Network construction string type photovoltaic system control method, electronic equipment, storage medium and product

Abstract

The invention discloses a network construction type string photovoltaic system control method, electronic equipment, a storage medium and a product, and relates to the technical field of photovoltaic systems, the disclosed network construction type string photovoltaic system control method comprises the following steps: controlling a first boost conversion circuit in each boost conversion circuit by adopting a maximum power tracking strategy, the maximum power value of the first boost conversion circuit is determined as a power given base value of the inverter circuit; a DC voltage given strategy is adopted to control a second boost conversion circuit in each boost conversion circuit, and the second boost conversion circuit is a circuit except the first boost conversion circuit in each boost conversion circuit; and the inverter circuit is controlled by adopting a network construction strategy. According to the invention, the control complexity of the network-forming string type photovoltaic system can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic systems, and in particular to control methods, electronic devices, storage media and products of grid-type string photovoltaic systems. Background Art

[0002] As the proportion of photovoltaic grid-connected power generation connected to the power grid increases, the mutual impact between photovoltaic grid-connected power generation systems and power systems cannot be ignored.

[0003] In the existing grid-type string photovoltaic technology, the main focus is on improving the control algorithm of the photovoltaic equipment as a whole to adapt to the needs of different scenarios. This involves more mode switching or the introduction of additional adaptive algorithms, which increases the control difficulty and complexity of the system.

[0004] In summary, how to reduce the control complexity of grid-type string photovoltaic systems has become a technical problem that needs to be urgently solved in this field. Summary of the invention

[0005] The main purpose of the present application is to provide a control method, electronic equipment, storage medium and product for a grid-type string photovoltaic system, aiming to reduce the control complexity of the grid-type string photovoltaic system.

[0006] To achieve the above-mentioned purpose, the present application proposes a control method for a grid-type string photovoltaic system, which is applied to a grid-type string photovoltaic system, wherein the system comprises a string photovoltaic unit, wherein the string photovoltaic unit comprises a plurality of photovoltaic modules, a plurality of boost conversion circuits and an inverter circuit, wherein each of the photovoltaic modules is correspondingly connected to each of the boost conversion circuits, each of the boost conversion circuits is respectively connected to the inverter circuit, and the inverter circuit is connected to a power grid;

[0007] The control method of the grid-type string photovoltaic system includes:

[0008] A maximum power tracking strategy is adopted to control a first boost conversion circuit in each of the boost conversion circuits, and a maximum power value of the first boost conversion circuit is determined as a power given base value of the inverter circuit;

[0009] A DC voltage setting strategy is used to control a second boost conversion circuit in each of the boost conversion circuits, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits other than the first boost conversion circuit;

[0010] A grid-building strategy is adopted to control the inverter circuit.

[0011] In one embodiment, the step of controlling the second boost conversion circuit in each of the boost conversion circuits by adopting a DC voltage setting strategy includes:

[0012] After receiving the system startup instruction, controlling the second boost conversion circuit to start, and determining the DC bus voltage value of the second boost conversion circuit according to the AC voltage value to be output of the inverter circuit;

[0013] The duty cycle of the second boost conversion circuit is set according to the DC voltage setting strategy and the DC bus voltage value, so that the DC voltage value output by the second boost conversion circuit is the DC bus voltage value.

[0014] In one embodiment, the step of controlling the inverter circuit using a networking strategy includes:

[0015] Determining whether the voltage is stable by monitoring the DC voltage value output by the second boost conversion circuit;

[0016] After determining that the voltage is stable, the inverter circuit is controlled to start at zero power, and the inverter circuit is controlled to synchronize with the power grid according to a grid-forming strategy.

[0017] In one embodiment, the step of controlling the first boost converter circuit in each of the boost converter circuits by adopting the maximum power tracking strategy includes:

[0018] After determining that the inverter circuit is successfully synchronized with the power grid, the first boost conversion circuit in the boost conversion circuit is controlled to start, and the first boost conversion circuit is controlled according to the strategy using maximum power.

[0019] In one embodiment, after the step of determining the maximum power value of the first boost conversion circuit as the power given base value of the inverter circuit, the method further includes:

[0020] Acquire an operation mode of the inverter circuit, wherein the operation mode is a full grid-building mode, a residual capacity full power generation mode, or a limited power generation mode;

[0021] The active power of the inverter circuit is adjusted according to the operation mode and the power given base value.

[0022] In one embodiment, the step of adjusting the active power of the inverter circuit according to the operation mode and the power given base value includes:

[0023] When the operation mode is the full grid mode, the active power value of the inverter circuit is set to the power given base value;

[0024] When the operation mode is the remaining capacity full power generation mode, a grid-forming adjustment power value is determined according to a preset frequency regulation requirement, and the active power value of the inverter circuit is set to be the full power value minus the grid-forming adjustment power value, wherein the full power value is the number of the boost conversion circuits multiplied by the power given base value;

[0025] When the operation mode is the limited power generation mode, the active power is set according to a preset Internet access requirement, and the value of the active power is between the power given base value and the full power value.

[0026] In one embodiment, the method further comprises:

[0027] Determining an active power given value according to the active power of the inverter circuit, a preset gain coefficient and a grid frequency deviation value;

[0028] Set the dynamic limit value of the active power given value to Wherein, Q represents the reactive power of the inverter circuit, n represents the number of the boost converter circuits, P mpp Indicates the power reference base value.

[0029] In addition, to achieve the above purpose, the present application also proposes a grid-type string photovoltaic system control device, the grid-type string photovoltaic system control device comprising:

[0030] A first boost conversion circuit control module, configured to control a first boost conversion circuit among the boost conversion circuits by adopting a maximum power tracking strategy, and determine a maximum power value of the first boost conversion circuit as a power given base value of the inverter circuit;

[0031] A second boost conversion circuit control module, used to control a second boost conversion circuit in each of the boost conversion circuits using a DC voltage setting strategy, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits except the first boost conversion circuit;

[0032] The inverter circuit control module is used to control the inverter circuit using a networking strategy.

[0033] In addition, to achieve the above-mentioned purpose, the present application also proposes an electronic device, which includes: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the grid-type string photovoltaic system control method as described above.

[0034] In addition, to achieve the above-mentioned purpose, the present application also proposes a storage medium, which is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by the processor, the steps of the control method of the grid-type string photovoltaic system as described above are implemented.

[0035] In addition, to achieve the above-mentioned purpose, the present application also provides a computer program product, which includes a computer program, and when the computer program is executed by a processor, it implements the steps of the grid-type string photovoltaic system control method as described above.

[0036] The present application proposes a control method for a grid-type string photovoltaic system, which is applied to a grid-type string photovoltaic system. The system includes a string photovoltaic unit, which includes multiple photovoltaic components, multiple boost conversion circuits and one inverter circuit. Each photovoltaic component is correspondingly connected to each boost conversion circuit, each boost conversion circuit is respectively connected to the inverter circuit, and the inverter circuit is connected to the power grid; a maximum power point tracking strategy is adopted to control the first boost conversion circuit in the string photovoltaic unit, and the maximum power value of the first boost conversion circuit is used as the power setting base value of the inverter circuit; for all other boost conversion circuits except the first boost conversion circuit (collectively referred to as the second boost conversion circuit), a DC voltage setting strategy is adopted for control; the inverter circuit is regulated by a grid-type control strategy to ensure that the system can be smoothly and efficiently integrated into the power grid for operation.

[0037] In summary, the present application clearly distinguishes and independently controls the first boost conversion circuit (maximum power point tracking strategy control) and the remaining boost conversion circuits (DC voltage setting strategy control). The maximum power tracking strategy ensures that the photovoltaic module can output maximum power under any lighting conditions, and sets the value of the maximum power as the power setting reference value of the inverter circuit, setting a reference for the energy output of the entire system to ensure that the power of the system can be transmitted to the power grid, while the DC voltage setting strategy ensures the stability of the internal voltage of the system and reduces energy loss. The grid-forming strategy controls the inverter circuit, improves the output power quality, and enhances the compatibility and stability of the system and the power grid, so that it can more flexibly adapt to different power grid conditions and operating environments, thereby avoiding complex mode switching and adaptive algorithm requirements, and reducing the control complexity of the grid-forming string photovoltaic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] FIG. 1( a ) is a schematic diagram of a control structure of a conventional photovoltaic system boost conversion circuit provided in the present application;

[0041] FIG1( b ) is a schematic diagram of a control structure of a conventional photovoltaic system inverter circuit provided in the present application;

[0042] Figure 2 A flow chart of the control method for a grid-type string photovoltaic system provided in Embodiment 1 of the present application;

[0043] Figure 3 A schematic diagram of the structure of a grid-type string-type photovoltaic system provided in Example 1 of the control method for a grid-type string-type photovoltaic system of the present application;

[0044] Figure 4 A schematic diagram of the structure of a string photovoltaic unit provided in Example 1 of the control method for a grid-type string photovoltaic system of the present application;

[0045] Figure 5 A schematic diagram of operating power points provided in Example 2 of the control method for a grid-type string photovoltaic system of the present application;

[0046] Figure 6 This is a schematic diagram of the module structure of a grid-type string photovoltaic system control device according to an embodiment of the present application;

[0047] Figure 7 Schematic diagram of the equipment structure of the hardware operating environment involved in the control method of the grid-type string photovoltaic system in the embodiment of the present application.

[0048] The purpose, features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0049] It should be understood that the specific embodiments described herein are only used to explain the technical solutions of the present application and are not used to limit the present application.

[0050] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0051] The main solution of the embodiment of the present application is: applied to a grid-type string photovoltaic system, the system includes a string photovoltaic unit, the string photovoltaic unit includes multiple photovoltaic components, multiple boost conversion circuits and one inverter circuit, each of the photovoltaic components is correspondingly connected to each of the boost conversion circuits, each of the boost conversion circuits is respectively connected to the inverter circuit, and the inverter circuit is connected to the power grid; a maximum power tracking strategy is adopted to control the first boost conversion circuit in each of the boost conversion circuits, and the maximum power value of the first boost conversion circuit is determined as the power given base value of the inverter circuit; a DC voltage given strategy is adopted to control the second boost conversion circuit in each of the boost conversion circuits, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits except the first boost conversion circuit; a grid-type strategy is adopted to control the inverter circuit.

[0052] In the existing grid-type string photovoltaic technology, the main focus is on improving the control algorithm of the photovoltaic equipment as a whole to adapt to the needs of different scenarios. This involves more mode switching or the introduction of additional adaptive algorithms, which increases the control difficulty and complexity of the system.

[0053] Specifically, the traditional grid-forming string photovoltaic control architecture is shown in Figure 1(a) and Figure 1(b), where Figure 1(a) is the control structure of the DC / DC side of the photovoltaic system (i.e., the boost conversion circuit), which switches between the grid forming mode (GF) and the limited grid forming mode (LGF) according to the specific scenario. In the GF mode, the output duty cycle d of the circuit is changed by the PI regulator to stabilize the DC voltage, thereby achieving the output DC voltage V dc For a given DC voltage V dc ref In LGF mode, the maximum power tracking is used to track the V pv and i pv , the maximum power point tracking (MPPT) algorithm is used to obtain the DC voltage V corresponding to the maximum power point pv ref , the PI regulator changes the output duty cycle d of the circuit to achieve the photovoltaic panel DC voltage V pv V pv ref Figure 1(b) shows the active outer loop control structure of the PV system DC / AC side (i.e., inverter circuit). The actual active power p passes through the low-pass filter p LPF Then it is compared with the power given p*, and the difference is generated through the droop link dw to generate the frequency difference and frequency feedforward w 0The control frequency w is generated by weighting, and the frequency w is passed through the integrator to generate the final control phase θ. For the limited grid mode, it is necessary to introduce an additional Δw term when generating the frequency. This is because the DC / DC side of the photovoltaic system in the limited grid mode no longer stably outputs the DC voltage V dc Therefore, this part of the function needs to be transferred to the DC / AC side of the photovoltaic system to complete, and V is realized by changing Δw through the PI regulator dc For a given DC voltage V dc ref Since the power of the photovoltaic system can only flow into the grid in one direction, the PI regulator needs to set the upper limit to 0 to prevent the power from flowing in reverse to the DC voltage V dc Charging. Therefore, in the traditional grid-forming string photovoltaic system control scheme, in order to have both DC bus voltage control and MPPT (Maximum Power Point Tracking) tracking functions, it is necessary to switch the model according to the lighting conditions or instruction requirements. When the light is insufficient or MPPT is required, switch to the restricted grid-forming mode. At the same time, in order to prevent the increase in DC voltage caused by the increase in DC side power during the MPPT process, the AC side needs to adjust the power angle synchronously. Considering the operation of the photovoltaic PU (power-voltage) curve in the stable area, an additional mode automatic switching judgment condition is added, that is, when the DC voltage is too low, it will naturally switch from the grid-forming mode to the restricted grid-forming mode to prevent the AC side power from continuously pulling down the DC voltage and causing the system to crash. The control difficulty and complexity of the whole process are relatively high.

[0054] The present application provides a solution, by clearly distinguishing and independently controlling the first boost conversion circuit (controlled by the maximum power point tracking strategy) and the remaining boost conversion circuits (controlled by the DC voltage setting strategy), the maximum power tracking strategy ensures that the photovoltaic module can output the maximum power under any lighting conditions, and sets the value of the maximum power as the power setting reference value of the inverter circuit, setting the reference for the energy output of the entire system, while the DC voltage setting strategy ensures the stability of the internal voltage of the system and reduces energy loss. The grid-forming strategy controls the inverter circuit, improves the output power quality, and enhances the compatibility and stability of the system with the power grid, so that it can adapt to different power grid conditions and operating environments more flexibly, thereby avoiding complex mode switching and adaptive algorithm requirements, and reducing the control complexity of the grid-forming string photovoltaic system.

[0055] It should be noted that the execution subject of this embodiment can be an electronic device with data processing, network communication and program running functions, such as a computer, a server, etc., or an electronic device capable of realizing the above functions, etc. The following takes the control terminal of a grid-type string photovoltaic system as an example to illustrate this embodiment and the following embodiments.

[0056] Based on this, the present application embodiment provides a control method for a grid-type string photovoltaic system, referring to Figure 2 , Figure 2 This is a flow chart of the first embodiment of the control method of the grid-type string photovoltaic system of the present application.

[0057] In this embodiment, a grid-type string photovoltaic system control method is applied to a grid-type string photovoltaic system, wherein the system includes a string photovoltaic unit, wherein the string photovoltaic unit includes a plurality of photovoltaic components, a plurality of boost conversion circuits and an inverter circuit, wherein each of the photovoltaic components is correspondingly connected to each of the boost conversion circuits, each of the boost conversion circuits is respectively connected to the inverter circuit, and the inverter circuit is connected to a power grid.

[0058] Based on this, in this embodiment, the control method of the grid-type string photovoltaic system includes steps S10 to S30:

[0059] Step S10, adopting a maximum power tracking strategy to control the first boost conversion circuit among the boost conversion circuits, and determining the maximum power value of the first boost conversion circuit as the power given base value of the inverter circuit;

[0060] It should be noted that the maximum power point tracking strategy is an intelligent control algorithm for photovoltaic systems. It adjusts the operating point of photovoltaic modules in real time so that they always operate under the voltage and current conditions that can output maximum power, thereby maximizing the power generation efficiency of the photovoltaic system.

[0061] The maximum power tracking strategy is adopted to optimize the control of the first boost conversion circuit in the string photovoltaic unit. The first boost conversion circuit in the unit is set to the first boost circuit controlled by the MPPT strategy to ensure that it operates at the maximum power point that the photovoltaic module can provide. The maximum power value reached by this first boost conversion circuit is set as the power given reference value of the inverter circuit, setting a reference for the energy output of the entire unit.

[0062] Step S20, using a DC voltage setting strategy to control a second boost conversion circuit in each of the boost conversion circuits, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits other than the first boost conversion circuit;

[0063] For all boost conversion circuits except the first boost conversion circuit (collectively referred to as the second boost conversion circuit), a DC voltage setting strategy is adopted for control to maintain the DC voltage at the output end of each second boost conversion circuit stable at a preset value, ensure the internal voltage balance of the system, and assist in achieving stable operation of the overall system.

[0064] Step S30: adopting a network-building strategy to control the inverter circuit.

[0065] The inverter circuit is controlled by a grid-building strategy, which can be droop control, virtual synchronous machine control, etc. This strategy can not only enable the photovoltaic system to better adapt to the dynamic changes of the power grid, such as voltage fluctuations and frequency offsets, but also improve the system's grid-connected friendliness and stability, and achieve harmonious interaction with the power grid.

[0066] For example, the grid-type string photovoltaic system in this embodiment is as follows: Figure 3 As shown in FIG. 1 , the system is composed of multiple string photovoltaic units, which converge at the PCC point (Point of Common Coupling) and then connect to the grid. Figure 4 As shown, a string photovoltaic unit integrates multiple photovoltaic modules, multiple boost conversion circuits (i.e., n DC / DC boost circuits in the figure) and one inverter circuit (i.e., DC / AC inverter circuit in the figure). The photovoltaic modules are connected to the corresponding boost conversion circuits one by one to achieve voltage boost. The first boost conversion circuit in the multiple boost conversion circuits adopts MPPT control and converts the current maximum power P mpp The second to nth step-up conversion circuits are controlled by the DC voltage setting strategy according to the given DC bus voltage value V deref Output DC voltage V dc The outputs of each boost converter circuit are gathered to the inverter circuit, which is controlled by a network-based control strategy, such as droop control, virtual synchronous machine control, etc. The network-based control of the inverter circuit can be specifically P ref =P set +K fdrp (1-w r pu ), where P ref Indicates the active power given value, P set Indicates active power, K fdrp Represents the gain factor, 1-w r pu It represents the frequency deviation value of the power grid, and finally converts the DC power into AC power through the inverter circuit and connects it to the power grid.

[0067] In summary, the embodiment of the present application clearly distinguishes and independently controls the first boost conversion circuit (maximum power point tracking strategy control) and the remaining boost conversion circuits (DC voltage setting strategy control). The maximum power tracking strategy ensures that the photovoltaic module can output maximum power under any lighting conditions, and sets the value of the maximum power as the power setting reference value of the inverter circuit, setting a reference for the energy output of the entire system, while the DC voltage setting strategy ensures the stability of the internal voltage of the system and reduces energy loss. The grid-forming strategy controls the inverter circuit, improves the output power quality, and enhances the compatibility and stability of the system with the power grid, so that it can more flexibly adapt to different power grid conditions and operating environments, thereby avoiding complex mode switching and adaptive algorithm requirements, and reducing the control complexity of the grid-forming string photovoltaic system.

[0068] Based on the first embodiment of the present application, in the second embodiment of the present application, the same or similar contents as those in the above-mentioned embodiment 1 can be referred to the above introduction, and will not be repeated later. On this basis, step S20 can include steps S201 to S202:

[0069] Step S201, after receiving the system startup instruction, controlling the second boost conversion circuit to start, and determining the DC bus voltage value of the second boost conversion circuit according to the AC voltage value to be output of the inverter circuit;

[0070] After the system receives the start-up instruction, it immediately controls the second boost conversion circuit to start, and calculates the required DC bus voltage value through the conversion algorithm according to the expected AC output voltage value of the inverter circuit, ensuring that the output DC voltage of the second boost conversion circuit can meet the needs of the inverter circuit.

[0071] Step S202, setting the duty cycle of the second boost converter circuit with the DC bus voltage value according to the DC voltage setting strategy, so that the DC voltage value output by the second boost converter circuit is the DC bus voltage value.

[0072] According to the determined DC bus voltage value, a DC voltage setting strategy is adopted to adjust the duty cycle of the second boost conversion circuit, that is, the proportion of the high level in the control signal, so as to accurately control the DC voltage value output by the second boost conversion circuit so that it is strictly equal to the preset DC bus voltage value, so as to ensure the voltage stability and reliability of the second boost conversion circuit output.

[0073] In a feasible embodiment, step S30 may include steps S301 to S302:

[0074] Step S301, determining whether the voltage is stable by monitoring the DC voltage value output by the second boost conversion circuit;

[0075] Before starting the inverter circuit, the DC voltage value output by the second boost converter circuit is first monitored to ensure that it has stabilized within a preset range to prevent malfunction or damage caused by voltage fluctuations.

[0076] Step S302, after determining that the voltage is stable, controlling the inverter circuit to start at zero power, and controlling the inverter circuit to synchronize with the power grid according to a grid-forming strategy.

[0077] After confirming that the DC voltage is stable, the inverter circuit is controlled to start at zero power, that is, it is started without supplying power to the grid to reduce the impact on the grid. The inverter circuit is controlled to synchronize with the grid according to the grid configuration strategy to ensure that the output waveform, frequency and other parameters of the inverter circuit are consistent with the grid to achieve smooth grid connection.

[0078] In a feasible embodiment, step S10 may include step S101:

[0079] Step S101, after determining that the inverter circuit is synchronized with the power grid successfully, controlling the first boost conversion circuit in the boost conversion circuit to start, and using maximum power to control the first boost conversion circuit according to a strategy.

[0080] After confirming that the inverter circuit has been successfully synchronized with the grid, the first boost conversion circuit is started and immediately controlled using the maximum power tracking strategy to avoid system instability or power waste that may be caused by starting the MPPT when the inverter circuit is not stable or synchronized, ensuring that the system can operate in the best condition.

[0081] In a feasible embodiment, after step S10, steps S40 to S50 may also be included:

[0082] Step S40, obtaining the operation mode of the inverter circuit, wherein the operation mode is a full grid-building mode, a residual capacity full power generation mode, or a limited power generation mode;

[0083] During the system operation, the current operation mode of the inverter circuit is obtained and determined in real time. The operation modes include but are not limited to the full grid-building mode, the remaining capacity full power generation mode and the limited power generation mode.

[0084] It should be noted that in the full-grid mode, the inverter circuit fully follows the grid-forming control strategy, actively adjusts its output characteristics to adapt to the grid needs, and achieves harmonious interaction with the grid.

[0085] When the system detects that the grid load is low or the grid has additional acceptance capacity, the inverter circuit switches to the residual capacity full power generation mode. In this mode, the inverter circuit will use the generated surplus electricity to generate full power as much as possible to maximize the system's power generation.

[0086] In some cases, such as power grid power restrictions, system safety restrictions, etc., the inverter circuit needs to work in a limited power generation mode. At this time, the inverter circuit will generate electricity according to the preset power limit to avoid impacting the grid or exceeding the system safety threshold. The above mode switching can be adaptively adjusted by the system according to the detection results, or it can be set by the user according to the application scenario and application requirements, which is not specifically limited in this embodiment.

[0087] Step S50: adjusting the active power of the inverter circuit according to the operation mode and the power reference base value.

[0088] After the operation mode of the inverter circuit is determined, the active power of the inverter circuit is dynamically adjusted according to the current operation mode and the determined power reference value. Specifically, the system sets the active power of the inverter circuit according to the requirements and restrictions of different operation modes to ensure that the system meets the grid requirements and achieves efficient power generation.

[0089] In a feasible embodiment, step S50 may include steps S501 to S503:

[0090] Step S501, when the operation mode is the full grid mode, setting the active power value of the inverter circuit to the power given base value;

[0091] When the operation mode of the inverter circuit is the full grid mode, the active power value of the inverter circuit is set to the power given base value.

[0092] Step S502, when the operation mode is the remaining capacity full power generation mode, determining a grid-forming adjustment power value according to a preset frequency regulation requirement, and setting the active power value of the inverter circuit to the full power value minus the grid-forming adjustment power value, wherein the full power value is the number of the boost conversion circuits multiplied by the power given base value;

[0093] When the operation mode of the inverter circuit is the residual capacity full power generation mode, the system calculates the grid-forming regulation power value according to the preset frequency regulation demand. The grid-forming regulation power value is used to provide additional frequency support or respond to the frequency fluctuation of the grid when the grid needs it, and sets the active power value of the inverter circuit to the full power value minus the grid-forming regulation power value, wherein the full power value is the total number of boost conversion circuits multiplied by the power given base value, representing the maximum power generation capacity that the unit can provide under the current conditions, so as to ensure that the frequency regulation demand of the grid is met while fully utilizing the residual power generation capacity.

[0094] Step S503, when the operation mode is the limited power generation mode, the active power is set according to the preset Internet access demand, and the value of the active power is between the power given base value and the full power value.

[0095] When the inverter circuit is in the limited power generation mode, the active power of the inverter circuit is set according to the preset Internet access requirements (such as power grid power restriction instructions, system safety restrictions, etc.). At this time, the active power value is set between the power given base value and the full power value. The specific value depends on the strictness of the Internet access requirements and the actual power generation capacity of the system. In this way, the power generation can be flexibly adjusted to meet the power restriction requirements of the power grid or the safety restrictions of the system itself while ensuring the safety of the power grid and the stable operation of the system.

[0096] For example, in a feasible implementation, for any group of string photovoltaic units in a grid-type string photovoltaic system, different power operation points of the inverter circuit in the configuration unit can correspond to the full grid-type mode, the remaining capacity full power generation mode and the limited power generation mode. The relationship between the different power operation points is as follows: Figure 5 As shown in the figure, the horizontal axis is the voltage value change, and the vertical axis is the power value change. Specifically, the first boost conversion circuit adopts maximum power tracking control and stably obtains the maximum power P of the circuit under the current illumination. mpp , the maximum power P mpp Transmitted to the inverter circuit as the power given base value of the inverter circuit. At this time, the available dispatching capacity of the inverter circuit is (n-1)P mpp , where n is the number of boost converter circuits in the group of string photovoltaic units.

[0097] When the inverter circuit is in full grid-building mode, the available capacity of the inverter circuit is fully used for grid-building inertia regulation and primary frequency regulation. At this time, the active power setting of the inverter circuit is P set1 =P mpp , that is, setting the active power value of the inverter circuit to the power given base value.

[0098] When the inverter circuit is in full power generation mode with remaining capacity, reserve P af As the grid adjustment power value, the remaining capacity is in full power generation mode, then the inverter circuit active power setting P set2 =nP mpp -P af , that is, the active power value of the inverter circuit is set to the full power value minus the grid-adjusted power value.

[0099] When the inverter circuit is in the limited power generation mode, the power generation and access to the grid is set to xP according to the power generation and access to the grid demand. mpp, where 1<x<n, the remaining capacity is all used for network adjustment. At this time, the active power of the inverter circuit is set to P set3 =xP mpp .

[0100] In a feasible embodiment, the control method of the grid-type string photovoltaic system may further include steps A10 to A20:

[0101] Step A10, determining an active power given value according to the active power of the inverter circuit, a preset gain coefficient and a grid frequency deviation value;

[0102] Step A20, setting the dynamic limit value of the active power given value to Wherein, Q represents the reactive power of the inverter circuit, n represents the number of the boost converter circuits, P mpp Indicates the power reference base value.

[0103] The current active power of the inverter circuit is obtained, and the active power given value is determined by combining a preset gain coefficient and the real-time monitored grid frequency deviation value. Specifically, the active power given value P ref =P set +K fdrp (1-w r pu ), where P ref Indicates the active power given value, P set Indicates active power, K fdrp Represents the gain factor, 1-w r pu Indicates the grid frequency deviation value.

[0104] At the same time, in order to ensure the stability and safety of system operation, a dynamic limit value is set for the determined active power given value. The dynamic limit value is set as Wherein, Q represents the reactive power of the inverter circuit, n represents the number of the boost converter circuits, P mpp It indicates the power given base value, thus taking into account the system's reactive power load, the expansion capacity of the conversion circuit, and the basic power limit, effectively avoiding the risk of system instability or damage caused by excessive power output, and ensuring the stability and safety of the system in complex operating environments.

[0105] Thus, from the perspective of the hybrid configuration of multiple boost conversion circuits of the string photovoltaic unit, this embodiment firstly uses the maximum power tracking control through the first boost conversion circuit to obtain the dynamic limit of the entire string photovoltaic unit, ensuring that the inverter circuit will not crash the system due to over-generation of power, and the second boost conversion circuit is used to maintain the DC bus voltage constant; secondly, the frequency modulation power of the inverter circuit is reserved according to the frequency modulation requirements, and the remaining available capacity is all used for power generation and access to the Internet or limited power operation as required. Thus, the real-time maximum power point can be obtained while stabilizing the DC bus voltage. In addition, according to the obtained real-time maximum power value, the power of the inverter circuit can be directly dynamically limited to avoid the inverter circuit power being too large to pull down the DC voltage. The whole process does not require mode switching or adding additional devices, and can adapt to the power generation and access to the Internet and frequency modulation requirements in different operating scenarios.

[0106] It should be noted that the above examples are only used to understand the present application and do not constitute a limitation on the control method of the grid-type string photovoltaic system of the present application. More simple transformations based on this technical concept are all within the scope of protection of the present application.

[0107] The present application also provides a grid-type string photovoltaic system control device, please refer to Figure 6 The control device of the grid-type string photovoltaic system includes:

[0108] A first boost conversion circuit control module 10, configured to control a first boost conversion circuit in each of the boost conversion circuits by adopting a maximum power tracking strategy, and determine a maximum power value of the first boost conversion circuit as a power given base value of the inverter circuit;

[0109] A second boost conversion circuit control module 20, configured to control a second boost conversion circuit in each of the boost conversion circuits using a DC voltage setting strategy, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits other than the first boost conversion circuit;

[0110] The inverter circuit control module 30 is used to control the inverter circuit using a grid-forming strategy.

[0111] Optionally, the second boost conversion circuit control module 20 is further configured to:

[0112] After receiving the system startup instruction, controlling the second boost conversion circuit to start, and determining the DC bus voltage value of the second boost conversion circuit according to the AC voltage value to be output of the inverter circuit;

[0113] The duty cycle of the second boost conversion circuit is set according to the DC voltage setting strategy and the DC bus voltage value, so that the DC voltage value output by the second boost conversion circuit is the DC bus voltage value.

[0114] Optionally, the inverter circuit control module 3 is further used for:

[0115] Determining whether the voltage is stable by monitoring the DC voltage value output by the second boost conversion circuit;

[0116] After determining that the voltage is stable, the inverter circuit is controlled to start at zero power, and the inverter circuit is controlled to synchronize with the power grid according to a grid-forming strategy.

[0117] Optionally, the first boost conversion circuit control module 10 is further used for:

[0118] After determining that the inverter circuit is successfully synchronized with the power grid, the first boost conversion circuit in the boost conversion circuit is controlled to start, and the first boost conversion circuit is controlled according to the strategy using maximum power.

[0119] Optionally, the inverter circuit control module 3 is further used for:

[0120] Acquire an operation mode of the inverter circuit, wherein the operation mode is a full grid-building mode, a residual capacity full power generation mode, or a limited power generation mode;

[0121] The active power of the inverter circuit is adjusted according to the operation mode and the power given base value.

[0122] Optionally, the inverter circuit control module 3 is further used for:

[0123] When the operation mode is the full grid mode, the active power value of the inverter circuit is set to the power given base value;

[0124] When the operation mode is the remaining capacity full power generation mode, a grid-forming adjustment power value is determined according to a preset frequency regulation requirement, and the active power value of the inverter circuit is set to be the full power value minus the grid-forming adjustment power value, wherein the full power value is the number of the boost conversion circuits multiplied by the power given base value;

[0125] When the operation mode is the limited power generation mode, the active power is set according to a preset Internet access requirement, and the value of the active power is between the power given base value and the full power value.

[0126] Optionally, the inverter circuit control module 3 is further used for:

[0127] Determining an active power given value according to the active power of the inverter circuit, a preset gain coefficient and a grid frequency deviation value;

[0128] Set the dynamic limit value of the active power given value to Wherein, Q represents the reactive power of the inverter circuit, n represents the number of the boost converter circuits, P mpp Indicates the power reference base value.

[0129] The grid-type string photovoltaic system control device provided in the embodiment of the present application adopts the grid-type string photovoltaic system control method in the above embodiment, which can reduce the control complexity of the grid-type string photovoltaic system. Compared with the prior art, the beneficial effects of the grid-type string photovoltaic system control device provided in the embodiment of the present application are the same as the beneficial effects of the grid-type string photovoltaic system control method provided in the above embodiment, and other technical features in the grid-type string photovoltaic system control device are the same as the features disclosed in the grid-type string photovoltaic system control method in the above embodiment, which will not be repeated here.

[0130] An embodiment of the present application provides an electronic device, which includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor so that the at least one processor can execute the control method of the grid-type string photovoltaic system in the above-mentioned embodiment 1.

[0131] Reference below Figure 7 , which shows a schematic diagram of the structure of an electronic device suitable for implementing the embodiments of the present application. The electronic device in the embodiments of the present application may include but is not limited to mobile terminals such as laptop computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Portable Application Descriptions), PMPs (Portable Media Players), etc., and fixed terminals such as digital TVs, desktop computers, etc. Figure 7 The electronic device shown is merely an example and should not bring any limitation to the functions and scope of use of the embodiments of the present application.

[0132] like Figure 7As shown, the electronic device may include a processing device 1001 (e.g., a central processing unit, a graphics processor, etc.), which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM: Read Only Memory) 1002 or a program loaded from a storage device 1003 to a random access memory (RAM: Random Access Memory) 1004. In RAM1004, various programs and data required for the operation of the electronic device are also stored. The processing device 1001, ROM1002, and RAM1004 are connected to each other through a bus 1005. An input / output (I / O) interface 1006 is also connected to the bus. Generally, the following systems can be connected to the I / O interface 1006: an input device 1007 including, for example, a touch screen, a touch pad, a keyboard, a mouse, an image sensor, a microphone, an accelerometer, a gyroscope, etc.; an output device 1008 including, for example, a liquid crystal display (LCD: Liquid Crystal Display), a speaker, a vibrator, etc.; a storage device 1003 including, for example, a magnetic tape, a hard disk, etc.; and a communication device 1009. The communication device 1009 can allow the electronic device to communicate with other devices wirelessly or by wire to exchange data. Although the figure shows an electronic device with various systems, it should be understood that it is not required to implement or have all the systems shown. More or fewer systems can be implemented or have alternatively.

[0133] In particular, according to the embodiments disclosed in the present application, the process described above with reference to the flowchart can be implemented as a computer software program. For example, the embodiments disclosed in the present application include a computer program product, which includes a computer program carried on a computer-readable medium, and the computer program includes a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from a network through a communication device, or installed from a storage device 1003, or installed from a ROM 1002. When the computer program is executed by the processing device 1001, the above-mentioned functions defined in the method of the embodiment disclosed in the present application are executed.

[0134] The electronic device provided in the embodiment of the present application adopts the control method of the grid-type string photovoltaic system in the above embodiment, which can reduce the control complexity of the grid-type string photovoltaic system. Compared with the prior art, the beneficial effects of the electronic device provided in the embodiment of the present application are the same as the beneficial effects of the control method of the grid-type string photovoltaic system provided in the above embodiment, and other technical features in the electronic device are the same as the features disclosed in the control method of the grid-type string photovoltaic system in the previous embodiment, which will not be repeated here.

[0135] It should be understood that the various parts disclosed in the embodiments of the present application can be implemented by hardware, software, firmware or a combination thereof. In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0136] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0137] An embodiment of the present application provides a computer-readable storage medium having computer-readable program instructions (ie, a computer program) stored thereon, the computer-readable program instructions being used to execute the control method for a grid-type string photovoltaic system in the above-mentioned embodiment.

[0138] The computer-readable storage medium provided in the embodiment of the present application may be, for example, a USB flash drive, but is not limited to electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems or devices, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM: Random Access Memory), a read-only memory (ROM: Read Only Memory), an erasable programmable read-only memory (EPROM: Erasable Programmable Read Only Memory or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM: CD-Read Only Memory), an optical storage device, a magnetic storage device, or any suitable combination of the above. In this embodiment, the computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in combination with an instruction execution system or device. The program code contained on the computer-readable storage medium may be transmitted using any appropriate medium, including but not limited to: wires, optical cables, RF (Radio Frequency: Radio Frequency), etc., or any suitable combination of the above.

[0139] The computer-readable storage medium may be included in the electronic device, or may exist independently without being installed in the electronic device.

[0140] The computer-readable storage medium carries one or more programs. When the one or more programs are executed by an electronic device, the electronic device: adopts a maximum power tracking strategy to control the first boost conversion circuit in each of the boost conversion circuits, and determines the maximum power value of the first boost conversion circuit as the power setting base value of the inverter circuit; adopts a DC voltage setting strategy to control the second boost conversion circuit in each of the boost conversion circuits, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits except the first boost conversion circuit; and adopts a meshing strategy to control the inverter circuit.

[0141] The computer program code for performing the operation of the embodiment of the present application can be written in one or more programming languages ​​or a combination thereof, and the above-mentioned programming languages ​​include object-oriented programming languages, such as Java, Smalltalk, C++, and also include conventional procedural programming languages, such as "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as an independent software package, partially on the user's computer and partially on the remote computer, or completely on the remote computer or server. In the case of a remote computer, the remote computer can be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., using an Internet service provider to connect through the Internet).

[0142] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present application. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0143] The modules involved in the embodiments described in this application may be implemented by software or hardware, wherein the name of the module does not constitute a limitation on the unit itself in some cases.

[0144] The readable storage medium provided in the embodiment of the present application is a computer-readable storage medium, which stores computer-readable program instructions (i.e., computer programs) for executing the above-mentioned grid-type string photovoltaic system control method, and can reduce the control complexity of the grid-type string photovoltaic system. Compared with the prior art, the beneficial effects of the computer-readable storage medium provided in the embodiment of the present application are the same as the beneficial effects of the grid-type string photovoltaic system control method provided in the above-mentioned embodiment, and will not be repeated here.

[0145] The present application also provides a computer program product, including a computer program, which implements the steps of the above-mentioned grid-type string photovoltaic system control method when executed by a processor.

[0146] The computer program product provided in this application can solve the technical problem of controlling a grid-type string photovoltaic system. Compared with the prior art, the beneficial effects of the computer program product provided in this application are the same as the beneficial effects of the control method of a grid-type string photovoltaic system provided in the above embodiment, and will not be described in detail here.

[0147] The above are only some embodiments of the present application, and are not intended to limit the patent scope of the present application. All equivalent structural changes made using the contents of the present application specification and drawings under the technical concept of the present application, or direct / indirect application in other related technical fields are included in the patent protection scope of the present application.

Claims

1. A control method for a grid-type string photovoltaic system, characterized in that: Applicable to a grid-type string photovoltaic system, the system includes a string photovoltaic unit, the string photovoltaic unit includes a plurality of photovoltaic modules, a plurality of boost conversion circuits and an inverter circuit, each of the photovoltaic modules is connected to each of the boost conversion circuits, each of the boost conversion circuits is connected to the inverter circuit, and the inverter circuit is connected to the grid; The method comprises: A maximum power tracking strategy is adopted to control a first boost conversion circuit in each of the boost conversion circuits, and a maximum power value of the first boost conversion circuit is determined as a power given base value of the inverter circuit; A DC voltage setting strategy is used to control a second boost conversion circuit in each of the boost conversion circuits, wherein the second boost conversion circuit is a circuit in each of the boost conversion circuits other than the first boost conversion circuit; A grid-building strategy is adopted to control the inverter circuit.

2. The control method of a grid-type string photovoltaic system according to claim 1, characterized in that: The step of using a DC voltage setting strategy to control the second boost conversion circuit in each of the boost conversion circuits comprises: After receiving the system startup instruction, controlling the second boost conversion circuit to start, and determining the DC bus voltage value of the second boost conversion circuit according to the AC voltage value to be output of the inverter circuit; The duty cycle of the second boost conversion circuit is set according to the DC voltage setting strategy and the DC bus voltage value, so that the DC voltage value output by the second boost conversion circuit is the DC bus voltage value.

3. The control method of a grid-type string photovoltaic system according to claim 2, characterized in that: The step of controlling the inverter circuit by adopting a network-building strategy comprises: Determining whether the voltage is stable by monitoring the DC voltage value output by the second boost conversion circuit; After determining that the voltage is stable, the inverter circuit is controlled to start at zero power, and the inverter circuit is controlled to synchronize with the power grid according to a grid-forming strategy.

4. The control method of a grid-type string photovoltaic system according to claim 3, characterized in that: The step of using the maximum power tracking strategy to control the first boost conversion circuit in each of the boost conversion circuits comprises: After determining that the inverter circuit is successfully synchronized with the power grid, the first boost conversion circuit in the boost conversion circuit is controlled to start, and the first boost conversion circuit is controlled according to the strategy using maximum power.

5. The control method of a grid-type string photovoltaic system according to claim 1, characterized in that: After the step of determining the maximum power value of the first boost conversion circuit as the power given base value of the inverter circuit, the method further includes: Acquire an operation mode of the inverter circuit, wherein the operation mode is a full grid-building mode, a residual capacity full power generation mode, or a limited power generation mode; The active power of the inverter circuit is adjusted according to the operation mode and the power given base value.

6. The control method of a grid-type string photovoltaic system according to claim 5, characterized in that: The step of adjusting the active power of the inverter circuit according to the operation mode and the power given base value comprises: When the operation mode is the full grid mode, the active power value of the inverter circuit is set to the power given base value; When the operation mode is the remaining capacity full power generation mode, a grid-forming adjustment power value is determined according to a preset frequency regulation requirement, and the active power value of the inverter circuit is set to be the full power value minus the grid-forming adjustment power value, wherein the full power value is the number of the boost conversion circuits multiplied by the power given base value; When the operation mode is the limited power generation mode, the active power is set according to a preset Internet access requirement, and the value of the active power is between the power given base value and the full power value.

7. The control method of a grid-type string photovoltaic system according to any one of claims 1 to 6, characterized in that: The method further comprises: Determining an active power given value according to the active power of the inverter circuit, a preset gain coefficient and a grid frequency deviation value; Set the dynamic limit value of the active power given value to Wherein, Q represents the reactive power of the inverter circuit, n represents the number of the boost converter circuits, P mpp Indicates the power reference base value.

8. An electronic device, characterized in that: The device comprises: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program is configured to implement the steps of the control method for a grid-connected string photovoltaic system as described in any one of claims 1 to 7.

9. A storage medium, characterized in that: The storage medium is a computer-readable storage medium, and a computer program is stored on the storage medium. When the computer program is executed by a processor, the steps of the control method of a grid-type string photovoltaic system according to any one of claims 1 to 7 are implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the steps of the control method of a grid-connected string photovoltaic system according to any one of claims 1 to 7 are implemented.

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