Anti-countercurrent control method of power grid, micro-inverse host, micro-inverse system and storage medium

Abstract

The invention relates to an anti-countercurrent control method of a power grid, a micro-inverse host, a micro-inverse system and a storage medium. The method is applied to a micro-inverse host in the micro-inverse system, the micro-inverse system further comprises a current acquisition unit and at least one micro-inverse slave, the current acquisition unit is connected with a power grid and the micro-inverse host, and the micro-inverse host is in communication connection with the micro-inverse slave and is connected with the power grid. The method comprises the following steps: determining active power flowing out of a power grid based on a current parameter which is sampled by a current acquisition unit and flows out of the power grid and a voltage parameter output by a micro-inverse host; based on the active power, determining whether countercurrent occurs in the power grid; and if countercurrent occurs, generating a power adjustment coefficient based on the active power and broadcasting the power adjustment coefficient, and reducing rated power by the micro-inverse host and the micro-inverse slave based on the power adjustment coefficient. The power output utilization rate of the micro-inverse system can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic equipment, and in particular to a method for controlling reverse flow of a power grid, a micro-inverter host, a micro-inverter system and a storage medium. Background Art

[0002] With the development of control technology for photovoltaic equipment, micro-inverter anti-backflow technology has emerged. Anti-backflow means that the electric energy output by the micro-inverter system is only used for local loads to avoid sending excess electricity into the grid.

[0003] In traditional technology, after determining that the grid has reverse flow, the AC side of the micro-inverter is usually disconnected to stop the micro-inverter from outputting power or the micro-inverter is actively shut down to reduce the output power of the micro-inverter system, thereby achieving reverse flow prevention. Among them, the micro-inverter system outputs power through the micro-inverter.

[0004] However, the current anti-backflow method may cause the output power to drop too much or the micro-inverter restart may take a certain amount of time due to local regulations, resulting in a waste of the output power of the micro-inverter system, thereby making the power output utilization rate of the micro-inverter system low. Summary of the invention

[0005] Based on this, it is necessary to provide a reverse flow control method for a power grid, a micro-inverter host, a micro-inverter system and a storage medium that can improve the power output utilization rate of the micro-inverter system in response to the above technical problems.

[0006] In a first aspect, the present application provides a reverse current control method for a power grid, which is applied to a micro-inverter host in a micro-inverter system, wherein the micro-inverter system further includes a current acquisition unit and at least one micro-inverter slave, wherein the current acquisition unit is connected to the power grid and the micro-inverter host, and the micro-inverter host is communicatively connected to the micro-inverter slave and connected to the power grid, including:

[0007] Determine the active power flowing out of the power grid based on the current parameter flowing out of the power grid sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host;

[0008] Based on the active power, determining whether a reverse flow occurs in the power grid;

[0009] If reverse flow occurs, a power adjustment coefficient is generated based on the active power and broadcasted, and the micro-inverter master and the micro-inverter slave reduce the rated power based on the power adjustment coefficient.

[0010] In one embodiment, determining whether reverse flow occurs in the power grid based on the active power includes:

[0011] Obtaining a difference value based on the active power and a preset limited inflow power;

[0012] If the difference is less than 0, it is determined that reverse flow occurs in the power grid.

[0013] In one embodiment, generating a power adjustment coefficient based on the active power includes:

[0014] Obtaining a difference between the active power and a preset limit inflow power;

[0015] The power adjustment coefficient is determined based on a ratio of the difference to a total rated power of the microinverter system.

[0016] In one embodiment, the microinverter master and the microinverter slave obtain a target rated power based on the power adjustment coefficient and the current rated power, and adjust the current rated power down to the target rated power; the target rated power is calculated based on the following formula:

[0017] P i1 =(1+D)*P i2

[0018] Among them, the P i1 is the P1 of the i-th micro-inverter, the i-th micro-inverter is the micro-inverter master or the micro-inverter slave, the P1 is the target rated power; the D is the power adjustment coefficient; the P i2 is P2 of the i-th micro-inversion, and P2 is the current rated power.

[0019] In one embodiment, the determining the active power flowing out of the power grid based on the current parameter flowing out of the power grid sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host comprises:

[0020] Based on the multiple current parameters sampled by the current acquisition unit and the multiple voltage parameters output by the micro-inverter host, multiple instantaneous active powers are obtained;

[0021] An average value of the multiple instantaneous active powers is calculated to obtain the active power.

[0022] In one embodiment, the multiple instantaneous active powers obtained based on the multiple current parameters sampled by the current acquisition unit and the multiple voltage parameters output by the micro-inverter host include:

[0023] Determining a preset number of sampling times of the current parameter based on the interruption time and the power frequency cycle;

[0024] If the current sampling number is less than the preset sampling number, the instantaneous active power is calculated based on the current parameter sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host;

[0025] Until the current sampling number is equal to the preset sampling number.

[0026] In a second aspect, the present application further provides a micro-inverter host, which is applied to a micro-inverter system, wherein the micro-inverter system further includes a current acquisition unit and at least one micro-inverter slave, wherein the current acquisition unit is connected to a power grid and the micro-inverter host, and the micro-inverter host is communicatively connected to the micro-inverter slave and connected to the power grid, including:

[0027] A power calculation module, used to determine the active power flowing out of the power grid based on the current parameters flowing out of the power grid sampled by the current acquisition unit and the voltage parameters output by the micro-inverter host;

[0028] A reverse flow determination module, used to determine whether a reverse flow occurs in the power grid based on the active power;

[0029] The adjustment coefficient generating module is used for generating a power adjustment coefficient based on the active power if reverse flow occurs, and broadcasting the power adjustment coefficient. The micro-inverter host and the micro-inverter slave adjust the rated power based on the power adjustment coefficient.

[0030] In one embodiment, the microinverter host further comprises:

[0031] Enhanced capture module eCAP, used to determine the power frequency period;

[0032] A processor, configured to determine a preset number of sampling times of the current parameter based on the interruption time and the power frequency cycle;

[0033] If the current sampling number is less than the preset sampling number, the instantaneous active power is calculated based on the current parameter sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host;

[0034] Until the current sampling number is equal to the preset sampling number.

[0035] In a third aspect, the present application also provides a micro-inverter system, comprising the micro-inverter host as described above, a current acquisition unit, and at least one micro-inverter slave, wherein the current acquisition unit is connected to a power grid and the micro-inverter host, and the micro-inverter host is communicatively connected to the micro-inverter slave and connected to the power grid.

[0036] In a fourth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the following steps are implemented:

[0037] Determine the active power flowing out of the power grid based on the current parameter flowing out of the power grid sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host;

[0038] Based on the active power, determining whether a reverse flow occurs in the power grid;

[0039] If reverse flow occurs, a power adjustment coefficient is generated based on the active power and broadcasted, and the micro-inverter master and the micro-inverter slave reduce the rated power based on the power adjustment coefficient.

[0040] The anti-backflow control method, micro-inverter host, micro-inverter system and storage medium of the above-mentioned power grid achieve anti-backflow by generating a power adjustment coefficient based on active power when a backflow occurs in the power grid, and broadcasting the power adjustment coefficient. The micro-inverter host and the micro-inverter slave reduce the rated power based on the power adjustment coefficient. There is no need to disconnect the AC side of the micro-inverter to stop the micro-inverter from outputting power or actively shut down the micro-inverter, so as to avoid excessive drop in the output power of the micro-inverter, and restarting the machine will also be affected by local regulations, and it will take a certain amount of time to start the machine and re-output power, resulting in a waste of generated power. Therefore, the embodiment of the present application enables the power output of the micro-inverter system to be just used by the load and will not flow into the power grid, that is, the power flowing into the power grid is 0 or within the power range allowed to flow in, thereby improving the power output utilization rate of the micro-inverter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 is a structural diagram of a microinversion system in one embodiment;

[0043] Figure 2 A schematic diagram of a flow chart of a method for preventing reverse flow control of a power grid in one embodiment;

[0044] Figure 3 A schematic diagram of a flow chart of a step of generating a power adjustment coefficient based on active power in one embodiment;

[0045] Figure 4 A schematic flow chart of a step of determining active power in another embodiment;

[0046] Figure 5 is a circuit diagram of an eCAP involved in an embodiment;

[0047] Figure 6 FIG. 1 is a flow chart of a step of determining active power in an embodiment. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0049] The anti-backflow method for the power grid provided in the embodiment of the present application can be applied to Figure 1 In the micro-inverter system shown, the micro-inverter system includes a micro-inverter host, a current acquisition unit, and at least one micro-inverter slave, the current acquisition unit is connected to the power grid and the micro-inverter host, and the micro-inverter host is in communication connection with the micro-inverter slave and connected to the power grid.

[0050] Among them, micro-inverter refers to a micro inverter, which generally refers to a micro inverter with a power of less than or equal to 1000 watts and component-level MPPT (Maximum Power Point Tracking) in the micro-inverter system. Its full name is micro photovoltaic grid-connected micro-inverter. It is used to output power to the load or the grid.

[0051] Among them, "micro" is relative to the traditional centralized inverter. The traditional photovoltaic inverter method is to connect all the DC power generated by all photovoltaic cells under sunlight in series and parallel, and then use an inverter to invert the DC power into AC power and connect it to the power grid; while the micro inverter inverts each photovoltaic module. Its advantage is that it can perform independent MPPT control on each photovoltaic module, which can greatly improve the overall efficiency, and at the same time avoid the DC high voltage, poor weak light effect, and barrel effect of centralized inverters.

[0052] The micro-inverter host 102 is used to obtain data and provide a power output decision based on the data, and the power output decision can adjust its own rated power and the rated power of the micro-inverter slave 106. The data includes current parameters, voltage parameters, etc. The micro-inverter host 102 adjusts the rated power of the micro-inverter slave 106 by communicating with it, specifically, the micro-inverter host 102 generates and broadcasts a power adjustment coefficient, and the micro-inverter slave 106 adjusts its own rated power after receiving the power adjustment coefficient.

[0053] It should be noted that the rated power refers to the maximum output power of the micro-inverter. By adjusting the rated power, the output power of the micro-inverter can be limited, thereby achieving backflow prevention.

[0054] The current acquisition unit 104 is used to acquire the current parameters on the grid side, that is, the current parameters flowing out of the grid. The current acquisition unit includes an electric meter, a power analyzer, an anti-backflow controller or a Hall sensor, etc.

[0055] Among them, the backflow prevention is performed by an electric meter, a power analyzer and an anti-backflow controller, and the operation is relatively complicated, resulting in low efficiency and low accuracy. Compared with electric meters, power analyzers, anti-backflow controllers, etc., Hall sensors can monitor current more accurately and have good measurement linearity and strong anti-interference ability, thereby improving the accuracy of the collected current parameters. In addition, by providing a power output decision through the micro-inverter host 102, the rated power of the micro-inverter host 102 and at least one micro-inverter slave 106 can be reduced, which can make the reduction speed faster.

[0056] The at least one micro-inverter slave 106 is used to receive the power adjustment coefficient and adjust its own rated power based on the power adjustment coefficient.

[0057] It should be noted that when the micro-inverter host 102 determines that a reverse flow occurs in the power grid, it generates a power adjustment parameter to reduce the rated power of itself and the micro-inverter slave 106. There is no need to disconnect the AC side of the micro-inverter to stop the micro-inverter from outputting power or to actively shut down the micro-inverter, thereby avoiding excessive reduction in the output power of the micro-inverter, and restarting the machine will also be affected by local regulations, and it will take a certain amount of time to start the machine and re-output power, resulting in a waste of generated power. Therefore, the embodiment of the present application enables the power output of the micro-inverter system to be used just for the load and will not flow into the power grid, that is, the power flowing into the power grid is 0 or within the power range allowed to flow in, thereby improving the power output utilization rate of the micro-inverter system.

[0058] In addition, it should be emphasized that if multiple micro-inverters are shut down at the same time, it may also cause fluctuations in the power grid flowing into the load, which is not conducive to the stability of the power grid. Therefore, it is beneficial to the stability of the power grid by reducing the rated power of the micro-inverter instead of shutting it down.

[0059] In an exemplary embodiment, Figure 2 As shown, a method for controlling reverse current of a power grid is provided, which is applied to a micro-inverter host in a micro-inverter system, wherein the micro-inverter system further comprises a current acquisition unit and at least one micro-inverter slave, wherein the current acquisition unit is connected to the power grid and the micro-inverter host, and the micro-inverter host is connected to the micro-inverter slave in communication and connected to the power grid, and the method comprises the following steps 202 to 206. Among them:

[0060] Step 202: determining the active power flowing out of the grid based on the current parameters flowing out of the grid sampled by the current acquisition unit and the voltage parameters output by the micro-inverter host.

[0061] Exemplarily, the current parameter and the voltage parameter are used to calculate active power, which is the product of the current value and the voltage value. In this embodiment, the current value for the current flowing out of the grid is positive, and the current value for the current flowing into the grid is negative.

[0062] Step 204: Determine whether reverse flow occurs in the power grid based on the active power.

[0063] Active power is generally a positive value, that is, current flows from the power grid to the load; active power can also be a negative value, that is, current flows from the power generation equipment into the power grid.

[0064] Exemplarily, when a micro-inverter system with reverse flow protection is connected to a power grid, if the active power is a negative value, it is determined that a reverse flow may occur in the power grid; if the active power is a positive value, it is determined that a reverse flow does not occur in the power grid.

[0065] Exemplarily, based on the active power, determining whether a reverse current occurs in the power grid includes: obtaining a difference based on the active power and a preset limited inflow power; if the difference is less than 0, determining that a reverse current occurs in the power grid.

[0066] Among them, in order to adapt to some fragile power grids and comply with some local regulations, a micro-inverter anti-backflow control function is added. The anti-backflow control function is implemented based on the preset limit inflow power, and the preset limit inflow power can be set by the host computer. The size of the preset limit inflow power is determined by the inflow requirements of the fragile power grid or the inflow requirements stipulated by some local regulations. Generally, the preset limit inflow power is 0, that is, the output power of the micro-inverter system is generally not allowed to flow into the power grid.

[0067] Therefore, when the difference is greater than or equal to 0, it is determined that no reverse flow occurs in the power grid, and at this time, the total rated power of the micro-inverter system flows entirely to the load.

[0068] Step 206: If reverse flow occurs, a power adjustment coefficient is generated based on the active power and broadcasted. The micro-inverter master and micro-inverter slave reduce the rated power based on the power adjustment coefficient.

[0069] The broadcast is realized by the first communication device of the microinverter master, specifically, generating a relevant message based on the power adjustment coefficient, and broadcasting the relevant message through the first communication device. After the microinverter slave receives the relevant message through its second communication device, it obtains the power adjustment coefficient from the relevant message.

[0070] In the above-mentioned anti-backflow control method of the power grid, when a backflow occurs in the power grid, a power adjustment coefficient is generated based on the active power, and the power adjustment coefficient is broadcasted, and the micro-inverter host and the micro-inverter slave reduce the rated power based on the power adjustment coefficient to achieve anti-backflow. There is no need to disconnect the AC side of the micro-inverter to stop the micro-inverter from outputting power or actively shut down the micro-inverter, so as to avoid excessive drop in the output power of the micro-inverter, and restarting the machine will also be affected by local regulations, and it will take a certain amount of time to start the machine and re-output power, resulting in a waste of generated power. Therefore, the embodiment of the present application enables the power output of the micro-inverter system to be just used by the load and will not flow into the power grid, that is, the power flowing into the power grid is 0 or within the power range allowed to flow in, thereby improving the power output utilization rate of the micro-inverter system.

[0071] Exemplarily, the rated power is adjusted down based on the power adjustment coefficient, that is, the product of the power adjustment coefficient and the current rated power is calculated to obtain the target rated power, so that the micro-inverter uses the target rated power to output power, thereby achieving backflow prevention. That is, the micro-inverter host and the micro-inverter slave obtain the target rated power based on the power adjustment coefficient and the current rated power, and adjust the current rated power down to the target rated power. The target rated power is calculated based on the following formula (I):

[0072] P i1 =(1+D)*P i2 (one)

[0073] Among them, P i1 is the P1 of the i-th micro-inverter, the i-th micro-inverter is a micro-inverter master or micro-inverter slave, and P1 is the target rated power; D is the power adjustment coefficient; P i2 is the P2 of the i-th micro-inversion, where P2 is the current rated power.

[0074] It should be noted that, since the microinverter master and the microinverter slave use the same power adjustment coefficient to adjust the rated power, this makes the adjustment faster and more efficient.

[0075] For example, if reverse flow occurs, the total rated power of the micro-inverter system needs to be reduced to prevent the output power of the micro-inverter system from flowing to the grid.

[0076] In one embodiment, generating the power adjustment coefficient based on the active power specifically includes: obtaining the difference between the active power and the preset limited inflow power; and determining the power adjustment coefficient based on the ratio of the difference to the total rated power of the microinverter system. That is, the power adjustment coefficient is a ratio.

[0077] The difference is the output power that needs to be reduced by the micro-inverter system.

[0078] The total rated power is obtained by accumulating all current rated powers of the micro-inverter master and each micro-inverter slave after the micro-inverter master communicates with each micro-inverter slave.

[0079] In this embodiment, if Figure 3 As shown in the figure, after the backflow prevention is enabled, the difference Perr between the active power Pvin and the preset limit inflow power Plimit is calculated. If the difference Perr<0, it means that the power flowing into the load from the grid is too small, or even the power of the micro-inverter system flows to the grid, then it is determined that the grid has a backflow, and the power output of the micro-inverter system needs to be limited by backflow prevention. When limiting the power output of the micro-inverter system, the ratio D of the difference Perr and the total rated power Prate1 is calculated, and the ratio D is a negative value at this time.

[0080] It can be understood that if the difference Perr ≥ 0, it means that the power flowing from the power grid to the load is normal. At this time, there is no reverse flow in the power grid and no reverse flow prevention is required.

[0081] After the ratio D is obtained, the product of the total rated power Prate1 and (1+ratio D) is calculated to obtain the target total rated power Prate2.

[0082] Afterwards, when the micro-inverter master and the micro-inverter slave reduce the rated power based on the power adjustment coefficient, the micro-inverter master and the micro-inverter slave can obtain their target rated power by multiplying the current rated power by (1+ratio D).

[0083] In addition, in order to ensure that the reverse flow is successfully eliminated, verification can also be performed after the rated power is lowered, and if the lowering is not in place, the difference Perr is determined again and the difference Perr<0, then the rated power is continued to be lowered according to the difference Perr until the difference Perr≥0. This process is to return to the step of calculating the difference Perr between the active power Pvin and the preset limit inflow power Plimit until the difference Perr≥0.

[0084] In the above-mentioned anti-backflow control method of the power grid, when a backflow occurs in the power grid, a power adjustment coefficient is generated based on the active power, and the power adjustment coefficient is broadcasted, and the micro-inverter host and the micro-inverter slave reduce the rated power based on the power adjustment coefficient to achieve anti-backflow. There is no need to disconnect the AC side of the micro-inverter to stop the micro-inverter from outputting power or actively shut down the micro-inverter, so as to avoid excessive drop in the output power of the micro-inverter, and restarting the machine will also be affected by local regulations, and it will take a certain amount of time to start the machine and re-output power, resulting in a waste of generated power. Therefore, the embodiment of the present application enables the power output of the micro-inverter system to be just used by the load and will not flow into the power grid, that is, the power flowing into the power grid is 0 or within the power range allowed to flow in, thereby improving the power output utilization rate of the micro-inverter system.

[0085] In an exemplary embodiment, Figure 4As shown, based on the current parameters of the outgoing grid sampled by the current acquisition unit and the voltage parameters output by the micro-inverter host, determining the active power outgoing grid includes steps 402 to 404. Among them:

[0086] Step 402, obtaining multiple instantaneous active powers based on multiple current parameters sampled by the current acquisition unit and multiple voltage parameters output by the micro-inverter host.

[0087] Among them, for instantaneous active power, the current and voltage of AC power change in real time, such as the current and voltage of sinusoidal AC power change periodically in the form of sine waves. Therefore, active power also changes periodically, and when calculating the active power of the power grid, it is necessary to obtain multiple instantaneous active powers.

[0088] Generally, the current and voltage can be sampled within one cycle of the alternating current, thereby calculating and obtaining a plurality of instantaneous active powers.

[0089] Exemplarily, the steps of obtaining multiple instantaneous active powers based on multiple current parameters sampled by the current acquisition unit and multiple voltage parameters output by the micro-inverter host include: determining a preset sampling number of current parameters based on the interruption time and the power frequency cycle; if the current sampling number is less than the preset sampling number, calculating the instantaneous active power based on the current parameters sampled by the current acquisition unit and the voltage parameters output by the micro-inverter host; until the current sampling number is equal to the preset sampling number.

[0090] The interruption time is determined by the microinverter host hardware, specifically by a timer therein, for example, if the timer interrupts once every 80us, the interruption time is 80us. The timer may be a DSP (Digital Signal Processing) chip.

[0091] The power frequency cycle refers to the cycle of the alternating current, and the power frequency cycle can be determined by combining eCAP (e-capture, enhanced capture module) and DSP.

[0092] The preset sampling times is the quotient of the power frequency period and the interruption time.

[0093] like Figure 5 As shown, a circuit diagram of an eCAP involved in an embodiment of the present application is provided. The eCAP includes a plurality of resistors, a plurality of capacitors and two transistors, and each transistor and a portion of the resistors and a portion of the capacitors respectively form an amplifier circuit and a hysteresis comparator. The amplifier circuit specifically includes R1, R2, R3, R4, C1, C2 and a transistor; the hysteresis comparator specifically includes R5, R6, R7, R8, R9, R10, C3, C4, C5 and another transistor.

[0094] The eCAP is connected to the power grid and DSP respectively, and its input end is connected to ACL and ACN, that is, the live wire and neutral wire of the power grid; its output end 502 (the output end also includes the "VAC" in the figure) is connected to the DSP. The eCAP provides an electrical signal for the DSP to obtain instantaneous voltage parameters based on the amplifier circuit and through the output end "VAC", and provides an electrical signal for the DSP to determine the power frequency cycle based on the hysteresis comparator and through the output end 502.

[0095] Among them, when the AC power frequency cycle is determined by combining eCAP and DSP:

[0096] When the voltage is positive, the signal obtained by DSP is 1; when the voltage is negative, the signal obtained by DSP is 0. Therefore, since the alternating current changes periodically, the power frequency cycle can be obtained by recording the two times when the signal changes from 0 to 1 twice adjacently and subtracting the times, or the two times when the signal changes from 1 to 0 twice adjacently and subtracting the times, and then filtering the result of the subtraction to prevent some interference from affecting the accuracy of the power frequency cycle.

[0097] For example, Figure 6 As shown, taking the power frequency period of 0.02s and the interruption time of 80us as an example, the preset sampling times are 250. Among them, after the timing interruption, AD (Analog to Digital, analog to digital converter) sampling is performed, that is, the instantaneous voltage parameter U is obtained. Among them, AD is inside the DSP and is the internal circuit of the DSP.

[0098] Among them, the initial value of n is 0. During the sampling process and when n<250, when the instantaneous voltage parameter U is obtained, the instantaneous current parameter I sampled by the current acquisition unit is obtained, and the instantaneous active power U*I is calculated based on the instantaneous voltage parameter U and the instantaneous current parameter I. n+1, and the instantaneous active power U*I is accumulated to obtain Psum. After the next interruption, it is continued to determine whether n≥250. When n≥250, the active power Pvin is calculated by Psum accumulated from the previous sampling.

[0099] Step 404, calculating the average value of multiple instantaneous active powers to obtain active power.

[0100] For example, Figure 6 As shown, active power Pvin=Psum / 250.

[0101] In this embodiment, the active power is determined by the current parameter sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host, which can achieve the effect of improving the efficiency of the backflow prevention.

[0102] It should be understood that, although the various steps in the flowcharts involved in the above-mentioned embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above-mentioned embodiments can include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0103] Based on the same inventive concept, an embodiment of the present application also provides a micro-inverter host, and the implementation solution for solving the problem provided by the micro-inverter host is similar to the implementation solution recorded in the above method. Therefore, the specific limitations in one or more micro-inverter host embodiments provided below can refer to the limitations on the anti-reverse flow control method of the power grid in the above text, and will not be repeated here.

[0104] In an exemplary embodiment, the micro-inverter host is applied to a micro-inverter system, the micro-inverter system further includes a current acquisition unit and at least one micro-inverter slave, the current acquisition unit is connected to the power grid and the micro-inverter host, the micro-inverter host is communicatively connected to the micro-inverter slave and connected to the power grid, the micro-inverter host includes: a power calculation module, a reverse flow determination module and an adjustment coefficient generation module, wherein:

[0105] A power calculation module, used to determine the active power flowing out of the power grid based on the current parameters flowing out of the power grid sampled by the current acquisition unit and the voltage parameters output by the micro-inverter host;

[0106] A reverse flow determination module is used to determine whether a reverse flow occurs in the power grid based on the active power; an adjustment coefficient generation module is used to generate a power adjustment coefficient based on the active power if a reverse flow occurs, and broadcast the power adjustment coefficient, and the micro-inverter host and the micro-inverter slave adjust the rated power based on the power adjustment coefficient.

[0107] Each module in the above-mentioned micro-inverter host can be implemented in whole or in part by software, hardware or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each module above.

[0108] In one embodiment, the present application further provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the following steps are implemented:

[0109] Determine the active power flowing out of the power grid based on the current parameter flowing out of the power grid sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host;

[0110] Based on the active power, determining whether a reverse flow occurs in the power grid;

[0111] If reverse flow occurs, a power adjustment coefficient is generated based on the active power and broadcasted, and the micro-inverter master and the micro-inverter slave reduce the rated power based on the power adjustment coefficient.

[0112] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0113] Obtaining a difference value based on the active power and a preset limited inflow power;

[0114] If the difference is less than 0, it is determined that reverse flow occurs in the power grid.

[0115] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0116] Obtaining a difference between the active power and a preset limit inflow power;

[0117] The power adjustment coefficient is determined based on a ratio of the difference to a total rated power of the microinverter system.

[0118] In one embodiment, the microinverter master and the microinverter slave obtain a target rated power based on the power adjustment coefficient and the current rated power, and adjust the current rated power down to the target rated power; the target rated power is calculated based on the following formula:

[0119] P i1 =(1+D)*P i2

[0120] Among them, the P i1 is the P1 of the i-th micro-inverter, the i-th micro-inverter is the micro-inverter master or the micro-inverter slave, the P1 is the target rated power; the D is the power adjustment coefficient; the P i2 is P2 of the i-th micro-inversion, and P2 is the current rated power.

[0121] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0122] Based on the multiple current parameters sampled by the current acquisition unit and the multiple voltage parameters output by the micro-inverter host, multiple instantaneous active powers are obtained;

[0123] An average value of the multiple instantaneous active powers is calculated to obtain the active power.

[0124] In one embodiment, when the computer program is executed by a processor, the following steps are also implemented:

[0125] Determining a preset number of sampling times of the current parameter based on the interruption time and the power frequency cycle;

[0126] If the current sampling number is less than the preset sampling number, the instantaneous active power is calculated based on the current parameter sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host;

[0127] Until the current sampling number is equal to the preset sampling number.

[0128] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by coefficient-related hardware through computer programs, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0129] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0130] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for controlling reverse current in a power grid, applied to a micro-inverter host in a micro-inverter system, wherein the micro-inverter system further comprises a current acquisition unit and at least one micro-inverter slave, wherein the current acquisition unit is connected to the power grid and the micro-inverter host, and the micro-inverter host is connected to the micro-inverter slave in communication with the power grid, wherein: The method comprises: Determine the active power flowing out of the power grid based on the current parameter flowing out of the power grid sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host; Based on the active power, determining whether a reverse flow occurs in the power grid; If reverse flow occurs, a power adjustment coefficient is generated based on the active power and broadcasted, and the micro-inverter master and the micro-inverter slave reduce the rated power based on the power adjustment coefficient.

2. The method according to claim 1, characterized in that The determining, based on the active power, whether a reverse flow occurs in the power grid comprises: Obtaining a difference value based on the active power and a preset limited inflow power; If the difference is less than 0, it is determined that reverse flow occurs in the power grid.

3. The method according to claim 1, characterized in that The generating power adjustment coefficient based on the active power comprises: Obtaining a difference between the active power and a preset limit inflow power; The power adjustment coefficient is determined based on a ratio of the difference to a total rated power of the microinverter system.

4. The method according to claim 1, characterized in that: The microinverter master and the microinverter slave obtain a target rated power based on the power adjustment coefficient and the current rated power, and adjust the current rated power down to the target rated power; the target rated power is calculated based on the following formula: P i1 =(1+D)*P i2 Among them, the P i1 is the P1 of the i-th micro-inverter, the i-th micro-inverter is the micro-inverter master or the micro-inverter slave, the P1 is the target rated power; the D is the power adjustment coefficient; the P i2 is P2 of the i-th micro-inversion, and P2 is the current rated power.

5. The method according to claim 1, characterized in that The determining of the active power flowing out of the power grid based on the current parameter flowing out of the power grid sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host comprises: Based on the multiple current parameters sampled by the current acquisition unit and the multiple voltage parameters output by the micro-inverter host, multiple instantaneous active powers are obtained; An average value of the multiple instantaneous active powers is calculated to obtain the active power.

6. The method according to claim 5, characterized in that The multiple instantaneous active powers obtained based on the multiple current parameters sampled by the current acquisition unit and the multiple voltage parameters output by the micro-inverter host include: Determining a preset number of sampling times of the current parameter based on the interruption time and the power frequency cycle; If the current sampling number is less than the preset sampling number, the instantaneous active power is calculated based on the current parameter sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host; Until the current sampling number is equal to the preset sampling number.

7. A micro-inverter host, applied to a micro-inverter system, the micro-inverter system further comprising a current acquisition unit and at least one micro-inverter slave, the current acquisition unit being connected to a power grid and the micro-inverter host, the micro-inverter host being communicatively connected to the micro-inverter slave and connected to the power grid, characterized in that: The microinverter host comprises: A power calculation module, used to determine the active power flowing out of the power grid based on the current parameters flowing out of the power grid sampled by the current acquisition unit and the voltage parameters output by the micro-inverter host; A reverse flow determination module, used to determine whether a reverse flow occurs in the power grid based on the active power; The adjustment coefficient generation module is used to generate a power adjustment coefficient based on the active power if reverse flow occurs, and broadcast the power adjustment coefficient. The micro-inverter host and the micro-inverter slave adjust the rated power based on the power adjustment coefficient.

8. The microinverter host according to claim 7, characterized in that: The microinverter host also includes: Enhanced capture module eCAP, used to determine the power frequency period; A processor, configured to determine a preset number of sampling times of the current parameter based on the interruption time and the power frequency cycle; If the current sampling number is less than the preset sampling number, the instantaneous active power is calculated based on the current parameter sampled by the current acquisition unit and the voltage parameter output by the micro-inverter host; Until the current sampling number is equal to the preset sampling number.

9. A microinversion system, characterized in that: The micro-inverter comprises the micro-inverter host as claimed in claim 6, a current acquisition unit, and at least one micro-inverter slave, wherein the current acquisition unit is connected to a power grid and the micro-inverter host, and the micro-inverter host is communicatively connected to the micro-inverter slave and connected to the power grid.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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