A control method and device of a parallel system and a readable storage medium

Abstract

Embodiments of the present application provide a control method and device of a parallel system and a readable storage medium. The method comprises: determining a grid-connection condition between the parallel system and a power grid coupled therewith; the grid-connection condition comprises grid-connection power and a flow direction of the grid-connection power; determining an energy storage condition of an energy storage unit included in each of at least two power conversion devices; the energy storage condition comprises an operating state and an operating power; determining a power generation condition of a power generation unit included in each of the power conversion devices; the power generation condition comprises power generation power; and adjusting inverter power output by the power conversion unit included in each of the power conversion devices according to the grid-connection condition, the energy storage condition of each of the energy storage units, the power generation condition of each of the power generation units, and a load condition of the parallel system, so as to control operation of the parallel system to satisfy a self-generation and self-use principle.

Description

Technical Field

[0001] This application relates to the field of parallel operation technology of power conversion devices, and in particular to a control method, device and readable storage medium for a parallel operation system. Background Technology

[0002] In power conversion systems, multiple sets of equipment are often connected in parallel to form a system with greater power output, i.e., a parallel system. Furthermore, photovoltaic energy storage systems typically employ a self-consumption mode to maximize the use of electricity generated by the photovoltaic system and minimize grid draw. Therefore, there is an urgent need for a control method to maximize the self-consumption efficiency of photovoltaic energy storage parallel systems. Summary of the Invention

[0003] In view of this, embodiments of this application provide a control method, apparatus, and readable storage medium for a parallel system.

[0004] In a first aspect, embodiments of this application provide a control method for a parallel system, wherein the parallel system includes at least two power conversion devices operating in parallel; each power conversion device includes: an energy storage unit, a power generation unit, and a power conversion unit; the method includes: in a certain control process of controlling the operation of the parallel system to meet the self-consumption principle, determining the grid connection status between the parallel system and its coupled power grid; the grid connection status includes: grid-connected power and the direction of power flow; determining the energy storage status of the energy storage unit included in each of the at least two power conversion devices; the energy storage status includes: operating state and operating power; determining the power generation status of the power generation unit included in each power conversion device; the power generation status includes power generation; and, according to the self-consumption principle, adjusting the inverter power output by the power conversion unit included in each power conversion device based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, so as to control the operation of the parallel system to meet the self-consumption principle.

[0005] In the above scheme, adjusting the inverter power output of the power conversion unit included in each power conversion device according to the self-consumption principle, based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, includes: adjusting the total inverter power output of the parallel system according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and adjusting the inverter power output of each power conversion unit based on the adjusted total inverter power.

[0006] In the above scheme, the parallel system includes a first control loop; the first control loop controls the total inverter power output of the parallel system; the self-consumption principle includes: the parallel system uses as much power provided by the power generation units and the power stored in the batteries as possible to supply power to the load, and feeds the remaining power back to the grid, taking as little power as possible from the grid; the adjustment of the total inverter power output of the parallel system according to the self-consumption principle, based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, includes: adjusting the total inverter power setpoint of the first control loop based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and inputting the adjusted total inverter power setpoint into the first control loop to adjust the total inverter power output of the parallel system.

[0007] In the above scheme, adjusting the total inverter power setpoint of the first control loop based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system includes: increasing the total inverter power setpoint based on the original value in response to the flow direction of the grid-connected power being from the grid to the parallel system, the increase being the grid-connected power; determining whether the operating status of the energy storage units included in each of the at least two power conversion devices is in a charging state and whether their respective operating power has reached a set maximum value in response to the flow direction of the grid-connected power being from the parallel system to the grid or in response to the grid-connected power being zero; and decreasing the total inverter power setpoint based on the original value in response to the existence of an energy storage unit that is not in a charging state or the existence of an energy storage unit that has not reached the set maximum value, the decrease being the grid-connected power.

[0008] In the above scheme, the method further includes: in response to the fact that the operating power corresponding to each of the energy storage units reaches a set maximum value, determining whether there is sufficient electrical energy provided by the power generation unit; in response to the fact that the electrical energy provided by each of the power generation units is insufficient, the total inverter power setpoint is not adjusted and remains the same as the total inverter power setpoint used last time; in response to the fact that there is sufficient electrical energy provided by the power generation unit, determining whether the grid-connected power is less than a set threshold; in response to the fact that the grid-connected power is not less than the set threshold, reducing the total inverter power setpoint based on the original value, the reduction amount being the difference between the grid-connected power and the set threshold; in response to the fact that the grid-connected power is less than the set threshold, increasing the total inverter power setpoint based on the original value, and the increase amount being a set value, and in subsequent control, gradually increasing the total inverter power setpoint according to the set value until the grid-connected power is not less than the set threshold.

[0009] In the above scheme, the parallel system includes a second control loop corresponding to each of the power conversion units; the second control loop controls the inverter power output by the corresponding power conversion unit; the adjustment of the inverter power output by each power conversion unit according to the adjusted total inverter power includes: allocating the adjusted total inverter power to the second control loop of each power conversion unit as an inverter power setpoint; for each power conversion unit, inputting the allocated inverter power setpoint to the second control loop to adjust the inverter power output by the corresponding power conversion unit.

[0010] In the above scheme, if the parallel system is started for the first time and is in an unstable state, the step of allocating the adjusted total inverter power to each of the power conversion units as the inverter power setpoint in the second control loop includes: distributing the adjusted total inverter power equally to each of the power conversion units as the inverter power setpoint in the second control loop.

[0011] In the above scheme, the method further includes: determining whether a preset adjustment condition is met; in response to meeting the preset adjustment condition, determining an adjustment strategy for the allocation of the adjusted total inverter power according to the self-consumption principle, based on the load condition, the energy storage condition of each energy storage unit, the power generation condition of each power generation unit, and the inverter power output of each power conversion unit; adjusting the inverter power input of the second control loop corresponding to each power conversion unit according to the adjustment strategy; wherein, the preset adjustment condition includes: the parallel system is operating in a stable state, and some of the energy storage units of the power conversion equipment are charging, while the energy storage units of other power conversion equipment are discharging.

[0012] Secondly, embodiments of this application also provide a control device for a parallel system, wherein the parallel system includes at least two power conversion devices operating in parallel; each power conversion device includes: an energy storage unit, a power generation unit, and a power conversion unit; the control device includes:

[0013] The determination module is used to determine the grid connection status between the parallel system and its coupled power grid during a control process that ensures the operation of the parallel system satisfies the principle of self-generation and self-consumption. The grid connection status includes: grid-connected power and the direction of power flow; determine the energy storage status of the energy storage unit included in each of the at least two power conversion devices. The energy storage status includes: operating status and operating power; and determine the power generation status provided by the power generation unit included in each power conversion device. The power generation status includes the power generation output.

[0014] The adjustment module is used to adjust the inverter power output of the power conversion unit included in each power conversion device according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, so as to control the operation of the parallel system to meet the self-generation and self-consumption principle.

[0015] In the above scheme, the adjustment module is specifically used to: adjust the total inverter power output of the parallel system according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, based on the principle of self-generation and self-consumption; and adjust the inverter power output of each power conversion unit according to the adjusted total inverter power.

[0016] In the above scheme, the parallel system includes a first control loop; the first control loop controls the total inverter power output of the parallel system; the self-consumption principle includes: the parallel system uses the electrical energy provided by the power generation unit and the electrical energy stored in the battery to supply power to the load as much as possible, and feeds the remaining electrical energy back to the grid, and draws as little power from the grid as possible; the adjustment module is specifically used to: adjust the total inverter power setpoint of the first control loop according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and input the adjusted total inverter power setpoint to the first control loop to adjust the total inverter power output of the parallel system.

[0017] In the above scheme, the adjustment module is specifically used for: responding to the flow direction of the grid-connected power being from the grid into the parallel system, increasing the total inverter power setpoint based on the original value, the increase being the grid-connected power; responding to the flow direction of the grid-connected power being from the parallel system into the grid or responding to the grid-connected power being zero, determining whether the operating state of the energy storage unit included in each of the at least two power conversion devices is in a charging state and whether the corresponding operating power has reached a set maximum value; responding to the existence of an energy storage unit whose corresponding operating state is not in a charging state or the existence of an energy storage unit whose corresponding operating power has not reached the set maximum value, decreasing the total inverter power setpoint based on the original value, the decrease being the grid-connected power.

[0018] In the above scheme, the adjustment module is further specifically used for: responding to the fact that the operating power corresponding to each of the energy storage units has reached the set maximum value, determining whether there is sufficient electrical energy provided by the power generation unit; responding to the fact that the electrical energy provided by each of the power generation units is insufficient, not adjusting the total inverter power setpoint, but still the total inverter power setpoint used last time; responding to the fact that there is sufficient electrical energy provided by the power generation unit, determining whether the grid-connected power is less than a set threshold; responding to the fact that the grid-connected power is not less than the set threshold, reducing the total inverter power setpoint based on the original value, the reduction amount being the difference between the grid-connected power and the set threshold; responding to the fact that the grid-connected power is less than the set threshold, increasing the total inverter power setpoint based on the original value, and the increase amount being the set value, and in subsequent control, gradually increasing the total inverter power setpoint according to the set value until the grid-connected power is not less than the set threshold.

[0019] In the above scheme, the parallel system includes a second control loop corresponding to each of the power conversion units; the second control loop controls the inverter power output by the corresponding power conversion unit; the adjustment module is specifically used to: allocate the adjusted total inverter power to the second control loop of each power conversion unit as an inverter power setpoint; for each power conversion unit, input the allocated inverter power setpoint to the second control loop to adjust the inverter power output by the corresponding power conversion unit.

[0020] In the above scheme, if the parallel system is started for the first time and is in an unstable state, the adjustment module is specifically used to: distribute the adjusted total inverter power equally to each of the power conversion units as the inverter power setpoint for the second control loop.

[0021] In the above scheme, the adjustment module is also specifically used to: determine whether the preset adjustment conditions are met;

[0022] In response to the satisfaction of the preset adjustment conditions, and in accordance with the principle of self-generation and self-consumption, an adjustment strategy for the allocation of the adjusted total inverter power is determined based on the load conditions, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the inverter power output of each power conversion unit. The inverter power input of the second control loop corresponding to each power conversion unit is adjusted according to the adjustment strategy. The preset adjustment conditions include: the parallel system is operating in a stable state, and some of the energy storage units of the power conversion equipment are charging, while the energy storage units of other power conversion equipment are discharging.

[0023] Thirdly, embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when loaded and executed by a processor, implements the method described in any of the above-mentioned embodiments.

[0024] This application provides a control method, apparatus, and readable storage medium for a parallel system. The parallel system includes at least two power conversion devices operating in parallel. Each power conversion device includes an energy storage unit, a power generation unit, and a power conversion unit. The method includes: during a control process that ensures the operation of the parallel system meets the self-consumption principle, determining the grid connection status between the parallel system and its coupled power grid; the grid connection status includes the grid-connected power and the direction of power flow; determining the energy storage status of the energy storage unit included in each of the at least two power conversion devices; the energy storage status includes the operating state and operating power; determining the power generation status of the power generation unit included in each power conversion device; the power generation status includes the power generation output; and adjusting the inverter power output of the power conversion unit included in each power conversion device according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, thereby controlling the operation of the parallel system to meet the self-consumption principle. The control method provided in this application adjusts the inverter power output of each power conversion unit according to the self-consumption principle, based on the determined grid-connected power, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status, thereby enabling the parallel system to operate in a self-consumption mode. Following the control method provided in this application, the system's self-consumption requirements can be met after several control cycles. Attached Figure Description

[0025] In accompanying drawings that are not necessarily drawn to scale, the same reference numerals can describe similar components in different views. The same numbers with different letter suffixes can represent different instances of similar components. The accompanying drawings generally illustrate the various embodiments discussed in this document by way of example, not limitation.

[0026] Figure 1 This is a schematic diagram of the structure of a parallel system provided in an embodiment of this application;

[0027] Figure 2 A flowchart illustrating a control method for a parallel system provided in an embodiment of this application;

[0028] Figure 3 A schematic diagram illustrating the process of adjusting the inverter power output of each power conversion unit in the parallel system provided in this application embodiment;

[0029] Figure 4 This is a schematic diagram of the control structure of a parallel system provided in an embodiment of this application;

[0030] Figure 5 A schematic diagram illustrating the process of adjusting the total inverter power of a parallel system, provided as an embodiment of this application;

[0031] Figure 6 A schematic diagram of a process for determining the total inverter power given in an embodiment of this application;

[0032] Figure 7 This is a schematic diagram illustrating the process of adjusting the inverter power output of a power conversion unit according to an embodiment of this application.

[0033] Figure 8 This is a schematic diagram of the structure of a parallel system provided in an embodiment of this application;

[0034] Figure 9 The embodiments provided in this application are based on Figure 8 The diagram shows a process flow for determining the given total inverter power in a parallel system.

[0035] Figure 10 A schematic diagram illustrating the total inverter power allocation process provided in this application embodiment;

[0036] Figure 11 A flowchart illustrating the sign determination of the inverter power change of each power conversion device provided in the embodiments of this application;

[0037] Figure 12 This is a schematic diagram of the control device for the parallel system provided in the embodiments of this application. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the specific technical solutions of this application will be further described in detail below with reference to the accompanying drawings of the embodiments of this application. The following embodiments are used to illustrate this application, but are not intended to limit the scope of this application.

[0039] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0040] Furthermore, in the embodiments of this application, directional terms such as "upper," "lower," "left," and "right" are defined relative to the orientation of the components in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and can change accordingly depending on the orientation of the components in the accompanying drawings.

[0041] In the embodiments of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a series of elements includes which elements, and also includes other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0042] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or related scheme described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0043] See Figure 1 This illustrates a schematic diagram of the parallel system provided in an embodiment of this application. Figure 1As shown, the parallel system 100 includes at least two power conversion devices 10 operating in parallel; each power conversion device 10 includes an energy storage unit 101, a power generation unit 102, and a power conversion unit 103. The at least two power conversion devices 10 can be connected in parallel via a parallel box 20. The parallel box 20 can be a specially developed device for connecting at least two power conversion devices 10 into a parallel system, where the total inverter power output of the parallel system is equal to the sum of the inverter power outputs of each power conversion device in the parallel system. The parallel box 20 may include a data acquisition unit (hereinafter referred to as KC541), a WIFI module, and a parallel control board. The parallel control board communicates with the at least two power conversion devices 10 via a CAN bus to implement parallel control functions. The KC541 communicates with the at least two power conversion devices 10 via two RS485 communication channels to implement parallel communication functions. Subsequently, the parallel box 20 transmits the parallel system operation information to an application (APP) carried on a cloud platform / terminal via the WIFI module, enabling human-machine interaction. In other words, at least two power conversion devices 10 described above are controlled in parallel through a parallel box 20. The parallel box 20 may also include a grid connection interface, which is coupled to the power grid to buy electricity from the grid or sell electricity to the grid.

[0044] in, Figure 1 An example of the parallel system is an energy storage inverter parallel system, in which the power conversion device can be an energy storage converter; the energy storage converter includes a battery (energy storage unit), a power generation unit that provides electrical energy using solar photovoltaic (PV) panels, a wind power generator, etc., and an inverter (i.e., a power conversion unit). The following description uses only an example of a PV panel as the power generation unit, a battery as the energy storage unit, and an inverter as the power conversion unit to illustrate this application.

[0045] Based on the aforementioned parallel system, embodiments of this application provide a control method for the parallel system, such as... Figure 2 As shown, the control method may include:

[0046] Step 201: During a certain control process that controls the operation of the parallel system to meet the principle of self-generation and self-consumption, determine the grid connection status between the parallel system and the power grid it is coupled to; the grid connection status includes: grid-connected power and the direction of power flow;

[0047] Step 202: Determine the energy storage status of the energy storage unit included in each of the at least two power conversion devices; the energy storage status includes: operating status and operating power;

[0048] Step 203: Determine the power generation status of the power generation unit included in each power conversion device; the power generation status includes the power generation output.

[0049] Step 204: In accordance with the principle of self-generation and self-consumption, adjust the inverter power output of each power conversion unit based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, so as to control the operation of the parallel system to meet the principle of self-generation and self-consumption.

[0050] It should be understood that in the field of automatic control, the output of the controlled object follows the given input. When the given input is constant, and the control system, including the controlled object, reaches stability, the output of the controlled object equals the given input. This adjustment process can be called a control process. In this application, the parallel system is a controlled object. To enable the parallel system to operate in a self-sufficient mode, several control processes are required from the start of operation. The given input changes in each control process, so that the output of the parallel system changes to achieve self-sufficiency. According to the above description, steps 201 to 204 are one of the several control processes for enabling the parallel system to achieve a self-sufficient operating mode. Furthermore, according to... Figure 1 The parallel system shown has a total inverter power output equal to the sum of the inverter power outputs of each power conversion device in the system. Therefore, adjusting the output of the parallel system is reflected in adjusting the output of each power conversion unit.

[0051] Here, the so-called self-consumption mode can be the main operating mode of the power conversion equipment, the mode most frequently used by customers. In this operating mode, the power generated by the power generation unit in the power conversion equipment is mainly used by the user, and the surplus power is fed into the grid; that is, self-consumption with surplus power fed into the grid. In this application, the control method provided is a control method for realizing the self-consumption operating mode of the parallel system.

[0052] Specifically, when enabling a parallel system to operate in a self-sufficient mode, the control scheme can be designed based on the following principles:

[0053] The first principle is: when the power provided by the PV is sufficient, the power generated by the PV should be used to power the load first, and the excess power should be used to charge the battery. Before the battery is fully charged, it must be ensured that no power is fed into the grid, nor is power absorbed from the grid. In other words, excess power is used to charge the battery first, so that the power is stored in the battery.

[0054] The second principle: If there is any remaining electrical energy provided by the PV after the battery is fully charged, it should be fed back to the grid. That is, based on the first principle, any excess electrical energy should be fed back into the grid (i.e., excess electrical energy should be sold).

[0055] The third principle: When the power provided by the PV is insufficient, the battery needs to discharge and the power provided by the PV together to supply the load until the battery is depleted (i.e., the battery's discharge limit is reached); if this is still insufficient, then power should be drawn from the grid. In other words, try to avoid absorbing power from the grid (i.e., try to avoid buying electricity).

[0056] Based on the self-consumption principle described above, simply put, it means using the electrical energy provided by PV and the electrical energy stored in the battery to power the load as much as possible; and when the electrical energy provided by PV is sufficient to meet the load demand, the excess electrical energy is first used to charge the battery; after the battery is fully charged, the excess electrical energy is fed back to the grid; and only the minimum amount of electricity is purchased from the grid to supply the load, thereby maximizing economic benefits.

[0057] Based on the above principle of spontaneous self-use, design as follows: Figure 2 The control steps shown enable the parallel system to achieve self-generation and self-consumption control. That is, based on the grid connection status of the parallel system, the energy storage status of the energy storage unit of each power conversion device, the power generation status of the power generation unit included in each power conversion device, and the load status, the inverter power output of each power conversion unit is adjusted in real time to ensure that the operation of the parallel system meets the principle of self-generation and self-consumption.

[0058] Here, the grid connection status reflects whether the parallel system is in a power purchase or power sale state, and specifically the power consumption of the purchased or sold power. That is, the grid connection status includes the grid-connected power and the direction of its flow. The grid-connected power refers to the magnitude of the power flowing between the parallel system and the power grid. The direction of the grid-connected power flow refers to the direction of the power flow between the parallel system and the power grid. This direction can include: flowing from the parallel system to the power grid, in which case the parallel system is in a power sale state. The direction of the grid-connected power flow can also include: flowing from the power grid to the parallel system, in which case the parallel system is in a power purchase state. In some embodiments, the symbol "+" indicates a power sale state; the symbol "-" indicates a power purchase state.

[0059] For example, the grid connection scenario could include: -5 watts (W), meaning the parallel system is in a power purchase state, in other words, the power provided by the generation unit and the energy storage unit is insufficient to meet the load. Alternatively, the grid connection scenario could include: +10W, meaning the parallel system is in a power sale state, in other words, the power provided by the generation unit is sufficient to meet the load, and after the battery is fully charged, there is still surplus power to sell back to the grid.

[0060] In practical applications, when the parallel system is first started, the power generation unit is not generating electricity and cannot provide power, and the battery has not stored any energy. At this time, the grid-connected power is negative. As the parallel system operates, the power generation unit can provide a certain amount of power. If this power can meet the load requirements, the remaining power should be stored in the energy storage unit as much as possible. If there is any remaining power, it will be connected to the grid.

[0061] Here, the energy storage status of the energy storage unit can include: operating status and operating power. The operating status can be charging status or discharging status; the operating power can refer to the charging power corresponding to the charging status or the discharging power corresponding to the discharging status.

[0062] Here, the power generation situation can include the power generation capacity of the power generation unit, or the electrical energy provided by the power generation unit. The electrical energy provided by the power generation unit can be reflected by the power generation capacity. Specifically, a higher power generation capacity means more electrical energy is provided in the same amount of time; a lower power generation capacity means less electrical energy is provided in the same amount of time. The load situation can include the power required by the load.

[0063] After obtaining the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status, in some embodiments, for step 204, such as... Figure 3 As shown, it may include:

[0064] Step 301: In accordance with the principle of self-generation and self-consumption, adjust the total inverter power output of the parallel system based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system.

[0065] Step 302: Adjust the inverter power output of each power conversion unit according to the adjusted total inverter power.

[0066] It should be noted that, as Figure 1 As shown, the parallel system 100 includes at least two power conversion devices, which are controlled by a parallel box and supply power to the load and are coupled to the power grid as a whole. Therefore, when controlling the parallel system to achieve self-consumption, the total inverter power of the parallel system can be adjusted, i.e., step 301; then, the output of each power conversion unit in the parallel system is adjusted according to the adjusted total inverter power, so that the operation of the entire parallel system meets the self-consumption principle, i.e., step 302.

[0067] In practical applications, see Figure 4This diagram illustrates a control structure of a parallel system provided in an embodiment of this application. The parallel system may include a first control loop and a second control loop. The first control loop controls the total inverter power output by the parallel system; the second control loop controls the inverter power output by the corresponding power conversion unit. An example of the controller in the first control loop is a first PI controller; an example of the controller in the second control loop is a second PI controller. That is, as... Figure 4 As shown, on the parallel box side, the total inverter power P output to the entire parallel system is... inv The first PI controller is used for control, where P inv_ref The total inverter power of the first control loop is given, which is an input to the first PI controller. Each power conversion device (ESS) is controlled by a second PI controller, where P... ESS_ref The inverter power of the second control loop is given, which is an input to the second PI controller; P ESS The inverter power output by the power conversion unit contained in the power conversion device.

[0068] Based on such Figure 4 The control structure shown indicates that the output of the parallel system is controlled by a first PI controller. Based on the first PI controller and the principle of self-generation and self-consumption, as follows... Figure 5 As shown, step 301 may include:

[0069] Step 501: Adjust the total inverter power input of the first PI controller according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system.

[0070] Step 502: Input the adjusted total inverter power to the first PI controller to adjust the total inverter power output by the parallel system.

[0071] It should be noted that, as mentioned above, the first PI controller here is the controller of the first control loop. According to the characteristics of PI control, the total inverter power changes in accordance with the total inverter power setpoint; in other words, when the total inverter power setpoint increases, the total inverter power also increases; when the total inverter power setpoint decreases, the total inverter power also decreases. Therefore, adjusting the total inverter power is essentially adjusting the total inverter power setpoint.

[0072] Therefore, in this embodiment of the application, for step 501, as follows Figure 6 As shown, it may include:

[0073] Step 601: In response to the direction of the grid-connected power flow being from the grid into the parallel system, the total inverter power is increased based on the original value, and the increase is the grid-connected power.

[0074] Step 602: In response to the direction of the grid-connected power flow being from the parallel system into the grid or in response to the grid-connected power being zero, determine whether the energy storage unit contained in each of the at least two power conversion devices is in a charging state and whether the corresponding operating power has reached a set maximum value.

[0075] Step 603: In response to the fact that the operating power corresponding to the energy storage unit has not reached the set maximum value, the total inverter power is reduced from the original value, and the reduction amount is the grid-connected power.

[0076] In some embodiments, such as Figure 6 As shown, step 501 may also include:

[0077] Step 604: In response to the fact that the operating power of each of the energy storage units has reached the set maximum value, determine whether the power generation unit provides sufficient electrical energy;

[0078] Step 605: In response to insufficient power provided by each of the power generation units, the total inverter power setting is not adjusted and remains the same as the total inverter power setting used last time;

[0079] Step 606: In response to the presence of sufficient electrical energy provided by the power generation unit, determine whether the grid-connected power is less than a set threshold;

[0080] Step 607: In response to the grid-connected power being not less than the set threshold, the total inverter power is reduced from its original value by the amount of reduction being the difference between the grid-connected power and the set threshold.

[0081] Step 608: In response to the grid-connected power being less than the set threshold, the total inverter power is increased based on the original value, and the increase is the set value. In subsequent control, the total inverter power is gradually increased according to the set value until the grid-connected power is not less than the set threshold.

[0082] It should be noted that during the initial startup of the parallel system, since the power generation units within the power conversion equipment are just starting up and the energy storage units have not yet stored any energy, power needs to be purchased from the grid to supply power to the load; that is, the parallel power is negative. Furthermore, after the parallel system starts operating, the total inverter power setpoint of the first PI controller is adjusted incrementally from zero, and each subsequent adjustment is based on the total inverter power setpoint adjusted in the previous step. Subsequently, during stable operation, the total inverter power setpoint is adjusted based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load conditions, thus adjusting the total inverter power setpoint of the first PI controller.

[0083] Specifically, an exemplary adjustment process can be as follows:

[0084] First, determine whether the parallel system is in a power purchase or power sale state based on the grid connection status.

[0085] When the flow direction of the grid-connected power is from the grid to the parallel system, i.e., when the grid-connected system is in a power purchase state, the total inverter power setpoint is increased based on the original value, and the increase is the same as the grid-connected power described above. In other words, according to the principle of self-consumption, the grid's power is used as little as possible; therefore, the total inverter power output of the parallel system is increased. This increase in total inverter power is achieved by increasing the total inverter power setpoint. This corresponds to step 601. It should be understood that in the field of automatic control, the output of the controlled object follows the change in the setpoint. To change the output of the controlled object, the setpoint can be changed. In practical applications, the setpoint is also changed gradually; in each subsequent control process, the setpoint changes based on the setpoint of the previous control process. Therefore, the original value mentioned here can refer to the setpoint value of the previous control process.

[0086] If the direction of power flow is from the parallel system to the grid or the power flow is zero (i.e., selling electricity or the system's own electrical energy is just enough), then it is determined whether the energy storage unit included in each power conversion device is in a charging state and whether its corresponding operating power has reached the set maximum value. This corresponds to step 602.

[0087] If an energy storage unit is not in a charging state or its operating power is below the set maximum value, the total inverter power is reduced from its original value by the amount of reduction, which is the grid-connected power. In other words, according to the self-consumption principle, the battery stores electrical energy first, and then the excess energy is fed back to the grid. Therefore, if the charging power of the energy storage unit is not at its maximum, it means the battery charging power can be increased further to improve the possibility of charging the battery, i.e., to charge the battery as much as possible, and finally feed the excess energy back to the grid. The means to achieve this is to reduce the total inverter power, that is, to reduce the total inverter power from its original value by the amount of reduction, which is the grid-connected power. This corresponds to step 603.

[0088] If the operating power of each energy storage unit reaches its set maximum value, determine whether the power generation unit provides sufficient electrical energy. This corresponds to step 604. Sufficient electrical energy from the power generation unit means that the power generated by the unit is sufficient for the load. To determine if the power generation is sufficient, compare the unit's power output with the load's power consumption. If the power output is greater than or equal to the load consumption, the power generation is considered sufficient; otherwise, if the power output is less than the load consumption, the power generation is considered insufficient. The following description of insufficient power generation means that the power generation is insufficient for the load; the specific determination is as described above.

[0089] If the electrical energy provided by each generator unit is insufficient, the total inverter power setting will not be adjusted and will remain the same as the previous total inverter power setting. This corresponds to step 605. The situation described here is that the electrical energy generated by each generator unit is insufficient for the load. In this case, the battery needs to supply power to the load along with the generator units. Therefore, the total inverter power setting of the parallel system does not need to be adjusted and can remain at its original value; that is, the total inverter power setting will remain the same as the setting from the previous control process.

[0090] If the power supplied by the existing power generation units is sufficient, determine whether the grid-connected power is less than a set threshold. This corresponds to step 606. It should be noted that in a photovoltaic energy storage system, when the power generated by the photovoltaic energy storage system exceeds the power consumption of the local load, the unconsumed power must be fed into the grid. Since this energy flow direction is photovoltaic module (i.e., power generation unit) - inverter (i.e., inverter component) - load - grid, which is different from the current direction of the grid system, it is called "reverse flow." The set threshold can be the maximum reverse flow power that the parallel system can transmit to the grid; this set threshold can be called the anti-reverse flow power. Therefore, for the stable operation of the grid, the grid-connected power must not exceed the set threshold.

[0091] When adjusting the total inverter power setpoint, if the grid-connected power is not less than the set threshold, the total inverter power setpoint is reduced from its original value by the difference between the grid-connected power and the set threshold. This corresponds to step 607.

[0092] In other words, if the grid-connected power is not less than the set threshold, that is, the increased grid-connected power exceeds the anti-reverse current power, then the total inverter power needs to be reduced. The means to achieve this is to reduce the total inverter power from its original value by the difference between the grid-connected power and the set threshold, that is, to reduce the inverter output of the power conversion unit to reduce the amount of electrical energy transmitted to the grid.

[0093] If the grid-connected power is less than the set threshold, the total inverter power is increased from its original value by the set amount. In subsequent control operations, the total inverter power is gradually increased according to the set value until the grid-connected power exceeds the set threshold. This corresponds to step 608.

[0094] In other words, if the grid-connected power is less than the set threshold, and the grid-connected power has not exceeded the anti-inverter power, the total inverter power can be appropriately increased to feed more energy back to the grid. The implementation method is to increase the total inverter power from its original value by the set amount, and then gradually increase the total inverter power according to the set value during subsequent control processes until the grid-connected power is not less than the set threshold. Here, the set value can refer to an incremental step size, for example, an increase of 10 watts (W) every 600 milliseconds (ms). This means that through multiple rounds of adjustment (including multiple control processes), the total inverter power of the parallel system can be made to meet the condition that the grid-connected power is not less than the set threshold. In other words, through multiple rounds of PI control adjustment, the total inverter power can be increased to feed energy back to the grid with the maximum possible grid-connected power, thereby reducing resource waste. In other words, when the grid-connected power is less than the set threshold and the power generation of the power generation unit is sufficient, the inverter output of the power conversion unit can be increased to maximize the amount of electrical energy transmitted to the grid and avoid waste.

[0095] After adjusting the total inverter power of the parallel system, in step 502, that is, after inputting the adjusted total inverter power into the first PI controller, the total inverter power is adjusted.

[0096] After adjusting the total inverter power and using a second PI controller to control the output of each power conversion unit, for step 302, as follows: Figure 7 As shown, it may include:

[0097] Step 701: Distribute the adjusted total inverter power to the second PI controller of each power conversion unit as the inverter power setpoint;

[0098] Step 702: For each of the power conversion units, the allocated inverter power is input to the second PI controller to adjust the inverter power output of the corresponding power conversion unit.

[0099] In practical applications, the distribution of the total inverter power output of this parallel system changes with the operating time.

[0100] In some embodiments, if the parallel system is powered on for the first time and is in an unstable state, step 701 may include: distributing the adjusted total inverter power equally to each of the power conversion units as the inverter power setpoint for the second PI controller.

[0101] Here, the second PI controller, as mentioned above, is the controller for the second control loop.

[0102] The above steps describe how, during the initial startup of the parallel system, the adjusted total inverter power can be evenly distributed to each power conversion unit as the inverter power setpoint for each second PI controller. Here, "evenly distributing the adjusted total inverter power to each power conversion unit" can mean evenly distributing the adjusted total inverter power to the power conversion units that are normally online in the parallel system. For example, assuming the parallel system contains three power conversion units, and only two power conversion units are normally online during the initial startup, then the adjusted total inverter power is evenly distributed to the two active power conversion units.

[0103] Specifically, the inverter power input for each power conversion device can be calculated using the following formula (1):

[0104]

[0105] Among them, P ESS The inverter power is given by the second PI controller corresponding to a certain power conversion unit; P inv out The total inverter power is adjusted; Ess_Normal_Num is the number of power conversion devices that are normally online.

[0106] As the parallel system operates, in some embodiments, the method may further include:

[0107] Determine whether the preset adjustment conditions are met;

[0108] In response to the satisfaction of the preset adjustment conditions, an adjustment strategy for the allocation of the adjusted total inverter power is determined according to the self-generation and self-consumption principle, based on the load conditions, the energy storage conditions of each energy storage unit, the power generation conditions of each power generation unit, and the inverter power output of each power conversion unit.

[0109] The inverter power input of the second PI controller corresponding to each power conversion unit is adjusted according to the adjustment strategy.

[0110] The preset adjustment conditions include: the parallel system is running in a stable state, and some of the energy storage units of the power conversion equipment are charging, while the energy storage units of other power conversion equipment are discharging.

[0111] It should be noted that as the parallel system operates, when the preset adjustment conditions are met, an adjustment strategy needs to be determined for the allocation of the total inverter power; then, the inverter power input of the second PI controller corresponding to each normally operating power conversion unit is adjusted according to the adjustment strategy.

[0112] Here, the preset adjustment conditions may include: the parallel system has reached a stable state, with some energy storage units of the power conversion equipment charging while others are discharging. The stable state can be determined based on the operating time of the parallel system; for example, the system may reach a stable state after 5 seconds of operation. The phrase "some energy storage units are charging while others are discharging" can mean that some generators can generate enough power to meet the load demand, while others cannot. In this case, the energy storage units whose power generation meets the load demand can charge, while those whose power generation does not meet the load demand need to discharge, thus supplying power to the load along with the generators, resulting in an imbalance in battery energy storage and the usage of each unit in the parallel system.

[0113] In this case, based on the principle of self-generation and self-consumption, an adjustment strategy for the allocation of the adjusted total inverter power is determined according to the actual load conditions, the energy storage conditions of each energy storage unit, the power generation conditions of each power generation unit, and the inverter power output of each power conversion unit, so as to readjust the inverter power output of each power conversion unit.

[0114] Specifically, the overall principle of the adjustment strategy can include increasing the amount of electricity generated by the power generation unit to meet the inverter power output of the corresponding power conversion unit used by the load, and reducing the amount of electricity generated by the power generation unit that does not meet the inverter power output of the corresponding power conversion unit used by the load. This is reflected in the allocation of total inverter power by increasing the amount of electricity generated by the power generation unit to meet the inverter power setpoint of the corresponding power conversion unit under the second PI control, and decreasing the amount of electricity generated by the power generation unit that does not meet the inverter power setpoint of the corresponding power conversion unit under the second PI control. In other words, more power is allocated to the power generation units that meet the power generation setpoint of the corresponding power conversion unit under the second PI control, and less is allocated to the power generation units that do not meet the power generation setpoint of the corresponding power conversion unit under the second PI control. Here, regardless of the allocation strategy, the sum of the second PI control setpoints for each corresponding power conversion unit equals the adjusted total inverter power.

[0115] For a better understanding of this application, see [link to application]. Figures 8 to 11 ,in, Figure 8 A schematic diagram of an exemplary structure of the parallel system provided in this application embodiment; Figure 9 A schematic diagram of the control structure in a parallel system is provided for the embodiments of this application; Figure 10 A flowchart illustrating the fine-tuning of the inverter power input of the second PI controller for each power conversion unit, provided in an embodiment of this application. Figure 11 This is a schematic diagram illustrating the process for determining the change in the inverter power setpoint of the second PI controller for each power conversion unit, as provided in an embodiment of this application.

[0116] exist Figure 8 The parallel system comprises two power conversion devices, ESS1 and ESS2. ESS1 includes a generator unit PV1, an energy storage unit BAT1, and a power conversion unit INV1; ESS2 includes a generator unit PV2, an energy storage unit BAT2, and a power conversion unit INV2. The system also includes a paralleling box that combines ESS1 and ESS2 to supply power to the load; this paralleling box is coupled to the power grid.

[0117] In such Figure 8 In the parallel system shown, such as Figure 4As shown, it includes a first PI controller and a second PI controller. The first PI controller controls the total inverter power output of the parallel system. Each second PI controller corresponds to a power conversion device and controls the output inverter power of that device. According to the control principle, to adjust the total inverter power, the input total inverter power setpoint in the first PI controller needs to be adjusted; to adjust the output inverter power of each power conversion device, the input inverter power setpoint of the corresponding second PI controller needs to be adjusted.

[0118] Based on this, such as Figure 9 As shown, the total inverter power is adjusted based on the grid connection, energy storage, power generation, and load conditions described above. For a detailed understanding, please refer to [link to relevant documentation]. Figure 6 The described technical solution specifically includes: first determining whether the grid-connected power is negative (i.e., whether the parallel system is in a power purchase state); if the grid-connected power is negative, the total inverter power is increased based on the original value, and the increase is the size of the grid-connected power described above (step 601).

[0119] If the grid-connected power is 0 or positive, determine whether the charging power of all batteries included in the ESS has reached the maximum limit (i.e., the set maximum value, corresponding to step 602). If not, reduce the total inverter power setting based on the original value, and the reduction amount is the grid-connected power (step 603). If yes, determine whether the power generation of any power generation unit is sufficient (step 604). If not, the total inverter power setting is not adjusted and remains the same as the previous total inverter power setting (step 605). If yes, determine whether the grid-connected power is less than the set threshold (step 606). If yes, increase the total inverter power setting based on the original value, and the increase amount is the set value. In each subsequent control process, the total inverter power setting is gradually increased according to the set value until the grid-connected power is greater than the set threshold (corresponding to step 608). If not, decrease the total inverter power setting based on the original value, and the reduction amount is the difference between the grid-connected power and the set threshold (step 607).

[0120] After obtaining the adjusted total inverter power as a given value, it is input to the first PI controller for adjustment of the total inverter power. Based on the adjusted total inverter power, the inverter power output of each inverter within the ESS is adjusted.

[0121] Specifically, based on the preceding description, such as Figure 10As shown, when the parallel system is first started, the total inverter power is evenly distributed, that is, the total inverter power is evenly distributed to the inverter power setpoint of the second PI controller corresponding to the inverters contained in the two ESSs. The change in inverter power is 0. It should be noted that ESS1 and ESS2 are both normally online devices. As the parallel system operates, the total inverter power distribution strategy needs to be adjusted, specifically, as follows: Figure 10 As shown, it is determined whether the inverter power fine-tuning condition (i.e., the preset adjustment condition) is met. If it is met, the inverter power change increases by 10W every 50ms; if it is not met, the inverter power change decreases by 10W every 50ms. Other step sizes are also possible; this is just an example and not a limitation. Finally, the inverter power setpoint corresponding to ESS1 is equal to each inverter power setpoint minus the inverter power change; the inverter power setpoint corresponding to ESS2 is equal to each inverter power setpoint plus the inverter power change. The sum of the inverter power setpoints corresponding to ESS1 and ESS2 equals the total adjusted inverter power described above. Therefore, when the fine-tuning condition is met, the inverter power setpoint corresponding to one ESS increases, and the inverter power setpoint corresponding to the other ESS decreases. The aforementioned inverter power change is the amount by which one ESS increases and the amount by which the other ESS decreases.

[0122] One type of fine-tuning condition may include the following three points:

[0123] 1. After the parallel system has been running normally on the grid for 5 seconds; and,

[0124] 2. The ESS2 battery is discharging, or the ESS2 battery is rechargeable but in a non-discharge state. Furthermore,

[0125] 3. (ESS1's battery is charging, &&ESS1's inverter power has not reached the rated power) || (ESS1's battery is not charging / no battery &&ESS1's PV provides sufficient power &&ESS1's inverter power < rated power).

[0126] All three conditions must be met simultaneously. Specifically, the first condition refers to the operation of the parallel system, which must be in a stable operating state after 5 seconds. The second condition concerns ESS2: either the ESS2 battery is discharging, or the ESS2 battery is rechargeable but in a state where discharge is prohibited. In other words, the batteries contained in ESS2 store electrical energy and are either in a discharging state or can be charged but are in a state where discharge is prohibited. The third condition concerns ESS1: either the ESS1 battery is charging and the ESS1 inverter power has not reached its rated power; or the ESS1 battery is not charging / has no battery and the PV power provided by ESS1 is sufficient, and the ESS1 inverter power is less than its rated power (e.g., 12 kW). The fine-tuning condition is to determine if there is a situation where "one inverter battery is discharging while the other inverter battery is charging." If so, the battery discharge should be reduced, and the reduced power should be compensated by the charging power of the other inverter's battery to achieve the goal of prioritizing the PV power load in the system.

[0127] Among them, the "+ / -" sign judgment before the inverter power change is illustrated in one example as follows: Figure 11 As shown, for inverters discharging batteries, the inverter power output should be reduced, so the sign should be "-". For example, in the previous example, if the battery of ESS2 is discharging or the battery of ESS2 is rechargeable but in a state where discharge is prohibited, the sign of the corresponding change in inverter power is "-". For inverters charging batteries, the inverter power should be increased, so the sign should be "+". For example, as described earlier, (the battery of ESS1 is charging, && the inverter power of ESS1 has not reached the rated power)||(the battery of ESS1 is prohibited from charging / no battery && the power provided by the PV of ESS1 is sufficient && the inverter power of ESS1 < the rated power), the sign of the corresponding change in inverter power is "+".

[0128] This application embodiment also provides a control device for a parallel system, the parallel system including at least two power conversion devices operating in parallel; each power conversion device includes: an energy storage unit, a power generation unit, and a power conversion unit; as shown... Figure 12 As shown, the control device 120 may include:

[0129] The determining module 1201 is used to determine the grid connection status between the parallel system and its coupled power grid during a certain control process that controls the operation of the parallel system to meet the self-consumption principle. The grid connection status includes: grid-connected power and the direction of power flow; determine the energy storage status of the energy storage unit included in each of the at least two power conversion devices. The energy storage status includes: operating status and operating power; and determine the power generation status provided by the power generation unit included in each power conversion device. The power generation status includes the power generation output.

[0130] The adjustment module 1202 is used to adjust the inverter power output of the power conversion unit included in each power conversion device according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, so as to control the operation of the parallel system to meet the self-generation and self-consumption principle.

[0131] In some embodiments, the adjustment module 1202 is specifically used to: adjust the total inverter power output of the parallel system according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, based on the principle of self-generation and self-consumption; and adjust the inverter power output of each power conversion unit according to the adjusted total inverter power.

[0132] In some embodiments, the parallel system includes a first control loop; the first control loop controls the total inverter power output by the parallel system; the self-consumption principle includes: the parallel system uses as much electrical energy provided by the power generation units and the electrical energy stored in the batteries as possible to supply power to the load, and feeds the remaining electrical energy back to the grid, while taking as little power from the grid as possible; the adjustment module is specifically used to: adjust the total inverter power setpoint of the first control loop according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and input the adjusted total inverter power setpoint to the first control loop to adjust the total inverter power output by the parallel system.

[0133] In some embodiments, the adjustment module is specifically configured to: in response to the flow direction of the grid-connected power being from the grid into the parallel system, increase the total inverter power given by a value equal to the grid-connected power; in response to the flow direction of the grid-connected power being from the parallel system into the grid or in response to the grid-connected power being zero, determine whether the operating state of the energy storage units included in each of the at least two power conversion devices is in a charging state and whether their respective operating power has reached a set maximum value; in response to the existence of an energy storage unit whose operating state is not in a charging state or the existence of an energy storage unit whose operating power has not reached the set maximum value, decrease the total inverter power given by a value equal to the grid-connected power.

[0134] In some embodiments, the adjustment module is further configured to: determine whether the power provided by the power generation unit is sufficient in response to the fact that the operating power corresponding to each of the energy storage units reaches a set maximum value; in response to the fact that the power provided by each of the power generation units is insufficient, the total inverter power setpoint is not adjusted and remains the same as the total inverter power setpoint used last time; in response to the fact that the power provided by the power generation unit is sufficient, determine whether the grid-connected power is less than a set threshold; in response to the fact that the grid-connected power is not less than the set threshold, reduce the total inverter power setpoint based on the original value, the reduction amount being the difference between the grid-connected power and the set threshold; in response to the fact that the grid-connected power is less than the set threshold, increase the total inverter power setpoint based on the original value, and the increase amount is a set value, and in subsequent control, the total inverter power setpoint is gradually increased according to the set value until the grid-connected power is not less than the set threshold.

[0135] In some embodiments, the parallel system includes a second control loop corresponding to each of the power conversion units; the second control loop controls the inverter power output by the corresponding power conversion unit; the adjustment module is specifically used to: allocate the adjusted total inverter power to the second control loop of each power conversion unit as an inverter power setpoint; for each power conversion unit, input the allocated inverter power setpoint to the second control loop to adjust the inverter power output by the corresponding power conversion unit.

[0136] In some embodiments, if the parallel system is powered on for the first time and is in an unstable state, the adjustment module is specifically used to: distribute the adjusted total inverter power equally to each of the power conversion units as the inverter power setpoint for the second control loop.

[0137] In some embodiments, the adjustment module is further configured to: determine whether a preset adjustment condition is met; in response to meeting the preset adjustment condition, determine an adjustment strategy for the total inverter power allocation after adjustment based on the load condition, the energy storage condition of each energy storage unit, the power generation condition of each power generation unit, and the inverter power output of each power conversion unit, according to the principle of self-generation and self-consumption; adjust the inverter power input of the second PI controller corresponding to each power conversion unit according to the adjustment strategy; wherein the preset adjustment condition includes: the parallel system is running to a stable state, and some of the energy storage units of the power conversion devices are charging, while the energy storage units of other power conversion devices are discharging.

[0138] It should be noted that the control device provided here is the implementation device of the control method described above. The technical features mentioned here have been explained in detail above. To save space, please refer to the previous description for understanding, and will not be repeated here.

[0139] This application also provides a computer-readable storage medium storing a computer program, which, when loaded and executed by a processor, implements the method described in any of the preceding claims. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0140] This application also provides a computer program product, including a computer program, which, when loaded and executed by a processor, implements the method described in any of the above embodiments.

[0141] It should be noted that the terms "first" and "second" appearing in this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0142] Furthermore, it should be understood from the several embodiments provided in this application that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components may be combined, or integrated into another system, or some features may be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0143] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0144] In addition, each functional unit in the various embodiments of this application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0145] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0146] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROM, RAM, magnetic disks, or optical disks.

[0147] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application.

Claims

1. A control method for a parallel system, characterized in that, The parallel system includes at least two power conversion devices operating in parallel; Each power conversion device includes: an energy storage unit, a power generation unit, and a power conversion unit; the method includes: In a certain control process that controls the operation of the parallel system to meet the principle of self-generation and self-consumption, the grid connection status between the parallel system and its coupled power grid is determined; the grid connection status includes: grid-connected power and the direction of power flow. The energy storage status of the energy storage unit included in each of the at least two power conversion devices is determined; the energy storage status includes: operating status and operating power; Determine the power generation status of the power generation unit included in each power conversion device; the power generation status includes the power generation output. According to the principle of self-generation and self-consumption, the inverter power output of the power conversion unit included in each power conversion device is adjusted based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system. The step of adjusting the inverter power output of each power conversion unit in each power conversion device according to the self-consumption principle, based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, includes: adjusting the total inverter power output of the parallel system according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and adjusting the inverter power output of each power conversion unit based on the adjusted total inverter power. The parallel system includes a first control loop; the first control loop controls the total inverter power output of the parallel system; the self-consumption principle includes: the parallel system uses the electrical energy provided by the power generation unit and the electrical energy stored by the energy storage unit to supply power to the load, and feeds back the remaining electrical energy to the grid when there is surplus electrical energy; when the electrical energy provided by the power generation unit and the electrical energy stored by the energy storage unit are insufficient, it draws power from the grid; the adjustment of the total inverter power output of the parallel system according to the self-consumption principle, based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, includes: adjusting the total inverter power setpoint of the first control loop based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and inputting the adjusted total inverter power setpoint to the first control loop to adjust the total inverter power output of the parallel system. The step of adjusting the total inverter power setpoint of the first control loop based on the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system includes: increasing the total inverter power setpoint from its original value in response to the flow direction of the grid-connected power being from the grid to the parallel system, the increase being the grid-connected power; determining whether the operating status of the energy storage units included in each of the at least two power conversion devices is in a charging state and whether their respective operating power has reached a set maximum value in response to the flow direction of the grid-connected power being from the parallel system to the grid or in response to the grid-connected power being zero; and decreasing the total inverter power setpoint from its original value in response to the existence of an energy storage unit that is not in a charging state or the existence of an energy storage unit that has not reached a set maximum value, the decrease being the grid-connected power.

2. The method according to claim 1, characterized in that, The method further includes: In response to the fact that the operating power of each of the energy storage units reaches the set maximum value, it is determined whether the power generation unit provides sufficient electrical energy. In response to insufficient power supplied by each of the power generation units, the total inverter power setting is not adjusted and remains the same as the total inverter power setting used last time; In response to the presence of sufficient electrical energy provided by the power generation unit, it is determined whether the grid-connected power is less than a set threshold. In response to the grid-connected power being not less than the set threshold, the total inverter power is reduced from its original value by the amount of reduction being the difference between the grid-connected power and the set threshold. In response to the grid-connected power being less than the set threshold, the total inverter power is increased from its original value by a set amount. In subsequent control, the total inverter power is gradually increased according to the set value until the grid-connected power is not less than the set threshold.

3. The method according to claim 1, characterized in that, The parallel system includes a second control loop corresponding to each of the power conversion units; the second control loop controls the inverter power output by the corresponding power conversion unit; adjusting the inverter power output by each power conversion unit according to the adjusted total inverter power includes: The adjusted total inverter power is allocated to the second control loop of each power conversion unit as the inverter power setpoint; For each of the power conversion units, the allocated inverter power is input to the second control loop to adjust the inverter power output of the corresponding power conversion unit.

4. The method according to claim 3, characterized in that, If the parallel system is started for the first time and is in an unstable state, the step of allocating the adjusted total inverter power to the second control loop of each power conversion unit as the inverter power setpoint includes: The adjusted total inverter power is evenly distributed to each of the power conversion units as the inverter power setpoint for the second control loop.

5. The method according to claim 4, characterized in that, The method further includes: Determine whether the preset adjustment conditions are met; In response to the satisfaction of the preset adjustment conditions, an adjustment strategy for the allocation of the adjusted total inverter power is determined according to the self-generation and self-consumption principle, based on the load conditions, the energy storage conditions of each energy storage unit, the power generation conditions of each power generation unit, and the inverter power output of each power conversion unit. The inverter power input of the second control loop corresponding to each power conversion unit is adjusted according to the adjustment strategy. The preset adjustment conditions include: the parallel system is running in a stable state, and some of the energy storage units of the power conversion equipment are charging, while the energy storage units of other power conversion equipment are discharging.

6. A control device for a parallel system, characterized in that, The parallel system includes at least two power conversion devices operating in parallel; Each power conversion device includes: an energy storage unit, a power generation unit, and a power conversion unit; the control device includes: The determination module is used to determine the grid connection status between the parallel system and its coupled power grid during a control process that ensures the operation of the parallel system satisfies the principle of self-generation and self-consumption. The grid connection status includes: grid-connected power and the direction of power flow; determine the energy storage status of the energy storage unit included in each of the at least two power conversion devices. The energy storage status includes: operating status and operating power; and determine the power generation status provided by the power generation unit included in each power conversion device. The power generation status includes the power generation output. The adjustment module is used to adjust the inverter power output of the power conversion unit included in each power conversion device according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, so as to control the operation of the parallel system to meet the self-generation and self-consumption principle. Specifically, the adjustment module is used to: adjust the total inverter power output of the parallel system according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system, based on the principle of self-generation and self-consumption; and adjust the inverter power output of each power conversion unit according to the adjusted total inverter power. The parallel system includes a first control loop; the first control loop controls the total inverter power output of the parallel system; the self-consumption principle includes: the parallel system uses the electrical energy provided by the power generation units and the electrical energy stored in the batteries to supply power to the load as much as possible, and feeds the remaining electrical energy back to the grid, minimizing the amount of power drawn from the grid; the adjustment module is specifically used to: adjust the total inverter power setpoint of the first control loop according to the grid connection status, the energy storage status of each energy storage unit, the power generation status of each power generation unit, and the load status of the parallel system; and input the adjusted total inverter power setpoint to the first control loop to adjust the total inverter power output of the parallel system; Specifically, the adjustment module is configured to: in response to the flow direction of the grid-connected power being from the grid into the parallel system, increase the total inverter power setpoint by the original value, the increase being the grid-connected power; in response to the flow direction of the grid-connected power being from the parallel system into the grid or in response to the grid-connected power being zero, determine whether the operating state of the energy storage unit included in each of the at least two power conversion devices is in a charging state and whether the corresponding operating power has reached a set maximum value; in response to the existence of an energy storage unit whose corresponding operating state is not in a charging state or the existence of an energy storage unit whose corresponding operating power has not reached the set maximum value, decrease the total inverter power setpoint by the original value, the decrease being the grid-connected power.

7. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is loaded and executed by the processor, it implements the method described in any one of claims 1 to 5.

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