Control method of power conversion device and power conversion device

Abstract

The invention provides a control method of a power conversion device and the power conversion device. The method comprises the following steps: acquiring actual total grid-connected power between a power conversion device and a power grid and actual grid-connected power corresponding to each phase line; when the actual total grid-connected power is greater than or equal to a preset grid-connected power threshold value, determining balanced grid-connected power according to the actual grid-connected power corresponding to each phase line and the actual charging and discharging power of the energy storage equipment; respectively determining a power deviation value between each actual grid-connected power and the balanced grid-connected power; the reference output power of the corresponding phase line is updated according to the power deviation value corresponding to each phase line; and controlling the power conversion device according to the reference output power of each phase line. According to the control method of the power conversion device provided by the invention, the actual grid-connected power on each phase line of the alternating current end of the power conversion device tends to be balanced.

Description

Technical Field

[0001] The present application relates to the technical field of electrical control, and particularly to a control method for a power conversion device and a power conversion device. Background Art

[0002] With the increasing intensification of climate change, clean energy technologies that can reduce carbon emissions (such as photovoltaic power generation technology, hydropower generation technology, and wind power generation technology) have received increasing attention.

[0003] In the related art, in order to make full use of clean energy technologies, a power supply system can be constructed based on power generation equipment using clean energy and a corresponding type of power conversion equipment to form a local microgrid system. Through the power exchange between the local microgrid system, the power grid, and the load, the effective utilization of clean energy can be realized. For example, in a power supply system including photovoltaic panels, an inverter can be used to convert the direct current output by the photovoltaic panels into alternating current to supply power to the load; and, the excess energy of the photovoltaic panels can also be supplied to an energy storage device, and the energy stored in the energy storage device can also be provided to the load for use when the output energy of the photovoltaic panels is insufficient.

[0004] Generally, the output power of the inverter is output in a balanced mode, that is, the output power of each phase line at the AC end of the inverter is equal. However, in actual application scenarios, different-sized loads may be connected to each phase line at the AC end of the inverter, resulting in unbalanced grid-connected power corresponding to each phase line and affecting the power quality of the power grid.

[0005] Moreover, due to the unbalanced grid-connected power corresponding to each phase line, even if the total grid-connected power is the feed-in power (that is, the inverter feeds electric energy into the power grid), it is possible that some phase lines draw power from the power grid and some phase lines feed power into the power grid. Since the unit price of electricity for drawing power from the power grid is much higher than the unit price of selling electricity for feeding power into the power grid, in the case of unbalanced grid-connected power corresponding to each phase line, even if the total grid-connected power is the feed-in power, it is possible that the selling electricity revenue of the user will be greatly reduced due to some phase lines drawing power from the power grid, and even the user may need to pay electricity charges, seriously affecting the economic interests of the user. Summary of the Invention

[0006] In view of this, the present application provides a control method for a power conversion device and a power conversion device to control the actual grid-connected power on each phase line at the AC end of the power conversion device to tend to be balanced.

[0007] The first aspect of the present application provides a control method for a power conversion device. The AC terminal of the power conversion device includes at least two-phase lines. The first DC terminal of the power conversion device is used to connect to the energy storage device, and the second DC terminal of the power conversion device is used to connect to the DC power generation device. Each phase line is used to connect to the power grid and is also used to connect to a load. The method includes: obtaining the actual total grid-connected power between the power conversion device and the power grid and the actual grid-connected power corresponding to each phase line; when the actual total grid-connected power is greater than or equal to a preset grid-connected power threshold, determining the balanced grid-connected power according to the actual grid-connected power corresponding to each phase line and the actual charge-discharge power of the energy storage device; respectively determining the power deviation value between each actual grid-connected power and the balanced grid-connected power; respectively updating the reference output power of the corresponding phase line according to the power deviation value corresponding to each phase line; and controlling the power conversion device according to the reference output power of each phase line.

[0008] In one embodiment, determining the balanced grid-connected power corresponding to each phase line according to the actual grid-connected power and the actual charge-discharge power of the energy storage device includes: averaging all the actual grid-connected powers to obtain an initial balanced power value for each phase line; determining a compensation balanced power value for each phase line according to the actual charge-discharge power; and determining the balanced grid-connected power for each phase line according to the compensation balanced power value and the initial balanced power value.

[0009] In one embodiment, determining the compensation balanced power value for each phase line according to the actual charge-discharge power includes: when the actual charge-discharge power is a discharge power and the actual total grid-connected power is greater than the actual charge-discharge power, calculating the average value of the actual charge-discharge power distributed to each phase line as the compensation balanced power value.

[0010] In one embodiment, determining the balanced grid-connected power for each phase line according to the compensation balanced power value and the initial balanced power value includes: using the value obtained by subtracting the compensation balanced power value from the initial balanced power value as the balanced grid-connected power for each phase line.

[0011] In one embodiment, determining the compensation balanced power value for each phase line according to the actual charge-discharge power further includes: when the actual charge-discharge power is a charge power, determining the remaining chargeable power according to the actual charge-discharge power and the preset rated charge power; and when the remaining chargeable power is less than or equal to the actual total grid-connected power, calculating the compensation balanced power value according to the remaining chargeable power.

[0012] In one embodiment, calculating the compensation balanced power value according to the remaining chargeable power includes: obtaining the power change step; determining the reference power change amount according to the remaining chargeable power and the power change step; and using the average value of the reference power change amount distributed to each phase line as the compensation balanced power value.

[0013] In one embodiment, determining the balanced grid-connection power of each phase line according to the compensated balanced power value and the initial balanced power value includes: using the value obtained by adding the compensated balanced power value to the initial balanced power value as the balanced grid-connection power of each phase line.

[0014] In one embodiment, updating the reference output power of the corresponding phase line according to the power deviation value corresponding to each phase line respectively includes: subtracting the power deviation value of each phase line from the reference output power of each phase line respectively to obtain the updated reference output power of each phase line.

[0015] In one embodiment, before controlling the power conversion device according to the reference output power of each phase line, the method further includes: obtaining the rated output power of each phase line; when there are over-output phase lines and non-over-output phase lines, determining the power to be allocated according to the reference output power and the rated output power corresponding to all over-output phase lines, wherein the reference output power of the over-output phase line is greater than the corresponding rated output power, and the reference output power of the non-over-output phase line is less than the corresponding rated output power; updating the reference output power of the over-output phase line to the corresponding rated output power; determining the corresponding allocation parameter based on the reference output power of each non-over-output phase line, and determining the allocated power of each non-over-output phase line according to the allocation parameter of each non-over-output phase line and the power to be allocated; updating the reference output power of the corresponding phase line according to the allocated power of each non-over-output phase line respectively.

[0016] In some embodiments, the control method of the power conversion device further includes: when the actual total grid-connection power is greater than or equal to the preset grid-connection power threshold, if the energy storage device is in the discharging state and the actual charge-discharge power of the energy storage device is greater than the actual total grid-connection power, updating the reference output power of each phase line according to the actual grid-connection power of each phase line, and controlling the power conversion device according to the updated reference output power of each phase line.

[0017] In one embodiment, the control method of the power conversion device further includes: when the actual total grid-connection power is greater than or equal to the preset grid-connection power threshold, if the energy storage device is in the charging state and the remaining rechargeable power of the energy storage device is greater than the actual total grid-connection power, updating the reference output power of each phase line according to the actual grid-connection power of each phase line, and controlling the power conversion device according to the updated reference output power of each phase line.

[0018] In some embodiments, the control method of the power conversion device further includes: when the actual total grid-connection power is less than the preset grid-connection power threshold, updating the reference output power of each phase line according to the actual grid-connection power of each phase line, and controlling the power conversion device according to the updated reference output power of each phase line.

[0019] In a second aspect of the present application, a power conversion device is provided. The AC side of the power conversion device includes at least two-phase lines. The first DC side of the power conversion device is used to connect to the energy storage device, and the second DC side of the power conversion device is used to connect to the DC power generation device. Each phase line is used to connect to the power grid and is also used to connect to the load. The power conversion device further includes a controller, which is used to execute the control method of the power conversion device as described in any one of the above.

[0020] In summary, for the control method of the power conversion device provided in the present application, when the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, first calculate the expected balanced grid-connected power according to the actual grid-connected power of each phase line and the actual charge-discharge power of the energy storage device, then calculate the power deviation values between the actual grid-connected power and the balanced grid-connected power of each phase line respectively, and then update the reference output power according to the power deviation values, and control the power conversion device according to the reference output power, so that the actual grid-connected power of each phase line is adjusted to the balanced grid-connected power, making the actual grid-connected power of each phase line tend to be balanced, thereby reducing the impact on the power grid. Among them, since the balanced grid-connected power is calculated according to the actual charge-discharge power of the energy storage device, in this way, while achieving the balance of the actual grid-connected power, the self-use efficiency of the local microgrid system can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application and should not be regarded as limiting the protection scope of the present application. In each drawing, similar components are numbered similarly.

[0022] Figure 1 It is a schematic circuit connection diagram of the local microgrid system provided in an embodiment of the present application.

[0023] Figure 2A It is a schematic diagram of the power flow direction of each phase line of the AC side of the power conversion device provided in an embodiment of the present application.

[0024] Figure 2B For Figure 2A It is a schematic diagram of the power flow direction of each phase line of the AC side of the power conversion device under ideal conditions shown.

[0025] Figure 3A It is a schematic diagram of the power flow direction of each phase line of the AC side of the power conversion device provided in another embodiment of the present application.

[0026] Figure 3B For Figure 3A It is a schematic diagram of the power flow direction of each phase line of the AC side of the power conversion device under ideal conditions shown.

[0027] Figure 4 Schematic flowchart of the control method for the power conversion device provided by an embodiment of the present application.

[0028] Figure 5 Schematic flowchart of the sub-steps of step S402 provided by an embodiment of the present application.

[0029] Figure 6 Schematic flowchart of the sub-steps of step S502 when the energy storage device is in the charging state in an embodiment of the present application.

[0030] Figure 7 Schematic flowchart of the sub-steps of step S602.

[0031] Figure 8 Partial schematic flowchart of the control method for the power conversion device before executing step S405 provided by an embodiment of the present application.

[0032] Figure 9 Functional block diagram of the power conversion device provided by an embodiment of the present application.

[0033] Figure 10 Functional block diagram of the electronic device provided by an embodiment of the present application.

[0034] Figure 11 Functional block diagram of the control device provided by an embodiment of the present application.

[0035] Figure 12 Schematic diagram of the computer-readable storage medium provided by an embodiment of the present application. Detailed implementation manners

[0036] Next, the technical solutions in the embodiments of the present application will be described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0037] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component. When a component is considered to be "provided on" another component, it can be directly provided on the other component or there may be an intermediate component. The terms "top", "bottom", "upper", "lower", "left", "right", "front", "rear", and similar expressions used herein are only for the purpose of illustration.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the description of this application in this application are only for the purpose of describing specific embodiments, and are not intended to limit this application.

[0039] The following will describe some embodiments in conjunction with the accompanying drawings. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0040] With the increasing intensification of climate change, clean energy technologies that can reduce carbon emissions (such as photovoltaic power generation technology, hydropower generation technology, and wind power generation technology) have attracted more and more attention.

[0041] In the related art, in order to make full use of clean energy technologies, a power supply system can be constructed based on power generation equipment using clean energy and a corresponding type of power conversion equipment to form a local microgrid system, and through the power exchange between the local microgrid system, the power grid, and the load, the effective utilization of clean energy can be realized. For example, please refer to Figure 1 , Figure 1 which is a schematic circuit connection diagram of the local microgrid system 10 provided in an embodiment of the present application.

[0042] Figure 1 The shown local microgrid system 10 includes a power conversion device 110, an energy storage device 120, and a DC power generation device 130. Among them, the energy storage device 120 and the DC power generation device 130 form a power supply system. The AC end of the power conversion device 110 includes at least two-phase lines. For example, the AC end of the power conversion device 110 may include phase line L1, phase line L2, phase line L3, and neutral line N. The first DC end of the power conversion device 110 (including the first positive DC terminal DC1+ and the first negative DC terminal DC1-) is connected to the energy storage device 120, and the second DC end of the power conversion device 110 (including the second positive DC terminal DC2+ and the second negative DC terminal DC2-) is connected to the DC power generation device 130. In some embodiments, both the first DC end and the second DC end of the power conversion device 110 are connected to a DC bus, and the DC bus includes a positive DC bus BUS+ and a negative DC bus BUS-. Each phase line is used to connect to the power grid 20. Specifically, phase line L1, phase line L2, and phase line L3 are respectively connected to the corresponding phase terminals of the power grid 20, and the neutral line N is connected to the neutral terminal of the power grid 20. Each phase line is also used to connect to a load. For example, phase line L1 is used to connect to the first load 30A, phase line L2 is used to connect to the second load 30B, and phase line L3 is used to connect to the third load 30C. The required powers of the first load 30A, the second load 30B, and the third load 30C may be equal or may not be equal.

[0043] Among them, the power conversion device 110 can be a bidirectional power conversion device. Thus, when the power conversion device 110 is in the inverter mode, it is used to convert the direct current received at the DC terminal into alternating current and output it through the AC terminal to at least supply power to the load and / or feed power to the power grid 20. When the power conversion device 110 is in the rectifier mode, it is used to convert the alternating current received at the AC terminal into direct current and output it to the DC bus through the DC terminal to at least charge the energy storage device 120.

[0044] In some embodiments, the power conversion device 110 may include a rectifier circuit and an inverter circuit. By controlling the switching logic and duty cycle of the rectifier circuit and the inverter circuit, the mode switching between the rectifier mode and the inverter mode of the power conversion device 110 and the control of the output voltage are realized. In some other embodiments, the power conversion device 110 may also select an existing bidirectional DC / AC conversion circuit to realize the mode switching between the rectifier mode and the inverter mode of the power conversion device 110 and the control of the output voltage through a bidirectional DC / AC conversion circuit. The specific circuit topology of the power conversion device 110 is not limited herein.

[0045] The energy storage device 120 can absorb direct current from the DC bus for charging, and / or the energy storage device 120 can also discharge to the DC bus to output direct current to the power conversion device 110.

[0046] In some embodiments, a DC / DC conversion circuit (not shown in the figure, that is, between the DC bus and the DC power generation device 120) is further provided between the second DC terminal of the power conversion device 110 and the DC power generation device 130, which is used to convert the voltage input by the DC power generation device 130 and output the voltage to the DC bus according to the conversion voltage threshold. The DC / DC conversion circuit can be, for example, a boost circuit, a buck circuit, and / or a buck-boost circuit, etc.

[0047] The DC power generation device 130 can be, for example, a photovoltaic module, a wind power generation device, etc. In particular, when the DC power generation device 130 is a photovoltaic module, the DC / DC conversion circuit can be a Maximum Power Point Tracking (MPPT) circuit to adjust the voltage output by the photovoltaic module to achieve maximum power tracking. This application does not limit the maximum power tracking algorithm adopted by the DC / DC conversion circuit when it is an MPPT circuit. When the DC power generation device 130 is a photovoltaic module, it may include a plurality of photovoltaic panels. The photovoltaic panels convert light energy into electrical energy to output direct current to the power conversion device 110. This application does not limit the connection method of the photovoltaic panels in the photovoltaic module. For example, in some embodiments, the photovoltaic panels in the photovoltaic module can be connected in series, in parallel, or first in series and then in parallel, etc. In other embodiments, the DC power generation device 130 can also be replaced by other electronic devices that can output direct current, such as a storage battery, a supercapacitor, etc.

[0048] The energy storage device 120 includes one or more series-connected and / or parallel-connected battery cells. The energy storage device 120 is used to store or release energy. In some embodiments, the energy storage device 120 can be an independently provided energy storage device or a battery pack, or can also be a battery module provided in an electronic device. This application does not limit the specific type of the energy storage device 120.

[0049] The power grid 20 can be, for example, a mains power grid or other power distribution systems. This application does not limit the type of alternating current of the power grid 20. In other embodiments, the power grid 20 can be a two-phase alternating current, a split-phase alternating current, or other polyphase alternating currents, etc. Correspondingly, the number of phase lines at the AC end of the power conversion device 110 can be adjusted according to the specific type of the corresponding power grid 20.

[0050] The load can be various electrical loads.

[0051] Thus, when the DC power generation device 130 includes photovoltaic panels, in Figure 1 the shown local microgrid system 10 including photovoltaic panels, the power conversion device 110 can be used to convert the direct current output by the photovoltaic panels into alternating current to supply power to the load; and, the redundant energy of the photovoltaic panels can also be supplied to the energy storage device 120, and the energy stored in the energy storage device 120 can also be provided to the load for use when the output energy of the photovoltaic panels is insufficient.

[0052] Generally, the output power of the power conversion device 110 is output in a balanced mode, that is, the output power of each phase line at the AC end of the power conversion device 110 is equal. However, in actual application scenarios, different-sized loads may be connected to each phase line at the AC end of the power conversion device 110, resulting in unbalanced grid-connected power corresponding to each phase line and affecting the power quality of the power grid 20.

[0053] For example, taking the output terminals of the power conversion device 110 including the phase line L1, the phase line L2, and the phase line L3 as an example, please refer to Figure 2A , where the neutral line N is not shown for the moment. The output power of each phase line of the power conversion device 110 is equal. However, when the local microgrid system 10 operates in the self-consumption mode, there may be a single-phase power-taking problem, that is, although the actual total grid-connected power of the local microgrid system 10 reaches the target total grid-connected power, there is a situation where the phase line L1 buys electricity and the phase line L3 sells electricity at the AC end of the power conversion device 110. In this way, for users with single-phase metering, the independent self-consumption operation of the loads on each phase line cannot be achieved. Moreover, since the electricity purchase unit price from the power grid 20 is much higher than the electricity selling unit price for feeding electricity to the power grid 20, therefore, in the case of unbalanced grid-connected power corresponding to each phase line, even if the total grid-connected power is the feeding power, it is possible that the electricity selling income of the user will be greatly reduced due to some phase lines taking electricity from the power grid 20, and even the user may need to pay electricity charges, seriously affecting the economic interests of the user. At this time, ideally, each phase line at the AC end of the power conversion device 110 needs to reach Figure 2B the power output situation shown, so as to make the actual grid-connected power of each phase line at the AC end of the power conversion device 110 balanced.

[0054] For another example Figure 3A in the situation shown, after the output power of each phase line meets the load, the phase lines L1 to L3 feed power to the grid at 1000W, 1500W, and 2000W respectively. The unbalanced power feeding causes power imbalance at the grid end and affects the grid quality. At this time, ideally, each phase line at the AC end of the power conversion device 110 needs to reach Figure 3B the power output situation shown, so as to make the actual grid-connected power of each phase line at the AC end of the power conversion device 110 balanced.

[0055] Based on this, the present application provides a control method for a power conversion device and a power conversion device to control the actual grid-connected power on each phase line at the AC end of the power conversion device to tend to be balanced. It can be understood that the control method for the power conversion device provided by the present application can be applied to Figure 1 the local microgrid system 10 shown. And the control method for the power conversion device can be executed by the controller of the power conversion device 110. Or the control method for the power conversion device can also be executed by a controller independent of the power conversion device 110. The present application does not limit this.

[0056] Please refer to Figure 4 , Figure 4 which is a schematic flowchart of the control method for the power conversion device provided by an embodiment of the present application. The control method for the power conversion device includes:

[0057] Step S401: Obtain the actual total grid-connected power between the power conversion device and the power grid, and the actual grid-connected power corresponding to each phase line.

[0058] Among them, the actual grid-connected power is used to represent the power supply relationship between the phase line corresponding to the AC terminal of the power conversion device 110, the load connected to this phase line, and the power grid 20, and can be understood as the power actually fed into the power grid or obtained from the power grid by the phase line.

[0059] According to the energy flow direction between this phase line, the load connected to this phase line, and the power grid 20, the actual grid-connected power can be positive, negative, or 0. In some embodiments, a positive actual grid-connected power can represent feeding power into the power grid; a negative actual grid-connected power can represent obtaining power from the power grid; 0 means neither feeding power into the power grid nor obtaining power from the power grid. In other embodiments, a positive actual grid-connected power can represent obtaining power from the power grid; a negative actual grid-connected power can represent feeding power into the power grid; 0 means neither feeding power into the power grid nor obtaining power from the power grid.

[0060] Taking the phase line L1 as an example, in some embodiments, when the phase line L1 outputs 10 W (watts) to the power grid 20, the actual grid-connected power between the phase line L1, the load connected to the phase line L1, and the power grid 20 is 10 W; when the power grid 20 outputs 10 W to the load connected to the phase line L1, the actual grid-connected power between the phase line L1, the load connected to the phase line L1, and the power grid 20 is -10 W; when the output power of the phase line L1 just meets the required power of the load connected to the phase line L1, that is, when the phase line L1 neither outputs power to the power grid 20 nor the power grid 20 outputs power to the load connected to the phase line L1, the actual grid-connected power is 0.

[0061] It can be understood that in other embodiments, it can also be that when the phase line L1 outputs 10 W (watts) to the power grid 20, the actual grid-connected power between the phase line L1, the load connected to the phase line L1, and the power grid 20 is -10 W; when the power grid 20 outputs 10 W to the load connected to the phase line L1, the actual grid-connected power between the phase line L1, the load connected to the phase line L1, and the power grid 20 is 10 W, and this application does not limit this.

[0062] The actual total grid-connected power can be the sum of the actual grid-connected powers corresponding to all phase lines at the AC terminal of the power conversion device 110.

[0063] Understandably, a grid monitoring module (not shown in the figure) can be provided between the output terminal of the power conversion device 110 and the point of common coupling (PCC) of the load and the power grid 20. The grid monitoring module is used to monitor the actual grid-connected power between each phase line of the AC side of the power conversion device 110 and the power grid 20. In this way, by communicating with the grid monitoring module, the controller of the power conversion device 110 can obtain the actual grid-connected power corresponding to each phase line of the AC side, and thus determine the total actual grid-connected power according to the actual grid-connected power of each phase line obtained. In some embodiments, the grid monitoring module can be an intelligent meter, and the intelligent meter can display the actual grid-connected power. In other embodiments, the grid monitoring module can also be other devices with power acquisition functions, and the present application does not limit this.

[0064] Understandably, the communication between the controller and the grid monitoring module can be wireless communication (such as Bluetooth communication, ZigBee communication, etc.), or can be wired communication (such as serial communication based on the RS-485 serial bus or the Controller Area Network (CAN) bus, or other parallel communication methods), and the present application does not limit the specific communication method.

[0065] In other embodiments, it is also possible to communicate with the load connected to each phase line through the controller to obtain the actual output power of each phase line and the actual power consumption of the corresponding connected load, so as to calculate the actual grid-connected power of each phase line according to the actual output power and the actual power consumption. For example, calculate the value obtained by subtracting the actual power consumption from the actual output power of the phase line as the actual grid-connected power of the corresponding phase line, and then calculate the sum of the actual grid-connected powers of all phase lines as the actual total grid-connected power.

[0066] Step S402: When the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, determine the balanced grid-connected power according to the actual grid-connected power corresponding to each phase line and the actual charge and discharge power of the energy storage device.

[0067] Among them, the preset grid-connected power threshold is used to characterize the expected value of the actual total grid-connected power between the power conversion device 110 and the power grid 20. The preset grid-connected power threshold can be set according to the actual needs of the user. For example, assuming that the user hopes that the local microgrid system 10 does not draw power from the power grid 20 as much as possible, the preset grid-connected power threshold can be set to 0; when the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, it can be considered that the local microgrid system 10 does not draw power from the power grid 20 at least currently. At this time, it is necessary to control the actual grid-connected power of each phase wire at the AC end of the power conversion device 110 to tend to be balanced. Thus, in some embodiments, the preset grid-connected power threshold can be 0 or any reasonable value. It is understandable that the present application does not limit the specific value of the target grid-connected power.

[0068] The balanced grid-connected power is used to characterize the expected value when the actual grid-connected power of each phase wire reaches balance. It is understandable that in the local microgrid system 10, when the energy storage device 120 is in the discharge state, it will release power to the power conversion device 110, and when the energy storage device 120 is in the charging state, it will obtain power from the DC bus (i.e., the power conversion device 110 / DC power generation device 130). Therefore, the actual charge-discharge power of the energy storage device 120 will affect the actual total grid-connected power, and thus affect the balanced grid-connected power. Moreover, in order to further improve the energy utilization efficiency of the local microgrid system 10 for self-use, when determining the balanced grid-connected power, the actual grid-connected power of each phase wire can be compensated according to the actual charge-discharge power of the energy storage device 120 to obtain the balanced grid-connected power.

[0069] For example, when the actual total grid-connected power is greater than the preset grid-connected power threshold, it indicates that there is surplus power fed into the power grid 20 in addition to the power generation power of the local microgrid system 10 meeting the required power of the load. Among them, the power generation power refers to the output power of the DC power generation device 130 and / or the discharge power of the energy storage device 120. At this time, if the energy storage device 120 obtains power from the DC bus for charging but the actual charge-discharge power does not reach the rated charging power, the actual charge-discharge power of the energy storage device 120 can be increased, thereby increasing the charging speed of the energy storage device 120, and as much as possible storing the excess energy generated by the local microgrid system 10 in the energy storage device 120 until the energy storage device 120 is fully charged, for example, the SOC of the energy storage device 120 reaches 100%. Also, when the actual total grid-connected power is greater than the preset grid-connected power threshold, if the energy storage device 120 is in the discharge state, the actual charge-discharge power of the energy storage device 120 can be reduced at this time, thereby reducing the actual total grid-connected power, reducing the power output of the energy storage device 120, and avoiding using the electric energy stored in the energy storage device 120 for feeding into the grid, so as to improve the self-use efficiency of the local microgrid system 10. Thus, the balanced grid-connected power can also be determined according to the discharge power of the energy storage device 120.

[0070] In summary, by performing step S402 to determine the balanced grid-connected power, the self-consumption efficiency of the local microgrid system 10 can be improved.

[0071] Step S403: Determine the power deviation value between each actual grid-connected power and the balanced grid-connected power respectively.

[0072] Among them, the power deviation value is used to characterize the power deviation between the actual grid-connected power and the balanced grid-connected power of the corresponding phase line. In step S403, the difference obtained by subtracting the actual grid-connected power from the balanced grid-connected power can be calculated as the power deviation value of the corresponding phase line. Understandably, taking the example that the AC terminal of the power conversion device 110 includes three phase lines, 3 power deviation values can be calculated in step S403. The power deviation values corresponding to each phase line may be equal or may not be equal.

[0073] Step S404: Update the reference output power of each corresponding phase line according to the power deviation value corresponding to each phase line respectively.

[0074] Among them, the reference output power is used to characterize the target value of the output power of the corresponding phase line. Specifically, the updated reference output power can be input into the grid-connected control loop, and the power conversion device can be controlled based on the control parameters output by the grid-connected control loop. Understandably, the control method of the power conversion device provided in this application can be executed periodically. Thus, in some embodiments, the reference output power of each phase line before update in step S404 can be the reference output power of the corresponding phase line in the previous execution cycle. At the initial moment of executing the control method of the power conversion device, the reference output power in the grid-connected control loop can be a pre-configured value.

[0075] Understandably, the grid-connected control loop is used to control the output power of the AC terminal of the power conversion device 110, so that the actual total grid-connected power obtained from the grid / feeding into the grid is stabilized around the preset grid-connected power threshold. This application does not limit the specific loop structure of the grid-connected control loop. For example, the grid-connected control loop may include at least one of a voltage loop, a current loop, and a power loop.

[0076] In step S404, the reference output power of each phase line is updated according to the power deviation value corresponding to each phase line. It can be to adjust the reference output power before updating of the corresponding phase line according to the power deviation value of each phase line to update the reference output power. Understandably, based on the regulation of each phase line according to each reference output power, the actual output power of each phase line at the AC end of the power conversion device 110 can be made close to the reference output power of the corresponding phase line. Moreover, there is a positive correlation between the actual output power and the actual grid-connected power. Thus, by adjusting the reference output power of each phase line, the actual grid-connected power of each phase line can be made close to the balanced grid-connected power. Also, since the power deviation value is the deviation between the balanced grid-connected power and the actual grid-connected power, thus, when the reference output power of the corresponding phase line is updated according to the power deviation value, when the controller adjusts according to the updated reference output power of each phase line, the actual grid-connected power of each phase line is close to the balanced grid-connected power.

[0077] Step S405: Control the power conversion device according to the reference output power of each phase line.

[0078] In step S405, the corresponding control parameters of the power conversion device 110, such as the duty cycle, can be calculated according to the updated reference output power of each phase line, and then the corresponding drive signal is generated according to the control parameters to control the output power on each phase line at the AC end of the power conversion device 110 to be close to the updated reference output power, so that the actual grid-connected power of each phase line is close to the balanced grid-connected power. Among them, the drive signal can be used to control the switching logic and duty cycle of the switching tubes in the power conversion device 110. For example, the drive signal can be a PWM (Pulse Width Modulation) signal.

[0079] In summary, for the control method of the power conversion device provided in this application, when the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, first calculate the expected balanced grid-connected power according to the actual grid-connected power of each phase line and the actual charge and discharge power of the energy storage device 120, then calculate the power deviation values between the actual grid-connected power of each phase line and the balanced grid-connected power respectively, and then update the reference output power according to the power deviation values, and control the power conversion device 110 according to the reference output power, so as to adjust the actual grid-connected power of each phase line to the balanced grid-connected power, make the actual grid-connected power of each phase line tend to be balanced, and thus reduce the impact on the power grid 20. Among them, since the balanced grid-connected power is calculated according to the actual charge and discharge power of the energy storage device 120, thus, while realizing the balance of the actual grid-connected power, the efficiency of self-use of the local microgrid system 10 can be further improved.

[0080] Please continue to refer to Figure 5 , in some embodiments, step S402 includes the following sub-steps:

[0081] Step S501: Average all the actual grid-connected powers and obtain the initial balance power value of each phase line.

[0082] Among them, averaging all the actual grid-connected powers can be to calculate the average value of the actual grid-connected powers of all phase lines based on the mean algorithm and use the calculated average value as the initial balance power value. In some embodiments, the mean algorithm can be to first calculate the sum of all the actual grid-connected powers and then divide the calculated sum by the total number of all phase lines to obtain the initial balance power value. That is to say, the value obtained by dividing the actual total grid-connected power by the total number of all phase lines can be used as the initial balance power value. In this way, the actual total grid-connected power and the initial balance power value are in a positive correlation. The present application does not specifically limit the mean algorithm.

[0083] Step S502: Determine the compensation balance power value of each phase line according to the actual charge-discharge power.

[0084] Among them, the compensation balance power value is used to represent the adjustment amount of the actual grid-connected power allocated to each phase line according to the actual charge-discharge power.

[0085] In step S502, when the energy storage device 120 is in the discharge state, that is, the actual charge-discharge power is the discharge power, the compensation balance power value of each phase line can be determined according to the actual charge-discharge power based on the magnitude relationship between the actual charge-discharge power and the actual total grid-connected power.

[0086] In some embodiments, if the actual charge-discharge power of the energy storage device 120 is less than or equal to the actual total grid-connected power, it means that all the discharge power of the energy storage device 120 at this time is used to feed into the power grid 20. Thus, the compensation balance power value of each phase line can be determined according to the actual charge-discharge power, and the compensation balance power value is used to reduce the initial balance power value of each phase line, so as to control the energy storage device 120 to stop discharging to reduce the actual total grid-connected power, thereby reducing the power consumption of the energy storage device 120 and improving the self-use efficiency of the local microgrid system 10.

[0087] In some other embodiments, if the actual charge-discharge power of the energy storage device 120 is greater than the actual total grid-connected power, it means that part of the power output from the energy storage device 120 to the power conversion device 110 is used to supply the load, and the remaining part of the power is fed into the power grid 20, and the value of the part of the power fed into the power grid 20 is the actual total grid-connected power. At this time, the reference output power of each phase line is directly adjusted according to the actual total grid-connected power.

[0088] In step S502, when the energy storage device 120 is in a charging state, that is, when the actual charge-discharge power is the charging power, the compensation balance power value of each phase can be determined based on the relationship between the actual charge-discharge power, the rated charging power, and the actual total grid-connected power. At this time, the compensation balance power value is also used to reduce the actual total grid-connected power.

[0089] In some embodiments, if the actual charge-discharge power of the energy storage device 120 is less than the rated charging power, it indicates that the charging power of the energy storage device 120 can still be increased at this time to increase the charging speed. If the chargeable power that the energy storage device 120 can increase is less than or equal to the actual total grid-connected power, it means that when reducing the actual total grid-connected power according to the chargeable power that the energy storage device 120 can increase, the local microgrid system 10 can still feed power to the grid 20. At this time, the compensation balance power value of each phase can be determined according to the actual charge-discharge power, so as to increase the charging speed by increasing the actual charge-discharge power and thus reducing the actual total grid-connected power.

[0090] In other embodiments, if the chargeable power that the energy storage device 120 can increase is greater than the actual total grid-connected power, it means that even if the actual total grid-connected power is reduced to 0, the energy storage device 120 cannot be charged at the rated charging power. And in order to maintain the actual total grid-connected power of the local microgrid system 10 to be at least equal to the preset grid-connected power threshold, the value of the chargeable power that the energy storage device 120 can increase at this time should be determined according to the value of the actual total grid-connected power, and the value of the chargeable power that the energy storage device 120 can increase is greater than 0. Therefore, in this case, the reference output power of each phase is directly adjusted according to the actual total grid-connected power.

[0091] Step S503: Determine the balanced grid-connected power of each phase according to the compensation balance power value and the initial balance power value.

[0092] In some embodiments, the difference obtained by directly calculating the initial balance power value minus the compensation balance power value can be used as the balanced grid-connected power of each phase.

[0093] In summary, by executing steps S501 to S503, the balanced average power can be determined according to the actual grid-connected power corresponding to each phase and the actual charge-discharge power of the energy storage device 120.

[0094] In some embodiments, the control method of the power conversion device further includes:

[0095] When the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, if the energy storage device is in a discharging state and the actual charge-discharge power of the energy storage device is greater than the actual total grid-connected power, update the reference output power of each phase according to the actual grid-connected power of each phase, and control the power conversion device according to the updated reference output power of each phase.

[0096] In some embodiments, the control method of the power conversion device further includes:

[0097] When the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, if the energy storage device is in a charging state and the remaining rechargeable power of the energy storage device is greater than the actual total grid-connected power, update the reference output power of each phase line according to the actual grid-connected power of each phase line, and control the power conversion device according to the updated reference output power of each phase line.

[0098] In some embodiments, the control method of the power conversion device further includes:

[0099] When the actual total grid-connected power is less than the preset grid-connected power threshold, update the reference output power of each phase line according to the actual grid-connected power of each phase line, and control the power conversion device according to the updated reference output power of each phase line.

[0100] Among them, updating the reference output power of each phase line according to the actual grid-connected power of each phase line may include:

[0101] Subtract the actual grid-connected power of each corresponding phase line from the reference output power of each phase line respectively to obtain the updated reference output power of each phase line.

[0102] Further, in some embodiments, when the energy storage device 120 is in a discharging state, step S502 includes:

[0103] When the actual charge-discharge power is the discharge power and the actual total grid-connected power is greater than the actual charge-discharge power, calculate the average value of the actual charge-discharge power distributed to each phase line as the compensation balance power value.

[0104] Among them, calculating the average value of the actual charge-discharge power distributed to each phase line as the compensation balance power value may be to calculate the value obtained by dividing the actual charge-discharge power by the total number of all phase lines as the compensation balance power value.

[0105] Correspondingly, in some embodiments, step S503 includes:

[0106] Use the value obtained by subtracting the compensation balance power value from the initial balance power value as the balanced grid-connected power of each phase line.

[0107] In this way, by performing the above steps, the balanced grid-connected power of each phase line when the energy storage device 120 is in a discharging state can be calculated.

[0108] Please continue to refer to Figure 6 , in some other embodiments, when the energy storage device 120 is in a charging state, step S502 includes:

[0109] Step S601: When the actual charge-discharge power is the charging power, determine the remaining chargeable power according to the actual charge-discharge power and the preset rated charging power.

[0110] Among them, the rated charging power is the maximum charging power of the energy storage device 120.

[0111] In step S601, the difference obtained by subtracting the actual charge-discharge power from the rated charging power can be calculated as the remaining chargeable power. The remaining chargeable power is used to represent the charge power that the charging device 120 can increase. The remaining chargeable power is less than or equal to the rated charging power and greater than or equal to 0.

[0112] When the remaining chargeable power is greater than 0, it means that there is still room for improvement in the actual charge-discharge power when the energy storage device 120 is in the charging state; when the remaining chargeable power is equal to 0, it means that the current actual charge-discharge power of the energy storage device 120 is already the rated charging power.

[0113] In some embodiments, the rated charging power can be a fixed value. In other embodiments, the rated charging power can be determined according to the stage of the power of the energy storage device 120. For example, when the power of the energy storage device 120 is close to the full charge amount and enters the end stage of charging, the rated charging power will decrease.

[0114] Step S602: When the remaining chargeable power is less than or equal to the actual total grid-connected power, calculate the compensation balance power value according to the remaining chargeable power.

[0115] In some embodiments, the value of the remaining chargeable power directly allocated to each phase line can be used as the compensation balance power value.

[0116] In this way, by executing step S601 to step S602, the compensation balance power value when the energy storage device 120 is in the charging state can be calculated according to the actual charge-discharge power.

[0117] Please continue to refer to Figure 7 , in some embodiments, step S602 includes the following sub-steps:

[0118] Step S701: Obtain the power change step.

[0119] Among them, the power change step is used to characterize the increase in the output power generated by the DC power generation device 130 through maximum power point tracking. The power change step can be a preset value or a variable value. In some embodiments, the power change step can be a preset 100W. In other embodiments, the power change step can also be set to other values.

[0120] Understandably, when the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold, the energy storage device 120 is in a charging state, and when the remaining rechargeable power of the energy storage device 120 is less than or equal to the actual total grid-connected power, if the compensation balance power value is determined only according to the actual charge-discharge power at this time, the compensation balance power value will cause the actual total grid-connected power to decrease, thereby reducing the economic benefits of the local microgrid system 10. Obviously, in order to obtain the highest possible economic benefits, the actual total grid-connected power should be reduced as little as possible. Also, since it is necessary to charge the energy storage device 120, in this case, the balanced grid-connected power of each phase line at the AC end of the power conversion device 110 can be appropriately increased, so as to force the DC power generation device 130 to track a possible greater power generation power by increasing the expected value of the balanced grid-connected power at the AC end of the power conversion device 110, thereby reducing the probability that the actual total grid-connected power of the local microgrid system 10 is reduced due to the energy storage device 120, so as to maintain or even obtain better economic benefits.

[0121] Step S702: Determine the reference power change amount according to the remaining rechargeable power and the power change step.

[0122] Among them, the reference power change amount is used to characterize the influence of the remaining rechargeable power and the power change step on the actual total grid-connected power at the AC end of the power conversion device 110. Among them, the remaining rechargeable power and the reference power change amount are negatively correlated, and the power change step and the reference power change amount are positively correlated.

[0123] In some embodiments, the difference obtained by calculating the power change step minus the remaining rechargeable power can be used as the reference power change amount. And when the reference power change amount is less than 0, it means that the increase in the output power of the DC power generation device 130 is not enough to make up for the power gap when the energy storage device 120 is charged at the rated charging power. At this time, the energy storage device 120 is given priority for charging, and the actual total grid-connected power is reduced; when the reference power change amount is equal to 0, it means that the increase in the output power of the DC power generation device 130 just makes up for the power gap when the energy storage device 120 is charged at the rated charging power; when the reference power change amount is greater than 0, it means that the increase in the output power of the DC power generation device 130 exceeds the power gap when the energy storage device 120 is charged at the rated charging power, and the output power generated by the DC power generation device 130 can be fed to the power grid 20 through the AC end of the power conversion device 110, so that the actual total grid-connected power at the AC end of the power conversion device 110 increases.

[0124] Step S703: Use the average value of the reference power change amount distributed to each phase line as the compensation balance power value.

[0125] In some embodiments, the average value obtained by calculating the reference power change amount divided by the total number of all phase lines can be used as the compensation balance power value.

[0126] Accordingly, in some embodiments, when the energy storage device 120 is in a charging state and the compensation balance power value is determined according to the power change step and the remaining rechargeable power, step S503 includes:

[0127] Taking the value obtained by adding the compensation balance power value and the initial balance power value as the balanced grid-connected power of each phase line.

[0128] It can be understood that since it takes time for the DC power generation device 130 to perform maximum power tracking, in this embodiment, by setting the power change step, the compensation balance power value at the AC end of the power conversion device 110 is gradually increased, so that on the premise of preferentially satisfying the rated charging power of the energy storage device 120, when the DC power generation device 130 tracks a larger output power, the excess power can be fed to the power grid 20, thereby while making the actual grid-connected power of each phase line at the AC end of the power conversion device 110 tend to be balanced, maintaining or even improving the economic benefits of the local microgrid system 10.

[0129] In some embodiments, step S404 includes:

[0130] Subtracting the power deviation value of each phase line from the reference output power of each phase line respectively to obtain the updated reference output power of each phase line.

[0131] It can be understood that since the power deviation value is obtained by subtracting the balanced grid-connected power from the actual grid-connected power, and the reference output power before updating is used to control the power conversion device 110 to obtain the actual grid-connected power. Therefore, in this embodiment, the reference output power of each phase line can be subtracted from the power deviation value of the corresponding phase line respectively to obtain the updated reference output power of each phase line. In this way, by controlling according to the updated reference output power of each phase line, the actual grid-connected power of each phase line can be made close to the balanced grid-connected power.

[0132] Please refer to Figure 8 , in some embodiments, before executing step S405, the method further includes:

[0133] Step S801: Obtain the rated output power of each phase line.

[0134] In some embodiments, the rated output power is pre-stored data stored in the storage unit of the power conversion device 110. In other embodiments, the rated output current and rated output voltage of each phase line can also be obtained to calculate the corresponding rated output power.

[0135] Step S802: When there are over-output phase lines and non-over-output phase lines, determine the power to be distributed according to the reference output power and the rated output power corresponding to all over-output phase lines.

[0136] Among them, the reference output power of the over-output phase line is greater than the corresponding rated output power, and the reference output power of the non-over-output phase line is less than the corresponding rated output power.

[0137] In step S802, the difference obtained by subtracting the corresponding rated output power from the reference output power of each over-output phase line can be calculated, and the sum of all the differences is used as the power to be distributed.

[0138] Step S803: Update the reference output power of the over-output phase line to the corresponding rated output power.

[0139] In this way, by executing step S803, it is possible to prevent the actual output power of the over-output phase line from exceeding the corresponding rated output power, thereby improving the safety of the power conversion device 110.

[0140] Step S804: Determine the corresponding distribution parameter based on the reference output power of each non-over-output phase line, and determine the distribution power of each non-over-output phase line according to the distribution parameter of each non-over-output phase line and the power to be distributed.

[0141] In some embodiments, determining the corresponding distribution parameter based on the reference output power of each non-over-output phase line includes:

[0142] Calculating the difference obtained by subtracting the reference output power from the rated output power of each non-over-output phase line as the output power margin;

[0143] Calculating the sum of the output power margins of all non-over-output phase lines as the total output power margin;

[0144] Calculating the proportion of the output power margin of each non-over-output phase line in the total output power margin as the distribution parameter of the corresponding non-over-output phase line.

[0145] After determining the distribution parameter in step S804, the product of the distribution parameter of each non-over-output phase line and the power to be distributed can be calculated as the distribution power of the corresponding non-over-output phase line.

[0146] Step S805: Update the reference output power of the corresponding phase line according to the distribution power of each non-over-output phase line respectively.

[0147] In step S805, the sum of the distribution power of each non-over-output phase line and the corresponding reference output power can be calculated as the updated reference output power of the corresponding non-over-output phase line.

[0148] In some embodiments, the updated reference output power can be further limited, the over-output phase lines and the non-over-output phase lines can be re-determined, and the excess power of the over-output phase lines can be distributed to the remaining non-over-output phase lines to further ensure that the output power of each phase line is less than the corresponding rated output power.

[0149] In this way, by performing steps S801-S805, it can be ensured that the output power of each phase line is less than the rated output power, thus ensuring the safe use of the power conversion device 110.

[0150] Please refer to Figure 9 and Figure 1 This application also provides a power conversion device 110. The AC terminal of the power conversion device 110 includes at least two phase lines. The first DC terminal of the power conversion device 110 is used to connect to the energy storage device 120, the second DC terminal of the power conversion device 110 is used to connect to the DC power generation device 130, each phase line is used to connect to the power grid 20, and each phase line is also used to connect to a load. The power conversion device 110 further includes a controller 111, and the controller 111 is used to execute the control method of the power conversion device described in any one of the above.

[0151] Please refer to Figure 10 This application also provides an electronic device 200, which includes a processor 210 and a memory 220. Among them, the memory 220 is used to store programs, instructions or codes for executing the control method of the above power conversion device. The processor 210 is used to execute the programs, instructions or codes stored in the memory 220. The programs, instructions or codes stored in the memory 220 can execute some or all of the steps of the control method of the power conversion device in any of the above embodiments.

[0152] An embodiment of this application also provides a control device 300, which is applied to a power conversion device 110 or an electronic device integrated with a power conversion device 110. Figure 11 Schematically shows the structural block diagram of the control device 300 provided by the embodiment of this application. As Figure 11 shown, the control device 300 includes:

[0153] An acquisition module 310, which is used to acquire the actual total grid-connected power between the power conversion device and the power grid and the actual grid-connected power corresponding to each phase line.

[0154] A first determination module 320, which is used to determine the balanced grid-connected power according to the actual grid-connected power corresponding to each phase line and the actual charge-discharge power of the energy storage device when the actual total grid-connected power is greater than or equal to the preset grid-connected power threshold.

[0155] A second determination module 330, which is used to respectively determine the power deviation value between each actual grid-connected power and the balanced grid-connected power.

[0156] An update module 340, configured to update the reference output power of each corresponding phase line according to the power deviation value corresponding to each phase line.

[0157] A control module 350, configured to control the power conversion device according to the reference output power of each phase line.

[0158] The specific details of the control device 300 provided in the embodiments of the present application for implementing the control method of the power conversion device have been described in detail in the embodiments of the control method of the corresponding power conversion device, and will not be elaborated here.

[0159] Please refer to Figure 12 , the present application also provides a computer-readable storage medium 400, on which a computer program 410 is stored. When the computer program is executed by a processor, it implements the control method of the power conversion device in the above technical solution. The computer-readable storage medium 400 may adopt a portable compact disc read-only memory (CD-ROM) and includes program codes, and may run on a terminal device, such as a personal computer. However, the program product of the present invention is not limited thereto. In this document, the readable storage medium may be any tangible medium that contains or stores a program, and the program may be used by or in combination with an instruction execution system, apparatus, or device.

[0160] The above program product may adopt any combination of one or more readable media. The readable media may be a readable signal medium or a readable storage medium. The readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0161] The computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries the readable program code. Such a propagated data signal may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable signal medium may also be any readable medium other than the readable storage medium, and the readable medium may send, propagate, or transmit a program for use by or in combination with an instruction execution system, apparatus, or device.

[0162] The program code contained on the readable medium may be transmitted by any suitable medium, including but not limited to wireless, wired, optical fiber, RF, etc., or any suitable combination of the above.

[0163] Program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, C++, etc., and also including conventional procedural programming languages such as the "C" language or similar programming languages. The program code may be executed entirely on the user's computing device, partially on the user's device, executed as a stand-alone software package, partially on the user's computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user's computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., by connecting through the Internet using an Internet service provider).

[0164] In addition, the above-mentioned drawings are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present invention, and are not for limiting purposes. It is easy to understand that the processes shown in the above-mentioned drawings do not indicate or limit the chronological order of these processes. Additionally, it is also easy to understand that these processes may be executed synchronously or asynchronously in, for example, multiple modules.

[0165] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A control method for a power conversion device, characterized in that, The AC terminal of the power conversion device includes at least two-phase lines. The first DC terminal of the power conversion device is used to connect to an energy storage device, and the second DC terminal of the power conversion device is used to connect to a DC power generation device. Each of the phase lines is used to connect to the power grid and is also used to connect to a load; the method includes: Obtain the actual total grid-connected power between the power conversion device and the power grid and the actual grid-connected power corresponding to each phase line; When the actual total grid-connected power is greater than or equal to a preset grid-connected power threshold, determine the balanced grid-connected power according to the actual grid-connected power corresponding to each phase line and the actual charge-discharge power of the energy storage device; Respectively determine the power deviation values between each of the actual grid-connected powers and the balanced grid-connected power; Respectively update the reference output power of the corresponding phase line according to the power deviation value corresponding to each phase line; Control the power conversion device according to the reference output power of each phase line.

2. The method according to claim 1, wherein The determining the balanced grid-connected power corresponding to each phase line according to the actual grid-connected power and the actual charge-discharge power of the energy storage device includes: Perform an average process on all the actual grid-connected powers and obtain the initial balanced power value of each phase line; Determine the compensation balanced power value of each phase line according to the actual charge-discharge power; Determine the balanced grid-connected power of each phase line according to the compensation balanced power value and the initial balanced power value.

3. The method according to claim 2, wherein The determining the compensation balanced power value of each phase line according to the actual charge-discharge power includes: When the actual charge-discharge power is a discharge power and the actual total grid-connected power is greater than the actual charge-discharge power, calculate the average value of the actual charge-discharge power distributed to each phase line as the compensation balanced power value.

4. The method according to claim 3, wherein The determining the balanced grid-connected power of each phase line according to the compensation balanced power value and the initial balanced power value includes: Use the value obtained by subtracting the compensation balanced power value from the initial balanced power value as the balanced grid-connected power of each phase line.

5. The method according to claim 2, wherein The determining the compensation balanced power value of each phase line according to the actual charge-discharge power further includes: When the actual charge-discharge power is a charge power, determine the remaining chargeable power according to the actual charge-discharge power and a preset rated charge power; When the remaining chargeable power is less than or equal to the actual total grid-connected power, calculate the compensation balanced power value according to the remaining chargeable power.

6. The method according to claim 5, characterized in that, The calculating the compensation balanced power value according to the remaining chargeable power includes: Obtain the power change step; Determine the reference power change amount according to the remaining chargeable power and the power change step; Use the average value of the reference power change amount distributed to each phase line as the compensation balanced power value.

7. The method according to claim 5, characterized in that The determining the balanced grid-connected power of each phase line according to the compensation balanced power value and the initial balanced power value includes: Use the value obtained by adding the compensation balanced power value to the initial balanced power value as the balanced grid-connected power of each phase line.

8. The method according to claim 1, characterized in that, Updating the reference output power of each corresponding phase line according to the power deviation value corresponding to each phase line respectively includes: Subtracting the power deviation value of each corresponding phase line from the reference output power of each phase line respectively to obtain the updated reference output power of each phase line.

9. The method according to claim 1, characterized in that, Before controlling the power conversion device according to the reference output power of each phase line, the method further includes: Obtaining the rated output power of each phase line; When there are over-output phase lines and non-over-output phase lines, determining the power to be allocated according to the reference output power and the rated output power corresponding to all the over-output phase lines, wherein the reference output power of the over-output phase lines is greater than the corresponding rated output power, and the reference output power of the non-over-output phase lines is less than the corresponding rated output power; Updating the reference output power of the over-output phase lines to the corresponding rated output power; Determining the corresponding allocation parameters based on the reference output power of each non-over-output phase line, and determining the allocated power of each non-over-output phase line according to the allocation parameters of each non-over-output phase line and the power to be allocated; Updating the reference output power of each corresponding phase line according to the allocated power of each non-over-output phase line respectively.

10. A power conversion device, characterized in that, The AC terminal of the power conversion device includes at least two phase lines. The first DC terminal of the power conversion device is used to connect the energy storage device, and the second DC terminal of the power conversion device is used to connect the DC power generation device. Each phase line is used to connect the power grid and is also used to connect the load; the power conversion device further includes a controller, and the controller is used to execute the control method of the power conversion device according to any one of claims 1 to 9.

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