Photovoltaic system load reverse flow prevention method, device, equipment, medium and product

Abstract

This application provides a method, device, equipment, medium, and product for preventing reverse current in photovoltaic system loads, relating to the field of photovoltaic power generation. The method accurately calculates the load power of each phase based on the instantaneous current of the three-phase load, and divides the inverter into non-overload and overload scenarios by pre-setting the rated power of each phase. By obtaining the power fluctuation frequency of the three-phase load and determining the power adjustment weight coefficient based on the load status, the power adjustment can dynamically adapt to the load fluctuation characteristics. In the non-overload state, based on the weight coefficient, the power adjustment unit achieves matching between the output power of each phase of the inverter and the corresponding phase load power, improving the green electricity utilization rate and the reverse current prevention control efficiency. In the overload state, it specifically compensates for the unbalanced current generated by the three-phase load to reduce the current imbalance, improving the system's operational stability. Under complex operating conditions, it ensures a high degree of adaptation between green electricity output and load demand while reliably preventing reverse current, thus improving the energy utilization efficiency of the photovoltaic system.

Description

Technical Field

[0001] This application relates to the field of photovoltaic power generation, and in particular to a method, device, equipment, medium and product for preventing reverse current in photovoltaic system loads. Background Technology

[0002] Anti-reverse current protection for photovoltaic (PV) systems refers to an operational strategy that controls the output of PV inverters to ensure that the generated electricity meets the needs of local three-phase loads, thereby preventing electricity from being fed back into the public power grid. If reverse current occurs in a PV system, it may not only trigger malfunctions of grid protection devices and affect the stable operation of the grid, but also cause waste of green electricity resources. Therefore, anti-reverse current protection for PV systems is crucial for ensuring grid security, improving the utilization rate of green electricity, and promoting the healthy development of the distributed PV industry.

[0003] In existing technologies, sensors installed at the grid connection point of a photovoltaic system detect the direction and magnitude of power or current flowing into the grid. When a reverse power flow is detected, the controller sends a command to the photovoltaic inverter to reduce its total three-phase output power until the grid connection point power returns to zero or a slight positive direction, thereby ensuring that no electricity is injected into the upstream grid. This power reduction achieves the anti-reverse flow function.

[0004] However, existing technologies suffer from low efficiency in preventing reverse current from entering the load. In three-phase unbalanced load scenarios, it is difficult to achieve precise matching between load power and green energy output. Control response lags when facing dynamic load fluctuations and single-phase overload conditions, failing to simultaneously ensure efficient utilization of green energy, reliable reverse current prevention, and system operational stability. The overall reverse current prevention effect falls significantly short of actual application requirements. Summary of the Invention

[0005] This application provides a method, apparatus, equipment, medium, and product for preventing reverse current in photovoltaic system loads, in order to solve the problem of low efficiency in preventing reverse current in the prior art.

[0006] In a first aspect, embodiments of this application provide a method for preventing reverse current in a photovoltaic system load, comprising:

[0007] Obtain the instantaneous current of the three-phase load and the output power of each phase of the inverter;

[0008] The power of each phase of the three-phase load is calculated based on the instantaneous current, and the power of each phase of the three-phase load is compared with the preset single-phase rated power of the inverter to obtain the load state of each phase load; wherein, the load state includes a non-overload state and an overload state, the non-overload state is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and the overload state is used to indicate that the power of each phase load is greater than the preset single-phase rated power;

[0009] Obtain the power fluctuation frequency of the three-phase load, and determine the weighting coefficient of power regulation based on the load state and the power fluctuation frequency;

[0010] If the load state is the non-overload state, based on the weighting coefficient, the output power of each phase of the inverter is adjusted by a preset power adjustment unit so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load;

[0011] If the load condition is the overload condition, the unbalanced current generated by the three-phase load is compensated to reduce the unbalanced current.

[0012] In one possible design, after adjusting the output power of each phase of the inverter based on the weighting coefficient and a preset power regulation unit when the load state is the non-overload state, so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load, the design further includes:

[0013] The power flow direction between the inverter and the three-phase load is obtained through a preset grid connection point monitoring unit, and the output power of each phase of the inverter is adjusted according to the power flow direction and the weighting coefficient to ensure that no electrical energy flows back from the inverter to the preset grid.

[0014] In one possible design, adjusting the output power of each phase of the inverter according to the power flow direction and the weighting coefficient includes:

[0015] Based on the weighting coefficients and the power flow direction, calculate the target adjustment amount of the output power of each phase of the inverter;

[0016] The output power of each phase of the inverter is adjusted according to the target adjustment amount of the output power of each phase of the inverter; wherein, the target adjustment amount is used to indicate the extent to which the output power of each phase of the inverter needs to be adjusted.

[0017] In one possible design, if the load condition is an overload condition, compensating for the unbalanced current generated by the three-phase load includes:

[0018] If the load state is the overload state, the unbalanced current is obtained, and the unbalanced current is compensated by adjusting the topology and current distribution of the inverter; wherein, the unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and the inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

[0019] In one possible design, after obtaining the unbalanced current and compensating for the unbalanced current by adjusting the inverter topology and current distribution if the load state is the overload state, the design further includes:

[0020] The remaining output capacity is obtained, and the active power demand of the overload phase is compensated according to the remaining output capacity, so that the output power of each phase of the inverter matches the active power demand of each phase load, and no electrical energy flows back from the inverter to the preset grid. Herein, the remaining output capacity refers to the unused portion of the preset three-phase rated total output capacity of the inverter after the unbalanced current compensation is completed, and the overload phase refers to the phase in the three-phase load whose active power demand is greater than the preset single-phase rated power.

[0021] In one possible design, before acquiring the unbalanced current and compensating for the unbalanced current by adjusting the inverter topology and current distribution if the load state is an overload state, the method further includes:

[0022] The historical power of each phase load within a preset first time period is obtained, and the power change trend of each phase load within a preset second time period is predicted based on the historical power of each phase load; wherein, the end time of the preset first time period is earlier than the current time, and the start time of the preset second time period is later than the current time.

[0023] The inverter topology requirements are determined based on the power change trend; wherein, the inverter topology requirements are used to guide the adjustment of the inverter topology to compensate for the unbalanced current.

[0024] In one possible design, compensating for the active power demand of the overload phase based on the remaining output capacity includes:

[0025] Calculate the active power deficit value based on the active power demand of the overload phase and the preset single-phase rated power;

[0026] Based on the remaining output capacity, the active power deficit value, and the preset overload phase power supply priority strategy, a dynamic power limit curve is generated for the overload phase; wherein, the dynamic power limit curve is used to represent the range of the compensation power provided by the inverter to the overload phase over time within the preset second time period.

[0027] Based on the dynamic power limit curve, the inverter is controlled to output compensation power to the overloaded phase.

[0028] In one possible design, comparing the power of each phase of the three-phase load with the preset single-phase rated power of the inverter to obtain the load state of each phase load includes:

[0029] Acquire multiple real-time environmental data, and adjust the preset single-phase rated power according to the multiple real-time environmental data to obtain the adjusted preset single-phase rated power;

[0030] If the power of each phase load in the three-phase load is less than or equal to the adjusted preset single-phase rated power, the load state of each phase load is determined as the non-overload state.

[0031] If the power of each phase of the three-phase load is greater than the adjusted preset single-phase rated power, the load state of each phase load is determined as the overload state.

[0032] In one possible design, obtaining the instantaneous current of the three-phase load and the output power of each phase of the inverter includes:

[0033] Obtain the original current of the three-phase load and the output power of each phase of the inverter;

[0034] The instantaneous current is obtained by performing real-time noise reduction and dynamic compensation on the original current.

[0035] Secondly, embodiments of this application provide a photovoltaic system load anti-reverse current device, comprising:

[0036] The first acquisition module is used to acquire the instantaneous current of the three-phase load and the output power of each phase of the inverter;

[0037] The first calculation module is used to calculate the power of each phase of the three-phase load based on the instantaneous current, and compare the power of each phase of the three-phase load with the preset single-phase rated power of the inverter to obtain the load state of each phase load; wherein, the load state includes a non-overload state and an overload state, the non-overload state is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and the overload state is used to indicate that the power of each phase load is greater than the preset single-phase rated power;

[0038] The second acquisition module is used to acquire the power fluctuation frequency of the three-phase load and determine the weighting coefficient of power regulation based on the load state and the power fluctuation frequency.

[0039] The first adjustment module is used to adjust the output power of each phase of the inverter based on the weighting coefficient and a preset power adjustment unit if the load state is the non-overload state, so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load.

[0040] The first compensation module is used to compensate for the unbalanced current generated by the three-phase load if the load state is the overload state, so as to reduce the unbalanced current.

[0041] In one possible design, the photovoltaic system load anti-reverse current device further includes:

[0042] The third acquisition module is used to acquire the power flow direction between the inverter and the three-phase load through a preset grid connection point monitoring unit, and adjust the output power of each phase of the inverter according to the power flow direction and the weighting coefficient to ensure that no electrical energy flows back from the inverter to the preset grid.

[0043] In one possible design, the third acquisition module includes:

[0044] The first calculation unit is used to calculate the target adjustment amount of the output power of each phase of the inverter based on the weighting coefficient and the power flow direction;

[0045] The first adjustment unit is used to adjust the output power of each phase of the inverter according to the target adjustment amount of the output power of each phase of the inverter; wherein, the target adjustment amount is used to represent the magnitude by which the output power of each phase of the inverter needs to be adjusted.

[0046] In one possible design, the first compensation module includes:

[0047] The first compensation unit is used to acquire the unbalanced current if the load state is the overload state, and to compensate for the unbalanced current by adjusting the topology and current distribution of the inverter; wherein the unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and the inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

[0048] In one possible design, the photovoltaic system load anti-reverse current device further includes:

[0049] The second compensation module is used to obtain the remaining output capacity and compensate the active power demand of the overload phase according to the remaining output capacity, so that the output power of each phase of the inverter matches the active power demand of each phase load, and no electrical energy flows back from the inverter to the preset grid. The remaining output capacity refers to the unused portion of the preset three-phase rated total output capacity of the inverter after the unbalanced current compensation is completed, and the overload phase refers to the phase in the three-phase load whose active power demand is greater than the preset single-phase rated power.

[0050] In one possible design, the photovoltaic system load anti-reverse current device further includes:

[0051] The prediction module is used to obtain the historical power of each phase load within a preset first time period, and predict the power change trend of each phase load within a preset second time period based on the historical power of each phase load; wherein, the end time of the preset first time period is earlier than the current time, and the start time of the preset second time period is later than the current time.

[0052] A determination module is used to determine the topology requirements of the inverter based on the power change trend; wherein the topology requirements of the inverter are used to guide the adjustment of the inverter's topology to compensate for the unbalanced current.

[0053] In one possible design, the second compensation module includes:

[0054] The second calculation unit is used to calculate the active power deficit value based on the active power demand of the overload phase and the preset single-phase rated power.

[0055] The first generation unit is used to generate a dynamic power limit curve for the overload phase based on the remaining output capacity, the active power deficit value, and a preset overload phase power supply priority strategy; wherein, the dynamic power limit curve is used to represent the range of the compensation power provided by the inverter to the overload phase over time within the preset second time period.

[0056] The second compensation unit is used to control the inverter to output compensation power to the overload phase based on the dynamic power limit curve.

[0057] In one possible design, the first computing module includes:

[0058] The first acquisition unit is used to acquire multiple real-time environmental data and adjust the preset single-phase rated power according to the multiple real-time environmental data to obtain the adjusted preset single-phase rated power.

[0059] The first determining unit is used to determine the load state of each phase load as the non-overload state if the power of each phase load in the three-phase load is less than or equal to the adjusted preset single-phase rated power.

[0060] The second determining unit is used to determine the load state of each phase load as the overload state if the power of each phase load in the three-phase load is greater than the adjusted preset single-phase rated power.

[0061] In one possible design, the first acquisition module includes:

[0062] The second acquisition unit is used to acquire the original current of the three-phase load and the output power of each phase of the inverter;

[0063] The noise reduction unit is used to perform real-time noise reduction and dynamic compensation on the original current to obtain the instantaneous current.

[0064] Thirdly, embodiments of this application provide an electronic device, including: a processor, and a memory communicatively connected to the processor;

[0065] The memory stores computer-executed instructions;

[0066] When the processor executes the computer execution instructions stored in the memory, it is used to implement the photovoltaic system load anti-reverse current method as described in any of the first aspects.

[0067] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the photovoltaic system load anti-reverse current method as described in any of the first aspects.

[0068] Fifthly, embodiments of this application provide a computer program product, including a computer program, which, when executed by a processor, is used to implement the photovoltaic system load anti-reverse current method as described in any of the first aspects.

[0069] This application provides a photovoltaic system load anti-reverse current method, device, equipment, medium, and product. It accurately calculates the load power of each phase based on the instantaneous current of the three-phase load, and combines this with the inverter's preset single-phase rated power to divide the load into non-overload and overload scenarios, ensuring the accuracy of load state determination and laying the foundation for differentiated control. By acquiring the three-phase load power fluctuation frequency and determining the power adjustment weight coefficient based on the load state, the power adjustment can dynamically adapt to the load fluctuation characteristics, avoiding the response lag problem caused by a fixed adjustment mode. In the non-overload state, based on the weight coefficient, the power adjustment unit achieves precise matching of the inverter's phase output power with the corresponding phase load power. The precise matching method abandons the traditional approach of uniformly reducing total output power, improves the utilization rate of green electricity and the efficiency of anti-reverse current control, and provides targeted compensation for the unbalanced current generated by the three-phase load under overload conditions to reduce the current imbalance. It avoids the impact of zero-sequence and negative-sequence components on the power grid and equipment, and improves the stability of system operation. Overall, it achieves the synergy of precise phase-by-phase control, load fluctuation adaptation, and overload problem prevention. Under the conditions of three-phase imbalance and dynamic load changes, it ensures that the green electricity output is highly adapted to the load demand and reliably prevents power reverse current, thereby improving the operational stability and energy utilization efficiency of the photovoltaic system and solving the problem of low load anti-reverse current efficiency in existing technologies. Attached Figure Description

[0070] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0071] Figure 1 This application scenario illustrates the application scenario of the photovoltaic system load anti-reverse current method provided in the embodiments of this application. Figure 1 ;

[0072] Figure 2 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 1 ;

[0073] Figure 3 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 2 ;

[0074] Figure 4 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 3 ;

[0075] Figure 5 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 4 ;

[0076] Figure 6 This application scenario illustrates the application scenario of the photovoltaic system load anti-reverse current method provided in the embodiments of this application. Figure 2 ;

[0077] Figure 7 A flowchart illustrating the current detection and limit logic under unbalanced load provided in this application embodiment;

[0078] Figure 8 This is a schematic diagram of the structure of the photovoltaic system load anti-reverse current device provided in the embodiments of this application;

[0079] Figure 9 This is a schematic diagram of the hardware structure of the electronic device provided in the embodiments of this application.

[0080] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0081] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0082] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0083] In the embodiments of this application, the terms "first" and "second" are used to distinguish identical or similar items with substantially the same function and effect. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that "first" and "second" do not necessarily imply difference. It should be noted that in the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner. In the embodiments of this application, "at least one" refers to one or more, and "more than one" refers to two or more.

[0084] It should be noted that the phrase "at...time" in the embodiments of this application can refer to the instant at which a certain situation occurs, or to a period of time after the occurrence of a certain situation; the embodiments of this application do not specifically limit this. Furthermore, the photovoltaic system load anti-reverse current method, device, equipment, medium, and product provided in the embodiments of this application are merely examples; a photovoltaic system load anti-reverse current method, device, equipment, medium, and product may also include more or fewer elements.

[0085] To facilitate a clear description of the technical solutions in the embodiments of this application, some terms and technologies involved in the embodiments of this application will be briefly introduced below:

[0086] Anti-backflow refers to the control process and technology used in distributed green energy (such as photovoltaic and wind power) generation systems to prevent the electricity generated by the system from flowing back into the public grid through real-time monitoring and power regulation. Its core objective is to achieve "self-consumption and no grid connection of surplus power," avoiding interference from excess power to the normal operation of the grid, affecting the judgment of line protection devices, and causing additional stress to grid equipment, thus ensuring the safe and stable operation of the grid and the generation system. In this application, anti-backflow specifically refers to the control effect of preventing reverse flow of electricity to the grid through precise power matching in a scenario where a hybrid inverter operates in conjunction with the load and the grid.

[0087] Unbalanced load: In a three-phase power supply system, the impedance, current, or power of each phase of the load differs, causing the three-phase current and power to be unable to maintain a symmetrical balance. Its core characteristic is the uneven distribution of active and reactive power in the three-phase load, commonly seen in industrial, commercial, and residential power consumption scenarios (such as mixed use of single-phase and three-phase equipment, random equipment start-up and shutdown, etc.). Unbalanced loads can cause zero-sequence and negative-sequence components, leading to problems such as line overheating, equipment aging, and deterioration of power quality. This application specifically refers to three-phase load scenarios that require precise compensation to achieve current and power balance.

[0088] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention as detailed in the appended claims.

[0089] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0090] To clearly understand the technical solution of this application, the existing technical solutions will first be described in detail. Anti-reverse current protection for photovoltaic (PV) system loads refers to an operational strategy that controls the output of the PV inverter to adapt the generated electrical energy to the needs of the local three-phase load, preventing electrical energy from being fed back into the public grid. If reverse current occurs in the PV system, it may not only trigger malfunctions of grid protection devices and affect the stable operation of the grid, but also cause a waste of green electricity resources. Therefore, anti-reverse current protection for PV system loads is crucial for ensuring grid security, improving the utilization rate of green electricity, and promoting the healthy development of the distributed PV industry.

[0091] In existing technologies, sensors installed at the grid connection point of a photovoltaic system detect the direction and magnitude of power or current flowing into the grid. When a reverse power flow is detected, the controller sends a command to the photovoltaic inverter to reduce its total three-phase output power until the grid connection point power returns to zero or a slight positive direction, thus ensuring no power is injected into the upstream grid. This power reduction achieves the anti-reverse current function. However, in three-phase unbalanced load scenarios, it is difficult to achieve precise matching between load power and green electricity output. Control response lags when facing dynamic load fluctuations and single-phase overload conditions, failing to simultaneously ensure efficient green electricity utilization, reliable anti-reverse current operation, and system operational stability. The overall anti-reverse current effect falls significantly short of actual application requirements. Therefore, existing technologies suffer from low load anti-reverse current efficiency.

[0092] Therefore, addressing the low efficiency of load reverse current prevention in existing technologies, the research found that to solve this problem, independent power detection and precise phase-by-phase adjustment of each phase of the three-phase load can be implemented to match the inverter's phase output power with the corresponding phase load power in real time, thereby improving load reverse current prevention efficiency: ① By independently detecting each phase of the three-phase load, the power consumption status of each phase load can be obtained in real time, and the inverter output can be adjusted differently based on the phase load information to improve the accuracy and response speed of reverse current prevention control. ② A matching power regulation method can be adopted to adapt the inverter's phase output power to the corresponding phase load power, achieving efficient matching of green electricity and load even under three-phase unbalanced conditions, thus improving system operational stability. ③ By establishing an independent adjustment mechanism for the load power of each phase and the inverter's single-phase output, the resource waste caused by overall power reduction can be avoided, improving green electricity utilization while ensuring the reliability of reverse current prevention.

[0093] Specifically, by independently detecting and judging the power of each phase of the three-phase load, the inverter can be independently adjusted based on the actual power demand of each phase load, so that the output of each phase of the inverter can be adaptively matched with the corresponding phase load demand. This can improve the dynamic response speed of the anti-reverse flow control and the stability of the system operation while avoiding power backflow.

[0094] This application discloses a photovoltaic system load anti-reverse current method, device, equipment, medium, and product. By accurately calculating the load power of each phase based on the instantaneous current of the three-phase load, and combining this with the inverter's preset single-phase rated power to divide the load into non-overload and overload scenarios, the accuracy of load state determination is ensured, laying the foundation for differentiated control. By acquiring the three-phase load power fluctuation frequency and determining the power adjustment weight coefficient based on the load state, the power adjustment can dynamically adapt to the load fluctuation characteristics, avoiding the response lag problem caused by a fixed adjustment mode. In the non-overload state, based on the weight coefficient, the power adjustment unit achieves accurate matching between the inverter's phase output power and the corresponding phase load power. By matching and abandoning the traditional method of uniformly reducing total output power, this technology improves the utilization rate of green electricity and the efficiency of anti-reverse current control. Under overload conditions, it specifically compensates for the unbalanced current generated by the three-phase load to reduce the current imbalance, avoids the impact of zero-sequence and negative-sequence components on the power grid and equipment, and improves the stability of system operation. Overall, it achieves the synergy of precise phase-by-phase control, load fluctuation adaptation, and overload problem prevention. Under the conditions of three-phase imbalance and dynamic load changes, it ensures that the green electricity output is highly adapted to the load demand and reliably prevents power reverse current, thereby improving the operational stability and energy utilization efficiency of the photovoltaic system and solving the problem of low load anti-reverse current efficiency in existing technologies.

[0095] Based on the above-mentioned inventive discovery, the technical solution of this application is proposed.

[0096] The following describes the application scenarios of the photovoltaic system load anti-reverse current method provided in the embodiments of the present invention. Figure 1 This application scenario illustrates the application scenario of the photovoltaic system load anti-reverse current method provided in the embodiments of this application. Figure 1 .like Figure 1 As shown, this application scenario includes a mobile terminal 101 and a control unit 102. The mobile terminal 101 collects the instantaneous current of the three-phase load and the output power of each phase of the inverter, and sends the instantaneous current of the three-phase load and the output power of each phase of the inverter to the control unit 102. The control unit 102 calculates the power of each phase of the three-phase load based on the instantaneous current, and compares the power of each phase of the three-phase load with the preset single-phase rated power of the inverter to obtain the load state of each phase of the load. The control unit 102 obtains the power fluctuation frequency of the three-phase load, and determines the weighting coefficient of power regulation based on the load state and the power fluctuation frequency. If the load state is not overloaded, the control unit 102 adjusts the output power of each phase of the inverter through the preset power regulation unit based on the weighting coefficient to match the output power of each phase of the inverter with the power of the corresponding phase of the three-phase load. If the load state is overloaded, the control unit 102 compensates for the unbalanced current generated by the three-phase load to reduce the unbalanced current.

[0097] The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0098] Figure 2 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 1 .like Figure 2 As shown, in this embodiment, the execution subject of this invention is a control unit. Therefore, the photovoltaic system load anti-reverse current method provided in this embodiment includes the following steps:

[0099] S201. Obtain the instantaneous current of the three-phase load and the output power of each phase of the inverter.

[0100] Specifically, current acquisition devices can be installed at the grid connection point of the photovoltaic system and the connection point of the three-phase load to collect the current signal of each phase of the three-phase load in real time and transmit it to the control unit. At the same time, the current output power of each phase of the inverter can be read through the communication interface between the control unit and the inverter to complete the acquisition of instantaneous current and output power of each phase. This step is used to provide basic data for subsequent calculation of load power of each phase, judgment of load status and adjustment of inverter output power.

[0101] The grid connection point is the electrical junction point where the inverter output side of the photovoltaic system connects to the user-side load and the upstream power grid. It is also the physical access point where the power generated by the photovoltaic system interacts with the power grid. The power generated by the photovoltaic system is converted by the inverter and then supplied to the load through this node. At the same time, this location is also a key node for determining whether power flows to the grid.

[0102] S202. Calculate the power of each phase load in the three-phase load based on the instantaneous current, and compare the power of each phase load in the three-phase load with the preset single-phase rated power of the inverter to obtain the load status of each phase load; wherein, the load status includes non-overload status and overload status. Non-overload status is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and overload status is used to indicate that the power of each phase load is greater than the preset single-phase rated power.

[0103] Specifically, the instantaneous current of each phase of the three-phase load can be obtained, and combined with the actual phase voltage of the corresponding phase, the actual power of each phase can be obtained through multiplication. Then, the actual power of each phase is compared with the preset single-phase rated power of the inverter. If the actual power of a phase is less than or equal to the preset single-phase rated power, the load state of that phase is determined to be non-overloaded. If the actual power of a phase is greater than the preset single-phase rated power, the load state of that phase is determined to be overloaded. This comparison and determination of each phase of the three-phase load is completed in sequence to obtain the load state corresponding to each phase. This step is used to accurately identify the actual operating state of each phase of the three-phase load, providing a direct basis for subsequent power regulation or current compensation operations for different load states.

[0104] The non-overload state is the operating state where the actual operating power of one phase of the three-phase load is less than or equal to the inverter's preset single-phase rated power. At this time, the power demand of the load of that phase is within the normal output capacity range of the inverter's single phase. The overload state is the operating state where the actual operating power of one phase of the three-phase load is greater than the inverter's preset single-phase rated power. At this time, the power demand of the load of that phase exceeds the normal output capacity range of the inverter's single phase.

[0105] The preset single-phase rated power is a power reference limit set by the inverter for the single-phase output terminal, which can ensure long-term stable output and prevent device malfunctions. This parameter can be factory-calibrated by the inverter based on its own hardware design specifications, the withstand capability of power devices, the level of circuit heat dissipation design, and other core hardware indicators. It can also be adapted based on the actual application scenario of the photovoltaic system and the conventional power demand range of the three-phase load. At the same time, this parameter can also be dynamically corrected based on real-time environmental data to match the parameter with the actual external operating conditions of the inverter. It becomes a key criterion for distinguishing whether each phase of the three-phase load exceeds the single-phase output capability of the inverter, and also provides a reference benchmark that fits the actual operating requirements for subsequent accurate identification of load status, differentiated power adjustment, and unbalanced current compensation.

[0106] S203. Obtain the power fluctuation frequency of the three-phase load, and determine the weighting coefficient of power regulation based on the load status and power fluctuation frequency.

[0107] Specifically, real-time power data of each phase of the three-phase load can be continuously collected within a preset time period. The fluctuation period of the power data of each phase over time can be extracted, and the power fluctuation frequency of each phase load can be obtained by period conversion. Then, according to the overload or non-overload state of each phase load, corresponding coefficient values ​​are matched for different fluctuation frequency ranges. The weighting coefficients for power adjustment corresponding to each phase load are obtained by superimposing the base coefficients corresponding to the state and the matching coefficients corresponding to the frequency. Different base coefficients are matched for non-overload and overload states. The higher the power fluctuation frequency, the corresponding coefficient value is adjusted accordingly. Finally, the weighting coefficients that adapt to the actual operating conditions of each phase are determined. This step is used to give the adjustment of the output power of each phase of the inverter an adaptation coefficient that fits the actual power change characteristics of the load, so that the amplitude and rate of power adjustment match the power fluctuation of the load, and provide a quantitative basis for subsequent precise adjustment of the output power of each phase of the inverter.

[0108] Among them, the power fluctuation frequency is the frequency at which the actual operating power of each phase of the three-phase load changes periodically over time. It reflects the number of times the load power fluctuates per unit time and can intuitively show the rate of change of load power. This parameter is determined by the load's own electrical characteristics and the operating status of the connected electrical equipment. Different types of loads and different operating conditions have significantly different power fluctuation frequencies. The weighting coefficient is a quantitative coefficient determined by combining the power fluctuation frequency of the three-phase load and the actual load status. It is an important adaptation parameter in the process of adjusting the output power of each phase of the inverter. Different load statuses and different power fluctuation frequencies correspond to different weighting coefficient values. This coefficient directly determines the amplitude and rate of output power adjustment of each phase of the inverter, so that the power adjustment action is adapted to the actual operating characteristics of the load.

[0109] S204. If the load condition is not overloaded, the output power of each phase of the inverter is adjusted by a preset power regulation unit based on the weighting coefficient, so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load.

[0110] Specifically, the difference between the current output power of each phase of the inverter and the actual power of the corresponding phase load can be calculated first. This difference is then used to perform corresponding calculations with the corresponding weighting coefficients to obtain the specific adjustment amount of the output power of each phase of the inverter. Then, the output power of each phase of the inverter is adjusted incrementally or decrementally according to the preset power adjustment unit, gradually calibrating the output power of each phase of the inverter until the output power of each phase of the inverter is consistent with the actual power of the corresponding phase load, thus completing the power matching operation. This step is used to ensure that the output power of each phase of the inverter matches the actual power requirements of each phase of the three-phase load, achieving precise matching between the inverter output and the load requirements in the photovoltaic system, and ensuring the stable operation of the photovoltaic system under non-overload conditions.

[0111] Among them, "matching the output power of each phase of the inverter with the power of the corresponding phase of the three-phase load" means achieving a precise single-phase correspondence between the inverter output and the load demand, that is, making the output power of the inverter's A, B, and C phases completely consistent with the actual power demand of the A, B, and C phases of the three-phase load, breaking the limitation of the traditional solution of "three-phase power binding". When the load is not overloaded, the control unit first obtains the real-time current of each phase load through the high-precision current detection unit, and calculates the instantaneous active power demand of each phase load in combination with the load voltage. For example, if the load of phase A needs 15kW, phase B needs 12kW, and phase C needs 8kW, then the control unit controls the preset power regulation unit (which can be integrated inside the inverter and includes power devices, topology adjustment modules, etc.) to independently adjust the output of each phase of the inverter. Only the output power of phase A is adjusted to 15kW, phase B to 12kW, and phase C to 8kW, instead of leveling the three-phase output according to the minimum phase of 8kW as in the traditional solution. In the end, the output power of each phase inverter is equal to the load power of the corresponding phase, ensuring that the load does not need to draw power from the grid, while avoiding the waste of green electricity due to three-phase binding, and taking into account both anti-reverse current and full self-use of green electricity.

[0112] Corresponding phases refer to the one-to-one matching relationship between the A-phase, B-phase, and C-phase output terminals of the inverter and the A-phase, B-phase, and C-phase input terminals of the three-phase load in a three-phase power supply system. That is, inverter A corresponds to load A phase, inverter B corresponds to load B phase, and inverter C corresponds to load C phase.

[0113] The power regulation unit is an actuator that enables independent and precise control of the output power of each phase of the inverter. Essentially, it is a modular unit integrating power electronic devices, control circuits, and feedback modules. It can dynamically adjust the output power of each phase based on commands from the control unit, ensuring matching with the corresponding phase load power. Structurally, it uses thyristors or solid-state relays as power switching elements, coupled with a phase-triggered control circuit, a current / voltage sampling feedback module, and a heat dissipation module. The thyristors are responsible for power switching and conduction angle adjustment. The trigger control circuit receives the power demand signal from the control unit and generates trigger pulses. The feedback module collects output current / voltage data in real time to achieve closed-loop regulation. The heat dissipation module ensures long-term stable operation of the components. In terms of connection, the power regulation unit is typically integrated inside the inverter. Its input is connected to the DC-side power module or AC-side bus of the inverter, and its output corresponds to the A, B, and C phase outputs of the inverter. Simultaneously, it establishes signal interaction with the control unit through a communication line, forming a complete control link of command reception, power regulation, and data feedback. The purpose of this unit is to break the traditional three-phase bound power control mode under non-overload conditions, and independently adjust the output power of each phase so that the output of each phase of the inverter is completely matched with the load power of the corresponding phase.

[0114] If the load condition is not overloaded, that is, when the load power of each phase is within the rated output capacity range of the single phase of the hybrid inverter, a closed-loop control strategy of "single-phase detection - single-phase compensation - precise matching" can be used to achieve full utilization of green electricity under the premise of anti-reverse current, including:

[0115] 1. Real-time accurate detection of single-phase load current: A high-precision current detection unit is set between the output terminal of each phase of the hybrid inverter and the load to collect the instantaneous current signal of each phase load in real time and transmit the detection data to the control unit, so as to realize the accurate perception of the operating status of each phase load and provide data support for subsequent compensation control.

[0116] 2. Independent active power compensation for single-phase load: Based on the detected single-phase load current signal and combined with the load voltage, the control unit calculates the instantaneous active power demand of each phase load, and then independently adjusts the output active power of each phase of the hybrid inverter to achieve individual compensation of the active power of each phase load, breaking the power limitation mode of the traditional "three-phase binding".

[0117] 3. Precise power matching and anti-reverse flow protection: Closed-loop control ensures that the load power of each phase is perfectly matched with the output power of the corresponding phase of the hybrid inverter, that is, the load power = the output power of each phase of the hybrid inverter. At the same time, the power flow direction at the grid connection point is monitored in real time to ensure that no power flows back to the grid, achieving the dual goals of "zero reverse flow" and "full self-use of green electricity". The load does not need to draw power from the grid, minimizing grid dependence and electricity costs.

[0118] S205. If the load is in an overload state, compensate for the unbalanced current generated by the three-phase load to reduce the unbalanced current.

[0119] Specifically, the actual value of the unbalanced current generated by the three-phase load can be collected first. The power distribution mode inside the inverter can be adjusted through the preset power regulation unit to allocate the appropriate compensation current to the phase with the larger current. At the same time, the output current of the other phases can be adjusted to the appropriate value. The current difference between the three phases can be offset by the coordinated adjustment of the current of each phase, and the unbalanced current generated by the three-phase load can be gradually reduced until the current drops to the appropriate operating value. This step is used to reduce the unbalanced current generated when the three-phase load is overloaded, so that the current output of the inverter matches the current demand of the three-phase load, and ensures the stable operation of the photovoltaic system under overload conditions.

[0120] For example, when an overload is detected in phase A of a three-phase load and an unbalanced current appears in the three-phase circuit, the actual operating current values ​​of phases A, B, and C are first obtained through the current acquisition module to determine the current difference between phase A and the other two phases. Then, the inverter topology is adjusted to a three-phase independent control mode through the power regulation unit, and the current distribution inside the inverter is adjusted to allocate appropriate compensation current to phases B and C. The output current of the two phases is gradually increased to a value that matches the overload current of phase A. The current difference in the circuit is offset by the coordinated adjustment of the three-phase current. The three-phase current values ​​are continuously collected and checked until the difference of the three-phase current is reduced to the range suitable for normal operation of the inverter, thus completing the compensation for the unbalanced current and achieving an effective reduction of the current.

[0121] Unbalanced current is an unbalanced current formed by the inconsistent active power demand of each phase of a three-phase load, resulting in differences in the actual operating current of each phase. This current, caused by the difference in power demand of the three-phase load, appears in the three-phase power supply circuit of the photovoltaic system and directly affects the normal operation of the inverter and the photovoltaic system. Compensating for the unbalanced current generated by the three-phase load involves combining the actual current values ​​of each phase of the three-phase load and adjusting the inverter's topology and current distribution method to supplement the current of the phases that are lacking current with the corresponding current value. At the same time, the output current of the remaining phases is adjusted accordingly to offset the current difference between the three phases, gradually reducing or even eliminating the unbalanced current in the circuit. This is the regulation action of the photovoltaic system under overload conditions.

[0122] The photovoltaic system load anti-reverse current method is mainly applied in the field of distributed photovoltaic grid-connected power generation technology. Typical scenarios include photovoltaic energy storage integrated power supply systems in industrial and commercial plants, residential rooftops, households, and small grid-connected points. Under actual operating conditions such as inverters carrying three-phase unbalanced loads, frequent load power fluctuations, and alternating overload and normal states, it solves the technical problems of traditional grid-connected systems, such as power backflow to the grid, current distortion caused by three-phase load imbalance, unreasonable power distribution during overload, and the inability of inverter rated capacity to dynamically adapt to environmental and load changes. It achieves coordinated and stable operation of precise power regulation, load balancing, overload compensation, and anti-reverse current.

[0123] This method can also be extended to the fields of microgrids and independent energy storage power supply technology. It is suitable for integrated photovoltaic and energy storage microgrid scenarios without stable large power grid support, such as islands, remote areas, base stations, and data centers. Under the conditions of mixed power consumption of multiple loads, large differences in three-phase loads, and the need to prioritize the power supply of important loads, it solves the problems of inflexible power allocation, difficulty in suppressing unbalanced current, insufficient power supply to overloaded phases, and low overall capacity utilization of traditional microgrids. It realizes the internal power autonomous balance of the photovoltaic and energy storage system, and improves the reliability of power supply and the safety of equipment operation.

[0124] This embodiment provides a photovoltaic system load anti-reverse current method. It accurately calculates the load power of each phase based on the instantaneous current of the three-phase load, and combines this with the inverter's preset single-phase rated power to divide the load into non-overload and overload scenarios, ensuring the accuracy of load state determination and laying the foundation for differentiated control. By acquiring the three-phase load power fluctuation frequency and determining the power adjustment weight coefficient based on the load state, the power adjustment can dynamically adapt to the load fluctuation characteristics, avoiding the response lag problem caused by fixed adjustment modes. In the non-overload state, based on the weight coefficient, the power adjustment unit achieves precise matching between the inverter's phase output power and the corresponding phase load power, eliminating the need for traditional methods. By uniformly reducing the total output power, the utilization rate of green electricity and the efficiency of anti-reverse current control are improved. Under overload conditions, the unbalanced current generated by the three-phase load is specifically compensated to reduce the current imbalance. The impact of zero-sequence and negative-sequence components on the power grid and equipment is avoided, and the system operation stability is improved. The system achieves synergy between precise phase control, load fluctuation adaptation, and overload problem prevention. Under the conditions of three-phase imbalance and dynamic load changes, it ensures that the green electricity output is highly adapted to the load demand and reliably prevents power reverse current, thereby improving the operation stability and energy utilization efficiency of the photovoltaic system and solving the problem of low load anti-reverse current efficiency in existing technologies.

[0125] In one possible design, S202 compares the power of each phase of the three-phase load with the inverter's preset single-phase rated power to obtain the load status of each phase, including:

[0126] S2021. Acquire multiple real-time environmental data, and adjust the preset single-phase rated power according to the multiple real-time environmental data to obtain the adjusted preset single-phase rated power.

[0127] Specifically, the control unit connects to temperature, voltage, and runtime acquisition modules to obtain real-time environmental data such as the inverter's internal operating temperature, DC input voltage, and continuous runtime. This data is then compared to a preset safe operating range within the control unit. When the operating temperature is within the normal range, the input voltage is stable, and the runtime is within the safe range, the preset single-phase rated power remains unchanged. When the operating temperature is too high, the input voltage is too low, or the runtime is too long, the preset single-phase rated power is reduced according to the degree of deviation from the normal range, ultimately resulting in an adjusted preset single-phase rated power adapted to the current environment. This step dynamically corrects the single-phase power limit based on the inverter's actual operating environment, ensuring that the load condition assessment accurately reflects the equipment's actual operating capacity and improving system operational safety.

[0128] S2022. If the power of each phase load in a three-phase load is less than or equal to the adjusted preset single-phase rated power, the load status of each phase load shall be determined as non-overload status.

[0129] Specifically, the control unit reads the real-time power value of each phase of the three-phase load one by one, and then compares it item by item with the previously adjusted preset single-phase rated power. First, the load power of phase A is read and compared with the adjusted preset single-phase rated power. Then, the same comparison operation is performed on phases B and C in turn. When the load power of a certain phase is less than or equal to the adjusted preset single-phase rated power, the control unit directly marks the load status of that phase as non-overloaded. The three phases are judged and marked independently without interference. After the judgment is completed, the status of each phase is stored in the control unit for direct recall in subsequent adjustment processes. This step is used to clearly distinguish whether the load of each phase is within the safe power supply range, providing direct status basis for whether to perform unbalance compensation, power compensation and other operations.

[0130] S2023. If the power of each phase of the three-phase load is greater than the adjusted preset single-phase rated power, the load status of each phase load shall be determined as an overload state.

[0131] Specifically, the control unit can sequentially retrieve the real-time power values ​​of phases A, B, and C of the three-phase load, and then independently compare them with the adjusted preset single-phase rated power. First, the comparison between the load power of phase A and the adjusted preset single-phase rated power is completed, and then the comparison operation of phases B and C is completed in the same way. When the load power of a certain phase is greater than the adjusted preset single-phase rated power, the control unit directly marks the load status of that phase as an overload state. Each of the three phases completes the judgment and marking, and the judgment results can be stored synchronously in the designated storage area of ​​the control unit for direct retrieval and use in subsequent control processes. This step is used to clearly identify the operating status of each phase load exceeding the current power supply capacity of the inverter, and provide direct status judgment results for subsequent targeted operations such as unbalanced current compensation and active power gap filling.

[0132] The technical effect of this solution in this embodiment is as follows: by acquiring multiple real-time environmental data and dynamically adjusting the preset single-phase rated power of the inverter accordingly, and then determining the overload and non-overload states of the load based on the adjusted power limit, the load state determination standard is made to fit the actual operating conditions of the inverter at present. This avoids the situation where the actual output capacity of the inverter changes due to environmental factors but the load state is still determined according to a fixed limit. This makes the load state identification more accurate and closer to the actual operating capacity of the equipment. At the same time, it makes the subsequent power adjustment, unbalanced current compensation and other operations for different load states more adaptable to actual needs. This ensures that the photovoltaic system can accurately determine the load state based on the actual output capacity of the inverter under different environmental conditions, thereby making the load anti-reverse current control action of the entire photovoltaic system more in line with the actual equipment and more stable in operation.

[0133] In one possible design, S201, obtaining the instantaneous current of the three-phase load and the output power of each phase of the inverter, includes:

[0134] S2011. Obtain the raw current of the three-phase load and the output power of each phase of the inverter.

[0135] Specifically, current sampling elements can be installed on the three-phase load output circuits of the inverter. These elements directly collect the current signals transmitted in the circuit to obtain the raw current of each of the three phases of the load. Simultaneously, power acquisition units are set up at the power output ports of each phase of the inverter to synchronously acquire the voltage and current signals output by each phase, obtaining the real-time power values ​​of each phase. The entire acquisition process is executed synchronously at fixed time intervals to ensure that the raw current and the output power of each phase are consistent in time. This step is used to obtain the most basic electrical operating data of the load and the inverter, providing a basic data source for subsequent current processing and status judgment.

[0136] S2012. Perform real-time noise reduction and dynamic compensation on the original current to obtain the instantaneous current.

[0137] Specifically, after the control unit receives the raw current signal, it first smooths the raw current values ​​collected at multiple consecutive moments, eliminating abnormal values ​​that suddenly jump or deviate from the normal range, thus achieving real-time noise reduction. Then, based on the current inverter's operating temperature and line losses, it makes a small correction to compensate for signal deviations caused by line transmission and device operation, completing dynamic compensation. The corrected stable current value is the instantaneous current used for subsequent judgment and control. This step eliminates interference signals and errors in the raw current, making the obtained instantaneous current more accurate and stable, providing a reliable data foundation for subsequent load status judgment and unbalanced current compensation.

[0138] The raw current refers to the real-time three-phase load current signal directly acquired by a high-precision current detection unit, such as a current transformer, between the output terminals of each phase of the inverter and the load, without any processing. This signal may contain irrelevant interference components such as line interference, device noise, and grid fluctuations. It can only reflect the initial state of the load current and cannot be directly used for accurate power calculation and compensation control. The instantaneous current is the accurate current value obtained after the raw current has been processed by real-time noise reduction and dynamic compensation. It can truly reflect the actual current demand of the three-phase load at a certain moment and is the key basis for the control unit to calculate the active power of each phase load, judge the load status, and execute the power compensation strategy.

[0139] The technical effect of this solution in this embodiment is that by performing real-time noise reduction and dynamic compensation processing on the raw current collected during the acquisition of three-phase load current and inverter output power, interference signals and errors in the acquisition process can be effectively eliminated, resulting in more accurate instantaneous current. This provides a reliable data basis for the accurate calculation of load power of each phase and the determination of load status, ensuring stable matching between inverter output power and corresponding phase load power, and solving the problem of noise and error in current acquisition signals affecting subsequent control accuracy.

[0140] In one possible design, if the load condition in S205 is overloaded, compensation is provided for the unbalanced current generated by the three-phase load, including:

[0141] S2051. If the load is in an overload state, obtain the unbalanced current and compensate for the unbalanced current by adjusting the inverter topology and current distribution; where unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

[0142] Specifically, after determining that the load is in an overload state, the actual operating current of each phase of the three-phase load is obtained through the current acquisition component. Combined with the active power demand of each phase, the current difference between the three phases is calculated, and this difference is the unbalanced current. Then, the inverter topology is switched to a three-phase independent control topology. Based on the current difference and active power demand of each phase, phase-adaptive output current is allocated to each phase. The phase with high active power demand and low current value is supplemented with corresponding current, and the output current of the phase with low active power demand and high current value is appropriately reduced. Through the precise allocation of current in each phase, the current difference between the three phases is offset, and the unbalanced current is compensated. This step is used to reduce the unbalanced current caused by the inconsistent active power demand of the three-phase load under overload conditions, so that the current output of the inverter is adapted to the actual demand of each phase of the three-phase load, ensuring the stable operation of the photovoltaic system under overload conditions.

[0143] For example, when overload is detected in phases A and C of a three-phase load, the real-time operating current of phases A, B, and C is first collected using current sensors at a frequency of 10Hz. The collected currents are 8A for phase A, 5A for phase B, and 9A for phase C. Combined with the active power demand of each phase, the active power demand is confirmed to be 1760W for phase A, 1100W for phase B, and 1980W for phase C. The inconsistency in the three-phase active power demand leads to significant differences in the three-phase currents. Specifically, the current difference between phases A and B is 3A, and the current difference between phases C and B is 4A. This difference is the unbalanced current. The control unit then sends a command to switch the inverter topology from a three-phase centralized topology to a three-phase independent H-bridge topology, enabling independent current regulation of phases A, B, and C. The current distribution module then redistributes the output current of each phase, adjusting the output current of phase B from 5A to 7.5A, phase A from 8A to 7.8A, and phase C from 9A to 7.7A. The current of each phase is continuously collected and fine-tuned until the currents of phases A, B, and C stabilize between 7.6A and 7.8A, with the three-phase current difference controlled within 0.2A, thus completing the compensation for the unbalanced current.

[0144] The topology is the circuit connection method inside the inverter that realizes power conversion and output regulation. Different topologies correspond to different combinations and connection forms of circuit components, which can realize different regulation modes such as centralized regulation or independent regulation of the three-phase output of the inverter, adapting to different operating conditions of the load. Current distribution is based on the actual active power demand and current conditions of each phase of the load. The output current under the inverter topology is reasonably allocated to each phase of the load, and the appropriate current value is assigned to each phase of the load. By adjusting the magnitude of the current output of each phase, the balanced output of the three-phase current is achieved, adapting to the differentiated current requirements of the three-phase load.

[0145] Adjusting the inverter's topology and current distribution to compensate for unbalanced current involves changing the operating mode and connection of the inverter's internal circuitry when the three-phase load is overloaded. This enables the inverter to have independent three-phase regulation capabilities. Then, based on the active power demand and current differences of each phase load, the output current of each phase is redistributed to make up for the current value of the phase with insufficient current and reduce the current value of the phase with excessive current. This reduces and eliminates the current difference between the three phases, thereby compensating for the unbalanced current.

[0146] The technical effect of this solution in this embodiment is as follows: by acquiring the unbalanced current caused by the inconsistent active power demand of each phase of the three-phase load, and adjusting the topology and current distribution of the inverter, the unbalanced current can be directly compensated. This can specifically eliminate the current deviation caused by the uneven power consumption of the three-phase load, allowing the inverter to maintain the relative balance of the three-phase current under overload conditions, avoiding the impact of current imbalance on the normal operation of the system. At the same time, it provides a stable current basis for further power compensation and maintaining reverse current-free operation, thereby improving the adaptability and operational stability of the photovoltaic system under overload scenarios.

[0147] Figure 3 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 2 In this embodiment, in Figure 2 Based on the provided embodiments, the method for preventing reverse current in photovoltaic system loads is further explained. The method for preventing reverse current in photovoltaic system loads includes:

[0148] S301: Obtain the instantaneous current of the three-phase load and the output power of each phase of the inverter.

[0149] S302. Calculate the power of each phase load in the three-phase load based on the instantaneous current, and compare the power of each phase load in the three-phase load with the preset single-phase rated power of the inverter to obtain the load status of each phase load; wherein, the load status includes non-overload status and overload status. Non-overload status is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and overload status is used to indicate that the power of each phase load is greater than the preset single-phase rated power.

[0150] S303. Obtain the power fluctuation frequency of the three-phase load, and determine the weighting coefficient of power regulation based on the load status and power fluctuation frequency.

[0151] S304. If the load condition is not overloaded, the output power of each phase of the inverter is adjusted by the preset power adjustment unit based on the weighting coefficient so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load.

[0152] S301-S304 are similar to S201-S204, and will not be described again in this embodiment.

[0153] S305. The power flow direction between the inverter and the three-phase load is obtained through the preset grid connection point monitoring unit, and the output power of each phase of the inverter is adjusted according to the power flow direction and weighting coefficient to ensure that no power flows back from the inverter to the preset grid.

[0154] Specifically, a grid connection point monitoring unit can be pre-set, consisting of a power sensor and a signal processing module. The power sensor is installed at the grid connection point of the photovoltaic system. The power sensor collects the instantaneous power signal at the connection node between the inverter output and the three-phase load in real time. The signal processing module filters and amplifies the collected instantaneous power signal to remove interference and impurities. Then, it determines the power flow direction by the positive or negative value of the power signal. When the power signal is positive, it indicates that power is flowing from the inverter to the three-phase load. When the power signal is negative, it indicates that power is about to flow or has already flowed from the inverter back to the grid. The signal processing module transmits the determined power flow direction information to the control unit. The control unit simultaneously retrieves the previous data. For each phase, a power regulation weighting coefficient is determined. If a reverse power flow is detected, the control unit calculates the corresponding output power adjustment for each phase of the inverter based on the weighting coefficient and sends a differentiated adjustment command to the power regulation unit. After receiving the command, the power regulation unit lowers the inverter output power according to the corresponding adjustment amount. During the adjustment process, it simultaneously receives the power flow direction signal fed back by the grid connection point monitoring unit and always adapts the adjustment range of each phase according to the weighting coefficient until the power flow direction is restored to the positive direction of the inverter flowing to the three-phase load, and keeps the power signal stable within a small positive range to ensure that no power flows back to the grid. If the power flow direction is always positive, the current output power of each phase of the inverter remains unchanged. This step is used to perform secondary verification and differentiated dynamic fine-tuning of the actual effect of the inverter power regulation based on the weighting coefficient of the load characteristics. This makes the power adjustment action more in line with the actual operating characteristics of each phase load, compensates for possible deviations in the previous adjustment, completely eliminates the situation of power being injected back into the grid, and ensures the reliability and accuracy of the anti-reverse flow function.

[0155] S306. If the load is in an overload state, compensate for the unbalanced current generated by the three-phase load to reduce the unbalanced current.

[0156] S306 is similar to S205, and will not be described again in this embodiment.

[0157] The technical effect of this solution in this embodiment is as follows: by obtaining the power flow direction between the inverter and the three-phase load through the grid connection point monitoring unit, and combining the weighting coefficient, the output power of each phase of the inverter is adjusted accordingly. This not only realizes the secondary verification and dynamic correction of the power regulation effect, but also makes the power adjustment range fit the actual power fluctuation characteristics of each phase load, avoiding the adjustment deviation caused by a single adjustment method. It forms a secondary protection against reverse flow from the power flow direction level, eliminating the situation where electrical energy flows back from the inverter to the grid, making the anti-reverse flow control of the photovoltaic system more accurate and more in line with the actual operating conditions of the load, and at the same time improving the stability and reliability of the photovoltaic system under non-overload conditions.

[0158] In one possible design, the S305 adjusts the output power of each phase of the inverter according to the power flow direction and weighting coefficient, including:

[0159] S3051. Calculate the target adjustment amount of the output power of each phase of the inverter based on the weighting coefficient and power flow direction.

[0160] Specifically, the power flow direction can be numerically calibrated first, clarifying that a fixed forward base value corresponds to forward power, and a fixed reverse base value corresponds to reverse power. The absolute value of the reverse base value is greater than the forward base value, thus distinguishing different power flow situations. Then, the weighting coefficient is multiplied by the base value corresponding to the power flow direction to obtain the flow direction adjustment base amount. Subsequently, the difference between the current inverter phase output power and the corresponding phase load power is obtained, and this difference is added to the flow direction adjustment base amount. The result is the target adjustment amount of the inverter's corresponding phase output power. Simultaneously, during the calculation process... If the target adjustment amount is positive, it means that the output power of the corresponding phase inverter needs to be increased by that value; if it is negative, it means that the output power of the corresponding phase inverter needs to be decreased by that value; if it is zero, it means that the output power of the corresponding phase inverter does not need to be adjusted and can be maintained in its current output state. This step is used to determine the specific range of adjustment required for the output power of each phase of the inverter through specific numerical calculations, providing a clear and directly implementable numerical basis for subsequent actual power regulation operations, ensuring that the adjusted output power of each phase of the inverter can both meet the load demand and prevent reverse power flow.

[0161] The target adjustment amount is the specific magnitude of the change that the output power of each phase of the inverter needs to be obtained after calculation by the control unit. It is used to directly indicate the specific amount by which the output power of the corresponding phase of the inverter needs to be increased or decreased. It is the direct operational basis used by the control unit when it performs output power adjustment on the inverter.

[0162] S3052. Adjust the output power of each phase of the inverter according to the target adjustment amount of the output power of each phase of the inverter; wherein, the target adjustment amount is used to indicate the magnitude of adjustment required for the output power of each phase of the inverter.

[0163] Specifically, the calculated target adjustment amount of output power for each phase can be converted into a corresponding level adjustment signal. This signal is then transmitted to the power drive circuit inside the inverter via a communication interface. The power drive circuit independently adjusts the power output circuit of each phase according to the signal content, increasing or decreasing the output power of the corresponding phase according to the value corresponding to the target adjustment amount. After the adjustment is completed, the current output power of each phase is fed back to the control unit to keep the output power of each phase consistent with the value after the target adjustment amount is corrected. The entire adjustment process is executed independently by phase without affecting each other. This step is used to perform actual modification operations on the output power of each phase of the inverter according to the target adjustment amount, thereby completing the precise correction of the inverter's output power.

[0164] The technical effect of this solution in this embodiment is that by combining the power fluctuation frequency of the three-phase load with the weighting coefficient to calculate the target adjustment amount of the output power of each phase of the inverter and performing corresponding adjustments, the system can adopt an appropriate adjustment strategy when facing load fluctuations of different degrees. This makes the power adjustment process more stable, accurate and in line with the actual working conditions, avoiding over-adjustment or under-adjustment, ensuring the stability and control accuracy of the system power matching, and solving the problems of single adjustment strategy and insufficient dynamic adaptability in the power flow adjustment process.

[0165] Figure 4 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 3 In this embodiment, in Figure 3 Based on the provided embodiments, the method for preventing reverse current in photovoltaic system loads is further explained. The method for preventing reverse current in photovoltaic system loads includes:

[0166] S401. If the load is in an overload state, obtain the unbalanced current and compensate for the unbalanced current by adjusting the inverter topology and current distribution; where unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

[0167] S401 is similar to S2051, and will not be described again in this embodiment.

[0168] S402. Obtain the remaining output capacity and compensate the active power demand of the overload phase according to the remaining output capacity, so that the output power of each phase of the inverter matches the active power demand of each phase load, and no electrical energy flows back from the inverter to the preset grid; whereby, the remaining output capacity refers to the unused portion of the preset three-phase rated total output capacity of the inverter after the unbalanced current compensation is completed, and the overload phase refers to the phase in the three-phase load whose active power demand is greater than the preset single-phase rated power.

[0169] Specifically, after unbalanced current compensation is completed, the rated total output capacity of the inverter's three phases is read. Then, the power output of each phase is added together to obtain the inverter's current actual total output power. The remaining output capacity is obtained by subtracting the current actual total output power from the rated total output capacity. Next, the phases in the three-phase load that are overloaded are identified. The portion of the overloaded phase's active power demand exceeding the preset single-phase rated power is taken as the power to be compensated. Within the allowable range of the remaining output capacity, the control unit sends a command to the inverter's power output unit to... The available remaining output capacity is gradually allocated to the overloaded phase to increase the active power output of that phase, while keeping the output power of the non-overloaded phases stable. During the compensation process, the output power of each phase is continuously compared with the active power demand of the corresponding phase load to keep them consistent. The overall output direction is always controlled so that the inverter flows to the three-phase load, and no power is transmitted to the grid. This step is used to meet the active power demand of the overloaded phase when the inverter has available output capacity, so that the output power of each phase of the inverter is consistent with the active power demand of each phase load, while maintaining the stability of the power transmission direction.

[0170] The remaining output capacity refers to the power space available for continued use after the inverter completes unbalanced current compensation, which is the total rated output capacity of the three phases minus the currently occupied output power. An overloaded phase refers to one or more phases in a three-phase load whose active power demand exceeds the inverter's preset single-phase rated power; these are load phases that require power supplementation.

[0171] If the load condition is overloaded, meaning that the load power of one or more phases exceeds the rated output power of a single phase of the hybrid inverter, a priority control strategy of "first compensating for unbalanced current, then compensating for residual active power" can be adopted. This solves the single-phase overload problem and maximizes the utilization of green electricity. The content includes:

[0172] 1. Overload identification and compensation priority determination: The control unit compares the load power of each phase with the inverter's preset single-phase rated power in real time. When it detects that the load power of a certain phase exceeds the rated value (i.e., the preset single-phase rated power), the priority compensation mechanism is immediately activated, clarifying the control logic that "unbalanced current compensation takes precedence over residual active power compensation".

[0173] 2. Prioritize compensation for unbalanced current: Based on the load current detection data of each phase, the control unit calculates the three-phase current imbalance. Through the topology adjustment and current regulation module of the hybrid inverter, it prioritizes compensation for the unbalanced current between each phase, reduces the impact of zero-sequence and negative-sequence components on the system, ensures the current balance between the grid side and the load side, and guarantees the safe and stable operation of the equipment.

[0174] 3. Precise Compensation of Residual Active Power: After completing the unbalanced current compensation, the control unit utilizes the remaining output capacity of the hybrid inverter to compensate for the residual active power demand of the overloaded phase. Even if the load power of that phase exceeds the inverter's preset single-phase rated power, the active power gap can still be partially compensated by the remaining green electricity resources, minimizing the power drawn from the grid and achieving efficient utilization of green electricity.

[0175] 4. Dual Objectives: While solving the problem of single-phase load overload and ensuring stable system operation, this strategy achieves the coordinated performance of unbalanced current compensation and active power compensation through priority ranking. This breaks through the limitations of existing technologies that either abandon green electricity or sacrifice power quality in overload scenarios, ensuring the maximum utilization rate of green electricity.

[0176] The technical effect of this solution in this embodiment is that by supplementing the active power demand of the overloaded phase according to the remaining output capacity of the inverter when the load is overloaded, the output power of each phase of the inverter can be kept consistent with the active power demand of each phase load. Under the premise of ensuring that no power flows back to the grid, the system's adaptability to overload and three-phase unbalanced conditions is improved, the accuracy of power matching and the stability of system operation are maintained, and the problem of difficulty in achieving accurate power matching under three-phase load imbalance and overload conditions is solved.

[0177] In one possible design, S402 compensates for the active power demand of the overloaded phase based on the remaining output capacity, including:

[0178] S4021. Calculate the active power deficit value based on the active power demand of the overload phase and the preset single-phase rated power.

[0179] Specifically, the active power demand value of the current overloaded phase can be read from the control unit first, and then the preset single-phase rated power value stored in the inverter can be read. The active power demand value of the overloaded phase is subtracted from the preset single-phase rated power value to obtain the difference between the two. This difference is the active power gap value corresponding to the overload. If there are multiple overloaded phases, the same calculation steps are performed for each phase to independently obtain the active power gap value of each phase. During the calculation process, the values ​​of each phase are kept independent of each other, and the specific value that can be used for subsequent compensation is directly obtained. This step is used to determine the amount of active power that the overloaded phase needs to supplement, providing a direct numerical basis for the subsequent generation of dynamic power limit curves and the execution of power compensation.

[0180] The active power deficit value refers to the current active power demand of the overloaded phase, which exceeds the inverter's preset single-phase rated power. It represents the amount of additional active power that the overloaded phase needs to supplement, directly reflecting the amount of power supply missing from the load of that phase.

[0181] S4022. Based on the remaining output capacity, active power deficit value and preset overload phase power supply priority strategy, generate a dynamic power limit curve for the overload phase; wherein, the dynamic power limit curve is used to represent the range of the compensation power provided by the inverter to the overload phase over time within a preset second time period.

[0182] Specifically, the available remaining output capacity, the calculated active power deficit for each overload phase, and the pre-set overload phase power supply priority strategy are first input into the control unit's processing unit. The available output capacity is then allocated sequentially according to the overload phase power supply priority, prioritizing higher-priority overload phases and allocating the remaining capacity to lower-priority overload phases. During allocation, the upper limit of compensation power obtainable by each phase per unit time is determined based on the active power deficit. Combined with time nodes within the second time period, the upper limits of compensation power at different times are sequentially arranged to form a continuously changing power limit sequence. The control unit converts this limit sequence into a continuously changing power range curve, which is the dynamic power limit curve for the overload phase. Throughout the generation process, the total compensation power of all overload phases is guaranteed not to exceed the remaining output capacity, and the compensation power of each phase does not exceed its own active power deficit value. This step determines the specific range and variation pattern of power compensation for each overload phase by the inverter in the subsequent period, providing an executable control basis for the control unit to stably output compensation power.

[0183] The remaining output capacity is the power space that can be allocated additionally after the inverter completes unbalanced current compensation, which is the total rated output capacity of the three phases minus the output power already used. It is the upper limit of the total power that can be used to compensate for the overload phase.

[0184] The overload phase power supply priority strategy is a set of allocation rules pre-written into the control unit. It determines the order and allocation ratio of compensation power for each phase when the inverter's remaining output capacity is limited and cannot simultaneously fully meet the power shortfall of all overload phases. The control unit prioritizes different overload phases according to this strategy. Higher-priority overload phases are given priority to occupy the remaining output capacity to meet their active power shortfall first, and then the remaining capacity is allocated to lower-priority overload phases, thereby ensuring stable power supply to critical loads.

[0185] The dynamic power limit curve is a continuously changing control curve generated on the time axis by the control unit, taking into account the remaining output capacity, the active power deficit of each overloaded phase, and the overloaded phase power supply priority strategy. It defines the upper limit of the compensation power that the inverter can output to the corresponding overloaded phase at each moment within the second time period. This curve changes gradually over time, ensuring that it does not exceed the total limit of the remaining output capacity, nor the active power deficit of each phase, while also meeting priority allocation requirements. This provides a directly executable dynamic range basis for the control unit to output compensation power.

[0186] S4023. Based on the dynamic power limit curve, control the inverter to output compensation power to the overload phase.

[0187] Specifically, the control unit reads the upper limit of the compensation power for the corresponding overload phase in the dynamic power limit curve hourly according to the time progression within the second time period. This upper limit value is compared with the actual output power of the current overload phase. Then, through the power regulation branch inside the inverter, the output power of the overload phase is gradually increased to keep the output power within the limit range corresponding to the curve. This ensures a smooth compensation process without abrupt changes. If multiple overload phases exist, they are controlled independently according to their respective curves. The compensation output of each phase does not exceed the range specified by its own curve, and the power flow direction is maintained from the inverter to the load throughout the process, preventing reverse flow. This step is used to stably output compensation power to the overload phase according to a predetermined compensation range, ensuring that the output of each phase of the inverter is consistent with the active power demand of the load.

[0188] The technical effect of this solution in this embodiment is as follows: By accurately calculating the active power deficit value of the overload phase during the active power compensation process, and then generating a dynamic power limit curve by combining the remaining output capacity of the inverter and the power supply priority strategy of the overload phase, the inverter outputs the corresponding compensation power based on this curve. This enables the refined and orderly allocation of compensation power, ensuring that the inverter output and the active power demand of the load remain accurately matched. At the same time, it ensures the stability of the system operation and the rationality of power allocation under overload conditions, thus solving the problems of insufficient accuracy and unreasonable allocation of overload phase power compensation.

[0189] Figure 5 A flowchart illustrating the photovoltaic system load anti-reverse current method provided in this application embodiment. Figure 4 In this embodiment, in Figure 2 Based on the provided embodiments, the method for preventing reverse current in photovoltaic system loads is further explained. The method for preventing reverse current in photovoltaic system loads includes:

[0190] S501. Obtain the historical power of each phase load within a preset first time period, and predict the power change trend of each phase load within a preset second time period based on the historical power of each phase load; wherein, the end time of the preset first time period is earlier than the current time, and the start time of the preset second time period is later than the current time.

[0191] Specifically, a fixed-duration first time period can be pre-set within the control unit. The control unit continuously collects the real-time power values ​​of each phase of the three-phase load within this time period at fixed time intervals. All collected power values ​​of each phase are stored sequentially in the storage unit of the control unit in chronological order, forming historical power data corresponding to each phase load. After acquiring the historical power data, all historical power values ​​of each phase are retrieved from the storage unit, and the power values ​​of the same phase at different time points are compared one by one to find the change pattern of the phase power value within the first time period, including the time points of power increase and decrease and the magnitude of change. Based on this change pattern, the same change logic is continued to infer the possible increase and decrease trends and approximate change range of the phase load power within the second time period. The above retrieval, comparison, and inference operations are performed independently for each of the three phases, and finally the power change trend of each phase load within the second time period is obtained. This step is used to understand the power change of each phase load within the second time period in advance, providing an accurate reference for determining the inverter topology requirements in the future. This allows the adjustment of the inverter topology to adapt to the changes in load power in advance, avoiding abnormal unbalanced current or system instability caused by adjustment lag.

[0192] S502. Determine the inverter topology requirements based on the power change trend; wherein, the inverter topology requirements are used to guide the adjustment of the inverter topology to compensate for unbalanced current.

[0193] Specifically, the predicted power change trend of each phase load during the second time period can be broken down into the direction and magnitude of power change in each phase. The changes in each phase can then be analyzed one by one to determine which phases will see a continuous increase in power, which will see a continuous decrease in power, which will remain stable, and the specific magnitude of the power change in each phase. Then, combined with the logic of unbalanced current generation under overload conditions, the degree of current imbalance that may occur after power changes can be determined. For example, phases with continuously increasing power are likely to become new overload phases, and their currents will further increase; phases with continuously decreasing power will see their currents further decrease, and the difference between the two will widen. This allows for the identification of key phases and adjustment directions for the inverter topology that need adjustment. Subsequently, based on the changes in each phase and the possible degree of current imbalance, the conduction priority and conduction amplitude of each phase topology branch of the inverter can be determined. The scope, and the timing of the topology switches to be adjusted, are determined, along with the current carrying capacity requirements for each phase topology. This ensures that the adjusted topology can adapt to the current distribution requirements after the power changes in each phase. These clear adjustment directions, priorities, ranges, and carrying capacity requirements together constitute the inverter's topology requirements. The determination of each topology requirement corresponds to a specific power change trend, ensuring that the requirements accurately correspond to actual load changes and current imbalance compensation requirements. This step is used to transform the predicted load power change trend into a specific and executable basis for inverter topology adjustment, clarifying the focus and direction of topology adjustment, so that subsequent adjustments to the inverter topology can accurately adapt to load power changes, effectively achieve unbalanced current compensation, and avoid compensation failure or system malfunction due to improper topology adjustment.

[0194] S503. If the load is in an overload state, obtain the unbalanced current and compensate for the unbalanced current by adjusting the inverter topology and current distribution; where unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

[0195] S503 is similar to S2051, and will not be described again in this embodiment.

[0196] The technical effect of this solution in this embodiment is that, before performing unbalanced current compensation under overload conditions, the power change trend of subsequent time periods is predicted based on the historical power of each phase load, and the inverter topology requirements are determined in advance based on the predicted power change trend. This makes the inverter topology adjustment more forward-looking and targeted, makes the unbalanced current compensation process more stable and orderly, ensures the power matching accuracy and operational reliability of the system under load fluctuations, and solves the problems of lagging topology adjustment and untimely compensation response when the load is overloaded.

[0197] For backflow prevention scenarios under unbalanced loads, the mainstream technical solutions in the industry and their shortcomings are as follows:

[0198] 1. Traditional Three-Phase Unified Control Scheme for Inverters: The core of this scheme is to treat the three-phase output of the inverter as a whole and use a unified power limiting strategy to achieve anti-reverse current control. Its main drawbacks include: First, it cannot adapt to unbalanced load scenarios. The three-phase output power is forcibly leveled by the smallest phase load, severely limiting the green electricity generation capacity and causing a large amount of usable green electricity to be wasted. Second, it lacks accurate detection and independent compensation mechanisms for single-phase load current. The load power and inverter output power cannot achieve precise single-phase matching, inevitably leading to some loads drawing power from the grid, resulting in low green electricity utilization. Third, when facing single-phase load overload, it can only be addressed through overall derating or tripping protection, failing to achieve continuous and stable power supply to the load, resulting in poor reliability.

[0199] 2. Simple Three-Phase Independent Output Control Scheme: Some improved schemes attempt to achieve independent three-phase output control of the inverter to adapt to unbalanced load scenarios. However, this type of scheme still has obvious defects: First, it can only achieve basic power distribution and lacks real-time accurate detection of single-phase load current and active power compensation closed-loop control, which is prone to power matching deviation, thus causing reverse current or insufficient load power supply. Second, no priority compensation mechanism is established. When the load power of a certain phase exceeds the inverter's preset single-phase rated power, it cannot take into account the compensation needs of unbalanced current and active power. It either prioritizes anti-reverse current at the expense of active power compensation or prioritizes load and ignores current imbalance, resulting in degraded power quality or excessive equipment stress. Third, the control algorithm lacks robustness. When facing dynamically changing loads (such as equipment start-stop switching in industrial scenarios), the response speed is slow, and power distribution delays or errors are prone to occur, making it impossible to maximize the utilization of green electricity.

[0200] 3. Energy Storage-Assisted Backflow Prevention Solution: Some solutions buffer surplus green electricity by configuring energy storage devices to reduce curtailment and prevent backflow. However, this solution also has significant drawbacks: First, the system is highly complex, significantly increasing construction and maintenance costs. Energy storage batteries have limited lifespans, resulting in poor long-term economic viability. Second, the coordinated control between energy storage devices, inverters, and loads is difficult. Most solutions can only achieve simple power buffering and cannot accurately regulate the single-phase compensation needs of unbalanced loads, limiting the improvement in green electricity utilization. Third, relying on wireless communication or complex energy management systems (EMS) for coordination makes it difficult to guarantee signal stability and response speed, easily leading to control delays and affecting the synchronization of backflow prevention and load compensation.

[0201] 4. Summary of Common Shortcomings of Existing Solutions: In summary, existing technical solutions have not effectively resolved the core contradiction between anti-reverse current and efficient green energy utilization in unbalanced load scenarios. Their common shortcomings can be summarized as follows: lack of a coordinated mechanism for accurate detection of single-phase load current and active power compensation, making it impossible to achieve accurate matching between load power and inverter single-phase output power; lack of a scientific priority compensation strategy when facing single-phase load overload, making it difficult to simultaneously achieve the three major goals of anti-reverse current, current balance, and active power utilization; poor adaptability of the overall control logic to dynamic loads, low green energy utilization rate, and insufficient load power supply stability, failing to meet the core requirements of distributed green energy systems for "efficient self-use, zero reverse current, and stable power supply".

[0202] The purpose of this application is to address the shortcomings of existing technologies in unbalanced load reverse current prevention scenarios, such as low green energy utilization, inaccurate single-phase load detection and compensation, lack of effective priority compensation mechanism for single-phase overload, and inability to simultaneously achieve the three objectives of reverse current prevention, current balance, and active power utilization, by directly sampling the grid-connected current through a current transformer (CT). Specifically, when the load is within the capacity range of the hybrid inverter, real-time accurate detection and independent active power compensation of the single-phase load current enable precise matching between the load power of each phase and the inverter output power, ensuring that the load does not need to draw power from the grid and there is no reverse current. When a single-phase load is overloaded, a priority strategy of "prioritizing compensation for unbalanced current, then compensating for remaining active power" solves the single-phase overload problem while maximizing the utilization of green energy to compensate for the active power shortfall. Ultimately, this achieves a significant increase in green energy utilization, precise reverse current prevention, adaptability to three-phase unbalanced load scenarios, stable power supply to the load, and safe system operation, without requiring additional complex energy storage devices, thus balancing operational stability and economy.

[0203] Figure 6 This application scenario illustrates the application scenario of the photovoltaic system load anti-reverse current method provided in the embodiments of this application. Figure 2 .like Figure 6As shown, the core connection relationships between the power grid, the converter (i.e., the hybrid inverter in the technical solution), A, B, C and N (three-phase four-wire power supply lines, corresponding to the three-phase live wires A, B and C and the neutral wire N), and the load are presented intuitively, as well as the basic architecture logic of green electricity utilization and anti-reverse flow control. The diagram uses a converter as its core hub, connecting to the public power grid at one end and a three-phase unbalanced load at the other end via lines A, B, C, and N. It also implicitly includes key components not directly labeled in the technical solution: a control unit, a single-phase current detection unit, and a grid connection point power monitoring unit. The control unit can be integrated inside the converter. It acquires real-time current data for each phase of the load in lines A, B, C, and N through the single-phase current detection unit. Combined with the power flow direction from the grid side fed back by the grid connection point power monitoring unit, it dynamically adjusts the converter output: when the load is within the converter's single-phase rated capacity, it achieves precise matching between the load power of each phase and the converter's output power, ensuring full self-consumption of green electricity and no reverse flow; when a single-phase load is overloaded, it allocates the remaining converter capacity according to a strategy of prioritizing compensation for unbalanced current, followed by compensation for remaining active power. This ensures stable power supply to the load while maximizing the utilization of green electricity, fully supporting the technical solution's goals of preventing reverse flow and efficiently utilizing green electricity in unbalanced load scenarios such as industrial, commercial, and residential applications.

[0204] The specific implementation of the photovoltaic system load anti-reverse current method provided in this application embodiment relies on a control system consisting of a hybrid inverter, a single-phase current detection unit, a control unit, and a grid connection point power monitoring unit. The specific implementation steps are as follows:

[0205] 1. System Deployment: High-precision current sensors are installed between the output terminals of each phase of the hybrid inverter and the load to collect single-phase load current signals in real time; a power monitoring unit is installed at the grid connection point to monitor the power flow direction and magnitude in real time to ensure the accuracy of anti-reverse current control; a high-speed communication connection is established between the control unit, the inverter, and the detection unit to ensure the real-time data transmission and control command response.

[0206] 2. Load capacity judgment: The control unit receives the load current signal of each phase in real time, calculates the load power of each phase, and compares it with the rated output power of a single phase of the hybrid inverter to determine whether the current load is within the capacity range, and then selects the corresponding compensation strategy.

[0207] 3. Strategy 1 Execution (Load within Capacity): Based on the single-phase load current detection data, the control unit calculates the active power demand of each phase load and independently adjusts the output power of each phase of the inverter to make the load power of each phase equal to the output power of the corresponding phase of the inverter. At the same time, the output power is dynamically fine-tuned through real-time feedback from the grid connection point monitoring unit to ensure no reverse current and no grid power draw.

[0208] 4. Strategy 2 Execution (Single-phase load overload): When the load power of a certain phase is detected to exceed the inverter's preset single-phase rated power, the control unit first activates the unbalanced current compensation program to adjust the inverter's internal topology and current distribution, reducing the three-phase current imbalance. After the current is balanced, the inverter's remaining output capacity is used to compensate for the remaining active power demand of the overloaded phase, dynamically balancing green energy utilization and load power supply demand, ensuring stable system operation and maximizing green energy utilization.

[0209] In the process of accurately quantifying and compensating for three-phase unbalanced current, it is necessary to first decompose the actual load current of each phase into sequence components, breaking down the three-phase current into zero-sequence, positive-sequence, and negative-sequence components. By calculating the active and reactive power corresponding to each sequence component, the root cause and quantified value of the unbalanced current can be accurately determined, providing a precise quantitative basis for subsequent topology adjustments and current distribution compensation. First, based on the real-time current data collected from phase A, the basic calculations of the zero-sequence active and reactive power of phase A are completed. Then, based on the symmetrical characteristics of the three-phase circuit, the zero-sequence active and reactive power values ​​of phases B and C are derived. Simultaneously, combining the phase characteristics of the negative-sequence current, the calculations of the negative-sequence active and reactive power of phase A are completed, and the negative-sequence active and reactive power values ​​of phases B and C are further derived. The actual load current collected from each phase can be obtained by superimposing the corresponding zero-sequence, positive-sequence, and negative-sequence current components. The specific decomposition and calculation relationships are as follows:

[0210] I. Zero-sequence active and reactive power calculation:

[0211] The zero-sequence component is the component of the three-phase current that is equal in magnitude and has the same phase. The calculation of its active and reactive power is the core step in quantifying the degree of three-phase imbalance. First, the basic calculation is completed based on the measured data of phase A, and then the values ​​of phases B and C are derived based on the symmetrical characteristics of the three-phase circuit.

[0212] 1. The zero-sequence active power of phase A is calculated using formula (1):

[0213]

[0214] in, This refers to the zero-sequence active power of phase A. for The relevant current components, for The relevant current components, The phase correlation angle of phase A voltage. The zero-sequence current phase, This refers to the phase of phase A voltage.

[0215] 2. The zero-sequence reactive power of phase A is calculated using formula (2):

[0216]

[0217] in, This refers to the zero-sequence reactive power of phase A. for The relevant current components, for The relevant current components, The phase correlation angle of phase A voltage. The zero-sequence current phase, This refers to the phase of phase A voltage.

[0218] 3. Calculation of zero-sequence active power of phase B: It is known that the phase of phase B voltage lags the phase of phase A voltage. ( And the zero-sequence current phase remains consistent across all three phases. Formula (3) is:

[0219]

[0220] in, This refers to the zero-sequence active power of phase B. This refers to the phase of the zero-sequence current in phase B. For phase B voltage, This refers to the zero-sequence active power of phase A. The formula for zero-sequence reactive power of phase A utilizes the phase difference characteristics of three-phase voltage to directly derive the value of phase B from the zero-sequence active and reactive power of phase A, avoiding repeated detection and improving calculation efficiency.

[0221] 4. The zero-sequence reactive power of phase B is calculated using formula (4):

[0222]

[0223] in, This refers to the zero-sequence reactive power of phase B. The zero-sequence current phase, The phase of phase A voltage. This refers to the zero-sequence active power of phase A. The zero-sequence reactive power of phase A is given by formula (3). Based on the phase difference change law, the zero-sequence reactive power of phase B is derived from the zero-sequence power component of phase A to ensure the completeness of the evaluation of the zero-sequence component of phase B.

[0224] 5. Calculation of zero-sequence active power of phase C, given that the phase C voltage phase leads the phase A voltage phase. ( The zero-sequence current phase remains consistent. Based on the equilibrium characteristics of the three-phase zero-sequence components, formula (5) is derived as follows:

[0225]

[0226] in, This refers to the zero-sequence active power of phase C. This is the phase of the zero-sequence current in phase C. For the C-phase voltage phase, This refers to the zero-sequence active power of phase A. This refers to the zero-sequence reactive power of phase A. The formula for the zero-sequence active power of phase B is derived by phase difference calculation in the first half and verified by the characteristic that the sum of the three-phase zero-sequence active power is zero, thus ensuring the accuracy of the zero-sequence active power calculation for phase C.

[0227] 6. The zero-sequence reactive power of phase C is calculated using formula (6):

[0228]

[0229] in, For the zero-sequence reactive power of phase C, the formula also adopts the dual logic of "phase difference calculation + three-phase balance verification". The zero-sequence reactive power of phase C is derived from the zero-sequence power of phase A, and the formula satisfies the characteristic that the sum of the three-phase zero-sequence reactive power is zero, thus ensuring data consistency.

[0230] II. Calculation of Negative Sequence Active and Reactive Power:

[0231] Negative sequence components are three-phase currents that are equal in magnitude but different in phase. Furthermore, the calculation of active and reactive power of the components opposite to the positive sequence is another core basis for imbalance quantification. Similarly, the calculation of phase A is completed first, and then the values ​​of phases B and C are derived.

[0232] 1. The negative sequence current phase correlation calculation is given by formula (7):

[0233]

[0234] in, for The sum of the cosine components of the negative sequence current. for The summation value of the sinusoidal components of the negative sequence current, where N is the correlation coefficient. This is the effective value of the negative sequence current. For the negative sequence current phase, this formula is obtained through The calculation of the axis current components establishes the relationship between the negative sequence current phase and the current components, providing a phase basis for subsequent calculations of negative sequence active and reactive power.

[0235] Formula (8) is:

[0236]

[0237] in, for The sum of the sinusoidal components of the negative sequence current. for The summation value of the cosine component of the negative sequence current is given by formula (7). This formula forms a system of equations with formula (7). By solving these equations simultaneously, the phase of the negative sequence current can be accurately determined. This provides key parameters for calculating negative sequence power.

[0238] 2. The calculation of the negative sequence active power of phase A is given by formula (9):

[0239]

[0240] in, This represents the negative sequence active power of phase A. This is the phase of the negative sequence current in phase A. The phase of phase A voltage. The phase correlation angle of phase A voltage. Negative sequence current related components and The core related component, through multi-layer trigonometric function simplification, transforms the phase difference between the negative sequence current and voltage of phase A into a quantified value of active power, thereby achieving accurate calculation of the negative sequence active power of phase A.

[0241] 3. The calculation of the negative sequence reactive power of phase A is given by formula (10):

[0242]

[0243] in, The formula quantifies the negative sequence reactive power of phase A by performing a sinusoidal calculation of the phase difference. Combined with formula (9), it fully covers the active and reactive characteristics of the negative sequence component of phase A.

[0244] 4. Calculation of negative sequence active power in phase B:

[0245] It is known that the phase of the negative sequence current of phase B leads the phase of the negative sequence current of phase A. ( Phase B voltage phase lags behind phase A voltage phase. ( Formula (11) is derived as follows:

[0246]

[0247] in, This refers to the negative sequence active power of phase B. This is the phase of the negative sequence current in phase B. For phase B voltage, This is the negative sequence current of phase A. The phase of phase A voltage. This represents the negative sequence active power of phase A. The formula derives the phase B value by using the calculated negative sequence power component of phase A through the equivalent transformation of the phase difference, thus ensuring calculation efficiency and data consistency.

[0248] 5. The calculation of the negative sequence reactive power of phase B is given by formula (12):

[0249]

[0250] in, The formula is for the negative sequence reactive power of phase B. By performing sinusoidal calculation of the phase difference and combining it with the negative sequence power component of phase A, the formula quantifies the negative sequence reactive power of phase B. Together with formula (11), it constitutes the complete evaluation data of the negative sequence component of phase B.

[0251] 6. Calculation of C-phase negative sequence active power:

[0252] It is known that the phase of the negative sequence current in phase C lags behind the phase of the negative sequence current in phase A. ( The phase C voltage phase leads the phase A voltage phase. ( ), combined with the three-phase negative sequence component balance characteristics, the derivation formula (13) is as follows:

[0253]

[0254] in, The active power of phase C is the negative sequence active power. This is the phase of the negative sequence current in phase C. The phase of the C-phase voltage is defined as follows: other parameters are defined in the same way as in formula (11). The first part of the formula is derived by equivalent conversion of phase difference, and the second part is verified by the characteristic that the sum of the three-phase negative sequence active power is zero, so as to ensure that the calculation of the C-phase negative sequence active power is accurate.

[0255] 7. The calculation of the negative sequence reactive power of phase C is given by formula (14):

[0256]

[0257] in, The negative sequence reactive power of phase C is defined as follows: the other parameters are defined in the same way as in formula (13). This formula adopts the logic of "phase difference calculation + three-phase balance verification", derives the negative sequence reactive power of phase C through the negative sequence power component of phase A, and satisfies the characteristic that the sum of the three-phase negative sequence reactive power is zero, thus ensuring the integrity of the data.

[0258] III. Correlation Calculation of Actual Current and Sequence Components in Each Phase:

[0259] Through the above calculations of zero-sequence, negative-sequence active and reactive power, the influence of each sequence component on the three-phase current can be clearly defined. The actual load current collected in each phase is formed by the superposition of zero-sequence, positive-sequence, and negative-sequence current components. The specific correlation formula (15) is as follows:

[0260]

[0261] in, This represents the actual load current collected for phase A. This represents the zero-sequence current component of phase A. This represents the positive sequence current component of phase A. The formula defines the composition of the actual current in phase A, which is the negative sequence current component of phase A, and provides a core correlation basis for the subsequent quantification and compensation of unbalanced current.

[0262] Formula (16) is:

[0263]

[0264] in, This represents the actual load current collected for phase B. This refers to the zero-sequence current component of phase B. This represents the positive sequence current component of phase B. The formula is consistent with the logic of formula (15) for the negative sequence current component of phase B, which clarifies the sequence component composition of the actual current of phase B and provides data support for the calculation of the three-phase current imbalance.

[0265] Formula (17) is:

[0266]

[0267] in, This represents the actual load current collected for phase C. This refers to the zero-sequence current component of phase C. This represents the positive sequence current component of phase C. The formula represents the negative sequence current component of phase C. It fully presents the sequence component composition of the actual three-phase current. Combined with the zero-sequence and negative-sequence power calculation results mentioned above, it can accurately quantify the three-phase current imbalance, providing a target basis for subsequent topology adjustments and current compensation.

[0268] Figure 7 This is a flowchart illustrating the current detection and limit logic under unbalanced load provided in an embodiment of this application. Figure 7This flowchart visually presents the complete process steps of the present invention in unbalanced load scenarios, including load current detection, judgment, and power compensation limit control. Starting with load current detection, the flowchart first extracts the active current data of each phase of the load through single-phase active current calculation. Then, it determines whether the single-phase active current detection result exceeds the inverter capacity to determine if a certain phase of the load is overloaded. If overload is confirmed, the unbalanced current calculation stage begins. Corresponding to steps 10, 11, and 12 in the flowchart, the active power of phases A, B, and C is calculated with the maximum total active power output of the inverter as the target. The effective value of the vector superposition of the unbalanced current and active current is then calculated. Subsequently, it is determined whether this effective value has a reverse trend. If a reverse trend exists, the output current is limited; if no reverse trend exists, single-phase active power compensation is directly executed, ultimately completing the entire current detection and limit control process. This provides a clear logical execution path for achieving accurate reverse current prevention and efficient green electricity utilization under unbalanced loads.

[0269] In unbalanced load scenarios, traditional solutions limit overall output based on the smallest phase load, failing to unleash the potential of green electricity generation. Loads must draw power from the grid, resulting in low green electricity utilization. Furthermore, the lack of precise detection and independent compensation mechanisms for single-phase load current leads to significant power matching deviations. This application addresses this by installing high-precision current detection units between the output terminals of each phase of the hybrid inverter and the load. These units collect single-phase load current in real time, while the control unit independently calculates the active power demand for each phase based on the detection data, adjusting the corresponding phase output power of the inverter. Closed-loop control ensures that the load power of each phase matches the inverter output power, while monitoring the grid connection point to prevent reverse current. This breaks the three-phase power binding limitation, fully releasing the green electricity generation potential of each phase, achieving full self-consumption of green electricity, significantly improving green electricity utilization, eliminating the need to draw power from the grid, reducing user electricity costs, and ensuring grid stability through precise power matching and prevention of reverse current.

[0270] When the single-phase load power exceeds the inverter's preset single-phase rated power, existing technologies lack an effective priority compensation mechanism, failing to balance unbalanced current compensation and active power compensation. This can easily lead to a decline in power quality or excessive equipment stress. This application compares the load power of each phase with the inverter's preset single-phase rated power in real time, identifies overloads, and activates a priority compensation mechanism. Simultaneously, it prioritizes compensation for three-phase unbalanced current based on current detection data, reducing the impact of zero-sequence and negative-sequence components. Furthermore, it utilizes the inverter's remaining capacity to compensate for the remaining active power demand of the overloaded phase. This application can solve the single-phase overload problem, ensure continuous and stable power supply to the load, improve system operational reliability, and simultaneously balance current balance and active power compensation, optimizing power quality, avoiding equipment aging issues, maximizing the utilization of surplus green electricity, and reducing reliance on grid power.

[0271] Existing solutions have poor overall adaptability. When faced with dynamically unbalanced loads, they are slow to respond and have low control precision, making it difficult to simultaneously meet the three major goals of anti-reverse current, efficient utilization of green electricity, and stable power supply to the load. The control unit of this application judges the load status (within capacity / overload) in real time and dynamically switches the compensation strategy. It relies on high-precision detection and closed-loop control throughout the process to ensure command response and adjustment accuracy. It can adapt to dynamically unbalanced load scenarios, with fast control response and high precision. It simultaneously achieves the three core goals of anti-reverse current, maximizing the utilization of green electricity, and stable power supply to the load. Moreover, it does not require additional energy storage equipment, has low system complexity, low maintenance costs, and good economic efficiency.

[0272] Figure 8 This is a schematic diagram of the structure of the photovoltaic system load anti-reverse current device provided in an embodiment of this application. Figure 8 As shown, the photovoltaic system load anti-reverse current device includes:

[0273] The first acquisition module 801 is used to acquire the instantaneous current of the three-phase load and the output power of each phase of the inverter.

[0274] The first calculation module 802 is used to calculate the power of each phase load in the three-phase load based on the instantaneous current, and compare the power of each phase load in the three-phase load with the preset single-phase rated power of the inverter to obtain the load status of each phase load; wherein, the load status includes non-overload status and overload status, the non-overload status is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and the overload status is used to indicate that the power of each phase load is greater than the preset single-phase rated power.

[0275] The second acquisition module 803 is used to acquire the power fluctuation frequency of the three-phase load and determine the weighting coefficient of power regulation based on the load status and the power fluctuation frequency.

[0276] The first adjustment module 804 is used to adjust the output power of each phase of the inverter based on a weighting coefficient and a preset power adjustment unit if the load condition is not overloaded, so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load.

[0277] The first compensation module 805 is used to compensate for the unbalanced current generated by the three-phase load if the load is in an overload state, so as to reduce the unbalanced current.

[0278] In one possible design, the photovoltaic system load anti-reverse current device also includes:

[0279] The third acquisition module is used to acquire the power flow direction between the inverter and the three-phase load through a preset grid connection point monitoring unit, and adjust the output power of each phase of the inverter according to the power flow direction and weighting coefficient to ensure that no power flows back from the inverter to the preset grid.

[0280] In one possible design, the third acquisition module includes:

[0281] The first calculation unit is used to calculate the target adjustment amount of the output power of each phase of the inverter based on the weighting coefficient and the power flow direction.

[0282] The first adjustment unit is used to adjust the output power of each phase of the inverter according to the target adjustment amount of the output power of each phase of the inverter; wherein, the target adjustment amount is used to indicate the magnitude of adjustment required for the output power of each phase of the inverter.

[0283] In one possible design, the first compensation module 805 includes:

[0284] The first compensation unit is used to obtain the unbalanced current if the load is in an overload state, and to compensate for the unbalanced current by adjusting the inverter topology and current distribution; wherein, the unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and the inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

[0285] In one possible design, the photovoltaic system load anti-reverse current device also includes:

[0286] The second compensation module is used to obtain the remaining output capacity and compensate the active power demand of the overload phase according to the remaining output capacity, so that the output power of each phase of the inverter matches the active power demand of each phase load, and no electrical energy flows back from the inverter to the preset grid. The remaining output capacity refers to the unused portion of the preset three-phase rated total output capacity of the inverter after the unbalanced current compensation is completed, and the overload phase refers to the phase in the three-phase load whose active power demand is greater than the preset single-phase rated power.

[0287] In one possible design, the photovoltaic system load anti-reverse current device also includes:

[0288] The prediction module is used to obtain the historical power of each phase load within a preset first time period, and predict the power change trend of each phase load within a preset second time period based on the historical power of each phase load; wherein, the end time of the preset first time period is earlier than the current time, and the start time of the preset second time period is later than the current time.

[0289] The determination module is used to determine the inverter's topology requirements based on power change trends; the inverter's topology requirements are used to guide adjustments to the inverter's topology to compensate for unbalanced current.

[0290] In one possible design, the second compensation module includes:

[0291] The second calculation unit is used to calculate the active power deficit value based on the active power demand of the overload phase and the preset single-phase rated power.

[0292] The first generation unit is used to generate a dynamic power limit curve for the overload phase based on the remaining output capacity, the active power deficit value and the preset overload phase power supply priority strategy; wherein, the dynamic power limit curve is used to represent the range of the compensation power provided by the inverter to the overload phase over time within a preset second time period.

[0293] The second compensation unit is used to control the inverter to output compensation power to the overload phase based on the dynamic power limit curve.

[0294] In one possible design, the first computing module 802 includes:

[0295] The first acquisition unit is used to acquire multiple real-time environmental data and adjust the preset single-phase rated power according to the multiple real-time environmental data to obtain the adjusted preset single-phase rated power.

[0296] The determination unit is used to determine the load state of each phase load as non-overload state if the power of each phase load in the three-phase load is less than or equal to the adjusted preset single-phase rated power.

[0297] The second determining unit is used to determine the load state of each phase load as overload state if the power of each phase load in the three-phase load is greater than the adjusted preset single-phase rated power.

[0298] In one possible design, the first acquisition module 801 includes:

[0299] The second acquisition unit is used to acquire the raw current of the three-phase load and the output power of each phase of the inverter.

[0300] The noise reduction unit is used to perform real-time noise reduction and dynamic compensation on the original current to obtain the instantaneous current.

[0301] The photovoltaic system load anti-reverse current device provided in this embodiment can perform... Figures 2 to 5 The technical solution of the embodiment of the photovoltaic system load anti-reverse current method shown is implemented in accordance with the principle and technical effect of the method. Figures 2 to 5 The embodiment of the photovoltaic system load anti-reverse current method shown is similar and will not be described in detail here.

[0302] Figure 9 This is a schematic diagram of the hardware structure of the electronic device provided in an embodiment of this application. Figure 9 As shown, the electronic device 90 includes at least one processor 901 and a memory 902. The electronic device 90 also includes a communication component 903. The processor 901, memory 902, and communication component 903 are connected via a bus 904.

[0303] In the specific implementation process, at least one processor 901 executes computer execution instructions stored in memory 902, so that at least one processor 901 is used to implement a photovoltaic system load anti-reverse current method of the above embodiment.

[0304] The specific implementation process of processor 901 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0305] In the above embodiments, it should be understood that the processor 901 can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0306] The memory 902 may include high-speed RAM memory, and may also include non-volatile memory (NVM), such as at least one disk storage.

[0307] Bus 904 can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Bus 904 can be divided into address bus, data bus, control bus, etc. For ease of illustration, the bus 904 in the accompanying drawings of this application is not limited to only one bus or one type of bus.

[0308] The above description of the functions implemented by electronic devices and main control devices has introduced the solutions provided by the embodiments of the present invention. It is understood that, in order to implement the above functions, the electronic device or main control device includes hardware structures and / or software modules corresponding to the execution of each function. By combining the units and algorithm steps of the various examples described in the embodiments of the present invention, the embodiments of the present invention can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed by hardware or by computer software driving hardware 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 the technical solutions of the embodiments of the present invention.

[0309] This application also provides a computer-readable storage medium storing computer-executable instructions. When executed by a processor, these instructions are used to implement a photovoltaic system load anti-reverse current method according to the above embodiments. In the specific implementation of the aforementioned photovoltaic system load anti-reverse current method, each module can be implemented as a processor.

[0310] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0311] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in application-specific integrated circuits (ASICs). Alternatively, the processor and the readable storage medium can exist as discrete components in an electronic device or a host device.

[0312] This application also provides a computer program product, including a computer program, which, when executed by a processor, is used to implement a photovoltaic system load anti-reverse current method according to the above embodiments.

[0313] The computer program is stored in a readable storage medium, and at least one processor can read the computer program from the readable storage medium and execute the computer program to perform the scheme provided in any of the above embodiments.

[0314] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disk, or optical disk.

[0315] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. 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 or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preventing reverse current in a photovoltaic system load, characterized in that, include: Obtain the instantaneous current of the three-phase load and the output power of each phase of the inverter; The power of each phase of the three-phase load is calculated based on the instantaneous current, and the power of each phase of the three-phase load is compared with the preset single-phase rated power of the inverter to obtain the load state of each phase load; wherein, the load state includes a non-overload state and an overload state, the non-overload state is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and the overload state is used to indicate that the power of each phase load is greater than the preset single-phase rated power; Obtain the power fluctuation frequency of the three-phase load, and determine the weighting coefficient of power regulation based on the load state and the power fluctuation frequency; If the load state is the non-overload state, based on the weighting coefficient, the output power of each phase of the inverter is adjusted by a preset power adjustment unit so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load; If the load condition is the overload condition, the unbalanced current generated by the three-phase load is compensated to reduce the unbalanced current; If the load state is the non-overload state, based on the weighting coefficient, the output power of each phase of the inverter is adjusted by a preset power adjustment unit to match the output power of each phase of the inverter with the power of the corresponding phase load in the three-phase load, and the method further includes: The power flow direction between the inverter and the three-phase load is obtained through a preset grid connection point monitoring unit, and the output power of each phase of the inverter is adjusted according to the power flow direction and the weighting coefficient to ensure that no electrical energy flows back from the inverter to the preset grid. If the load state is the overload state, after obtaining the unbalanced current and compensating for the unbalanced current by adjusting the inverter topology and current distribution, the method further includes: The remaining output capacity is obtained, and the active power demand of the overload phase is compensated according to the remaining output capacity, so that the output power of each phase of the inverter matches the active power demand of each phase load, and no electrical energy flows back from the inverter to the preset grid. Herein, the remaining output capacity refers to the unused portion of the preset three-phase rated total output capacity of the inverter after the unbalanced current compensation is completed, and the overload phase refers to the phase in the three-phase load whose active power demand is greater than the preset single-phase rated power.

2. The photovoltaic system load anti-reverse current method according to claim 1, characterized in that, The step of adjusting the output power of each phase of the inverter according to the power flow direction and the weighting coefficient includes: Based on the weighting coefficients and the power flow direction, calculate the target adjustment amount of the output power of each phase of the inverter; The output power of each phase of the inverter is adjusted according to the target adjustment amount of the output power of each phase of the inverter; wherein, the target adjustment amount is used to indicate the extent to which the output power of each phase of the inverter needs to be adjusted.

3. The photovoltaic system load anti-reverse current method according to claim 1, characterized in that, If the load condition is an overload condition, the compensation for the unbalanced current generated by the three-phase load includes: If the load state is the overload state, the unbalanced current is obtained, and the unbalanced current is compensated by adjusting the topology and current distribution of the inverter; wherein, the unbalanced current refers to the current generated by the inconsistent power demand of the three-phase load, and the inconsistent power demand of the three-phase load refers to the inconsistent active power demand of each phase of the three-phase load.

4. The photovoltaic system load anti-reverse current method according to claim 1, characterized in that, Before acquiring the unbalanced current and compensating for the unbalanced current by adjusting the inverter topology and current distribution if the load state is the overload state, the method further includes: The historical power of each phase load within a preset first time period is obtained, and the power change trend of each phase load within a preset second time period is predicted based on the historical power of each phase load; wherein, the end time of the preset first time period is earlier than the current time, and the start time of the preset second time period is later than the current time. The inverter topology requirements are determined based on the power change trend; wherein, the inverter topology requirements are used to guide the adjustment of the inverter topology to compensate for the unbalanced current.

5. The photovoltaic system load anti-reverse current method according to claim 4, characterized in that, The compensation for the active power demand of the overload phase based on the remaining output capacity includes: Calculate the active power deficit value based on the active power demand of the overload phase and the preset single-phase rated power; Based on the remaining output capacity, the active power deficit value, and the preset overload phase power supply priority strategy, a dynamic power limit curve is generated for the overload phase; wherein, the dynamic power limit curve is used to represent the range of time-varying compensation power provided by the inverter to the overload phase within the preset second time period. Based on the dynamic power limit curve, the inverter is controlled to output compensation power to the overloaded phase.

6. The photovoltaic system load anti-reverse current method according to claim 1, characterized in that, The step of comparing the power of each phase of the three-phase load with the preset single-phase rated power of the inverter to obtain the load status of each phase load includes: Acquire multiple real-time environmental data, and adjust the preset single-phase rated power according to the multiple real-time environmental data to obtain the adjusted preset single-phase rated power; If the power of each phase load in the three-phase load is less than or equal to the adjusted preset single-phase rated power, the load state of each phase load is determined as the non-overload state. If the power of each phase of the three-phase load is greater than the adjusted preset single-phase rated power, the load state of each phase load is determined as the overload state.

7. The photovoltaic system load anti-reverse current method according to claim 1, characterized in that, The acquisition of the instantaneous current of the three-phase load and the output power of each phase of the inverter includes: Obtain the original current of the three-phase load and the output power of each phase of the inverter; The instantaneous current is obtained by performing real-time noise reduction and dynamic compensation on the original current.

8. A photovoltaic system load anti-reverse current device, characterized in that, include: The first acquisition module is used to acquire the instantaneous current of the three-phase load and the output power of each phase of the inverter; The first calculation module is used to calculate the power of each phase of the three-phase load based on the instantaneous current, and compare the power of each phase of the three-phase load with the preset single-phase rated power of the inverter to obtain the load state of each phase load; wherein, the load state includes a non-overload state and an overload state, the non-overload state is used to indicate that the power of each phase load is less than or equal to the preset single-phase rated power, and the overload state is used to indicate that the power of each phase load is greater than the preset single-phase rated power; The second acquisition module is used to acquire the power fluctuation frequency of the three-phase load and determine the weighting coefficient of power regulation based on the load state and the power fluctuation frequency. The first adjustment module is used to adjust the output power of each phase of the inverter based on the weighting coefficient and a preset power adjustment unit if the load state is the non-overload state, so that the output power of each phase of the inverter matches the power of the corresponding phase load in the three-phase load. The first compensation module is used to compensate for the unbalanced current generated by the three-phase load if the load state is the overload state, so as to reduce the unbalanced current. The third acquisition module is used to acquire the power flow direction between the inverter and the three-phase load through a preset grid connection point monitoring unit, and adjust the output power of each phase of the inverter according to the power flow direction and the weighting coefficient to ensure that no electrical energy flows back from the inverter to the preset grid. The second compensation module is used to obtain the remaining output capacity and compensate the active power demand of the overload phase according to the remaining output capacity, so that the output power of each phase of the inverter matches the active power demand of each phase load, and no electrical energy flows back from the inverter to the preset grid. The remaining output capacity refers to the unused portion of the preset three-phase rated total output capacity of the inverter after the unbalanced current compensation is completed, and the overload phase refers to the phase in the three-phase load whose active power demand is greater than the preset single-phase rated power.

9. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; When the processor executes the computer execution instructions stored in the memory, it is used to implement the photovoltaic system load anti-reverse current method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the photovoltaic system load anti-reverse current method as described in any one of claims 1 to 7.

11. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, is used to implement the photovoltaic system load anti-reverse current method as described in any one of claims 1 to 7.

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