Network construction control method and device of photovoltaic inverter and electronic equipment

Abstract

The invention discloses a networking control method and device of a photovoltaic inverter and electronic equipment. The method comprises the following steps: acquiring a working mode of the direct-current boost converter; obtaining a first operation state parameter of a photovoltaic array, a second operation state parameter of a photovoltaic inverter and a third operation state parameter of a power grid; generating a target pulse width modulation signal based on the first operation state parameter, the second operation state parameter and / or the third operation state parameter; and controlling the operation of the direct current boost converter with the working mode being a network construction control mode based on the first pulse width modulation signal, controlling the operation of the direct current-to-alternating current converter based on the second pulse width modulation signal, and controlling the operation of the direct current boost converter with the working mode being a power point tracking mode based on the third pulse width modulation signal. According to the invention, the technical problem of low accuracy and timeliness of network construction control of the photovoltaic inverter in the prior art is solved.

Description

Technical Field

[0001] This invention relates to the fields of new energy technology and power grid construction control, and more specifically, to a grid construction control method, device, and electronic equipment for a photovoltaic inverter. Background Technology

[0002] With the development of new energy power generation and smart grids, photovoltaic inverters, as devices connecting photovoltaic arrays to the power grid, face the following technical challenges. When distributed photovoltaic arrays are connected to the grid on a large scale, traditional grid control methods typically employ a single control mode to control each component in the photovoltaic inverter. This makes it difficult to effectively cope with dynamic changes in the power grid, such as frequency and power fluctuations, resulting in low accuracy and timeliness of grid control for photovoltaic inverters in related technologies.

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This invention provides a grid-connection control method, apparatus, and electronic device for photovoltaic inverters, which at least solves the technical problem of low accuracy and timeliness in grid-connection control of photovoltaic inverters in related technologies.

[0005] According to one aspect of the present invention, a grid-connected control method for a photovoltaic inverter is provided. The photovoltaic inverter includes: multiple DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminals of the DC-DC boost converters are connected to a photovoltaic array, the output terminals of the DC-DC boost converters are connected to the DC bus, the input terminals of the DC-to-AC converters are connected to the DC bus, and the output terminals of the DC-to-AC converters are connected to the power grid. The method includes: acquiring the operating mode of the DC-DC boost converters, wherein the operating mode includes one of the following: power point tracking mode and grid-connected control mode; and acquiring first operating state parameters of the photovoltaic array. The system uses the second operating state parameters of the photovoltaic inverter and the third operating state parameters of the power grid. Based on the first, second, and / or third operating state parameters, a target pulse width modulation signal is generated, wherein the target pulse width modulation signal includes: a first pulse width modulation signal, a second pulse width modulation signal, and a third pulse width modulation signal. The system controls the operation of the DC-DC boost converter in grid control mode based on the first pulse width modulation signal, controls the operation of the DC-DC to AC converter based on the second pulse width modulation signal, and controls the operation of the DC-DC boost converter in power point tracking mode based on the third pulse width modulation signal.

[0006] In this embodiment of the invention, generating a first pulse width modulation signal based on a first operating state parameter, a second operating state parameter, and a third operating state parameter includes: determining target control parameters based on the first operating state parameter, the second operating state parameter, and / or the third operating state parameter, wherein the target control parameters include virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. The virtual inertia control parameters represent control parameters for adding simulated inertial effects to the photovoltaic inverter, the primary frequency modulation control parameters represent parameters for controlling the photovoltaic inverter to participate in grid frequency regulation, and the DC bus voltage compensation control parameters represent control parameters for voltage compensation of the DC bus in the photovoltaic inverter; and generating the first pulse width modulation signal based on the virtual inertia control parameters, the primary frequency modulation control parameters, and the DC bus voltage compensation control parameters.

[0007] In this embodiment of the invention, determining virtual inertia control parameters based on a third operating state parameter includes: obtaining the power grid frequency change rate in the third operating state parameter; and determining the virtual inertia control parameters based on a preset virtual inertia coefficient and the power grid frequency change rate.

[0008] In this embodiment of the invention, determining the primary frequency regulation control parameters based on the third operating state parameters includes: obtaining the actual grid frequency in the third operating state parameters; and determining the primary frequency regulation control parameters based on the preset primary frequency regulation coefficient, the grid rated frequency, and the actual grid frequency.

[0009] In this embodiment of the invention, determining the DC bus voltage compensation control parameters based on the second operating state parameters includes: acquiring the DC bus voltage in the second operating state parameters; and using the first preset voltage loop proportional-integral controller in the photovoltaic inverter to determine the DC bus voltage compensation control parameters based on the rated DC bus voltage and the DC bus voltage of the photovoltaic inverter.

[0010] In this embodiment of the invention, a first pulse width modulation signal is generated based on virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. This includes: determining the sum of the virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters; performing amplitude limiting calculation on the sum to obtain the target inductor current parameter; and using the second preset voltage loop proportional-integral controller in the photovoltaic inverter, the first pulse width modulation signal is determined based on the DC bus voltage in the second operating state parameters, the photovoltaic cell voltage in the first operating state parameters, and the target inductor current parameter.

[0011] In this embodiment of the invention, generating a second pulse width modulation signal based on a second operating state parameter includes: acquiring the DC bus voltage in the second operating state parameter; and determining the second pulse width modulation signal based on a preset power command and the DC bus voltage using a third preset voltage loop proportional-integral controller in the photovoltaic inverter.

[0012] In this embodiment of the invention, generating a third pulse width modulation signal based on a first operating state parameter includes: acquiring the photovoltaic cell voltage and photovoltaic cell current in the first operating state parameter; and using a fourth preset voltage loop proportional-integral controller in the photovoltaic inverter to determine the third pulse width modulation signal based on the photovoltaic cell voltage and photovoltaic cell current.

[0013] According to another aspect of the present invention, a grid-connected control device for a photovoltaic inverter is also provided. The photovoltaic inverter includes: a plurality of DC-DC boost converters, a DC bus, and a DC-to-AC converter, wherein the input terminals of the DC-DC boost converters are connected to a photovoltaic array, the output terminals of the DC-DC boost converters are connected to the DC bus, the input terminals of the DC-to-AC converters are connected to the DC bus, and the output terminals of the DC-to-AC converters are connected to the power grid. The device includes: a first acquisition module for acquiring the operating mode of the DC-DC boost converters, wherein the operating mode includes one of the following: power point tracking mode and grid-connected control mode; and a second acquisition module for acquiring the first operating state of the photovoltaic array. The system comprises: a first operating state parameter, a second operating state parameter of the photovoltaic inverter, and a third operating state parameter of the power grid; a generation module for generating a target pulse width modulation signal based on the first operating state parameter, the second operating state parameter, and / or the third operating state parameter, wherein the target pulse width modulation signal includes: a first pulse width modulation signal, a second pulse width modulation signal, and a third pulse width modulation signal; and a control module for controlling the operation of the DC-DC boost converter in grid control mode based on the first pulse width modulation signal, controlling the operation of the DC-DC to AC converter based on the second pulse width modulation signal, and controlling the operation of the DC-DC boost converter in power point tracking mode based on the third pulse width modulation signal.

[0014] According to another aspect of the present invention, an electronic device is also provided, comprising: a memory storing an executable program; and a processor for running the program, wherein the program executes the methods of various embodiments of the present invention during runtime.

[0015] According to another aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored executable program, wherein, when the executable program is executed, it controls the device where the computer-readable storage medium is located to perform the methods of various embodiments of the present invention.

[0016] According to another aspect of the present invention, a computer program product is also provided, including a computer program that, when executed by a processor, implements the methods of various embodiments of the present invention.

[0017] According to another aspect of the present invention, a computer program product is also provided, including a non-volatile computer-readable storage medium storing a computer program that, when executed by a processor, implements the methods of various embodiments of the present invention.

[0018] According to another aspect of the present invention, a computer program is also provided, which, when executed by a processor, implements the methods of the various embodiments of the present invention.

[0019] In this embodiment of the invention, the photovoltaic inverter includes: multiple DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminals of the DC-DC boost converters are connected to the photovoltaic array, the output terminals of the DC-DC boost converters are connected to the DC bus, the input terminals of the DC-to-AC converters are connected to the DC bus, and the output terminals of the DC-to-AC converters are connected to the power grid. The grid connection control method for the photovoltaic inverter includes: first, obtaining the operating mode of the DC-DC boost converter, which includes one of the following: power point tracking mode and grid connection control mode; then, obtaining the first operating state parameters of the photovoltaic array, and the first operating state parameters of the photovoltaic inverter... The method involves considering two operating state parameters and a third operating state parameter of the power grid. Next, based on these parameters, a target pulse width modulation (PWM) signal is generated, comprising a first PWM signal, a second PWM signal, and a third PWM signal. Finally, the method controls the operation of a DC-DC boost converter in grid-connected control mode based on the first PWM signal, the operation of a DC-to-AC converter based on the second PWM signal, and the operation of a DC-DC boost converter in power point tracking mode based on the third PWM signal. This proposed photovoltaic inverter grid-connected control method dynamically acquires the operating modes of each DC-DC boost converter in the photovoltaic inverter and comprehensively considers the first operating state parameters of the photovoltaic array, the second operating state parameters of the photovoltaic inverter itself, and the third operating state parameters of the power grid to generate a target PWM signal. Based on a multi-parameter control decision strategy, it can more comprehensively reflect the operating status of each device, making the control decision of the photovoltaic inverter more accurate and timely, and avoiding the delays and errors caused by single-parameter control. By using the first pulse width modulation signal, the second pulse width modulation signal, and the third pulse width modulation signal to control the DC-DC boost converter in grid control mode, the DC-DC to AC converter, and the DC-DC boost converter in power point tracking mode, respectively, the photovoltaic inverter can achieve efficient conversion of photovoltaic energy and precise support for the power grid. This can improve energy conversion efficiency and enhance the grid connection capability of the photovoltaic inverter. When the grid frequency and voltage fluctuate, the photovoltaic inverter can respond quickly, thus solving the technical problem of low accuracy and timeliness of grid connection control of photovoltaic inverters in related technologies. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0021] Figure 1 This is a flowchart of a grid control method for a photovoltaic inverter according to an embodiment of the present invention;

[0022] Figure 2This is a schematic diagram of the structure and connection relationship of an optional photovoltaic inverter according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of a grid control device for a photovoltaic inverter according to an embodiment of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of the present invention.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] According to one aspect of the present invention, a grid-connected control method for a photovoltaic inverter is provided. The photovoltaic inverter includes: multiple DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminal of the DC-DC boost converter is connected to a photovoltaic array, the output terminal of the DC-DC boost converter is connected to the DC bus, the input terminal of the DC-to-AC converter is connected to the DC bus, and the output terminal of the DC-to-AC converter is connected to the power grid.

[0027] The aforementioned photovoltaic inverter can refer to a device that converts the direct current generated by a photovoltaic array into alternating current so that the electrical energy can be fed into the power grid.

[0028] The aforementioned DC-DC boost converter can refer to a power electronic converter that boosts the lower voltage DC power from the photovoltaic array to a higher voltage DC power.

[0029] The aforementioned DC bus can refer to the power transmission line within a photovoltaic inverter used to connect the outputs of multiple DC-DC boost converters to the input of a DC-to-AC converter.

[0030] The aforementioned DC-to-AC converter can refer to a device that converts DC power from a DC bus into AC power that matches the frequency and phase of the power grid.

[0031] The aforementioned photovoltaic array can refer to an assembly of multiple photovoltaic panels combined in a certain electrical and mechanical manner. A photovoltaic array can convert solar energy into direct current.

[0032] The aforementioned power grid can refer to a power transmission and distribution network consisting of transmission lines, substations, distribution networks, and power users.

[0033] Figure 1 This is a flowchart of a grid control method for a photovoltaic inverter according to an embodiment of the present invention. It should be noted that the steps shown in the flowchart can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that presented here. Figure 1 As shown, the method includes the following steps:

[0034] Step S102: Obtain the operating mode of the DC-DC boost converter.

[0035] The operating modes include one of the following: power point tracking mode and network control mode.

[0036] The aforementioned power point tracking (PPT) mode refers to a control strategy that enables the DC-DC boost converter to operate at the optimal operating point of the photovoltaic array, thereby maximizing energy conversion efficiency. The PPT algorithm can dynamically adjust the parameters of the DC-DC boost converter to ensure optimal energy harvesting even under varying illumination conditions.

[0037] The aforementioned grid control mode can refer to an active control strategy that enables DC-DC boost converters to convert electrical energy and participate in grid stability and control, and may include functions such as frequency regulation, voltage support, and power factor correction.

[0038] In one optional embodiment, the operating mode of each DC-DC boost converter in the photovoltaic inverter can be detected or determined, i.e., whether each DC-DC boost converter is in power point tracking mode or grid control mode. Furthermore, by receiving signals from photovoltaic array sensors, the output voltage and current of the photovoltaic cells can be analyzed to determine the current light intensity and temperature conditions, thereby deciding whether the DC-DC boost converter needs to enter power point tracking mode to track and maintain operation at a higher power point, maximizing energy utilization. Simultaneously, the grid status, including grid frequency and voltage parameters, can be monitored. When the grid becomes unstable or requires additional support, such as frequency fluctuations or voltage drops, the relevant DC-DC boost converters can be switched to grid control mode to actively participate in grid frequency and voltage regulation, improving the overall stability of the grid.

[0039] In the above process, the photovoltaic inverter employs state recognition technology and adaptive control strategies, enabling it to quickly adjust the operating modes of each DC-DC boost converter according to changes in the external environment and grid demand. This intelligent control mechanism significantly improves the flexibility and response speed of the photovoltaic inverter. Under sufficient sunlight, the photovoltaic inverter can use power point tracking mode to ensure the photovoltaic array operates at a higher power point, maximizing the capture of solar energy and improving the energy utilization efficiency of both the photovoltaic array and the photovoltaic inverter.

[0040] Step S104: Obtain the first operating status parameters of the photovoltaic array, the second operating status parameters of the photovoltaic inverter, and the third operating status parameters of the power grid.

[0041] The aforementioned first operating status parameter can refer to the real-time operating data of the photovoltaic array, which may include, but is not limited to, parameters such as photovoltaic cell voltage and photovoltaic cell current. It can be used to evaluate the power generation capacity and status of the photovoltaic array and provide a basis for decision-making in control strategies.

[0042] The aforementioned second operating status parameter can refer to the real-time operating data of the photovoltaic inverter itself, which may include, but is not limited to, parameters such as DC bus voltage and photovoltaic inverter output current, and can reflect the operating status and working efficiency of the photovoltaic inverter.

[0043] The aforementioned third operating status parameter can refer to the real-time operating data of the power grid, including but not limited to parameters such as power grid frequency and voltage. It can be used to reflect the operating status of the power grid, so that the photovoltaic inverter can adjust its output to achieve stable and efficient operation of the power grid.

[0044] In one optional embodiment, the operating status parameters of the photovoltaic array, photovoltaic inverter, and power grid can be acquired in real time. Acquiring the first operating status parameter may include measuring the photovoltaic array status under current illumination conditions using sensors installed at the output end of the photovoltaic array. Temperature sensors can be used to monitor the temperature of the photovoltaic cells, as temperature affects the output characteristics of the photovoltaic cells. Illumination sensors can also record the light intensity to assist in the dynamic adjustment of the power point tracking algorithm. Acquiring the second operating status parameter may include monitoring the DC bus voltage level. The operating status of each component in the photovoltaic inverter can also be monitored in real time to ensure that the AC output of the photovoltaic inverter meets the frequency, phase, and amplitude requirements of the power grid. Acquiring the third operating status parameter may include obtaining the current frequency of the power grid for frequency regulation and synchronization control. The grid voltage can also be measured to determine whether voltage support is needed, ensuring that the inverter output is synchronized with the grid and avoiding power quality problems caused by current loss of synchronization. The acquisition of the first operating state parameters of the photovoltaic array, the second operating state parameters of the photovoltaic inverter, and the third operating state parameters of the power grid can rely on various sensors, and can also be sorted and analyzed by data acquisition and processing systems to extract useful information and provide accurate data support for the generation of pulse width modulation signals.

[0045] In the above process, real-time and accurate operating status parameters provide the basis for the refined control of the photovoltaic inverter, ensuring that the dynamic adjustment of the pulse width modulation signal matches actual needs. Real-time feedback on the status of the photovoltaic array and photovoltaic inverter provides a data foundation for system-level energy management, helping to improve energy dispatch, reduce energy consumption, and increase overall efficiency. Sensing the grid status enables the photovoltaic inverter to respond and adjust quickly under grid frequency and voltage fluctuations, maintaining compatibility with the grid and reducing negative impacts on the grid.

[0046] Step S106: Generate a target pulse width modulation signal based on the first operating state parameter, the second operating state parameter, and / or the third operating state parameter.

[0047] The target pulse width modulation signal includes: a first pulse width modulation signal, a second pulse width modulation signal, and a third pulse width modulation signal.

[0048] The aforementioned target pulse width modulation signal can refer to the signal used to control the switching elements in the photovoltaic converter. The photovoltaic inverter can be accurately controlled by adjusting the target pulse width modulation signal to achieve efficient and precise conversion of electrical energy.

[0049] The aforementioned first pulse width modulation signal can refer to a signal used to control the DC-DC boost converter in grid control mode. By adjusting the output of the DC-DC boost converter, it participates in grid stability control, such as frequency regulation and voltage compensation.

[0050] The aforementioned second pulse width modulation signal can refer to a signal used to control the DC-to-AC converter. It can include control information such as power commands and frequency response to adapt to dynamic changes in the power grid and ensure that the AC power quality output by the DC-to-AC converter meets the requirements of the power grid.

[0051] The aforementioned third pulse width modulation signal can refer to the signal used to control the DC-DC boost converter in power point tracking mode. It can maximize the energy harvesting efficiency of the photovoltaic array and maintain operation near a higher power point by adjusting the switching mode of the DC-DC boost converter.

[0052] In one optional embodiment, by utilizing real-time collected first, second, and / or third operating state parameters, and through a series of algorithms and control strategies, a precise target pulse width modulation (PWM) signal can be generated. The collected first, second, and / or third operating state parameters can be analyzed to identify current lighting conditions, equipment operating status, and grid demands. Examples include the grid frequency change rate, DC bus voltage level, and photovoltaic cell output characteristics. Based on this analysis, control objectives can be set, including but not limited to maximizing photovoltaic energy harvesting, maintaining grid frequency stability, and voltage support. These control objectives can guide the generation of the target PWM signal. When the grid frequency fluctuates, the inertial response of a traditional power generation unit can be simulated by calculating virtual inertia control parameters and primary frequency regulation control parameters to smooth the grid frequency. Considering that fluctuations in the DC bus voltage within the photovoltaic inverter can affect the stability and efficiency of the equipment, the DC bus voltage can be maintained within an ideal range by calculating DC bus voltage compensation control parameters and utilizing a voltage loop proportional-integral controller.

[0053] In the above process, by dynamically generating the target pulse width modulation signal, the operating status of each DC-DC boost converter and DC-to-AC converter can be precisely controlled, ensuring efficient energy conversion and management under various conditions. The generation of the target pulse width modulation signal takes into account the needs of the power grid and can actively participate in frequency and voltage regulation, significantly improving the stability and reliability of the power grid. Through precise generation of the target pulse width modulation signal, efficient coordination between the photovoltaic inverter and the power grid can be achieved, improving energy utilization efficiency and enhancing the stability of the power grid and the adaptive capabilities of the photovoltaic inverter.

[0054] Step S108: The DC-DC boost converter is operated in network control mode based on the first pulse width modulation signal, the DC-DC to AC converter is operated in DC-DC to AC mode based on the second pulse width modulation signal, and the DC-DC boost converter is operated in power point tracking mode based on the third pulse width modulation signal.

[0055] In one optional embodiment, during the actual execution phase of the photovoltaic inverter grid control, various components of the photovoltaic inverter can be controlled according to different pulse width modulation (PWM) signals to achieve better power conversion and grid support effects. The DC-DC boost converter in grid control mode can be controlled based on a first PWM signal. Upon receiving the first PWM signal, the DC-DC boost converter in grid control mode will adjust its switching state according to the duty cycle and frequency of the first PWM signal, thereby controlling the boost output. Control of the DC-DC boost converter in grid control mode may include providing virtual inertia and participating in primary frequency regulation to help the grid recover stability during frequency fluctuations, and may also include compensation for the DC bus voltage to maintain the voltage stability of the photovoltaic inverter. The DC-to-AC converter can be controlled based on a second PWM signal, which can be designed to control the DC-to-AC converter to ensure that the AC output of the DC-to-AC converter is consistent with the frequency, phase, and voltage of the grid. By controlling the DC-to-AC converter based on the second pulse-width modulation (PWM) signal, the DC-to-AC converter can ensure coordinated connection with the grid and adjust the output power according to demand to support the grid and maximize energy utilization. The third PWM signal can control the DC-to-boost converter in power point tracking (PPT) mode. For the DC-to-boost converter in PPT mode, the third PWM signal can improve the energy capture of the photovoltaic array. By adjusting the third PWM signal, the DC-to-boost converter can be controlled to track the maximum power point of the photovoltaic cells—the maximum power point that the photovoltaic cells can generate under given illumination and temperature conditions.

[0056] In the aforementioned process, by controlling various components of the photovoltaic inverter according to different pulse width modulation signals, the photovoltaic inverter can provide frequency and voltage support to the power grid. Controlling the DC-DC boost converter in power point tracking mode ensures that the photovoltaic array can output greater power under different illumination conditions, significantly improving the energy utilization efficiency of the photovoltaic inverter and reducing energy waste. The dynamic control strategy for the DC-to-AC converter allows the photovoltaic inverter to adjust its output power according to grid demand, supporting stable grid operation under different load conditions and achieving flexible energy dispatch and management. By precisely controlling the functions of each part within the photovoltaic inverter, its overall performance can be improved, including power conversion efficiency, grid support capability, and equipment stability.

[0057] In this embodiment of the invention, the photovoltaic inverter includes: multiple DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminals of the DC-DC boost converters are connected to the photovoltaic array, the output terminals of the DC-DC boost converters are connected to the DC bus, the input terminals of the DC-to-AC converters are connected to the DC bus, and the output terminals of the DC-to-AC converters are connected to the power grid. The grid connection control method for the photovoltaic inverter includes: first, obtaining the operating mode of the DC-DC boost converter, which includes one of the following: power point tracking mode and grid connection control mode; then, obtaining the first operating state parameters of the photovoltaic array, and the first operating state parameters of the photovoltaic inverter... The method involves considering two operating state parameters and a third operating state parameter of the power grid. Next, based on these parameters, a target pulse width modulation (PWM) signal is generated, comprising a first PWM signal, a second PWM signal, and a third PWM signal. Finally, the method controls the operation of a DC-DC boost converter in grid-connected control mode based on the first PWM signal, the operation of a DC-to-AC converter based on the second PWM signal, and the operation of a DC-DC boost converter in power point tracking mode based on the third PWM signal. This proposed photovoltaic inverter grid-connected control method dynamically acquires the operating modes of each DC-DC boost converter in the photovoltaic inverter and comprehensively considers the first operating state parameters of the photovoltaic array, the second operating state parameters of the photovoltaic inverter itself, and the third operating state parameters of the power grid to generate a target PWM signal. Based on a multi-parameter control decision strategy, it can more comprehensively reflect the operating status of each device, making the control decision of the photovoltaic inverter more accurate and timely, and avoiding the delays and errors caused by single-parameter control. By using the first pulse width modulation signal, the second pulse width modulation signal, and the third pulse width modulation signal to control the DC-DC boost converter in grid control mode, the DC-DC to AC converter, and the DC-DC boost converter in power point tracking mode, respectively, the photovoltaic inverter can achieve efficient conversion of photovoltaic energy and precise support for the power grid. This can improve energy conversion efficiency and enhance the grid connection capability of the photovoltaic inverter. When the grid frequency and voltage fluctuate, the photovoltaic inverter can respond quickly, thus solving the technical problem of low accuracy and timeliness of grid connection control of photovoltaic inverters in related technologies.

[0058] In this embodiment of the invention, generating a first pulse width modulation signal based on a first operating state parameter, a second operating state parameter, and a third operating state parameter includes: determining target control parameters based on the first operating state parameter, the second operating state parameter, and / or the third operating state parameter, wherein the target control parameters include virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. The virtual inertia control parameters represent control parameters for adding simulated inertial effects to the photovoltaic inverter, the primary frequency modulation control parameters represent parameters for controlling the photovoltaic inverter to participate in grid frequency regulation, and the DC bus voltage compensation control parameters represent control parameters for voltage compensation of the DC bus in the photovoltaic inverter; and generating the first pulse width modulation signal based on the virtual inertia control parameters, the primary frequency modulation control parameters, and the DC bus voltage compensation control parameters.

[0059] The aforementioned target control parameters can refer to a series of control variables calculated based on the operating status parameters of the photovoltaic array, photovoltaic inverter, and power grid. These parameters can be used to guide the operating strategy of the photovoltaic inverter to achieve efficient and stable power conversion and support grid dynamics.

[0060] The aforementioned virtual inertia control parameters can refer to parameters used to simulate the inertial effect added to the photovoltaic inverter. Virtual inertia control parameters allow the photovoltaic inverter to reduce the impact of frequency changes by temporarily storing or releasing energy when the grid frequency fluctuates, thereby improving the stability of the grid.

[0061] The aforementioned primary frequency regulation control parameters refer to the control parameters that enable the photovoltaic inverter to automatically adjust its output power according to changes in the grid frequency, allowing the photovoltaic inverter to participate in the grid frequency regulation process and enhancing its support capability for the grid.

[0062] The aforementioned DC bus voltage compensation control parameters refer to the control parameters that ensure the DC bus voltage remains within a set range by adjusting the control strategy of the photovoltaic inverter. This can prevent equipment efficiency from decreasing or the photovoltaic inverter from overloading due to voltage fluctuations, thus maintaining the stable operation of the equipment.

[0063] In one optional embodiment, key information such as photovoltaic cell voltage and current, photovoltaic inverter DC bus voltage, and grid frequency and voltage can be extracted by comprehensively analyzing the first, second, and third operating state parameters. Based on one or more of the first, second, and third operating state parameters, virtual inertia control parameters, primary frequency regulation control parameters, and DC bus voltage compensation control parameters can be calculated. For example, the virtual inertia control parameters can be calculated based on the grid frequency change rate and a pre-set virtual inertia coefficient, while the primary frequency regulation control parameters can consider the deviation between the actual grid frequency and the rated frequency, as well as a preset primary frequency regulation coefficient. Finally, the virtual inertia control parameters, primary frequency regulation control parameters, and DC bus voltage compensation control parameters can be combined using mathematical algorithms and an inverter control model to generate a first pulse width modulation (PWM) signal. The first PWM signal can reflect the grid demand, the real-time status of the photovoltaic inverter and photovoltaic array, and the control objectives of the photovoltaic inverter, such as frequency stability, voltage compensation, and energy management. After generating the first PWM signal, amplitude limiting can be performed to ensure equipment safety. By setting reasonable upper and lower limits for voltage and current, damage to internal components of the photovoltaic inverter due to excessive control signals can be avoided, ensuring that the equipment operates within a safe range.

[0064] In the aforementioned process, the application of virtual inertia control parameters and primary frequency regulation control parameters enables the photovoltaic inverter to actively participate in grid frequency stabilization, improving the overall stability and reliability of the grid. The introduction of DC bus voltage compensation control parameters helps maintain the stability of the DC bus voltage within the photovoltaic inverter and adjusts the conversion efficiency from DC to AC. The control parameters can adaptively adjust based on real-time photovoltaic array, photovoltaic inverter, and grid conditions, achieving intelligent control of the photovoltaic inverter and improving its adaptability and response speed to changes in the external environment.

[0065] In this embodiment of the invention, determining virtual inertia control parameters based on a third operating state parameter includes: obtaining the power grid frequency change rate in the third operating state parameter; and determining the virtual inertia control parameters based on a preset virtual inertia coefficient and the power grid frequency change rate.

[0066] The aforementioned rate of change of grid frequency refers to the amount of change in grid frequency per unit time. The rate of change of grid frequency in a power grid reflects the balance between power supply and demand; when there is an imbalance between power generation and consumption in the grid, the rate of change of grid frequency can change.

[0067] The aforementioned preset virtual inertia coefficient refers to a parameter pre-set in the photovoltaic inverter to simulate the inertial response of a generator. The magnitude of the preset virtual inertia coefficient can affect the response speed and amplitude of the photovoltaic inverter to changes in grid frequency. Since photovoltaic inverters do not have physical rotational inertia, adjusting the virtual inertia coefficient through software and control strategies allows the photovoltaic inverter to smoothly transition like a larger generator when detecting changes in grid frequency, absorbing or releasing electrical energy to help stabilize the grid frequency.

[0068] In one optional embodiment, the monitoring device in the photovoltaic inverter can continuously track the frequency changes of the power grid, accurately measuring the rate of change of the power grid frequency through real-time sampling and signal processing technology. The preset virtual inertia coefficient can be determined in advance during the photovoltaic inverter design phase, and can be set based on factors such as the rated power of the photovoltaic inverter, the power grid frequency standard, and the expected frequency regulation capability. Different preset virtual inertia coefficients can be set for different photovoltaic inverters and different power grid environments to achieve better frequency regulation effects. Then, based on the real-time measured rate of change of the power grid frequency and the preset virtual inertia coefficient, the virtual inertia control parameters can be calculated using the photovoltaic inverter's controller. The calculated virtual inertia control parameters can then be used to dynamically adjust the control strategy of the photovoltaic inverter. Applying virtual inertia control parameters allows for the addition of a simulated inertial effect to the photovoltaic inverter by adjusting its output power when abnormal fluctuations occur in the power grid frequency, thus slowing down the rate of frequency change and providing immediate frequency support to the power grid.

[0069] In the above process, the virtual inertia control of the photovoltaic inverter can effectively mitigate the rate of change of the grid frequency, avoiding large frequency fluctuations in the event of sudden load changes or grid faults, thus protecting the power system from shocks. Virtual inertia control of the photovoltaic inverter also improves its grid connection performance, enabling it to better integrate into the grid.

[0070] In this embodiment of the invention, determining the primary frequency regulation control parameters based on the third operating state parameters includes: obtaining the actual grid frequency in the third operating state parameters; and determining the primary frequency regulation control parameters based on the preset primary frequency regulation coefficient, the grid rated frequency, and the actual grid frequency.

[0071] The aforementioned actual grid frequency can refer to the actual frequency of the current grid operation. The actual grid frequency can be affected by the balance between power supply and demand in the grid. Due to the dynamic changes in power supply and demand, the actual grid frequency will fluctuate around the standard value and can be stabilized through frequency regulation mechanisms.

[0072] The aforementioned preset primary frequency regulation coefficient refers to the pre-set control parameters used to calculate the photovoltaic inverter's participation in the grid's primary frequency regulation. The preset primary frequency regulation coefficient can reflect the speed and magnitude of the photovoltaic inverter's response frequency deviation. The setting of the preset primary frequency regulation coefficient can comprehensively consider factors such as the photovoltaic inverter's capacity, the frequency range of grid frequency changes, and the expected frequency regulation effect.

[0073] The aforementioned rated frequency of the power grid can refer to the rated frequency set in the design and operation of the power grid. For example, the rated frequency of the power grid can be 50Hz or 60Hz, etc.

[0074] In one optional embodiment, the process of determining the primary frequency regulation control parameters in the grid-connected control method for a photovoltaic inverter may include real-time monitoring of the actual grid frequency, using a frequency sensor or frequency measurement circuit for continuous monitoring. Next, the real-time measured actual grid frequency can be compared with the grid's rated frequency to calculate the frequency deviation. Then, the primary frequency regulation control parameters can be calculated based on a preset primary frequency regulation coefficient and the calculated frequency deviation. These parameters guide the photovoltaic inverter on how to adjust its output power in response to grid frequency changes. Based on these parameters, the photovoltaic inverter can adjust its output power; when the actual grid frequency is lower than the grid's rated frequency, the inverter can increase its output power; when the actual grid frequency is higher than the grid's rated frequency, the inverter can decrease its output power. This rapid response mechanism contributes to grid frequency stability.

[0075] In the above process, the primary frequency regulation mechanism allows the photovoltaic inverter to actively participate in frequency regulation when the grid frequency changes, accelerating the process of frequency recovery to the grid's rated frequency and improving the grid's frequency stability. Through the rapid response of the photovoltaic inverter, grid oscillations caused by frequency fluctuations can be mitigated, preventing damage to power equipment and ensuring the reliable operation of the grid.

[0076] In this embodiment of the invention, determining the DC bus voltage compensation control parameters based on the second operating state parameters includes: acquiring the DC bus voltage in the second operating state parameters; and using the first preset voltage loop proportional-integral controller in the photovoltaic inverter to determine the DC bus voltage compensation control parameters based on the rated DC bus voltage and the DC bus voltage of the photovoltaic inverter.

[0077] The aforementioned DC bus voltage refers to the voltage on the DC bus inside the photovoltaic inverter, connecting the DC-DC boost converter and the DC-to-AC converter. A stable DC bus voltage helps ensure the normal operation of the internal components of the photovoltaic inverter, improves energy conversion efficiency, and ensures the stability and quality of the photovoltaic inverter's output current.

[0078] The aforementioned first preset voltage loop proportional-integral controller can refer to a pre-set proportional-integral controller, and the specific parameters of the first preset voltage loop proportional-integral controller can be determined according to actual needs. The first preset voltage loop proportional-integral controller can comprehensively consider the rated voltage of the DC bus and the DC bus voltage to accurately generate DC bus voltage compensation control parameters.

[0079] The aforementioned rated DC bus voltage refers to the reference voltage value determined during the design of the photovoltaic inverter. The rated DC bus voltage represents the ideal operating state of the DC bus voltage inside the photovoltaic inverter. Maintaining the DC bus voltage near the rated DC bus voltage ensures the efficient and stable operation of the photovoltaic inverter.

[0080] In one optional embodiment, in the photovoltaic inverter grid control method based on real-time state parameters, the process of determining the DC bus voltage compensation control parameters may include: real-time monitoring of the DC bus voltage to ensure the photovoltaic inverter can respond quickly to voltage fluctuations; then, comparing the monitored DC bus voltage with the rated DC bus voltage to calculate the voltage deviation; then, inputting the voltage deviation into a first preset voltage loop proportional-integral controller, and generating DC bus voltage compensation control parameters through dynamic calculation of control parameters; the DC bus voltage compensation control parameters can adjust the operating state of the photovoltaic inverter to offset the voltage deviation and bring the DC bus voltage back to near the rated DC bus voltage.

[0081] In the above process, the DC bus voltage compensation control parameters are determined using a first preset voltage loop proportional-integral controller. A stable DC bus voltage is a prerequisite for the high-performance operation of the photovoltaic inverter. Through dynamic adjustment of the DC bus voltage compensation control parameters, the photovoltaic inverter can maintain good performance under different operating environments, such as changes in sunlight intensity and grid load fluctuations. Ensuring that the DC bus voltage is stable near the rated DC bus voltage helps the photovoltaic inverter to connect to the grid more smoothly, avoids grid connection problems caused by voltage instability, and enhances the overall safety and compatibility of the photovoltaic inverter.

[0082] In this embodiment of the invention, a first pulse width modulation signal is generated based on virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. This includes: determining the sum of the virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters; performing amplitude limiting calculation on the sum to obtain the target inductor current parameter; and using the second preset voltage loop proportional-integral controller in the photovoltaic inverter, the first pulse width modulation signal is determined based on the DC bus voltage in the second operating state parameters, the photovoltaic cell voltage in the first operating state parameters, and the target inductor current parameter.

[0083] The aforementioned target inductor current parameter can refer to the sum of the virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters, and the parameter obtained after limiting the sum.

[0084] The aforementioned second preset voltage loop proportional-integral controller can refer to a pre-set proportional-integral controller, and its specific parameters can be determined according to actual needs. The second preset voltage loop proportional-integral controller can comprehensively consider the DC bus voltage, photovoltaic cell voltage, and target inductor current parameters to accurately generate the first pulse width modulation signal.

[0085] The photovoltaic cell voltage mentioned above can refer to the voltage value generated by a single photovoltaic cell or a series-parallel combination of photovoltaic cells in a photovoltaic array under illumination. The photovoltaic cell voltage can be affected by light intensity, cell temperature, and load conditions.

[0086] In one optional embodiment, the sum of virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters can be calculated. Then, the sum can be subjected to amplitude limiting calculation to prevent the control signal from exceeding the physical limitations or safety range of the photovoltaic inverter, thus obtaining the target inductor current parameter. Next, the DC bus voltage, photovoltaic cell voltage, and target inductor current parameter can be used as inputs and fed into a second preset voltage loop proportional-integral controller. Based on the closed-loop control system of the second preset voltage loop proportional-integral controller, a first pulse width modulation signal can be generated to adjust the current and voltage of the internal circuitry of the photovoltaic inverter, thereby achieving grid support and efficient operation of the photovoltaic inverter.

[0087] In the above process, the target inductor current parameter after limiting can quickly and accurately guide the adjustment of the internal current of the photovoltaic inverter, shortening the time from detection to response and improving the photovoltaic inverter's response speed to grid changes. The introduction of the second preset voltage loop proportional-integral controller helps the photovoltaic inverter maintain efficient energy conversion under various operating conditions. When the photovoltaic cell voltage changes, it can dynamically adjust the first pulse width modulation signal, improving the power output of the photovoltaic inverter.

[0088] In this embodiment of the invention, generating a second pulse width modulation signal based on a second operating state parameter includes: acquiring the DC bus voltage in the second operating state parameter; and determining the second pulse width modulation signal based on a preset power command and the DC bus voltage using a third preset voltage loop proportional-integral controller in the photovoltaic inverter.

[0089] The aforementioned third preset voltage loop proportional-integral controller can refer to a pre-set proportional-integral controller, and its specific parameters can be determined according to actual needs. The third preset voltage loop proportional-integral controller can comprehensively consider the preset power command and the DC bus voltage to accurately generate the second pulse width modulation signal.

[0090] The aforementioned preset power command can refer to the power output target issued to the photovoltaic inverter by the photovoltaic system monitoring or management system. The preset power command can be determined based on the available power of the current photovoltaic array, grid demand, and user dispatch instructions.

[0091] In one optional embodiment, in the grid control method of the photovoltaic inverter, a second pulse width modulation signal can be determined based on the DC bus voltage and a preset power command. Specifically, the internal sensors of the photovoltaic inverter can continuously monitor and read the DC bus voltage. Then, the DC bus voltage can be compared with the target voltage value under the preset power command to calculate the voltage deviation. Next, a third preset voltage loop proportional-integral controller can be used to generate the second pulse width modulation signal based on the voltage deviation and the controller's built-in parameters. The second pulse width modulation signal can control the corresponding switching transistors in the photovoltaic inverter, adjusting the output power of the photovoltaic inverter to ensure that the photovoltaic inverter can operate stably according to the preset power command.

[0092] In the above process, combined with preset power commands, the solar energy resources can be utilized to a greater extent according to the real-time energy generation of the photovoltaic array, while meeting the needs of the power grid and the stability of the photovoltaic inverter operation, thus achieving effective energy allocation and use.

[0093] In this embodiment of the invention, generating a third pulse width modulation signal based on a first operating state parameter includes: acquiring the photovoltaic cell voltage and photovoltaic cell current in the first operating state parameter; and using a fourth preset voltage loop proportional-integral controller in the photovoltaic inverter to determine the third pulse width modulation signal based on the photovoltaic cell voltage and photovoltaic cell current.

[0094] The photovoltaic cell current mentioned above refers to the direct current generated by the photovoltaic cell under current illumination conditions. The photovoltaic cell current can be affected by light intensity, cell temperature, cell physical characteristics, and the circuit load connected to the cell.

[0095] The aforementioned fourth preset voltage loop proportional-integral controller can refer to a pre-set proportional-integral controller, and its specific parameters can be determined according to actual needs. The fourth preset voltage loop proportional-integral controller can comprehensively consider both the photovoltaic cell voltage and photovoltaic cell current to accurately generate the third pulse width modulation signal.

[0096] In an optional embodiment, the specific steps for determining the third pulse width modulation signal based on the photovoltaic cell voltage and current in the grid control method of the photovoltaic inverter may include: sensors in the photovoltaic inverter can monitor the voltage and current of the photovoltaic cells in real time. Then, a fourth preset voltage loop proportional-integral controller can be used to execute a power point tracking algorithm based on the changing trends of the photovoltaic cell voltage and current to find the voltage and current combination point where the photovoltaic cells can output maximum power under the current conditions, i.e., the maximum power point. The third pulse width modulation signal can be determined using the fourth preset voltage loop proportional-integral controller in the photovoltaic inverter. The third pulse width modulation signal can be used to control the DC-DC boost converter directly connected to the photovoltaic cells, ensuring that the photovoltaic cells can operate near the maximum power point, thereby maximizing energy conversion efficiency. The process of determining the third pulse width modulation signal can be dynamic; as the illumination conditions change, the voltage and current of the photovoltaic cells will change, and the fourth preset voltage loop proportional-integral controller can quickly respond to these changes and continuously adjust the third pulse width modulation signal to maintain the maximum power output state of the photovoltaic cells.

[0097] In the above process, by determining the third pulse width modulation signal, the maximum power point of the photovoltaic cell can be dynamically tracked. This allows the photovoltaic inverter to extract as much energy as possible from the photovoltaic cell, significantly improving the overall energy conversion efficiency of the inverter. Stable control of the photovoltaic cell current helps maintain the stable operation of the inverter's internal circuitry, preventing system failures caused by instability during energy conversion.

[0098] The technical solution proposed in this application is described below with reference to an optional embodiment. This application proposes a grid control method for a photovoltaic inverter without energy storage. This application allows a photovoltaic inverter with multi-channel power point tracking (DPPT) function to accurately assess reserved power when operating under power constraints, achieving grid control without energy storage. The photovoltaic inverter and grid control method proposed in this application include three parts: a DC-DC boost converter with power point tracking control, a DC-DC boost converter with grid control, and a DC-to-AC converter with grid control. The DC-DC boost converter with power point tracking control and the DC-DC boost converter with grid control are connected to the grid via a DC bus and then fed into the grid through the DC-to-AC converter with grid control.

[0099] Figure 2 This is a schematic diagram illustrating the structure and connection relationship of an optional photovoltaic inverter according to an embodiment of the present invention, as shown below. Figure 2As shown in the figure, the photovoltaic inverter includes a DC boost transformer 1 adopting the maximum power point tracking (MPPT) mode, a DC boost transformer 2 adopting the MPPT mode, and so on, a DC boost transformer N adopting the MPPT mode, a DC boost transformer N+1 adopting the grid-forming control mode, and so on, a DC boost transformer M adopting the grid-forming control mode. The input end of the DC boost transformer 1 in the MPPT mode is connected to the photovoltaic array 1, the DC boost transformer 2 adopting the MPPT mode is connected to the photovoltaic array 2, and so on, the DC boost transformer N adopting the MPPT mode is connected to the photovoltaic array N, the DC boost transformer N+1 adopting the grid-forming control mode is connected to the photovoltaic array N+1, and so on, the DC boost transformer M adopting the grid-forming control mode is connected to the photovoltaic array M. The output ends of the DC boost transformer 1 adopting the MPPT mode, the DC boost transformer 2 adopting the MPPT mode, and so on, the DC boost transformer N adopting the MPPT mode, the DC boost transformer N+1 adopting the grid-forming control mode, and so on, the DC boost transformer M adopting the grid-forming control mode are connected to the DC bus. The input end of the DC-to-AC converter adopting the grid-forming control mode is connected to the DC bus, and the output end of the DC-to-AC converter adopting the grid-forming control mode is connected to the power grid. The MPPT control module in the photovoltaic inverter is connected to multiple DC boost transformers adopting the MPPT mode and outputs information to the reserved power evaluation module. The reserved power evaluation module can output signals to the grid-forming control module. The grid-forming control module is connected to multiple DC boost transformers adopting the grid-forming control mode and is connected to the DC-to-AC converter adopting the grid-forming control mode.

[0100] The control strategy of the photovoltaic inverter can include three parts: a reserved power evaluation module, a grid-forming control module, and an MPPT control module. Among them, the reserved power evaluation module can accurately evaluate the reserved power of the photovoltaic inverter and provide real-time and accurate reserved power capacity evaluation for primary frequency modulation and inertia support control. The specific method is as follows: Among the M MPPT branches accessed by the photovoltaic inverter, in the k-th time period, randomly select N branches (N<M) operating in the MPPT mode, and assume that the output power of this branch is P MPPT_i (k), (i = 1...N), then according to the following formula, the maximum power P max that the photovoltaic inverter can output under the current temperature and light conditions can be calculated.

[0101]

[0102] And to ensure the accuracy of the calculation, in the k+1 time period, randomly select N branches again.

[0103] Next, the actual output power P 输出 of the photovoltaic inverter at this time can be calculated:

[0104]

[0105] In the formula, P i (k), (i=1,...M) represents the actual output power of branch k.

[0106] Next, the reserved power P of the photovoltaic inverter can be calculated at this time. 预留 :

[0107] P 预留 =P max -P 输出 ;

[0108] The network control module may consist of multiple sub-modules, including virtual inertia control, primary frequency regulation control, DC bus voltage compensation control, inductor current reference command generation, DC boost converter current control, and DC-to-AC converter power control.

[0109] The virtual inertia control submodule can use frequency derivative df / dt feedback for inertia support control.

[0110]

[0111] in, k is the virtual inertia control parameter. H The virtual inertia coefficient is the preset virtual inertia coefficient; the rate of change of the power grid frequency df / dt during the disturbance can be measured and recorded in real time by the feedback control system.

[0112] The primary frequency control submodule can use frequency feedback for primary frequency control.

[0113]

[0114] in, For primary frequency modulation control parameters, k f is the primary frequency regulation coefficient, i.e., the preset primary frequency regulation coefficient; f* is the rated frequency of the power grid, and f is the actual frequency of the power grid measured by the feedback control system.

[0115] The DC bus voltage compensation control submodule can use DC bus voltage feedback for DC bus voltage compensation control.

[0116]

[0117] in, Here are the DC bus voltage compensation control parameters, and G1(s) is the voltage loop proportional-integral (PI) controller, expressed as: That is, the first preset voltage loop proportional-integral controller; The rated voltage of the DC bus, V dc This is the DC bus voltage.

[0118] The inductor current reference command generation submodule can calculate the sum of the inductor current reference values ​​obtained from the above virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. After limiting calculation, it is evenly distributed among (MN) DC boost converters as the reference command for the inductor current of each DC boost converter.

[0119] I * L =min(I * L2 I * L2_max );

[0120] Among them, I * L For the target inductor current parameter, I * L2 =(I * Ldf +I * Lf +I * L1 ) / (MN).

[0121] The DC-DC boost converter current control submodule can control the current based on the inductor current reference command I. L It generates a duty cycle d and produces a pulse width modulation signal to drive the DC-DC boost converter.

[0122]

[0123] Wherein, G3(s) is a voltage loop proportional-integral (PI) controller, expressed as: That is, the second preset voltage loop proportional-integral controller; V PV This refers to the voltage of the photovoltaic cell.

[0124] DC-to-AC converter power control can be based on preset power commands. A power closed-loop is used in the inverter so that the output power of the DC-to-AC converter is P. f This allows us to determine the second pulse width modulation signal.

[0125] The power point tracking control module can sample the photovoltaic cell voltage V. PV and photovoltaic cell current I PV And the power point tracking voltage is calculated. and the photovoltaic cell voltage V PV Perform closed-loop calculations to obtain the larger value I of the DC-DC boost converter inductor current. *L2_max .

[0126]

[0127] Wherein, G2(s) is a voltage loop proportional-integral (PI) controller, and its expression is: That is, the fourth preset voltage loop proportional-integral controller.

[0128] This application can be applied to photovoltaic inverters, and can achieve grid control of photovoltaic inverters by controlling the photovoltaic branches without the need for energy storage.

[0129] According to another aspect of the present invention, a grid-connection control device for a photovoltaic inverter is also provided. The photovoltaic inverter includes: a plurality of DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminal of the DC-DC boost converter is connected to the photovoltaic array, the output terminal of the DC-DC boost converter is connected to the DC bus, the input terminal of the DC-to-AC converter is connected to the DC bus, and the output terminal of the DC-to-AC converter is connected to the power grid. This device can execute the grid-connection control method for the photovoltaic inverter described in the above embodiments. The specific implementation method and preferred application scenarios are the same as those in the above embodiments, and will not be repeated here.

[0130] Figure 3 This is a schematic diagram of a grid control device for a photovoltaic inverter according to an embodiment of this application, as shown below. Figure 3 As shown, the device includes the following: a first acquisition module 302, a second acquisition module 304, a generation module 306, and a control module 308.

[0131] The system comprises: a first acquisition module 302 for acquiring the operating mode of the DC-DC boost converter, wherein the operating mode includes one of the following: power point tracking mode and grid control mode; a second acquisition module 304 for acquiring the first operating state parameters of the photovoltaic array, the second operating state parameters of the photovoltaic inverter, and the third operating state parameters of the power grid; a generation module 306 for generating a target pulse width modulation signal based on the first operating state parameters, the second operating state parameters, and / or the third operating state parameters, wherein the target pulse width modulation signal includes: a first pulse width modulation signal, a second pulse width modulation signal, and a third pulse width modulation signal; and a control module 308 for controlling the DC-DC boost converter operating in grid control mode based on the first pulse width modulation signal, controlling the DC-DC to AC converter operating based on the second pulse width modulation signal, and controlling the DC-DC boost converter operating in power point tracking mode based on the third pulse width modulation signal.

[0132] In this embodiment of the invention, generating a first pulse width modulation signal based on a first operating state parameter, a second operating state parameter, and a third operating state parameter includes: determining target control parameters based on the first operating state parameter, the second operating state parameter, and / or the third operating state parameter, wherein the target control parameters include virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. The virtual inertia control parameters represent control parameters for adding simulated inertial effects to the photovoltaic inverter, the primary frequency modulation control parameters represent parameters for controlling the photovoltaic inverter to participate in grid frequency regulation, and the DC bus voltage compensation control parameters represent control parameters for voltage compensation of the DC bus in the photovoltaic inverter; and generating the first pulse width modulation signal based on the virtual inertia control parameters, the primary frequency modulation control parameters, and the DC bus voltage compensation control parameters.

[0133] In this embodiment of the invention, determining virtual inertia control parameters based on a third operating state parameter includes: obtaining the power grid frequency change rate in the third operating state parameter; and determining the virtual inertia control parameters based on a preset virtual inertia coefficient and the power grid frequency change rate.

[0134] In this embodiment of the invention, determining the primary frequency regulation control parameters based on the third operating state parameters includes: obtaining the actual grid frequency in the third operating state parameters; and determining the primary frequency regulation control parameters based on the preset primary frequency regulation coefficient, the grid rated frequency, and the actual grid frequency.

[0135] In this embodiment of the invention, determining the DC bus voltage compensation control parameters based on the second operating state parameters includes: acquiring the DC bus voltage in the second operating state parameters; and using the first preset voltage loop proportional-integral controller in the photovoltaic inverter to determine the DC bus voltage compensation control parameters based on the rated DC bus voltage and the DC bus voltage of the photovoltaic inverter.

[0136] In this embodiment of the invention, a first pulse width modulation signal is generated based on virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters. This includes: determining the sum of the virtual inertia control parameters, primary frequency modulation control parameters, and DC bus voltage compensation control parameters; performing amplitude limiting calculation on the sum to obtain the target inductor current parameter; and using the second preset voltage loop proportional-integral controller in the photovoltaic inverter, the first pulse width modulation signal is determined based on the DC bus voltage in the second operating state parameters, the photovoltaic cell voltage in the first operating state parameters, and the target inductor current parameter.

[0137] In this embodiment of the invention, generating a second pulse width modulation signal based on a second operating state parameter includes: acquiring the DC bus voltage in the second operating state parameter; and determining the second pulse width modulation signal based on a preset power command and the DC bus voltage using a third preset voltage loop proportional-integral controller in the photovoltaic inverter.

[0138] In this embodiment of the invention, generating a third pulse width modulation signal based on a first operating state parameter includes: acquiring the photovoltaic cell voltage and photovoltaic cell current in the first operating state parameter; and using a fourth preset voltage loop proportional-integral controller in the photovoltaic inverter to determine the third pulse width modulation signal based on the photovoltaic cell voltage and photovoltaic cell current.

[0139] Embodiments of this application also provide an electronic device, including: a memory storing an executable program; and a processor for running the program, wherein the program executes the methods in various embodiments of the present invention during runtime.

[0140] The aforementioned memory can refer to devices inside a computer used to store data and programs, including RAM, hard disks, etc. RAM can be used to temporarily store running programs and data, while hard disks can be used to store programs and data long-term. Memory enables the computer to read and write data and execute programs. The aforementioned processor is responsible for executing instructions in computer programs and performing data processing. It can also be responsible for controlling and executing various operations, including arithmetic operations, logical operations, and data transmission.

[0141] Embodiments of this application also provide a computer-readable storage medium including a stored executable program, wherein, when the executable program is running, it controls the device where the computer-readable storage medium is located to perform the methods of various embodiments of the present invention.

[0142] The aforementioned computer storage media can refer to the media used in computer memory to store certain discontinuous physical quantities. Computer storage media mainly include semiconductors, magnetic cores, magnetic drums, magnetic tapes, laser discs, etc. Computer-readable storage media include stored programs, which can be a set of instructions that a computer can recognize and execute, running on an electronic computer to meet certain information needs.

[0143] Embodiments of this application also provide a computer program product, including a computer program that, when executed by a processor, implements the methods of various embodiments of the present invention.

[0144] The aforementioned computer program products can refer to software programs that have been written, tested, and released, and can run on computers or other devices. Computer program products can include application programs, operating systems, utility software, etc., used to achieve specific functions or solve specific problems.

[0145] Embodiments of this application also provide a computer program product, including a non-volatile computer-readable storage medium for storing a computer program that, when executed by a processor, implements the methods in various embodiments of the present invention.

[0146] The aforementioned non-volatile computer-readable storage medium can refer to a medium for storing data. Non-volatile computer-readable storage media can retain data without loss when power is off and can be used to store long-term data, such as operating systems, applications, and user files. Non-volatile storage media can include hard disk drives, solid-state drives, optical disks, and flash memory storage devices, etc.

[0147] Embodiments of this application also provide a computer program that, when executed by a processor, implements the methods described in the various embodiments of the present invention.

[0148] The aforementioned computer program can refer to a set of instructions used to tell the computer to perform specific tasks or operations. Computer programs can be written by programmers using specific programming languages ​​and can include algorithms, data structures, logic, and control flow. Computer programs can be used for a variety of purposes, including application software, operating systems, etc.

[0149] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0150] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection can be through some interfaces; the indirect coupling or communication connection between units or modules can be electrical or other forms.

[0151] 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 units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0152] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0153] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0154] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A grid-connected control method for a photovoltaic inverter, characterized in that, The photovoltaic inverter includes: multiple DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminals of the DC-DC boost converters are connected to the photovoltaic array, the output terminals of the DC-DC boost converters are connected to the DC bus, the input terminals of the DC-to-AC converters are connected to the DC bus, and the output terminals of the DC-to-AC converters are connected to the power grid. The method includes: Obtain the operating mode of the DC-DC boost converter, wherein the operating mode includes one of the following: power point tracking mode and grid control mode; Obtain the first operating status parameters of the photovoltaic array, the second operating status parameters of the photovoltaic inverter, and the third operating status parameters of the power grid; Based on the first operating state parameter, the second operating state parameter and / or the third operating state parameter, a target pulse width modulation signal is generated, wherein the target pulse width modulation signal includes: a first pulse width modulation signal, a second pulse width modulation signal and a third pulse width modulation signal; The DC-DC boost converter is controlled to operate in the network control mode based on the first pulse width modulation signal, the DC-to-AC converter is controlled to operate based on the second pulse width modulation signal, and the DC-DC boost converter is controlled to operate in the power point tracking mode based on the third pulse width modulation signal.

2. The grid control method for photovoltaic inverters according to claim 1, characterized in that, Based on the first operating state parameter, the second operating state parameter, and the third operating state parameter, the first pulse width modulation signal is generated, including: Based on the first operating state parameter, the second operating state parameter, and / or the third operating state parameter, target control parameters are determined, wherein the target control parameters include virtual inertia control parameters, primary frequency regulation control parameters, and DC bus voltage compensation control parameters. The virtual inertia control parameters are used to represent control parameters for adding simulated inertial effects to the photovoltaic inverter. The primary frequency regulation control parameters are used to represent parameters for controlling the photovoltaic inverter to participate in the frequency regulation of the power grid. The DC bus voltage compensation control parameters are used to represent control parameters for voltage compensation of the DC bus in the photovoltaic inverter. The first pulse width modulation signal is generated based on the virtual inertia control parameters, the primary frequency modulation control parameters, and the DC bus voltage compensation control parameters.

3. The grid control method for photovoltaic inverters according to claim 2, characterized in that, Based on the third operating state parameter, the virtual inertia control parameters are determined, including: Obtain the grid frequency change rate from the third operating state parameter; The virtual inertia control parameters are determined based on the preset virtual inertia coefficient and the power grid frequency change rate.

4. The grid control method for photovoltaic inverters according to claim 2, characterized in that, Based on the third operating state parameter, the primary frequency regulation control parameters are determined, including: Obtain the actual power grid frequency from the third operating state parameters; The primary frequency regulation control parameters are determined based on the preset primary frequency regulation coefficient, the rated frequency of the power grid, and the actual frequency of the power grid.

5. The grid control method for a photovoltaic inverter according to claim 2, characterized in that, Based on the second operating state parameters, the DC bus voltage compensation control parameters are determined, including: Obtain the DC bus voltage from the second operating status parameters; Using the first preset voltage loop proportional-integral controller in the photovoltaic inverter, the DC bus voltage compensation control parameters are determined based on the rated DC bus voltage and the DC bus voltage of the photovoltaic inverter.

6. The grid control method for photovoltaic inverters according to claim 2, characterized in that, Based on the virtual inertia control parameters, the primary frequency modulation control parameters, and the DC bus voltage compensation control parameters, the first pulse width modulation signal is generated, including: Determine the sum of the virtual inertia control parameters, the primary frequency modulation control parameters, and the DC bus voltage compensation control parameters; The sum is subjected to amplitude limiting calculation to obtain the target inductor current parameters; The first pulse width modulation signal is determined using the second preset voltage loop proportional-integral controller in the photovoltaic inverter, based on the DC bus voltage in the second operating state parameters, the photovoltaic cell voltage in the first operating state parameters, and the target inductor current parameter.

7. The grid control method for a photovoltaic inverter according to claim 1, characterized in that, Based on the second operating state parameters, the second pulse width modulation signal is generated, including: Obtain the DC bus voltage from the second operating status parameters; The second pulse width modulation signal is determined using the third preset voltage loop proportional-integral controller in the photovoltaic inverter, based on the preset power command and the DC bus voltage.

8. The grid control method for a photovoltaic inverter according to claim 1, characterized in that, Based on the first operating state parameters, the third pulse width modulation signal is generated, including: Obtain the photovoltaic cell voltage and photovoltaic cell current from the first operating state parameters; The third pulse width modulation signal is determined based on the photovoltaic cell voltage and the photovoltaic cell current using the fourth preset voltage loop proportional-integral controller in the photovoltaic inverter.

9. A grid-connection control device for a photovoltaic inverter, characterized in that, The photovoltaic inverter includes: multiple DC-DC boost converters, a DC bus, and a DC-to-AC converter. The input terminals of the DC-DC boost converters are connected to the photovoltaic array, the output terminals of the DC-DC boost converters are connected to the DC bus, the input terminals of the DC-to-AC converters are connected to the DC bus, and the output terminals of the DC-to-AC converters are connected to the power grid. The device includes: The first acquisition module is used to acquire the operating mode of the DC-DC boost converter, wherein the operating mode includes one of the following: power point tracking mode and grid control mode; The second acquisition module is used to acquire the first operating status parameters of the photovoltaic array, the second operating status parameters of the photovoltaic inverter, and the third operating status parameters of the power grid. The generation module is used to generate a target pulse width modulation signal based on the first operating state parameter, the second operating state parameter and / or the third operating state parameter, wherein the target pulse width modulation signal includes: a first pulse width modulation signal, a second pulse width modulation signal and a third pulse width modulation signal; The control module is configured to control the operation of the DC-DC boost converter in the network control mode based on the first pulse width modulation signal, control the operation of the DC-to-AC converter based on the second pulse width modulation signal, and control the operation of the DC-DC boost converter in the power point tracking mode based on the third pulse width modulation signal.

10. An electronic device, characterized in that, include: Memory, which stores executable programs; A processor for running the program, wherein the program executes the grid control method for a photovoltaic inverter according to any one of claims 1 to 8 when it runs.

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