Grid-connected system, program product, grid-connected equipment, anti-countercurrent method of grid-connected equipment and controller

Abstract

The invention provides a grid-connected system, a program product, grid-connected equipment, an anti-countercurrent method of the grid-connected equipment and a controller, and relates to the technical field of grid connection. In the anti-countercurrent method, the grid-connected equipment satisfies the first preset countercurrent condition to indicate that the grid-connected equipment has countercurrent, and the grid-connected equipment does not satisfy the second preset countercurrent condition to indicate that the grid-connected equipment does not have countercurrent. Therefore, according to the countercurrent prevention method, countercurrent of the grid-connected equipment does not occur through corresponding control under the condition that countercurrent of the grid-connected equipment occurs, so that the grid-connected equipment has a countercurrent prevention function through the countercurrent prevention method. Because the output power of the grid-connected equipment is controlled to be switched to the first preset value, which means that the output power of the grid-connected equipment is suddenly changed, the power output by the power grid to the load connected with the grid-connected equipment is suddenly changed, so that the existence time of the reverse current is shortened; therefore, the anti-countercurrent effect of the anti-countercurrent function of the grid-connected equipment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of grid connection, and in particular to a grid connection system, a program product, a grid connection device, and an anti-backflow method and a controller thereof. Background Art

[0002] At present, in order to ensure the safety and stability of the power grid, power grid companies strictly prohibit private grid connection devices from transmitting power to the power grid, that is, strictly prohibit grid connection devices from generating reverse current. Therefore, most grid connection devices have an anti-backflow function, that is, a function of preventing the generation of reverse current.

[0003] However, if the load changes greatly, even if the grid connection device has an anti-backflow function, reverse current may still be generated, which may affect the safety and stability of the power grid.

[0004] Therefore, how to improve the anti-backflow effect of the anti-backflow function of grid connection devices is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] In view of this, the present invention provides a grid connection system, a program product, a grid connection device, and an anti-backflow method and a controller thereof to improve the anti-backflow effect of the anti-backflow function of grid connection devices.

[0006] To achieve the above object, the embodiments of the present invention provide the following technical solutions:

[0007] The first aspect of the present application provides an anti-backflow method for a grid connection device, including:

[0008] Determine whether the grid connection device meets a first preset reverse current condition;

[0009] If the grid connection device meets the first preset reverse current condition, control the output power of the grid connection device to switch to a first preset value so that the grid connection device does not meet a second preset reverse current condition.

[0010] Optionally, the first preset value is equal to zero.

[0011] Optionally, after performing the step of controlling the output power of the grid connection device to switch to a first preset value so that the grid connection device does not meet a second preset reverse current condition, or, while performing the step of determining whether the grid connection device meets a first preset reverse current condition, further include:

[0012] When the grid connection device does not meet a first preset maximum power condition, control the output power of the grid connection device to gradually increase so that the grid connection device meets a second preset maximum power condition; the target power is the power flowing into the power grid.

[0013] Optionally, the first preset maximum power condition includes: the target power is less than or equal to a second preset value; the target power is the power flowing into the grid.

[0014] The second preset maximum power condition includes: the target power is less than or equal to a third preset value.

[0015] Optionally, after performing the step of controlling the output power of the grid-connected device to be switched to a first preset value so that the grid-connected device does not meet the second preset reverse current condition, the method further includes:

[0016] When the grid-connected device meets the third preset reverse current condition, controlling the output power of the grid-connected device to gradually decrease so that the grid-connected device does not meet the fourth preset reverse current condition.

[0017] Optionally, the third preset reverse current condition includes: the target power is less than a fourth preset value; the target power is the power flowing into the grid;

[0018] The fourth preset reverse current condition includes: the target power is less than a fifth preset value.

[0019] Optionally, the first preset reverse current condition includes: the target power is less than a sixth preset value; the target power is the power flowing into the grid;

[0020] The second preset reverse current condition includes: the target power is less than a seventh preset value.

[0021] The second aspect of the present application provides a grid-connected device, which is configured to execute the anti-reverse current method of the grid-connected device according to any one of the first aspects of the present application.

[0022] The third aspect of the present application provides a grid-connected system, including: the grid-connected device according to the second aspect of the present application;

[0023] The AC side of the grid-connected device is respectively used to connect to a load and the grid.

[0024] Optionally, it further includes: a collector and a controller

[0025] The AC side of the grid-connected device is connected to one side of the collector, and the other side of the collector is used to connect to the grid;

[0026] The collector is configured to collect the target power, and the target power is the power flowing into the grid;

[0027] The controller is respectively communicatively connected to the collector and the grid-connected device;

[0028] The controller is used to monitor the working state of the grid-connected device and the target power fed back by the collector, and execute the anti-counterflow method of the grid-connected device according to any one of the first aspects of this application.

[0029] As can be seen from the above technical solutions, the present invention provides an anti-counterflow method for a grid-connected device. In this anti-counterflow method, since the grid-connected device satisfying the first preset counterflow condition indicates that the grid-connected device has a counterflow, and the grid-connected device not satisfying the second preset counterflow condition indicates that the grid-connected device does not have a counterflow, so this anti-counterflow method is equivalent to making the grid-connected device not have a counterflow through corresponding control in the case of the grid-connected device having a counterflow. Therefore, this anti-counterflow method enables the grid-connected device to have an anti-counterflow function. Also, since controlling the output power of the grid-connected device to switch to the first preset value is equivalent to making the output power of the grid-connected device change suddenly, it can make the power output by the power grid to the load connected to the grid-connected device change suddenly. Therefore, the existence time of the reverse current is reduced, thereby improving the anti-counterflow effect of the anti-counterflow function of the grid-connected device. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0031] Figures 1-3 They are respectively the flow schematic diagrams of three implementation manners of the anti-counterflow method of the grid-connected device provided by the embodiments of this application;

[0032] Figure 4 It is a schematic diagram of the change in the output power of the grid-connected device in the prior art;

[0033] Figure 5 It is a schematic diagram of the change in the output power of the grid-connected device in this application;

[0034] Figure 6 and Figure 7 They are respectively the structural schematic diagrams of two implementation manners of the grid-connected system provided by the embodiments of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will clearly and completely describe the technical solutions in the embodiments of this application with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of this application.

[0036] In this application, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0037] To improve the anti-counterflow effect of the anti-counterflow function of grid-connected equipment, an embodiment of this application provides an anti-counterflow method for grid-connected equipment, and its specific process is as Figure 1 shown, and specifically includes the following steps:

[0038] S110. Determine whether the grid-connected equipment meets the first preset counterflow condition.

[0039] If the grid-connected equipment meets the first preset counterflow condition, then execute step S120; if the grid-connected equipment does not meet the first preset counterflow condition, then return to execute S110.

[0040] Under normal circumstances, the AC side of the grid-connected equipment is respectively connected to the load and the power grid. If the output power of the grid-connected equipment is less than the load power, then both the grid-connected equipment and the power grid will output electrical energy to the load. If the output power of the grid-connected equipment is greater than the load power, then the grid-connected equipment will not only output electrical energy to the load but also output electrical energy to the power grid. When the grid-connected equipment outputs electrical energy to the power grid, it indicates that the grid-connected equipment has a counterflow. When the power grid outputs electrical energy to the load, it indicates that the grid-connected equipment does not have a counterflow.

[0041] The first preset counterflow condition is the determination condition for the grid-connected equipment to have a counterflow, that is: if the grid-connected equipment meets the first preset counterflow condition, it indicates that the grid-connected equipment has a counterflow. If the grid-connected equipment does not meet the first preset counterflow condition, it indicates that the grid-connected equipment does not have a counterflow.

[0042] S120. Control the output power of the grid-connected equipment to be switched to the first preset value so that the grid-connected equipment does not meet the second preset counterflow condition.

[0043] The second preset counterflow condition is the determination condition for the grid-connected equipment to have a counterflow, that is: if the grid-connected equipment meets the second preset counterflow condition, it indicates that the grid-connected equipment has a counterflow. If the grid-connected equipment does not meet the second preset counterflow condition, it indicates that the grid-connected equipment does not have a counterflow.

[0044] Optionally, the second preset reverse current condition may be the same as the first preset reverse current condition, or the second preset reverse current condition may be different from the first preset reverse current condition. There is no specific limitation here and it can be determined according to the specific situation, all within the protection scope of this application. Usually, the second preset reverse current condition is the same as the first preset reverse current condition.

[0045] In this embodiment, since the grid-connected device satisfying the first preset reverse current condition indicates that the grid-connected device has reverse current, and the grid-connected device not satisfying the second preset reverse current condition indicates that the grid-connected device does not have reverse current, so this anti-reverse current method is equivalent to making the grid-connected device not have reverse current through corresponding control when the grid-connected device has reverse current. Therefore, this anti-reverse current method enables the grid-connected device to have an anti-reverse current function. Also, since controlling the output power of the grid-connected device to switch to the first preset value is equivalent to causing a sudden change in the output power of the grid-connected device, it can cause a sudden change in the power output from the power grid to the load connected to the grid-connected device. Therefore, the existence time of the reverse current is reduced, thereby improving the anti-reverse current effect of the anti-reverse current function of the grid-connected device.

[0046] Another embodiment of this application provides specific implementation manners of the first preset reverse current condition and the second preset reverse current condition. Specifically as follows:

[0047] The specific implementation manner of the first preset reverse current condition is that the target power is less than the sixth preset value.

[0048] The specific implementation manner of the second preset reverse current condition is that the target power is less than the seventh preset value.

[0049] The target power is the power flowing into the power grid. In practical applications, when the target power is greater than zero, it indicates that the power flowing into the power grid is greater than zero; when the target power is less than zero, it indicates that the power flowing into the power grid is less than zero, that is, at this time the target power represents the power flowing out of the power grid.

[0050] The target power being less than the sixth preset value indicates that the target power is small. On the contrary, the target power being greater than or equal to the sixth preset value indicates that the target power is not small. In practical applications, the sixth preset value is set according to the specific situation and there is no specific limitation here. Usually, the sixth preset value is equal to 50W.

[0051] The target power being less than the seventh preset value indicates that the target power is small. On the contrary, the target power being greater than or equal to the seventh preset value indicates that the target power is not small. In practical applications, the seventh preset value is set according to the specific situation and there is no specific limitation here. Usually, the seventh preset value is equal to 50W.

[0052] If the second preset reverse current condition is the same as the first preset reverse current condition, the seventh preset value is equal to the sixth preset value; if the second preset reverse current condition is different from the first preset reverse current condition, the seventh preset value is not equal to the sixth preset value.

[0053] In this embodiment, under normal circumstances, when there is a reverse current in the grid-connected device, the grid-connected device outputs electric energy to the grid, that is, the target power is less than zero, which means the target power is small. When there is no reverse current in the grid-connected device, the grid outputs electric energy to the load, that is, the target power is greater than zero, which means the target power is not small. Therefore, if the target power is small, there is a reverse current in the grid-connected device; if the target power is not small, there is no reverse current in the grid-connected device. Also, since the target power being less than the sixth preset value can indicate that the target power is small, and the target power being greater than or equal to the sixth preset value can indicate that the target power is not small, so the target power being less than the sixth preset value can indicate that there is a reverse current in the grid-connected device, and the target power being greater than or equal to the sixth preset value can indicate that there is no reverse current in the grid-connected device. Therefore, the target power being less than the sixth preset value can be used as a preset reverse current condition. Similarly, the target power being less than the seventh preset value can be used as a preset reverse current condition.

[0054] The above is only a specific implementation manner of the first preset reverse current condition and a specific implementation manner of the second preset reverse current condition. In practical applications, including but not limited to this, no specific limitation is made here, and all are within the protection scope of this application.

[0055] Another embodiment of this application provides another implementation manner of the anti-reverse current method for the grid-connected device. On the basis of the implementation manner provided in the previous embodiment, it is further limited that the first preset value is equal to zero, that is, the output power of the grid-connected device is controlled to switch to zero.

[0056] Specifically, if the first preset value is equal to zero, the output power of the grid-connected device is controlled to switch to the first preset value, specifically: controlling the grid-connected device to switch to the shutdown state or the standby state.

[0057] It should be noted that the shutdown state or the grid-connected device being in the standby state is already very mature in the prior art, and no further detailed description will be given here.

[0058] In this embodiment, since the first preset value is equal to zero, the load power is entirely provided by the grid, so there will be no reverse current in the grid-connected device. Also

[0059] Since the first preset value is equal to zero, which is equivalent to controlling the grid-connected device to switch to the shutdown state or the standby state. Therefore, after the output power of the grid-connected device is switched to the first preset value, the load power is entirely provided by the power grid, and thus there will be no reverse current in the grid-connected device. Also, since it takes less time to control the grid-connected device to switch to the shutdown state or the standby state, the existence time of the reverse current is further reduced, thereby further improving the anti-reverse current effect of the anti-reverse current function of the grid-connected device.

[0060] Another embodiment of the present application provides another implementation manner of the anti-reverse current method for grid-connected devices. The specific process can be referred to Figure 2 ( Figure 2 Taking the example of executing step S210 after step S120 for display only), after executing S120 in any of the implementation manners provided in the above embodiments, or, while executing S110, the following steps are further included:

[0061] S210. Determine whether the grid-connected device meets the first preset maximum power condition.

[0062] If the grid-connected device does not meet the first preset maximum power condition, then execute S220; if the grid-connected device meets the first preset maximum power condition, then return to execute S110.

[0063] The first preset maximum power condition is the determination condition for the grid-connected device to reach the maximum output power, that is: if the grid-connected device meets the first preset maximum power condition, it indicates that the grid-connected device reaches the maximum output power; if the grid-connected device does not meet the first preset maximum power condition, it indicates that the grid-connected device does not reach the maximum output power.

[0064] S220. Control the output power of the grid-connected device to gradually increase so that the grid-connected device meets the second preset maximum power condition.

[0065] The second preset maximum power condition is the determination condition for the grid-connected device to reach the maximum output power, that is: if the grid-connected device meets the second preset maximum power condition, it indicates that the grid-connected device reaches the maximum output power; if the grid-connected device does not meet the second preset maximum power condition, it indicates that the grid-connected device does not reach the maximum output power.

[0066] In a specific example, the second preset maximum power condition is the same as the first preset maximum power condition.

[0067] In another specific example, the second preset maximum power condition is different from the first preset maximum power condition.

[0068] In this example, since the second preset maximum power condition is different from the first preset maximum power condition, after the grid-connected device meets the second preset maximum power condition, even if the load power fluctuates slightly, the grid-connected device will not immediately fail to meet the first preset maximum power condition, and thus will not immediately control the output power of the grid-connected device to gradually increase, thereby reducing the frequency of regulating the output power of the grid-connected device, that is, the output power of the grid-connected device will not change frequently.

[0069] The above two examples show two relationships between the second preset maximum power condition and the first preset maximum power condition, which are not specifically limited here and can be determined according to specific circumstances, and are all within the protection scope of this application. Generally, the second preset maximum power condition is different from the first preset maximum power condition.

[0070] In a specific example, controlling the output power of the grid-connected device to gradually increase is specifically: performing MPPT control on the grid-connected device.

[0071] It should be noted that the MPPT control performed on the grid-connected device is already very mature in the prior art, and no further detailed description will be given here.

[0072] The above example only shows a specific implementation manner of controlling the output power of the grid-connected device to gradually increase. In actual applications, including but not limited to this, it is not specifically limited here and can be determined according to specific circumstances, and are all within the protection scope of this application.

[0073] In this embodiment, since the grid-connected device not meeting the first preset maximum power condition indicates that the grid-connected device has not reached the maximum output power, and the grid-connected device meeting the second preset maximum power condition indicates that the grid-connected device has reached the maximum output power, so in this implementation manner, when the grid-connected device has not reached the maximum output power, by controlling the output power of the grid-connected device to gradually increase, the grid-connected device reaches the maximum output power. Therefore, the output power of the grid-connected device is increased as much as possible, thereby reducing the time for the power grid to supply power to the load.

[0074] Another embodiment of this application provides specific implementation manners of the first preset maximum power condition and the second preset maximum power condition. Specifically as follows:

[0075] The specific implementation manner of the first preset maximum power condition is: the target power is less than or equal to the second preset value.

[0076] The specific implementation manner of the second preset maximum power condition is: the target power is less than or equal to the third preset value.

[0077] It should be noted that the target power has been described in detail in the above embodiments and will not be elaborated here.

[0078] When the target power is less than or equal to the second preset value, it indicates that the target power is small. On the contrary, when the target power is greater than the second preset value, it indicates that the target power is not small. In practical applications, the second preset value is set according to specific circumstances and is not specifically limited here. Usually, the second preset value is equal to 150W.

[0079] When the target power is less than or equal to the third preset value, it indicates that the target power is small. On the contrary, when the target power is greater than the third preset value, it indicates that the target power is not small. In practical applications, the third preset value is set according to specific circumstances and is not specifically limited here. Usually, the third preset value is equal to 100W.

[0080] If the second preset maximum power condition is the same as the first preset maximum power condition, then the third preset value is equal to the second preset value; if the second preset maximum power condition is different from the first preset maximum power condition, then the third preset value is not equal to the second preset value.

[0081] In this embodiment, usually, when the grid-connected device reaches the maximum output power, the target power is small, and when the grid-connected device does not reach the maximum output power, the target power is not small. Therefore, if the target power is small, it means the grid-connected device reaches the maximum output power, and if the target power is not small, it means the grid-connected device does not reach the maximum output power. Also, since the target power being less than or equal to the second preset value can indicate that the target power is small, and the target power being greater than the second preset value can indicate that the target power is not small, so the target power being less than or equal to the second preset value can indicate that the grid-connected device reaches the maximum output power, and the target power being greater than the second preset value can indicate that the grid-connected device does not reach the maximum output power. Therefore, the target power being less than or equal to the second preset value can be used as the preset maximum power condition. Similarly, the target power being less than or equal to the third preset value can be used as the preset maximum power condition.

[0082] The above is only a specific implementation manner of the first preset maximum power condition and a specific implementation manner of the second preset maximum power condition. In practical applications, including but not limited to this, it is not specifically limited here, and all are within the protection scope of this application.

[0083] Another embodiment of this application provides another implementation manner of the anti-counterflow method for the grid-connected system, and its specific process can be referred to Figure 3 ( Figure 3 only shown on the basis of Figure 2 ). After S120 in the implementation manner provided by any of the above embodiments, this implementation manner further includes the following steps:

[0084] S310. Determine whether the grid-connected device meets the third preset counterflow condition.

[0085] If the grid-connected device meets the third preset reverse current condition, then execute S320; if the grid-connected device does not meet the third preset reverse current condition, then return to execute step S110.

[0086] The third preset reverse current condition is the determination condition for the grid-connected device to have reverse current, that is: if the grid-connected device meets the third preset reverse current condition, it indicates that the grid-connected device has reverse current; if the grid-connected device does not meet the third preset reverse current condition, it indicates that the grid-connected device does not have reverse current.

[0087] Optionally, the third preset reverse current condition may be the same as the first preset reverse current condition, or the third preset reverse current condition may be different from the first preset reverse current condition. There is no specific limitation here and it can be determined according to the specific situation, and all are within the protection scope of this application. Usually, the third preset reverse current condition is the same as the first preset reverse current condition.

[0088] S320: Control the output power of the grid-connected device to gradually decrease so that the grid-connected device does not meet the fourth preset reverse current condition.

[0089] The fourth preset reverse current condition is the determination condition for the grid-connected device to have reverse current, that is: if the grid-connected device meets the fourth preset reverse current condition, it indicates that the grid-connected device has reverse current; if the grid-connected device does not meet the fourth preset reverse current condition, it indicates that the grid-connected device does not have reverse current.

[0090] In a specific example, the fourth preset reverse current condition is the same as the third preset reverse current condition.

[0091] In another specific example, the fourth preset reverse current condition is different from the third preset reverse current condition.

[0092] In this example, since the fourth preset reverse current condition is different from the third preset reverse current condition, after the grid-connected device does not meet the fourth preset reverse current condition, even if there is a slight fluctuation in the load power, the grid-connected device will not immediately meet the third preset reverse current condition, so that the output power of the grid-connected device will not be immediately controlled to gradually decrease, thereby reducing the regulation frequency of the output power of the grid-connected device, that is, the output power of the grid-connected device will not change frequently.

[0093] The above two examples show two relationships between the fourth preset reverse current condition and the third preset forward current condition. There is no specific limitation here and it can be determined according to the specific situation, and all are within the protection scope of this application. Usually, the fourth preset reverse current condition is different from the third preset reverse current condition.

[0094] In this embodiment, this implementation method is equivalent to controlling the output power of the grid-connected device to gradually decrease when the grid-connected device does not meet the second preset reverse current condition but meets the third preset reverse current condition, so that the grid-connected device does not meet the fourth preset reverse current condition. Therefore, compared with the second preset reverse current condition, the third preset reverse current condition and the fourth preset reverse current condition are more capable of ensuring the determination conditions for the grid-connected device to have reverse current. Thus, by using the anti-reverse current method provided in this embodiment to regulate the grid-connected device, it is possible to increase the possibility that the regulated grid-connected device does not have reverse current under the condition that the load power remains unchanged.

[0095] It should be noted that if both S210 and S310 are included after S120, then S310 and S210 are executed simultaneously.

[0096] Another embodiment of the present application provides specific implementation manners of the third preset reverse current condition and the fourth preset reverse current condition. Specifically as follows:

[0097] The specific implementation manner of the third preset reverse current condition is: the target power is less than the fourth preset value.

[0098] The specific implementation manner of the fourth preset reverse current condition is: the target power is less than the fifth preset value.

[0099] It should be noted that the target power has been described in detail in the above embodiments and will not be elaborated here.

[0100] The target power being less than the fourth preset value indicates that the target power is small. On the contrary, the target power being greater than or equal to the fourth preset value indicates that the target power is not small. In practical applications, the fourth preset value is set according to specific circumstances and is not specifically limited here. Usually, the fourth preset value is equal to 50W.

[0101] The target power being less than the fifth preset value indicates that the target power is small. On the contrary, the target power being greater than or equal to the fifth preset value indicates that the target power is not small. In practical applications, the fifth preset value is set according to specific circumstances and is not specifically limited here. Usually, the fifth preset value is equal to 70W.

[0102] If the specific implementation manner of the first preset reverse current condition is: the target power is less than the sixth preset value, then when the third preset reverse current condition is the same as the first preset reverse current condition, the fourth preset value is equal to the sixth preset value; when the third preset reverse current condition is different from the first preset reverse current condition, the fourth preset value is not equal to the sixth preset value.

[0103] If the fourth preset reverse current condition is the same as the third preset reverse current condition, then the fifth preset value is equal to the fourth preset value; if the fourth preset reverse current condition is different from the third preset reverse current condition, then the fifth preset value is not equal to the fourth preset value.

[0104] In this embodiment, under normal circumstances, when there is a reverse current in the grid-connected device, the grid-connected device outputs electric energy to the power grid, that is, the target power is less than zero, which means the target power is relatively small. When there is no reverse current in the grid-connected device, the power grid outputs electric energy to the load, that is, the target power is greater than zero, which means the target power is not relatively small. Therefore, if the target power is relatively small, there is a reverse current in the grid-connected device; if the target power is not relatively small, there is no reverse current in the grid-connected device. Also, since the target power being less than the fourth preset value can indicate that the target power is relatively small, and the target power being greater than or equal to the fourth preset value can indicate that the target power is not relatively small, so the target power being less than the fourth preset value can indicate that there is a reverse current in the grid-connected device, and the target power being greater than or equal to the fourth preset value can indicate that there is no reverse current in the grid-connected device. Therefore, the target power being less than the fourth preset value can be used as a preset reverse current condition. Similarly, the target power being less than the fifth preset value can be used as a preset reverse current condition.

[0105] The above are only a specific implementation manner of the third preset reverse current condition and a specific implementation manner of the fourth preset reverse current condition. In practical applications, including but not limited to this, no specific limitation is made here, and all are within the protection scope of this application.

[0106] Assume that the load is 500W and the output power of the grid-connected device is 400W. At this time, the target power is 100W, the sixth preset value is 50W, the second preset value is 150W, and the third preset value is 100W. If the load power suddenly decreases to 200W at time t1, the target power changes to -200W at this time. Since the target power is less than the sixth preset value, the grid-connected device meets the first preset reverse current condition and triggers the anti-reverse current mechanism. Since it takes time to control the grid-connected device, it is considered that t1 - t2 is this time. Therefore, the grid-connected device operates at time t2.

[0107] In the prior art, after time t2, the output power of the grid-connected device gradually decreases, as Figure 4 shown. In this application, at time t2, the grid-connected device switches to the shutdown state or the standby state, that is, the output power of the grid-connected device becomes 0 at time t2, as Figure 5 shown. From Figure 4 and Figure 5 it can be seen that in this application, at time t2, the target power becomes positive, that is, there is no reverse current at time t2, while in the prior art, at time t3, the target power becomes positive, that is, the reverse current disappears at time t3. Therefore, the anti-reverse current method of the grid-connected device provided by this application reduces the existence time of the reverse current. Therefore, the anti-reverse current method of the grid-connected device provided by this application can improve the anti-reverse current effect of the anti-reverse current function of the grid-connected device.

[0108] In this application, as Figure 5As shown in the figure, at time t2, the target power becomes 200W. At this time, the target power is greater than the second preset value, that is, the grid-connected device does not meet the first preset maximum power condition, and the economic benefit of the grid-connected device is not the best. Therefore, the output power of the grid-connected device gradually increases, and the target power gradually decreases until time t3, when the target power drops to the third preset value, that is, the grid-connected device meets the second preset maximum power condition.

[0109] In the present application, as Figure 5 shown, if the load power suddenly increases to 400W at time t4, at this time the target power becomes 300W, and the target power is greater than the second preset value, that is, the grid-connected device does not meet the first preset maximum power condition. Therefore, the output power of the grid-connected device gradually increases, and the target power gradually decreases until time t6, when the target power drops to the third preset value, that is, the grid-connected device meets the second preset maximum power condition. Since it takes time to control the grid-connected device, it is considered that t4 - t5 is this time.

[0110] It should be noted that the solid line is the load power, the dashed line is the output power of the grid-connected device, and the dotted line is the target power.

[0111] Corresponding to the above method embodiment, the embodiment of the present application also provides a controller for a grid-connected device, which includes at least one processor and a memory connected to the processor.

[0112] The memory is used to store computer programs.

[0113] The processor is used to execute the computer program so that the controller can implement the anti-counterflow method of the grid-connected device provided in any of the above embodiments.

[0114] The embodiment of the present application provides a grid-connected device, including: a power converter and the controller of the grid-connected device provided above.

[0115] The AC side of the power converter serves as the AC side of the grid-connected device and is respectively used to connect the load 01 and the power grid 02.

[0116] The controller is communicatively connected to the power converter. The controller is used to monitor the working state of the power converter.

[0117] It should be noted that the power converter is already very mature in the prior art and will not be described in detail here. In addition, the controller also analyzes the scheduling actions that the grid-connected device needs to take through the built-in algorithm and controls the grid-connected device to make power adjustments.

[0118] The embodiment of the present application provides a grid-connected system, which specifically includes: the grid-connected device provided above.

[0119] If the controller in the grid-connected device is separated from the grid-connected device, then asFigure 6 As shown, the independent controller is 20. In this case, Figure 6 The solid line in [ ] shows the AC side of the power converter, Figure 6 The dotted line in [ ] shows the communication connection between the controller and the power converter.

[0120] Another embodiment of the present application also provides another implementation manner of the grid-connected system, and its specific structure is as shown in Figure 7 . Based on the implementation manner provided in the above embodiment, this implementation manner further includes: a collector 30.

[0121] The AC side of the grid-connected device 10 is connected to one side of the collector 30, and the other side of the collector 30 is used to connect to the power grid 02, as shown by the solid line in Figure 7 .

[0122] The collector 30 is used to collect the target power. In addition, the collector 30 also collects information such as the current, voltage, power consumption, and current direction flowing through itself, and transmits it to the controller 20 for the controller 20 to analyze and schedule.

[0123] It should be noted that the target power has been described in detail in the above embodiment, and will not be elaborated here.

[0124] If the controller in the grid-connected device is separated from the grid-connected device, the controller 20 is communicatively connected to the collector 30, as shown by the dotted line in Figure 7 . In addition, in this case, the controller 20 is also used to monitor the target power fed back by the collector 30.

[0125] It should be noted that the controller 20 also analyzes the scheduling actions that the grid-connected device 10 needs to perform through the built-in algorithm and controls the grid-connected device 10 to perform power regulation.

[0126] Optionally, the connection between the grid-connected device 10 and the collector 30 includes PLC (Power Line Carrier) communication. In practical applications, it includes but is not limited to this. No specific limitation is made here, and it can be determined according to specific circumstances, and all are within the protection scope of the present application.

[0127] Optionally, the grid-connected device 10 can be an inverter or a micro-inverter. In practical applications, it includes but is not limited to this. No specific limitation is made here, and it can be determined according to specific circumstances.

[0128] If the grid-connected device 10 is an inverter, the DC side of the grid-connected device 10 is connected to the photovoltaic string, or the DC side of the grid-connected device 10 is connected to the photovoltaic array.

[0129] If the grid-connected device 10 is a micro-inverter, the DC side of the grid-connected device 10 is connected to the photovoltaic module.

[0130] It should be noted that photovoltaic modules, photovoltaic strings, and photovoltaic arrays are already very mature in the prior art, and thus will not be described in detail herein.

[0131] Another embodiment of the grid-connected system is provided in the embodiments of the present application. Based on the embodiment provided in the previous embodiment, the following improvements are made:

[0132] The connection between the grid-connected device 10 and the collector 30, the communication connection between the controller 20 and the grid-connected device 10, and the communication connection between the controller 20 and the collector 30 are all PLC communications.

[0133] Since the connection between the grid-connected device 10 and the collector 30, the communication connection between the controller 20 and the grid-connected device 10, and the communication connection between the controller 20 and the collector 30 are all PLC communications, and in PLC communications, all communication information is transmitted along the power line, no additional wiring is required and the signal stability is relatively good.

[0134] The embodiments of the present application also provide a computer program product, including computer-readable instructions. When the computer-readable instructions run on the controller, the controller is enabled to implement the anti-counterflow method of the grid-connected device provided in any one of the above embodiments.

[0135] The embodiments of the present application also provide a computer-readable storage medium. The storage medium carries one or more computer programs. When the one or more computer programs are executed by the controller, the controller can be enabled to implement the anti-counterflow method of the grid-connected device provided in any one of the above embodiments of the present application.

[0136] Regarding the above description of the disclosed embodiments, the features described in each embodiment in this specification can be replaced or combined with each other, enabling those skilled in the art to implement or use the present application. The above are only preferred embodiments of the present invention and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the protection of the technical solution of the present invention.

Claims

1. A method for preventing reverse current of grid-connected equipment, characterized in that, Including: Determine whether the grid-connected device meets the first preset reverse current condition; If the grid-connected device meets the first preset reverse current condition, control the output power of the grid-connected device to switch to a first preset value, so that the grid-connected device does not meet the second preset reverse current condition.

2. The anti-backflow method of the grid-connected device according to claim 1, characterized in that, The first preset value is equal to zero.

3. The anti-counterflow method of the grid-connected device according to claim 1, characterized in that, After performing the step of controlling the output power of the grid-connected device to switch to the first preset value so that the grid-connected device does not meet the second preset reverse current condition, or, while performing the step of determining whether the grid-connected device meets the first preset reverse current condition, further including: When the grid-connected device does not meet the first preset maximum power condition, control the output power of the grid-connected device to gradually increase, so that the grid-connected device meets the second preset maximum power condition.

4. The anti-counterflow method for grid-connected equipment according to claim 3, characterized in that The first preset maximum power condition includes: the target power is less than or equal to a second preset value; the target power is the power flowing into the grid; The second preset maximum power condition includes: the target power is less than or equal to a third preset value.

5. The anti-counterflow method for grid-connected equipment according to any one of claims 1 to 4, characterized in that, After performing the step of controlling the output power of the grid-connected device to switch to the first preset value so that the grid-connected device does not meet the second preset reverse current condition, further including: When the grid-connected device meets the third preset reverse current condition, control the output power of the grid-connected device to gradually decrease, so that the grid-connected device does not meet the fourth preset reverse current condition.

6. The anti-counterflow method of the grid-connected device according to claim 5, characterized in that, The third preset reverse current condition includes: the target power is less than a fourth preset value; the target power is the power flowing into the grid; The fourth preset reverse current condition includes: the target power is less than a fifth preset value.

7. The anti-counterflow method of the grid-connected device according to any one of claims 1 to 4, characterized in that, The first preset reverse current condition includes: the target power is less than a sixth preset value; the target power is the power flowing into the grid; The second preset reverse current condition includes: the target power is less than a seventh preset value.

8. A controller for a grid-connected device, characterized in that, Including: At least one processor, and a memory connected to the processor; The memory is used to store a computer program; The processor is used to execute the computer program, so that the controller can implement the anti-reverse current method of the grid-connected device according to any one of claims 1 to 7.

9. A grid-connected device, characterized in that, Including: A power converter and a controller of the grid-connected device according to claim 8; The AC side of the power converter serves as the AC side of the grid-connected device, and is respectively used to connect a load and the grid; The controller is communicatively connected to the power converter.

10. A grid-connected system, characterized in that, Including: The grid-connected device according to claim 9.

11. A computer program product, characterized in that, Including computer-readable instructions, when the computer-readable instructions run on the controller, the controller implements the anti-reverse current method of the grid-connected device according to any one of claims 1 to 7.

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