Photovoltaic power consumption method of parallel system, three-phase inverter and storage medium

Abstract

The application provides a photovoltaic accommodation method of a parallel system, and the method comprises the following steps: a current three-phase inverter unit obtains average grid-connected power, average inverter power, average photovoltaic power and average charge-discharge power of each three-phase inverter unit in the parallel system; if the current three-phase inverter unit is a battery unit, target inverter power is determined according to current inverter power and average grid-connected power of the current three-phase inverter unit; if the current three-phase inverter unit is a non-battery unit, load power of the parallel system is determined according to average photovoltaic power, average charge-discharge power, average grid-connected power and the number of units of the parallel system, target inverter power is determined according to the load power and current photovoltaic power of the current three-phase inverter unit; and the current three-phase inverter adjusts inverter power of itself to the target inverter power. Through the above method, the photovoltaic accommodation rate of the parallel system can be improved.

Description

Technical Field

[0001] This application belongs to the field of power generation technology, and in particular relates to a photovoltaic absorption method for a parallel system, a three-phase inverter, and a computer-readable storage medium. Background Technology

[0003] Currently, conventional three-phase energy storage parallel systems generally adopt an average power distribution control strategy, which means that all inverter units in the parallel system, regardless of whether they are equipped with battery energy storage units, share the total load power of the system equally and perform inverter output and power regulation synchronously.

[0004] In a three-phase energy storage inverter parallel system, when there are both battery-equipped energy storage units and battery-free photovoltaic units in the system, and the system is in a condition where power transmission to the public grid is prohibited, if the parallel system adopts the conventional average load power sharing control strategy, part of the photovoltaic output power of the battery-equipped units will be occupied by the inverter load supply operation, and cannot be fully used for battery charging. As a result, the battery charging power cannot reach the maximum value, and the photovoltaic output energy of the battery-free units cannot be fully consumed locally through the inverter, resulting in a waste of photovoltaic energy. Summary of the Invention

[0005] In view of this, this application provides a photovoltaic absorption method for a parallel system, a three-phase inverter, and a computer-readable storage medium, which can improve the photovoltaic absorption rate of the parallel system.

[0006] In a first aspect, this application provides a method for photovoltaic (PV) grid integration in a parallel system, the parallel system comprising multiple three-phase inverter units, including at least one battery-equipped unit and at least one battery-free unit, the method being applied to each of the three-phase inverter units in the parallel system, the method comprising: The current three-phase inverter units obtain the average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power of each three-phase inverter unit in the parallel system; If the current three-phase inverter unit is the battery-equipped unit, then the target inverter power is determined based on the current inverter power of the current three-phase inverter unit and the average grid-connected power. If the current three-phase inverter unit is the battery-free unit, then the load power of the parallel system is determined based on the average photovoltaic power, the average charging and discharging power, the average grid-connected power, and the number of units in the parallel system. The target inverter power is determined based on the load power and the current photovoltaic power of the current three-phase inverter unit. The current three-phase inverter adjusts its own inverter power to the target inverter power.

[0007] Secondly, this application provides a three-phase inverter, including a memory and a processor. The memory stores a computer program, and the processor is used to call and run the computer program from the memory, so that the three-phase inverter performs the method provided in the first aspect above.

[0008] Thirdly, this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the method provided in the first aspect.

[0009] Fourthly, this application provides a computer program product that, when running on a three-phase inverter, causes the three-phase inverter to perform the method provided in the first aspect above.

[0010] In the photovoltaic consumption method for the parallel system provided in the first aspect above, the current three-phase inverter unit obtains the average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power of each three-phase inverter unit in the parallel system; if the current three-phase inverter unit is a battery-equipped unit, the target inverter power is determined based on the current inverter power and the average grid-connected power of the current three-phase inverter unit; if the current three-phase inverter unit is a battery-free unit, the load power of the parallel system is determined based on the average photovoltaic power, the average charge / discharge power, the average grid-connected power, and the number of units in the parallel system, and the target inverter power is determined based on the load power and the current photovoltaic power of the current three-phase inverter unit; the current three-phase inverter adjusts its own inverter power to the target inverter power. Thus, this solution uses differentiated power control to enable battery-free units to increase their inverter power to improve their own photovoltaic utilization rate, while enabling battery-equipped units to reduce their inverter power and increase their charging power, thereby improving the photovoltaic energy storage capacity and overall absorption efficiency of the entire system.

[0011] It is understood that the beneficial effects of the second to fourth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a schematic flowchart of the photovoltaic power consumption method for a parallel system provided in the embodiments of this application; Figure 2 This is a schematic diagram of the structure of a three-phase inverter provided in the embodiments of this application. Detailed Implementation

[0014] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0015] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0016] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0017] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0018] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0019] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0020] First, the technical terms mentioned in the embodiments of this application will be explained.

[0021] A three-phase inverter is a power converter primarily used to convert direct current (DC) power into alternating current (AC) power. Its operating principle is based on power electronics technology and control principles; through effective circuit design and adjustment, it achieves the DC-to-AC conversion.

[0022] Grid connection: Grid connection refers to connecting the power generated by the three-phase inverter to the mains power grid, enabling both to jointly supply power to the load or feed power back to the grid. During grid connection, the three-phase inverter needs to ensure that its output voltage, frequency, and phase match the mains power grid.

[0023] Reverse flow: Under the condition of prohibition of grid connection, the system should not have any power interaction with the public power grid. The electricity generated by photovoltaic and battery can only be used to supply the on-site load and charge the battery. Once more electricity is generated and less electricity is used, the excess electricity that is not consumed will "flow back" into the grid. This process is called reverse flow.

[0024] In a three-phase energy storage inverter parallel system, the system includes multiple three-phase inverter units that can operate collaboratively. Some of these units are energy storage inverter units equipped with battery energy storage units (hereinafter referred to as battery-equipped units), while others are photovoltaic inverter units that are not equipped with battery energy storage units and are only connected to photovoltaic modules (hereinafter referred to as battery-free units). At the same time, the system is under the constraint of prohibiting the transmission of power to the public grid. The power generated by the photovoltaic modules in the system can only be consumed locally through two paths: local load consumption and battery charging and storage. It is strictly prohibited to transmit excess power back to the grid.

[0025] For the aforementioned parallel systems, existing conventional parallel control schemes generally adopt a load-sharing control logic: that is, the parallel system evenly distributes the real-time total load power to each operating unit, requiring all units, regardless of whether they are equipped with batteries, to output inverter power according to their allocated equal power share to jointly power the system load. The initial intention of this control logic is to balance the operating load of each unit and avoid overloading a single unit. However, in the specific operating conditions of mixed grid connection with and without batteries, where grid connection is prohibited, this directly leads to a significant reduction in the system's photovoltaic absorption efficiency: First, the photovoltaic charging capacity of battery-equipped units is severely limited, failing to maximize charging power. For battery-equipped units, the DC power generated by their photovoltaic modules has two inversely related absorption paths: one is through inversion to AC power to provide power to the system load; the other is through conversion to DC charging power to charge their own battery cells. Given a fixed real-time photovoltaic module power generation, the more power used for inverter power supply, the less power is available for battery charging. Under the load-sharing control logic, battery-equipped units must bear a fixed load share and continuously output the corresponding amount of inverter power. A fixed proportion of their photovoltaic power generation is occupied by the inverter's load-supply operation and cannot be fully used for battery charging. This directly results in the battery charging power not reaching its maximum value under the current operating conditions, leading to a significant waste of the system's photovoltaic energy storage capacity. Secondly, battery-free units cannot fully invert and absorb the photovoltaic energy. For battery-free units, which lack battery storage units, the DC power generated by the photovoltaic modules has only one absorption path: conversion to AC power to supply the system load. They cannot store excess power in batteries or transmit it to the grid (due to grid connection restrictions). Under the load-sharing control logic, the maximum inverter output power of battery-free units is strictly limited to the system's allocated load share. Even if the real-time power generation of their photovoltaic modules exceeds this allocated share, the inverter output power cannot be increased to absorb the excess photovoltaic power. The photovoltaic power exceeding the allocated share has no inverter supply channel and no other legal consumption path, so it can only be abandoned. This directly results in the photovoltaic energy of the battery-less unit not being fully inverted, and the overall photovoltaic utilization rate of the system drops significantly.

[0026] Figure 1 A flowchart illustrating a photovoltaic (PV) grid integration method for a parallel system according to an embodiment of this application is shown. This PV grid integration method for a parallel system is applied to a three-phase inverter unit, and the method is described in detail below: Step 101: The current three-phase inverter unit obtains the average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power of each three-phase inverter unit in the parallel system.

[0027] Step 102: If the current three-phase inverter unit is the battery-equipped unit, then determine the target inverter power based on the current inverter power of the current three-phase inverter unit and the average grid-connected power.

[0028] Step 103: If the current three-phase inverter unit is the battery-free unit, then determine the load power of the parallel system based on the average photovoltaic power, the average charge and discharge power, the average grid-connected power and the number of units in the parallel system, and determine the target inverter power based on the load power and the current photovoltaic power of the current three-phase inverter unit.

[0029] Step 104: The current three-phase inverter adjusts its own inverter power to the target inverter power.

[0030] The parallel system comprises multiple three-phase inverter units capable of coordinated operation. These units include at least one battery-equipped unit and at least one battery-free unit. The battery-equipped unit is a three-phase inverter unit with a battery energy storage unit, enabling both photovoltaic power inversion and battery charging / discharging control. The battery-free unit is a three-phase inverter unit without a battery energy storage unit, connected only to photovoltaic modules, and can only invert and supply photovoltaic power. The photovoltaic absorption method described in this embodiment is applied to each three-phase inverter unit in the parallel system. That is, all three-phase inverter units within the parallel system independently execute the corresponding steps of this method, achieving coordinated power regulation and optimized photovoltaic absorption across the entire system.

[0031] The term "current three-phase inverter unit" refers to a single three-phase inverter unit in a parallel system that is currently executing the steps of this method. This unit can be either a battery-equipped unit or a battery-free unit. The average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power are the arithmetic mean of the operating power of all units of the same type in the parallel system.

[0032] If the current three-phase inverter unit is a battery-powered unit, the target inverter power is determined based on the current inverter power and average grid-connected power of the current three-phase inverter unit. The current inverter power is the real-time output power of the battery-powered unit used to supply power to the system load at the current moment; the target inverter power is the target inverter output value that the battery-powered unit needs to achieve after adjustment. By determining the adjustment target through the system's average grid-connected power and the unit's current inverter power, the inverter power of the battery-powered unit can be precisely reduced, releasing more photovoltaic energy for battery charging while suppressing the risk of reverse current in the system.

[0033] If the current three-phase inverter unit is a battery-free unit, the load power of the parallel system is determined based on the average photovoltaic power, average charge / discharge power, average grid-connected power, and the number of units in the parallel system. Then, the target inverter power is determined based on the load power and the current photovoltaic power of the current three-phase inverter unit. The number of units in the parallel system refers to the total number of three-phase inverter units currently in operation. The load power is the real-time total power consumption of all electrical equipment in the parallel system. The current photovoltaic power is the real-time output power of the battery-free unit's own photovoltaic modules at the current moment. In this way, by first reconstructing the load demand of the entire system using system-level average power parameters, and then combining this with the unit's own photovoltaic power generation capacity to determine the inverter output target, the inverter power of the battery-free unit can be maximized, maximizing its ability to handle system load and improving the local consumption rate of photovoltaic power.

[0034] After determining their target inverter power, both battery-equipped and battery-free units synchronously perform inverter power adjustment: adjusting their real-time inverter power to the corresponding target inverter power. Through the synchronous adjustment of all units in the parallel system, the battery-free units maximize their load on the system, while the battery-equipped units minimize their inverter output and maximize the power exchange effect of photovoltaic charging. Ultimately, this maximizes the utilization of photovoltaic power in the parallel system, while also adapting to the constraints of grid connection prohibition.

[0035] In some embodiments, determining the load power of the parallel system based on the average photovoltaic power, the average charge / discharge power, the average grid-connected power, and the number of units in the parallel system includes: The slave device determines the total photovoltaic power of the parallel system based on the average photovoltaic power and the number of units in the parallel system; The slave device determines the total charging and discharging power of the parallel system based on the average charging and discharging power and the number of units in the parallel system; The slave unit determines the total grid-connected power of the parallel system based on the average grid-connected power and the number of units in the parallel system; The slave device determines the load power of the parallel system based on the total photovoltaic power, the total charging and discharging power, and the total grid-connected power.

[0036] Specifically, in the parallel system, each slave unit sends its own photovoltaic power and its own charging / discharging power to the master unit. The master unit sums the photovoltaic power of all units in the entire parallel system and then averages the results to obtain the average photovoltaic power. The master unit also sums the charging / discharging power of all units in the entire parallel system and then averages the results to obtain the average charging / discharging power. The master unit directly collects the total grid-connected power of the entire parallel system and divides the total grid-connected power by the number of units to obtain the average grid-connected power. Then, the master unit can distribute the calculated average photovoltaic power, average charging / discharging power, and average grid-connected power to each slave unit in the parallel system. In this embodiment, the slave unit multiplies the average photovoltaic power by the total number of units in the parallel system to obtain the total photovoltaic power of all units in the parallel system. The total photovoltaic power quantifies the total photovoltaic power generation of the parallel system at the current moment. The slave unit multiplies the average charging / discharging power by the total number of units in the parallel system to obtain the sum of the charging / discharging power of all battery-equipped units in the parallel system. The total charging / discharging power quantifies the total power input and output on the battery side of the parallel system. By multiplying the average grid-connected power by the total number of generating units in the parallel system, the total interactive power between the parallel system and the public grid can be obtained. The total grid-connected power quantifies the total power delivered by the parallel system to the grid.

[0037] Based on the fundamental principle of power conservation in power systems, the actual power demand on the system side can be reconstructed using power parameters from both the generation side and the grid interaction side of the entire system. The resulting load power can then quantify the real-time total power consumption of all electrical equipment within the parallel system. Using this method, battery-free units can quickly reconstruct the actual load demand of the fully parallel system through uniformly distributed average power parameters, eliminating the need for additional full-load detection equipment and reducing system hardware costs.

[0038] In some embodiments, determining the target inverter power based on the load power and the current photovoltaic power of the current three-phase inverter unit includes: The smaller of the load power and the current photovoltaic power is determined as the target inverter power.

[0039] After calculating the load power, the target inverter power for battery-free units is determined using the following logic: The load power is compared with the current photovoltaic power of the three-phase inverter unit itself, and the smaller of the two values ​​is taken as the target inverter power. Since battery-free units do not have battery storage units, the inverter output power comes entirely from the real-time generation of its own photovoltaic modules, and the inverter output power can never exceed the current photovoltaic power. Under the constraint that the parallel system is prohibited from transmitting power to the grid, the inverter power of a single unit cannot exceed the load power of the parallel system. This upper limit prevents excess power from being transmitted back to the grid, thus meeting compliance requirements. By using this method of taking the smaller value, battery-free units can maximize their inverter output capacity within compliance limits, absorbing as much system load as possible and achieving full utilization of their own photovoltaic power.

[0040] Optionally, determining the target inverter power based on the current inverter power of the current three-phase inverter unit and the average grid-connected power includes: The target inverter power is obtained by subtracting the average grid-connected power from the current inverter power.

[0041] In this embodiment of the application, the target inverter power of the battery-powered unit can be determined in the following way: the current inverter power of the current three-phase inverter unit is subtracted from the average grid-connected power, and the result is determined as the target inverter power.

[0042] The current inverter power is the real-time output of the battery-powered units used to supply power to the system load at the current moment; the average grid-connected power is the average of the individual grid-connected power of all operating units in the parallel system. Thus, by subtracting the average grid-connected power from the current inverter power, the inverter output of the battery-powered units is directly reduced, decreasing the amount of electrical energy injected into the AC bus from the generation side, quickly offsetting the reverse current in the system, and meeting the constraint that the system is prohibited from sending power to the grid. After the inverter power of the battery-powered units is reduced, the photovoltaic power originally used for inverter power supply can be converted into battery charging power, further releasing the energy storage and absorption capacity of the battery-powered units.

[0043] It should be understood that the inverter power reduction action of battery-equipped units and the inverter power increase action of battery-free units are executed synchronously to ensure that the total inverter power of the system always matches the load power, thus avoiding problems such as load power interruption or unstable power supply.

[0044] In some embodiments, the current three-phase inverter unit acquires the average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power of each three-phase inverter unit in the parallel system, including: the current three-phase inverter unit receiving the average grid-connected power, the average inverter power, the average photovoltaic power, and the average charge / discharge power from the host in the parallel system.

[0045] In this embodiment of the application, each unit in the parallel system acquires its own three power data in real time through CT current sampling and voltage sampling: Inverter power: The power that the inverter itself converts DC (photovoltaic / cell) into AC to supply the load; Photovoltaic power: The real-time output power of its own photovoltaic modules; Charging and discharging power: the power of its own battery (negative for charging and positive for discharging; this item is always 0 for units without batteries).

[0046] In the parallel system, the host unit also obtains the total grid-connected power of the parallel system in real time through CT current sampling and voltage sampling. The total grid-connected power is divided by the number of units to obtain the average grid-connected power, and then the average grid-connected power is sent to each slave unit.

[0047] Specifically, before the parallel system is officially started and put into operation, one of the multiple three-phase inverter units will be selected as the master unit, and the remaining units will act as slave units that establish communication connections with the master unit. The selected master unit will also act as a normally operating unit in the parallel system, synchronously performing the entire process of power sampling, target inverter power calculation, and inverter power adjustment, and participating in the system power supply together with the other units.

[0048] During the operation of the parallel system, each three-phase inverter unit, whether acting as a master or slave, collects three power parameters in real time through its current and voltage sampling circuits: inverter power, photovoltaic power, and charging / discharging power. All slave three-phase inverter units upload their collected power parameters to the master unit via the inter-unit communication link. Upon receiving the uploaded power parameters, the master unit synchronously aggregates its own collected power parameters and those uploaded by all slave units, forming a comprehensive power dataset covering all operating units in the system. Based on this dataset, the master unit performs average calculations for each type of power parameter: summing all values ​​of the same power type to obtain the total system power, and then dividing the total system power by the total number of operating units in the parallel system to calculate the average inverter power, average photovoltaic power, and average charging / discharging power for the entire system. In the parallel system, the host unit also obtains the total grid-connected power of the parallel system in real time through CT current sampling and voltage sampling. The total grid-connected power is divided by the number of units to obtain the average grid-connected power, and then the average grid-connected power is sent to each slave unit.

[0049] After the master unit completes the calculation of all average power parameters, it distributes the four average power parameters to all slave units in the parallel system in real time through the inter-unit communication link. Currently, whether the three-phase inverter unit acts as a master or a slave unit, it can obtain the unified average power parameters of the entire system: the slave unit directly receives the four average power parameters from the master unit, and the master unit directly calls upon the four average power parameters calculated by itself.

[0050] Optionally, if the current three-phase inverter unit is the battery-free unit, the method further includes: When the average grid-connected power is detected to be greater than or equal to a preset threshold, the current three-phase inverter unit will reduce its own inverter power to the average grid-connected power.

[0051] In this embodiment of the application, when the average grid-connected power is detected to be greater than or equal to a preset threshold, the current three-phase inverter unit directly reduces its own inverter power to the corresponding amount of average grid-connected power.

[0052] The average grid-connected power is received by the battery-free unit from the main unit in the parallel system. A positive value indicates that the parallel system is experiencing reverse current flow, sending power back to the grid. The magnitude of the value directly corresponds to the level of reverse current power in the parallel system. The preset threshold is a critical value for reverse current power set in advance in the unit control program, used to determine whether the system has experienced a significant reverse current condition requiring emergency handling.

[0053] When the total load of the parallel system drops rapidly, the inverter power of the batteryless generator cannot keep up with the load change, resulting in the total power generation of the system exceeding the load power. This excess energy is then fed back into the grid, creating a reverse current. At this time, the meters or current transformer (CT) sampling circuits within the parallel system detect the reverse current power in real time. When the value reaches or exceeds a preset threshold, an emergency adjustment is immediately triggered. In this emergency adjustment, the inverter power reduction for a single generator is equal to the average grid-connected power. The average grid-connected power is equal to the total reverse current power of the parallel system divided by the total number of generators in the parallel system, meaning each generator simultaneously bears an equal share of the reverse current reduction. After all generators in the parallel system execute this emergency adjustment simultaneously, the total inverter power of the parallel system drops rapidly, and the total energy output by the inverter decreases in a very short time, directly offsetting the total reverse current power in the parallel system. This achieves rapid suppression of the reverse current, preventing it from expanding and violating the prohibition on grid connection. Thus, without a complex load power recalculation process, the inverter power can be reduced immediately upon the occurrence of reverse current. Simultaneously, all units in the fully parallel system synchronously reduce their power by an equal amount, ensuring balanced output power across all units during the adjustment process and preventing system power imbalance caused by a sudden drop in power from a single unit. After the emergency adjustment is completed, the battery-free units will re-execute the main process of load power calculation and target inverter power determination.

[0054] In some embodiments, if the current three-phase inverter unit is the battery-free unit, the method further includes: When the average grid-connected power is detected to be greater than 0 and less than a preset threshold, the current three-phase inverter unit adjusts the operating voltage of its own photovoltaic modules to match the photovoltaic power of the current three-phase inverter unit with the load power.

[0055] When the average grid-connected power is detected to be greater than 0 and less than a preset threshold, the current three-phase inverter unit adjusts the operating voltage of its own photovoltaic modules to ultimately match the photovoltaic power of the current three-phase inverter unit with the load power.

[0056] An average grid-connected power greater than 0 indicates that the parallel system has exhibited reverse current behavior, sending power back to the grid; an average grid-connected power less than a preset threshold indicates a minor reverse current, which can be eliminated through fine-tuning. The preset threshold is a critical value for reverse current power set in advance in the unit control program.

[0057] The real-time output power (PV power) of a photovoltaic (PV) module is directly determined by its own operating voltage. Under fixed illumination conditions, when the operating voltage of a PV module is actively adjusted to deviate from its maximum power point voltage, the output power of the PV module will decrease accordingly. Furthermore, since battery-less units do not have battery energy storage units, the inverter power on the AC side is entirely determined by the real-time output power of the DC-side PV modules. By adjusting the operating voltage of the PV modules to control the PV output power, the actual inverter power of the unit can be controlled.

[0058] Specifically, when a slight reverse current meeting the trigger conditions is detected, it indicates that the current photovoltaic power of the unit is higher than the power required by the load, and the excess power forms a slight reverse current. At this time, the unit will actively raise the operating voltage of the photovoltaic modules through the upstream DC / DC boost converter until the photovoltaic power is fully matched with the load power, the current grid-connected power drops back to 0, and the reverse current is eliminated. When the system load slightly increases, the unit will simultaneously reduce the operating voltage of the photovoltaic modules, catching up with the voltage at the maximum power point, gradually increasing the photovoltaic power, and maximizing the photovoltaic absorption rate without generating reverse current. In this way, minor reverse currents caused by slight load fluctuations can be eliminated without lowering the inverter power limit, avoiding the risk of a sudden rise in DC bus voltage and unit overvoltage protection shutdown caused by conventional current limiting methods. At the same time, the adjustment process is smooth and shock-free, achieving both zero reverse current control and maximizing photovoltaic absorption without affecting the stability of the system power supply.

[0059] In some embodiments, determining the load power of the parallel system based on the total photovoltaic power, the total charging and discharging power, and the total grid-connected power includes: The load power of the parallel system is obtained by subtracting the total grid-connected power from the sum of the total photovoltaic power and the total charging and discharging power.

[0060] As can be seen from the above, in this application, differentiated power control enables battery-free units to increase inverter power to improve their own photovoltaic utilization rate, while battery-equipped units reduce inverter power and increase charging power, thereby improving the photovoltaic energy storage capacity and overall absorption efficiency of the entire system.

[0061] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0062] Figure 2 This is a schematic diagram of a three-phase inverter provided in one embodiment of this application. Figure 2 As shown, the three-phase inverter 2 in this embodiment includes: at least one processor 20 ( Figure 2 Only one is shown in the diagram), memory 21, and computer program 22 stored in the memory 21 and executable on at least one processor 20. When the processor 20 executes the computer program 22, it causes the three-phase inverter to perform the photovoltaic consumption method of the parallel system described above.

[0063] The aforementioned three-phase inverter 2 may include, but is not limited to, a processor 20 and a memory 21. Those skilled in the art will understand that... Figure 2 This is merely an example of a three-phase inverter 2 and does not constitute a limitation on the three-phase inverter 2. It may include more or fewer components than shown in the figure, or combine certain components, or different components, such as input / output devices, network access devices, etc.

[0064] The processor 20 may be a Central Processing Unit (CPU), or it may be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0065] In some embodiments, the aforementioned memory 21 may be an internal storage unit of the three-phase inverter 2, such as a hard disk or memory of the three-phase inverter 2. In other embodiments, the aforementioned memory 21 may be an external storage device of the three-phase inverter 2, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc., equipped on the three-phase inverter 2. Furthermore, the aforementioned memory 21 may include both internal storage units and external storage devices of the three-phase inverter 2. The aforementioned memory 21 is used to store operating systems, application programs, bootloaders, data, and other programs, such as the program code of the aforementioned computer programs. The aforementioned memory 21 may also be used to temporarily store data that has been output or will be output.

[0066] It should be noted that the information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0067] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the above device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments 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. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0068] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the various method embodiments described above.

[0069] This application provides a computer program product that, when run on a three-phase inverter, causes the three-phase inverter to execute the steps described in the various method embodiments above.

[0070] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a three-phase inverter, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0071] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0072] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0073] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units described above is only 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 coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0074] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for photovoltaic power consumption in a parallel system, characterized in that, The parallel system includes multiple three-phase inverter units, among which at least one unit is equipped with a battery and at least one unit is without a battery. The method is applied to each of the three-phase inverter units in the parallel system, and the method includes: The current three-phase inverter units obtain the average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power of each three-phase inverter unit in the parallel system; If the current three-phase inverter unit is the battery-equipped unit, then the target inverter power is determined based on the current inverter power of the current three-phase inverter unit and the average grid-connected power. If the current three-phase inverter unit is the battery-free unit, then the load power of the parallel system is determined based on the average photovoltaic power, the average charging and discharging power, the average grid-connected power, and the number of units in the parallel system. The target inverter power is determined based on the load power and the current photovoltaic power of the current three-phase inverter unit. The current three-phase inverter adjusts its own inverter power to the target inverter power.

2. The method as described in claim 1, characterized in that, The step of determining the load power of the parallel system based on the average photovoltaic power, the average charging and discharging power, the average grid-connected power, and the number of units in the parallel system includes: The total photovoltaic power of the parallel system is determined based on the average photovoltaic power and the number of units in the parallel system; The total charging and discharging power of the parallel system is determined based on the average charging and discharging power and the number of units in the parallel system. The total grid-connected power of the parallel system is determined based on the average grid-connected power and the number of units in the parallel system. The load power of the parallel system is determined based on the total photovoltaic power, the total charging and discharging power, and the total grid-connected power.

3. The method as described in claim 1, characterized in that, Determining the target inverter power based on the load power and the current photovoltaic power of the current three-phase inverter unit includes: The smaller of the load power and the current photovoltaic power is determined as the target inverter power.

4. The method as described in claim 1, characterized in that, Determining the target inverter power based on the current inverter power of the current three-phase inverter unit and the average grid-connected power includes: The target inverter power is obtained by subtracting the average grid-connected power from the current inverter power.

5. The method as described in claim 1, characterized in that, The current three-phase inverter unit obtains the average grid-connected power, average inverter power, average photovoltaic power, and average charge / discharge power of each three-phase inverter unit in the parallel system, including: The current three-phase inverter unit receives the average grid-connected power, the average inverter power, the average photovoltaic power, and the average charge / discharge power from the host in the parallel system.

6. The method as described in claim 1, characterized in that, If the current three-phase inverter unit is the battery-free unit, the method further includes: When the average grid-connected power is detected to be greater than or equal to a preset threshold, the current three-phase inverter unit will reduce its own inverter power to the average grid-connected power.

7. The method as described in claim 1, characterized in that, If the current three-phase inverter unit is the battery-free unit, the method further includes: When the average grid-connected power is detected to be greater than 0 and less than a preset threshold, the current three-phase inverter unit adjusts the operating voltage of its own photovoltaic modules to match the photovoltaic power of the current three-phase inverter unit with the load power.

8. The method as described in claim 2, characterized in that, Determining the load power of the parallel system based on the total photovoltaic power, the total charging and discharging power, and the total grid-connected power includes: The load power of the parallel system is obtained by subtracting the total grid-connected power from the sum of the total photovoltaic power and the total charging and discharging power.

9. A three-phase inverter, characterized in that, The device includes a memory and a processor, wherein the memory stores a computer program, and the processor is configured to call and run the computer program from the memory, causing the three-phase inverter to perform the method as described in any one of claims 1-8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 8.

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