embodiments, or by the controller of the inverter device. There is no limitation here, and it depends on the specific application environment.

[0161] S103. Based on the electrical parameter reference values, control at least one inverter to act as a slave inverter device and operate in constant power mode.

[0162] The specific process of S103 may include: determining and outputting the control signal for the conversion circuit in the slave inverter when the slave inverter operates in constant power mode. Depending on the structure of the slave inverter, the specific steps of this process may vary, for example:

[0163] For a master inverter that includes a DC / AC conversion circuit, the process may specifically include: determining or receiving electrical parameter reference values; and determining and outputting control signals for the slave inverter's DC / AC conversion circuit to operate in constant power mode according to the electrical parameter reference values.

[0164] For a main inverter device including a DC / AC conversion circuit and at least one DC / DC conversion circuit, the process may specifically include: determining or receiving reference values ​​for various electrical parameters; determining and outputting control signals for the corresponding DC / DC conversion circuits when the output voltage of the corresponding DC / DC conversion circuit is stabilized at the bus voltage reference value; and determining and outputting control signals for the DC / AC conversion circuits of the slave inverter device when it operates in constant power mode according to the electrical parameter reference values.

[0165] For a main inverter device that includes a DC / AC conversion circuit and has at least one DC / DC converter connected to the DC side, the process may specifically include: determining or receiving reference values ​​for various electrical parameters; determining and outputting a control signal for the corresponding DC / DC converter when the output voltage of the corresponding DC / DC converter is stabilized at the bus voltage reference value; and determining and outputting a control signal for the DC / AC conversion circuit of the slave inverter device when it operates in constant power mode according to the electrical parameter reference values.

[0166] For the specific process of S103 for inverters with different structures, please refer to the above embodiments regarding... Figure 5 or Figure 7 The explanation will not be repeated here.

[0167] By adopting this power reservation method, the inverter system can achieve PV-VSG functionality, while reducing its control complexity and the possibility of power quality fluctuations, and improving system stability.

[0168] Another embodiment of this application also provides a control device, such as... Figure 9 As shown, the control device may include a memory 201 and a processor 202. The processor 202 may be connected to an inverter or a main controller and may drive the power switching transistors in the conversion circuit of the inverter.

[0169] The memory 201 can specifically be RAM (random access memory), flash memory, ROM (read only memory), EPROM (Electronic Programmable ROM, a type of non-volatile read-only memory), registers, hard disks, removable disks, etc.

[0170] The memory 201 is used to store computer instructions. When the computer instructions stored in the memory 201 are executed by the processor 202, the processor 202 can be used to execute the power reservation method described in any of the above embodiments. The memory 201 can also store data, such as the power reservation parameter ΔP involved in the above embodiments. Of course, the power reservation parameter ΔP can also be issued by a host computer, which is not limited here.

[0171] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, DSL (digital subscriber line)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; or, the available media can be semiconductor media, such as SSDs (solid state disks); the available media can also be other media, without limitation.

[0172] Another embodiment of this application provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute the power reservation method as described in any of the above embodiments.

[0173] That is, the computer-readable storage medium is used to store the methods or algorithms provided in the above embodiments. Specifically, it can be RAM, flash memory, ROM, EPROM, registers, hard disk, removable disk, or any other form of storage medium in the art.

[0174] Similar or identical parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0175] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0176] The features described above regarding the disclosed embodiments can be substituted for or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An inverter system, characterized in that, The application relates to a photovoltaic inverter system, comprising: at least two inverters; wherein, the direct current side of the inverters is used for connecting photovoltaic strings; and the alternating current side of the inverters is used for connecting a power grid; at least one of the inverters is used as a master inverter device and works in a maximum power point tracking mode; at least one of the inverters is used as a slave inverter device and works in a constant power mode.

2. The inverter system according to claim 1, characterized by, a preset relationship exists between an electrical parameter reference value in the constant power mode, an electrical parameter of the master inverter device and a power reservation parameter.

3. The inverter system of claim 2, wherein, the electrical parameter reference value is a power reference value, the electrical parameter is power, and the power reservation parameter is power that needs to be reserved by the inverter system; the preset relationship is that the power reference value is the product of a total reference power of all the slave inverter devices and a second coefficient; and the total reference power is the difference between the sum of the powers of all the master inverter devices and the power reservation parameter under a first coefficient.

4. The inverter system according to claim 3, characterized by, the first coefficient is the ratio of the sum of the rated powers of all the master inverter devices to the sum of the rated powers of all the slave inverter devices; and the second coefficient is the ratio of the rated power of the corresponding slave inverter device to the sum of the rated powers of all the master inverter devices; alternatively, when the individual rated power of the photovoltaic strings connected by each inverter is the same, the first coefficient is the ratio of the sum of the numbers of the photovoltaic strings connected by all the master inverter devices to the sum of the numbers of the photovoltaic strings connected by all the slave inverter devices; and the second coefficient is the ratio of the number of the photovoltaic strings connected by the corresponding slave inverter device to the sum of the numbers of the photovoltaic strings connected by all the master inverter devices.

5. The inverter system of claim 2, wherein the electrical parameter reference value is a power reference value, the electrical parameter is power, and the power reservation parameter is power that needs to be reserved by the inverter system; the preset relationship is that the power reference value is the difference between a reference power and a reserved power distribution value; the reference power is the product of the sum of the powers of all the master inverter devices and a second coefficient; and the reserved power distribution value is the product of the power reservation parameter and a third coefficient.

6. The inverter system of claim 5, wherein, the second coefficient is the ratio of the rated power of the corresponding slave inverter device to the sum of the rated powers of all the master inverter devices; and the third coefficient is the ratio of the rated power of the corresponding slave inverter device to the sum of the rated powers of all the slave inverter devices; alternatively, when the individual rated power of the photovoltaic strings connected by each inverter is the same, the second coefficient is the ratio of the number of the photovoltaic strings connected by the corresponding slave inverter device to the sum of the numbers of the photovoltaic strings connected by all the master inverter devices; and the third coefficient is the ratio of the number of the photovoltaic strings connected by the corresponding slave inverter device to the sum of the numbers of the photovoltaic strings connected by all the slave inverter devices.

7. The inverter system according to any one of claims 1 to 6, characterized by, any inverter is a centralized inverter, a string inverter or a centralized and distributed inverter; the direct current side of the centralized inverter is directly or through at least one bus box connected with photovoltaic strings; the direct current side of the string inverter has at least one interface for connecting photovoltaic strings; the direct current side of the centralized and distributed inverter is connected with photovoltaic strings through at least one DC / DC converter.

8. The inverter system according to any one of claims 1 to 6, characterized by, The controller of each of the inverters is communicatively connected; For the master inverter device, the controller is configured to determine and output control signals for the conversion circuit in the master inverter device when the master inverter device operates in a maximum power point tracking mode; For the slave inverter device, the controller is configured to determine and output control signals for the conversion circuit in the slave inverter device when the slave inverter device operates in a constant power mode.

9. The inverter system of claim 8, wherein, When the inverter is a centralized inverter, the controller thereof comprises a power controller and a DC / AC controller; For the master inverter device, the power controller is configured to determine the maximum power point current and the maximum power point voltage corresponding to the DC side of the master inverter device when the master inverter device operates in a maximum power point, and the DC / AC controller is configured to determine and output control signals for the DC / AC conversion circuit in the master inverter device when the master inverter device operates in a maximum power point; For the slave inverter device, the power controller is configured to determine the electrical parameter reference value in the constant power mode or receive the electrical parameter reference value issued by a total controller communicatively connected with each of the controllers, and the DC / AC controller is configured to determine and output control signals for the DC / AC conversion circuit when the slave inverter device operates in the constant power mode according to the electrical parameter reference value.

10. The inverter system of claim 8, wherein, When the inverter is a group string inverter, it comprises a DC / AC conversion circuit and at least one DC / DC conversion circuit connected to the DC side thereof; The controller of the group string inverter comprises at least one power controller, at least one DC / DC controller and a DC / AC controller; For the master inverter device: the power controller is configured to determine the maximum power point current and the maximum power point voltage corresponding to the input side of the corresponding DC / DC conversion circuit when it operates in a maximum power point; the DC / DC controller is configured to determine and output control signals for the corresponding DC / DC conversion circuit when the voltage on the output side thereof is stabilized at a bus voltage reference value according to the maximum power point voltage; and the DC / AC controller is configured to determine and output control signals for the DC / AC conversion circuit when the master inverter device operates in a maximum power point under the bus voltage reference value; For the slave inverter device: the power controller is configured to determine the electrical parameter reference value in the constant power mode or receive the electrical parameter reference value issued by a total controller communicatively connected with each of the controllers; the DC / DC controller is configured to determine and output control signals for the corresponding DC / DC conversion circuit when the voltage on the output side thereof is stabilized at a bus voltage reference value; and the DC / AC controller is configured to determine and output control signals for the DC / AC conversion circuit when the slave inverter device operates in the constant power mode according to the electrical parameter reference value.

11. The inverter system of claim 8, wherein, When the inverter is a centralized and distributed inverter, at least one DC / DC converter is connected to the DC side thereof, and the controller thereof is communicatively connected with a branch controller corresponding to the DC / DC converter; The branch controller comprises a power controller and a DC / DC controller, and the controller comprises a DC / AC controller; For the main inverter device, the power controller is configured to determine the maximum power point current and the maximum power point voltage corresponding to the input side of the corresponding DC / DC converter when the DC / DC converter operates at the maximum power point; the DC / DC controller is configured to determine the control signal for stabilizing the output side voltage of the corresponding DC / DC converter at the bus voltage reference value according to the maximum power point voltage of the corresponding DC / DC converter and output the control signal; and the DC / AC controller is configured to determine the control signal for the DC / AC conversion circuit in the main inverter device when the main inverter device operates at the maximum power point at the bus voltage reference value and output the control signal. For the slave inverter device, the power controller is configured to determine the electrical parameter reference value in the constant power mode or receive the electrical parameter reference value issued by the total controller in communication connection with each controller; the DC / DC controller is configured to determine the control signal for the corresponding DC / DC converter when the output side voltage of the corresponding DC / DC converter is stabilized at the bus voltage reference value and output the control signal; and the DC / AC controller is configured to determine the control signal for the DC / AC conversion circuit when the slave inverter device operates at the constant power mode according to the electrical parameter reference value and output the control signal.

12. A photovoltaic power system, characterized by Comprise: at least two photovoltaic strings, and an inverter system as claimed in any one of claims 1 to 11; wherein, the DC side of each inverter in the inverter system is connected to at least one photovoltaic string.

13. The photovoltaic power system of claim 12, wherein, each inverter and the photovoltaic string connected thereto belong to the same power station; alternatively, the main inverter device and the photovoltaic string connected thereto in the inverter system, and the slave inverter device and the photovoltaic string connected thereto in the inverter system, belong to different power stations.

14. A power reservation method of an inverter system, characterized by, The inverter system comprises at least two inverters, the DC side of the inverter is used to connect the photovoltaic string, and the AC side of the inverter is used to connect the power grid; the power reservation method comprises: controlling at least one inverter as a main inverter device to operate in a maximum power point tracking mode; determining an electrical parameter reference value in a constant power mode according to the electrical parameters and the power reservation parameter of the main inverter device; controlling at least one inverter as a slave inverter device to operate in a constant power mode according to the electrical parameter reference value.

15. The power reservation method of an inverter system according to claim 14, wherein, The electrical parameter reference value is a power reference value, the electrical parameter is power, and the power reservation parameter is the power that needs to be reserved by the inverter system; In the power reservation method, determining the electrical parameter reference value in the constant power mode according to the electrical parameters and the power reservation parameter of the main inverter device comprises: calculating the sum of the powers of all the main inverter devices and the product of a first coefficient and the power reservation parameter; calculating the difference between the sum of the powers and the product as the total reference power of all the slave inverter devices; converting the total reference power according to a second coefficient to obtain the electrical parameter reference value. Alternatively, the electric parameter reference value in the constant power mode is determined according to the electric parameter and the power reservation parameter of the master inverter device, and includes: The product of the sum of the power of all the master inverter devices and a second coefficient is calculated as a reference power; The product of the power reservation parameter and a third coefficient is calculated as a reservation power distribution value; The difference between the reference power and the reservation power distribution value is calculated as the electric parameter reference value.

16. The power reservation method of an inverter system according to claim 15, wherein, The first coefficient is the ratio of the sum of the rated power of all the master inverter devices to the sum of the rated power of all the slave inverter devices; the second coefficient is the ratio of the rated power of the corresponding slave inverter device to the sum of the rated power of all the master inverter devices; and the third coefficient is the ratio of the rated power of the corresponding slave inverter device to the sum of the rated power of all the slave inverter devices. Alternatively, when the individual rated power of the photovoltaic module string connected to each inverter is the same, the first coefficient is the ratio of the sum of the number of photovoltaic module strings connected to all the master inverter devices to the sum of the number of photovoltaic module strings connected to all the slave inverter devices; the second coefficient is the ratio of the number of photovoltaic module strings connected to the corresponding slave inverter device to the sum of the number of photovoltaic module strings connected to all the master inverter devices; and the third coefficient is the ratio of the number of photovoltaic module strings connected to the corresponding slave inverter device to the sum of the number of photovoltaic module strings connected to all the slave inverter devices.

17. The power reservation method of an inverter system according to any one of claims 14 to 16, characterized by, The at least one inverter is controlled as a master inverter device to work in the maximum power point tracking mode, including: The control signal to the conversion circuit in the master inverter device when the master inverter device works in the maximum power point tracking mode is determined and output.

18. The power reservation method of an inverter system according to claim 17, wherein, The control signal to the conversion circuit in the master inverter device when the master inverter device works in the maximum power point tracking mode is determined and output, including: If the master inverter device is a centralized inverter, the maximum power point current and the maximum power point voltage corresponding to the DC side of the master inverter device when the master inverter device works in the maximum power point are determined, and the control signal to the DC / AC conversion circuit of the master inverter device when the master inverter device works in the maximum power point is determined and output; If the master inverter device is a string inverter, the maximum power point current and the maximum power point voltage corresponding to the input side of each DC / DC conversion circuit when the master inverter device works in the maximum power point are determined, the control signal to the output side of each DC / DC conversion circuit when the voltage of the output side of each DC / DC conversion circuit is stabilized at the bus voltage reference value is determined and output according to the maximum power point voltage of each DC / DC conversion circuit, and the control signal to the DC / AC conversion circuit of the master inverter device when the master inverter device works in the maximum power point is determined and output according to the bus voltage reference value. If the main inverter device is a centralized inverter, then: determining or receiving the electrical parameter reference value; and determining the control signal for the DC / AC conversion circuit of the main inverter device so that the main inverter device operates at the maximum power point according to the electrical parameter reference value.

19. The power reservation method of an inverter system according to any one of claims 14 to 16, characterized by, According to the electrical parameter reference value, controlling at least one of the inverters as a slave inverter device to operate at a constant power mode, including: determining the control signal for the conversion circuit of the slave inverter device so that the slave inverter device operates at the constant power mode.

20. The power reservation method of an inverter system according to claim 19, wherein, determining the control signal for the conversion circuit of the slave inverter device so that the slave inverter device operates at the constant power mode, including: If the slave inverter device is a centralized inverter, then: determining or receiving the electrical parameter reference value; and determining the control signal for the DC / AC conversion circuit of the slave inverter device so that the slave inverter device operates at the constant power mode according to the electrical parameter reference value. If the slave inverter device is a group string inverter, then: determining or receiving each of the electrical parameter reference values; determining the control signal for each DC / DC conversion circuit of the slave inverter device so that the output side voltage of the corresponding DC / DC conversion circuit is stabilized at the bus voltage reference value; and determining the control signal for the DC / AC conversion circuit of the slave inverter device so that the slave inverter device operates at the constant power mode according to the electrical parameter reference values. If the slave inverter device is a centralized inverter, then: determining or receiving the electrical parameter reference value; and determining the control signal for the DC / AC conversion circuit of the slave inverter device so that the slave inverter device operates at the constant power mode according to the electrical parameter reference value.

21. A control device characterized by comprising: including a processor and a memory, the memory being used to store programs, instructions or codes, and the processor being used to execute the programs, instructions or codes in the memory to complete the power reservation method of the inverter system as claimed in any one of claims 14 to 20.

22. A computer-readable storage medium, characterized in that, having a computer program stored therein, the computer program being loaded by a processor to execute the power reservation method of the inverter system as claimed in any one of claims 14 to 20.

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