Control method and control device for power conversion device, and power conversion device

Abstract

The invention discloses a control method and a control device of a power conversion device and the power conversion device, and belongs to the field of photovoltaic technology. The method comprises the following steps: acquiring the current metering power of a grid-connected point under the condition that a target electricity load operates in a photovoltaic residual power supply mode, and acquiring the current electricity power of the target electricity load; determining a first power output value of the output phase based on the first power feedback value and the first power reference value of the output phase; determining a second power output value of the output phase based on a second power feedback value and a second power reference value of the output phase; obtaining the target accumulated power of the photovoltaic power generation device; and based on the first power output value corresponding to the output, taking the second power output value corresponding to the output and the target accumulated power as power reference limit values, determining a target power reference value of the output phase, and controlling the output power of the output phase. The method can make full use of the photovoltaic residual electricity, dynamically responds to the power demand of the load, and effectively improves the energy utilization efficiency.

Description

Control methods, control devices, and power conversion devices for power conversion devices Technical Field

[0001] This application belongs to the field of photovoltaic technology, and in particular relates to a control method, control device, and power conversion device for a power conversion device. Background Technology

[0002] A photovoltaic-storage system consists of photovoltaic strings, photovoltaic inverters, and energy storage batteries. The direct current generated by the photovoltaic strings is converted into alternating current by power conversion devices such as photovoltaic inverters, which then supply power to the load or feed it into the grid.

[0003] Taking a three-phase system as an example, when the photovoltaic inverter does not apply active power control, the photovoltaic power generation is usually evenly distributed across the three phases. When an unbalanced load is connected to the system, it will cause differences in the photovoltaic power injected into the grid from the three phases, resulting in inconsistent surplus photovoltaic power in each phase.

[0004] For smart loads that are only allowed to use surplus photovoltaic power and not energy storage power, their power consumption limit is restricted by the grid connection point. If power is absorbed from the grid at the grid connection point, the smart load will stop, resulting in the actual available power of the load being lower than the surplus photovoltaic power of the system. This limits the load's operating capacity, wastes photovoltaic power generation resources, and reduces the overall energy utilization efficiency of the photovoltaic-storage system. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a control method, a control device, and a power conversion device, which can fully utilize surplus photovoltaic power, dynamically respond to the power demand of the load, and effectively improve energy utilization efficiency.

[0006] In a first aspect, this application provides a control method for a power conversion device, wherein the input terminal of the power conversion device is connected to a photovoltaic power generation device, and the output terminal of the power conversion device is connected to a target electrical load at a grid connection point. The output terminal of the power conversion device includes at least two output phases. The method includes: when the target electrical load is operating in a photovoltaic surplus power supply mode, obtaining the current metered power of the grid connection point and obtaining the current electrical power consumption of the target electrical load, wherein the current metered power includes at least two single-phase metered power corresponding one-to-one with the at least two output phases, and the current electrical power consumption includes at least two single-phase electrical power corresponding one-to-one with the at least two output phases; and using the difference between the single-phase metered power and the single-phase electrical power of the output phase as the first power feedback of the output phase. The system calculates the first power output value of the output phase based on the first power feedback value and the first power reference value of the output phase; it uses the single-phase metering power corresponding to the output as the second power feedback value of the output phase, and determines the second power output value of the output phase based on the second power feedback value and the second power reference value of the output phase; it obtains the target cumulative power of the photovoltaic power generation device, which is determined based on the photovoltaic power limiting power of the power conversion device and the preset power increment; it determines the target power reference value of the output phase based on the first power output value corresponding to the output, using the second power output value corresponding to the output and the target cumulative power as power reference limits, and controls the output power of the output phase based on the target power reference value.

[0007] According to the control method of the power conversion device of this application, by acquiring the first power output value, the second power output value and the target cumulative power of each output phase, using the first power output value as the input value, and using the corresponding second power output value and the target cumulative power as the power reference limit, the first power output value is limited to determine the target power reference value of each output phase, and the output power of each output phase is controlled. This method is applicable to situations where the target electrical load operates in a photovoltaic surplus power supply mode. By utilizing the unbalanced control capability of the power conversion device, the photovoltaic surplus power is redistributed, making full use of the photovoltaic surplus power, dynamically responding to the power demand of the load, and effectively improving energy utilization efficiency.

[0008] According to one embodiment of this application, the target cumulative power includes a first cumulative power and a second cumulative power; obtaining the target cumulative power of the photovoltaic power generation device includes: obtaining the first cumulative power; and obtaining the second cumulative power when the first cumulative power reaches the rated output power of the power conversion device, wherein the first cumulative power is taken as the rated output power of the power conversion device.

[0009] According to one embodiment of this application, determining a target power reference value for the output phase based on the first power output value corresponding to the output, using the second power output value corresponding to the output and the target cumulative power as power reference limits, includes: determining a first power reference value based on the first power output value and using the first cumulative power as a power reference lower limit; determining a second power reference value based on the first power reference value and using the second power output value as a power reference upper limit; and determining the target power reference value based on the second power reference value and using the second cumulative power as a power reference lower limit.

[0010] According to one embodiment of this application, when the single-phase power consumption of each output phase is less than or equal to the minimum of the at least two single-phase metered power values, the target power reference value of each output phase is determined to be the second cumulative power.

[0011] According to one embodiment of this application, when the single-phase power consumption of the first output phase is greater than the single-phase metering power, the target power reference value of the first output phase is the second power output value, and the target power reference value of the second output phase is the second cumulative power. The first output phase is the output phase corresponding to the minimum value of the at least two single-phase metering powers, and the second output phase is the output phase other than the first output phase among the at least two output phases.

[0012] According to one embodiment of this application, when the power of at least two single-phase meters is 0, the target power reference value for each output phase is the second power output value.

[0013] According to one embodiment of this application, the first cumulative power and the second cumulative power are calculated by a surplus power calculation module, which performs the following steps: when it is determined that the power reference value for the photovoltaic power generation device to perform maximum power point tracking is greater than the power output value, the photovoltaic power limiting power is accumulated; the output power of the power conversion device is increased by the preset power increment at preset time intervals until the output power of the power conversion device reaches the rated output power; based on the photovoltaic power limiting power and the preset power increment, the target cumulative power output by the surplus power calculation module is determined.

[0014] According to one embodiment of this application, the first power reference value is 0, and the second power reference value is 0.

[0015] Secondly, this application provides a control device for a power conversion device. The input terminal of the power conversion device is connected to a photovoltaic power generation device, and the output terminal of the power conversion device is connected to a target electrical load at a grid connection point. The output terminal of the power conversion device includes at least two output phases. The control device includes: a first processing module, configured to, when the target electrical load is operating in a photovoltaic surplus power supply mode, obtain the current metering power of the grid connection point and the current electrical power of the target electrical load, wherein the current metering power includes at least two single-phase metering powers corresponding one-to-one with the at least two output phases, and the current electrical power includes at least two single-phase electrical power corresponding one-to-one with the at least two output phases; and a second processing module, configured to calculate the difference between the single-phase metering power and the single-phase electrical power of the output phases. A first power feedback value is used as the first power feedback value of the output phase, and a first power output value of the output phase is determined based on the first power feedback value and a first power reference value of the output phase; a third processing module is used to use the single-phase metering power corresponding to the output as the second power feedback value of the output phase, and a second power output value of the output phase is determined based on the second power feedback value and the second power reference value of the output phase; a fourth processing module is used to obtain the target cumulative power of the photovoltaic power generation device; a fifth processing module is used to determine the target power reference value of the output phase based on the first power output value corresponding to the output, the second power output value corresponding to the output, and the target cumulative power as power reference limits, and control the output power of the output phase based on the target power reference value.

[0016] Thirdly, this application provides a power conversion device, wherein the input end of the power conversion device is connected to a photovoltaic power generation device, the output end of the power conversion device is connected to a target electrical load at a grid connection point, and the output end of the power conversion device includes at least two output phases; the power conversion device includes a control device as described in the second aspect above.

[0017] According to one embodiment of this application, the target electrical load includes at least one target sub-load, which is a single-phase electrical load or a multi-phase electrical load.

[0018] According to one embodiment of this application, the output phase of the power conversion device is connected to one phase of the grid connection point of the single-phase power converter.

[0019] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0020] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: FIG1 is a schematic flowchart of a control method for a power conversion device provided in an embodiment of this application; FIG2 is a schematic flowchart of a calculation of a first power output value provided in an embodiment of this application; FIG3 is a schematic flowchart of a calculation of a second power output value provided in an embodiment of this application; FIG4 is a schematic flowchart of a calculation of a target power reference value provided in an embodiment of this application; FIG5 is one of a schematic diagram of the connection relationship of a power conversion device provided in an embodiment of this application; FIG6 is another schematic diagram of the connection relationship of a power conversion device provided in an embodiment of this application; FIG7 is a schematic structural diagram of a control device for a power conversion device provided in an embodiment of this application; FIG8 is a schematic structural diagram of an electronic device provided in an embodiment of this application.

[0021] Figure reference numerals: photovoltaic power generation device 510, power conversion device 520, power grid 530, target power load 540. Detailed Implementation

[0022] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0023] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0024] The control method, control device, electronic device, and readable storage medium of the power conversion device 520 provided in this application will be described in detail below with reference to the accompanying drawings and through specific embodiments and application scenarios.

[0025] The power conversion device 520 in this application embodiment can be an inverter that converts direct current to alternating current, and the power conversion device 520 can be applied to photovoltaic, photovoltaic energy storage and other systems.

[0026] The input terminal of the power conversion device 520 is connected to the photovoltaic power generation device 510, and the output terminal of the power conversion device 520 is connected to the target electrical load 540 at the grid connection point. The power conversion device 520 can convert the DC power generated by the photovoltaic power generation device 510 into AC power, which is then supplied to the target electrical load 540 or fed into the grid 530.

[0027] Understandably, the grid connection point is the location where the system connects to the power grid 530. A power sensor can be installed at the grid connection point to detect the power data in real time and determine the operating status of the power supply system.

[0028] Among them, the target electrical load 540 is a controllable electrical load, also known as a smart load. It controls the start-up, shutdown and operating power of the target electrical load 540 by establishing a communication connection with control units such as the energy management system.

[0029] The target electrical load 540 can be divided into switching type and power regulation type according to the control type. For the switching type target electrical load 540, the load can be started and stopped. For the power regulation type target electrical load 540, power commands can be issued to regulate the operating power of the target electrical load 540.

[0030] It is understandable that photovoltaic and photovoltaic energy storage systems can be connected to ordinary loads in addition to the target power load 540. The target power load 540 operates in photovoltaic surplus power supply mode, which means that the target power load 540 is only allowed to use the photovoltaic surplus power remaining after the photovoltaic power generation device 510 has met the power demand of the ordinary load. In other words, the energy storage battery is not allowed to supply power to the target power load 540.

[0031] The output of the power conversion device 520 includes at least two output phases, which can convert the DC power generated by the photovoltaic power generation device 510 into at least two-phase AC power output, with each output being relative to one phase of AC power output.

[0032] For example, the power conversion device 520 can be a three-phase inverter, including three output phases, which can convert the DC power generated by the photovoltaic power generation device 510 into three-phase AC power output.

[0033] In related technologies, for three-phase photovoltaic inverters, the photovoltaic power generation is usually evenly distributed to phases A, B, and C. However, when an unbalanced load is connected to the system, it will cause differences in the photovoltaic power injected into the grid by the three phases, resulting in inconsistent residual photovoltaic power in each phase.

[0034] For smart loads that are only allowed to use surplus photovoltaic power and not energy storage power, their power consumption limit is restricted by the grid connection point. Specifically, the following two situations may occur: First, for single-phase smart loads, their maximum power consumption after startup must not exceed the real-time surplus photovoltaic power of that phase. If this limit is exceeded, that phase will absorb power from the grid at the grid connection point, thus stopping the smart load. That is, for a single-phase smart load, its maximum available power is the surplus photovoltaic power of the phase to which the smart load is connected. Second, for three-phase smart loads, their maximum power consumption after startup must not exceed three times the minimum surplus photovoltaic power of the three phases. If this limit is exceeded, the phase with the minimum surplus photovoltaic power will first absorb power from the grid, thus stopping the smart load. That is, for a three-phase smart load, its maximum available power is three times the surplus photovoltaic power of the phase with the minimum surplus photovoltaic power.

[0035] Such a control strategy severely limits the load operating capacity, resulting in a waste of photovoltaic power generation resources and reducing the overall energy utilization efficiency of the photovoltaic-storage system.

[0036] This application provides a control method for a power conversion device 520, applicable to the operating mode of a smart load (i.e., the target electrical load 540) that only allows the use of surplus photovoltaic power. By dynamically adjusting the power and utilizing the unbalanced control capability of the power conversion device 520, the surplus photovoltaic power is redistributed, making full use of the surplus photovoltaic power, dynamically responding to the power demand of the load, and effectively improving energy utilization efficiency.

[0037] The control method for the power conversion device 520 provided in this application embodiment can be executed by an electronic device or a functional module or functional entity in the electronic device that can implement the control method for the power conversion device 520.

[0038] As shown in Figure 1, the control method of the power conversion device 520 includes steps 110, 120, 130, 140 and 150.

[0039] Step 110: When the target electrical load 540 is operating in the photovoltaic surplus power supply mode, obtain the current metering power of the grid connection point and the current electrical power of the target electrical load 540.

[0040] It is understandable that the photovoltaic surplus power supply mode refers to the operating mode in which the target electrical load 540 is only allowed to use the photovoltaic surplus power of the photovoltaic power generation device 510, and is not allowed to use the energy storage power.

[0041] In this step, the current metered power at the grid connection point can be collected in real time by a power sensor installed at the grid connection point. The current metered power can refer to the active power at the grid connection point in real time.

[0042] Understandably, the operating status of the system in which the photovoltaic power generation device 510 and the target electrical load 540 are located can be determined based on the current power measurement value and direction, and the energy balance relationship between the power generation and load of the system can be evaluated.

[0043] The current metered power includes at least two single-phase metered powers that correspond one-to-one with at least two output phases.

[0044] For example, power grid 530 includes three phases A, B, and C. The current metered power includes three single-phase metered power, and the three single-phase metered power corresponds one-to-one with the three phases A, B, and C.

[0045] In this step, the current power consumption of the target electrical load 540 can be obtained by collecting data such as current and voltage of the target electrical load 540.

[0046] The current power consumption includes at least two single-phase power consumptions that correspond one-to-one with at least two output phases.

[0047] For example, grid 530 includes three phases A, B, and C, and target load 540 is connected to the grid connection point. The current power consumption of target load 540 includes three single-phase power consumptions, which correspond one-to-one with the three phases A, B, and C.

[0048] It should be noted that single-phase power consumption refers to the power consumption of the target electrical load 540 on one output phase, excluding the power consumption of other ordinary loads.

[0049] Step 120: Take the difference between the single-phase metered power and the single-phase power consumption of the output phase as the first power feedback value of the output phase, and determine the first power output value of the output phase based on the first power feedback value and the first power reference value of the output phase.

[0050] In this step, for at least two output phases of the power conversion device 520, the first power feedback value for each output phase is calculated individually.

[0051] In some embodiments, the target electrical load 540 includes at least one target sub-load, which is a single-phase electrical load or a multi-phase electrical load.

[0052] It is understandable that a single-phase electrical load is connected to one output phase of the power conversion device 520, and a multi-phase electrical load is connected to multiple output phases of the power conversion device 520. A multi-phase electrical load can be regarded as multiple single-phase electrical loads connected to different phases. For example, a three-phase electrical load is connected to phases A, B, and C. A three-phase electrical load can be regarded as three single-phase electrical loads connected to phases A, B, and C respectively.

[0053] The single-phase power consumption of a certain output phase is equal to the sum of the power consumption of the target sub-loads connected to that output phase, which is also equal to the sum of the power consumption of the single-phase loads connected to that output phase.

[0054] For example, in a photovoltaic-storage system, phase x is connected to n single-phase electrical loads. Let the real-time power consumption of the i-th single-phase electrical load be denoted as . The single-phase power consumption of phase x is The calculation formula is as follows:

[0055] That is, the single-phase power consumption of phase x is equal to the sum of the power consumption of the single-phase electrical loads connected to phase x.

[0056] In this embodiment, the output terminal of the power conversion device 520 is connected to the grid connection point of the target electrical load 540, and the first power feedback value of the output phase is equal to the difference between the single-phase metering power and the single-phase power consumption of the output phase.

[0057] For example, the single-phase power consumption of phase x is The single-phase metering power of phase x is First power feedback value .

[0058] In this embodiment, for at least two output phases of the power conversion device 520, the first power output value of each output phase is calculated separately, and the first power output value is determined based on the first power feedback value and the first power reference value of the output phase.

[0059] It should be noted that the first power feedback value is the feedback value for grid-connected power control of the output phase, and the first power reference value is the reference value for grid-connected power control of the output phase. For the power conversion device 520, the goal of grid-connected power control is to adjust the output power in real time so that the first power feedback value can accurately and stably track the first power reference value.

[0060] For example, as shown in Figure 2, the first power feedback value of phase x is The first power reference value is The difference between the first power feedback value and the first power reference value is calculated. This difference is used as the input to controller 1. After calculation by controller 1, the output is... As the first power output value.

[0061] In actual implementation, controller 1 can be a P (proportional) controller, a PI (proportional-integral) controller, or a PID (proportional-integral-derivative) controller.

[0062] In some embodiments, the first power reference value is 0.

[0063] In this embodiment, the first power reference value is set to 0, and the goal of grid connection point power control is to avoid purchasing electricity from the grid 530 to supply ordinary loads, without considering the power consumption of the target load 540.

[0064] Step 130: Take the corresponding single-phase metering power as the second power feedback value of the output phase, and determine the second power output value of the output phase based on the second power feedback value and the second power reference value of the output phase.

[0065] In this step, for at least two output phases of the power conversion device 520, the second power feedback value of each output phase is calculated separately, and the single-phase metering power corresponding to the output can be used as the second power feedback value of the output phase.

[0066] For example, the single-phase metering power of phase x is Second power feedback value .

[0067] In this embodiment, the second power feedback value is the feedback value for grid-connected power control of the output phase, and the second power reference value is the reference value for grid-connected power control of the output phase. For the power conversion device 520, the goal of grid-connected power control is to adjust the output power in real time so that the second power feedback value can accurately and stably track the second power reference value.

[0068] For example, as shown in Figure 3, the second power feedback value of phase x is The second power reference value is The difference between the second power feedback value and the second power reference value is calculated. This difference is used as the input to controller 1, and after calculation by controller 2, the output is... As the second power output value.

[0069] In actual implementation, controller 2 can be a P (proportional) controller, a PI (proportional-integral) controller, or a PID (proportional-integral-derivative) controller.

[0070] In some embodiments, the second power reference value is 0.

[0071] In this embodiment, the second power reference value is set to 0, and the goal of grid point power control is to avoid purchasing electricity from the grid 530 to supply the target load 540 and ordinary loads.

[0072] Step 140: Obtain the target cumulative power of the photovoltaic power generation device 510.

[0073] It should be noted that the target cumulative power can refer to the cumulative photovoltaic power that cannot be transferred when the power conversion device 520 is in a limited state.

[0074] In actual operation, the energy management system of the power conversion device 520 can calculate the target cumulative power in real time.

[0075] The target cumulative power is determined based on the photovoltaic power limit of the power conversion device 520 and the preset power increment.

[0076] In this embodiment, the power conversion device 520 can operate in maximum power point tracking (MPPT) mode, adjusting the output power according to different ambient temperature, light intensity and other characteristics, so that the photovoltaic power generation device 510 can output maximum power.

[0077] In actual implementation, MPPT control takes the input voltage of the power conversion device 520 as the control object and the power magnitude as the observation object. By using the form of disturbance voltage and combining it with the corresponding power change, it determines whether more photovoltaic power can be obtained from the photovoltaic power generation device 510. The preset power increment can refer to the power increment corresponding to the disturbance voltage under MPPT control.

[0078] It should be noted that the photovoltaic power limit is the absolute upper limit of the power output allowed by the power conversion device 520, and the preset power increment is the output power that the power conversion device 520 gradually increases during operation. The target cumulative power can be calculated based on the photovoltaic power limit and the preset power increment.

[0079] Step 150: Based on the first power output value corresponding to the output, and using the second power output value corresponding to the output and the target cumulative power as power reference limits, determine the target power reference value of the output phase, and control the output power of the output phase based on the target power reference value.

[0080] In this embodiment, for at least two output phases of the power conversion device 520, a target power reference value is calculated for each output phase individually, and the output power of the output phase is adjusted individually based on the target power reference value.

[0081] When the target electrical load 540 is a single-phase electrical load, the output power of each output phase of the power conversion device 520 is controlled to transfer the surplus photovoltaic power between each output phase, thereby directionally transferring the photovoltaic power of the power surplus phase to the connected phase of the single-phase electrical load and increasing the available surplus photovoltaic power of that phase.

[0082] When the target electrical load 540 is a three-phase electrical load, the output power of each output phase of the power conversion device 520 is controlled to perform asymmetrical output, which compensates for the imbalance of photovoltaic surplus power caused by the asymmetrical load and restores it to a three-phase symmetrical state, so that the three-phase electrical load can make full use of the photovoltaic surplus power.

[0083] It should be noted that the first power output value is calculated based on the first power feedback value, which is the difference between the single-phase metered power and the single-phase power consumption. The first power output value is the power value that satisfies the requirement that ordinary loads be powered by the photovoltaic energy storage system without drawing power from the grid 530.

[0084] The second power output value is calculated based on the second power feedback value, which is the single-phase metering power. The second power output value is the power value that satisfies the requirement that ordinary loads and target electrical loads 540 be powered by the photovoltaic energy storage system without drawing power from the grid 530.

[0085] In this step, the first power output value corresponding to the output can be used as the input value, and the second power output value corresponding to the output and the target cumulative power can be used as the power reference limit. The first power output value is limited. Under the premise of ensuring safe and stable operation, the power control of each output phase of the power conversion device 520 is performed. The unbalance control capability of the power conversion device 520 is used to redistribute the surplus photovoltaic power, dynamically respond to the power demand of the load, and effectively improve the energy utilization efficiency.

[0086] It should be noted that in the process of solving the target power reference value, the second power output value can be used as the upper limit of the power reference. When the photovoltaic surplus power is insufficient, the second power output value does not take effect, and the energy storage battery will not discharge to the target power load 540, thus meeting the requirement that the target power load 540 operates in the photovoltaic surplus power supply mode.

[0087] According to the control method of the power conversion device 520 provided in the embodiments of this application, by acquiring the first power output value, the second power output value and the target cumulative power of each output phase, using the first power output value as the input value, and using the corresponding second power output value and the target cumulative power as power reference limits, the first power output value is limited to determine the target power reference value of each output phase, and the output power of each output phase is controlled. This method is applicable to the case where the target electrical load 540 is operating in the photovoltaic surplus power supply mode. By utilizing the unbalance control capability of the power conversion device 520, the photovoltaic surplus power is redistributed, making full use of the photovoltaic surplus power, dynamically responding to the power demand of the load, and effectively improving energy utilization efficiency.

[0088] When the power conversion device 520 operates in MPPT mode, and the output power cannot be further increased regardless of the disturbance of the input voltage, the power conversion device 520 is in a limited state. The reference value and feedback value of the input voltage controlled by MPPT are different. Due to the limitation of the rated output power of the power conversion device 520, the power conversion device 520 cannot transfer and output more photovoltaic power, and it is believed that there may still be excess photovoltaic power.

[0089] It should be noted that the hardware architecture of the power conversion device 520 can be divided into a two-stage circuit structure: a DC-DC converter in the front stage and a DC-AC converter in the back stage, which are connected by a DC bus capacitor. The power conversion device 520 operates in MPPT mode, where the input voltage of the DC-DC converter is controlled by the MPPT algorithm to track the maximum power point of the photovoltaic power generation device 510, and the DC-AC converter stabilizes the DC bus voltage. When the MPPT cannot control the input voltage, it indicates that the power conversion device 520 is in a limited state.

[0090] In some embodiments, the target cumulative power includes a first cumulative power and a second cumulative power.

[0091] Step 140: Obtaining the target cumulative power of the photovoltaic power generation device 510 may include: obtaining a first cumulative power; and obtaining a second cumulative power when the first cumulative power reaches the rated output power of the power conversion device 520, wherein the first cumulative power is the rated output power of the power conversion device 520.

[0092] In this embodiment, the cumulative power is calculated in real time according to the relevant algorithm of photovoltaic surplus power. First, the first cumulative power is obtained. When the first cumulative power output by the surplus power calculation module reaches the rated output power of the power conversion device 520, the first cumulative power no longer increases and remains at the rated output power of the power conversion device 520, and the second cumulative power is calculated.

[0093] In actual implementation, the energy management system or control unit of the power conversion device 520 is equipped with a surplus power calculation module. The relevant algorithm of photovoltaic surplus power is pre-written in the surplus power calculation module to calculate the target cumulative power. When the first cumulative power output by the surplus power calculation module reaches the rated output power of the power conversion device 520, the surplus power calculation module starts to calculate the second cumulative power.

[0094] For example, the target cumulative power includes the first cumulative power. Second cumulative power The rated output power of the power conversion device 520 When the residual power calculation module outputs hour, No more increases, start outputting. .

[0095] In some embodiments, the first cumulative power and the second cumulative power are calculated by the surplus power calculation module, which performs the following steps: when it is determined that the power reference value for the photovoltaic power generation device 510 to perform maximum power point tracking is greater than the power output value, the photovoltaic power limiting power is accumulated; the output power of the power conversion device 520 is increased by a preset power increment at preset time intervals until the output power of the power conversion device 520 reaches the rated output power; and the target cumulative power output by the surplus power calculation module is determined based on the photovoltaic power limiting power and the preset power increment.

[0096] It is understandable that the power conversion device 520 operates in MPPT mode. When the MPPT control cannot transfer the photovoltaic power of the photovoltaic power generation device 510, that is, when the power reference value of the photovoltaic power generation device 510 for maximum power point tracking is greater than the power output value, the MPPT operation state is limited.

[0097] In this embodiment, the cumulative power output by the residual power calculation module is the sum of two parts: the first part is the cumulative photovoltaic power limit when the MPPT is in a limited operating state, and the second part is the cumulative preset power increment when the MPPT attempts to increase the output power at preset time intervals.

[0098] For example, a preset power increment is added to the current output power every 5 seconds. If the output power of the corresponding power conversion device 520 increases, the power continues to increase at time intervals. If the output power of the corresponding power conversion device 520 no longer increases, that is, the rated output power is reached, the power is no longer increased.

[0099] In actual implementation, there can be two residual power calculation modules: residual power calculation module 1 and residual power calculation module 2. Residual power calculation module 1 is used to accumulate power and output the first accumulated power. When the first accumulated power reaches the rated output power of the power conversion device 520, residual power calculation module 1 stops accumulating, and residual power calculation module 2 starts accumulating power and outputs the second accumulated power.

[0100] It should be noted that when When the rated output power is reached, the value output by the residual power calculation module 1 remains fixed and is distorted, while the value output by the residual power calculation module 2 is... Dynamic and accurate, through It accurately reflects the surplus electricity situation of photovoltaic power.

[0101] It is understood that the photovoltaic surplus power algorithm and its implementation method involved in the surplus power calculation module are well known in the art. In this application embodiment, the output result of the photovoltaic surplus power algorithm (first cumulative power and second cumulative power) is applied to the power output control of the power conversion device 520. Combined with the second power output value, the first power output value is limited to obtain the target power reference value of the output phase.

[0102] In some embodiments, determining a target power reference value for an output phase based on a first power output value corresponding to the output, and using a second power output value corresponding to the output and a target cumulative power as power reference limits, includes: determining a first power reference value based on the first power output value and using a first cumulative power as a power reference lower limit; determining a second power reference value based on the first power reference value and using a second power output value as a power reference upper limit; and determining a target power reference value based on the second power reference value and using a second cumulative power as a power reference lower limit.

[0103] In this embodiment, the first power output value is used as input, and the power is successively limited by the first cumulative power, the second power output value, and the second cumulative power to obtain the target power reference value for output power control.

[0104] Based on the first power output value, and with the first cumulative power as the lower limit of the power reference, the first power reference value is determined. If the first power output value is greater than or equal to the first cumulative power, that is, the power input is greater than or equal to the lower limit of the power, then the first power reference value is the first power output value. If the first power output value is less than the first cumulative power, and the power input is less than the lower limit of the power, the amplitude is limited by the lower limit of the power, and the first power reference value is the first cumulative power.

[0105] Based on the first power reference value, the second power output value is used as the upper limit of the power reference to determine the second power reference value. If the first power reference value is less than or equal to the second power output value, the second power reference value is taken as the first power reference value; if the first power reference value is greater than the second power output value, the amplitude is limited by the upper limit of the power, and the second power reference value is taken as the second power output value.

[0106] Based on the second power reference value, and with the second cumulative power as the lower limit of the power reference, the target power reference value is determined. If the second power reference value is greater than or equal to the second cumulative power, the target power reference value is the second power reference value. If the second power reference value is less than the second cumulative power, the power input is less than the lower limit of the power, and the lower limit of the power is used for limiting. The target power reference value is the second cumulative power.

[0107] For example, as shown in Figure 4, for phase x of the power conversion device 520, the first power output value output by controller 1 is... As input, the first accumulated power output by the residual power calculation module 1 is... The first power reference value is obtained by using the first power reference lower limit as input and performing the first power output value. As the upper limit of the power reference, a second limiting is performed to obtain the second power reference value; finally, using the second power reference value as input, the residual power calculation module 2 outputs the second cumulative power. As the lower limit of the power reference, a third limiting is performed to obtain the target power reference value for phase x. It is used for output power control of phase x in power conversion device 520.

[0108] In this embodiment, if This indicates that the power conversion device 520 is unable to transfer all the surplus photovoltaic power at this point, and the surplus power calculation module 1 begins to further accumulate power until... Once the rated output power of the power conversion device 520 is reached, the residual power calculation module 2 begins to accumulate power. This indicates that the output power of the power conversion device 520 is limited by the residual power calculation module 2.

[0109] It should be noted that the second power output value can be used as a reference upper limit for power. When the photovoltaic surplus power is insufficient, the second power output value... It is not effective; the energy storage battery will not discharge to the target electrical load 540, thus meeting the requirement that the target electrical load 540 operates in the photovoltaic surplus power supply mode.

[0110] In some embodiments, when the single-phase power consumption of each output phase is less than or equal to the minimum of at least two single-phase metered power values, the target power reference value for each output phase is determined to be the second cumulative power.

[0111] In this embodiment, the single-phase power consumption of the target electrical load 540 in each output phase is less than the minimum value among all single-phase metered power, indicating that the surplus photovoltaic power of each output phase can meet the load power consumption. The target power reference value calculated based on the first power output value, the second power output value, the first cumulative power, and the second cumulative power is taken as the second cumulative power.

[0112] For example, the power conversion device 520 includes three output phases. For phase x (x=a, b, c) of the power conversion device 520, the single-phase power consumption is... Single-phase metering power is The minimum value of single-phase metered power is .

[0113] In this embodiment, when The surplus photovoltaic power of each output phase can meet the power demand of the load. .

[0114] In some embodiments, when the single-phase power consumption of the first output phase is greater than the single-phase metering power, the target power reference value of the first output phase is the second power output value, and the target power reference value of the second output phase is the second cumulative power.

[0115] The first output phase is the output phase corresponding to the minimum value of at least two single-phase metered power, and the second output phase is the output phase other than the first output phase among the at least two output phases.

[0116] In this embodiment, the single-phase power consumption of the first output phase is greater than the single-phase metering power, indicating that the photovoltaic surplus power of the output phase corresponding to the minimum single-phase metering power cannot meet the load power consumption. The output phase corresponding to the minimum single-phase metering power may engage in power purchase behavior, and the corresponding power purchase can be detected by the power sensor at the grid connection point.

[0117] The output phase corresponding to the minimum single-phase metered power is taken as the first output phase, and the other output phases are taken as the second output phases. The target power reference value of the first output phase is taken as the second power output value, and the target power reference value of the second output phase is taken as the second cumulative power.

[0118] For example, the power conversion device 520 includes three output phases. For phase x (x=a, b, c) of the power conversion device 520, the single-phase power consumption is... Single-phase metering power is .

[0119] The output phase corresponding to the minimum single-phase metered power is phase a, and the minimum single-phase metered power is... .

[0120] In this embodiment, When this occurs, it indicates that the surplus photovoltaic power of phase a, the phase with the lowest grid connection power, cannot meet the load power demand. According to the calculation logic shown in Figure 4, the target power reference value of the first output phase is taken as the second power output value, and the target power reference value of the second output phase is taken as the second cumulative power. The target power reference values ​​for each output phase are as follows:

[0121] After grid connection point power control is performed based on the target power reference value, the single-phase metering power of the three phases has the following relationship:

[0122] Among them, phase a is the first output phase, and phases b and c are the second output phases.

[0123] In this embodiment, the target power reference value of the first output phase is taken as the second power output value, and the target power reference value of the second output phase is taken as the second cumulative power. The three-phase output power of the power conversion device 520 is asymmetrical. According to the law of conservation of energy, the following formula exists:

[0124] As can be seen, compared with the related technologies that distribute photovoltaic power generation evenly across the three phases, the target load 540 in this embodiment has a larger available power. By using the power conversion device 520 to perform asymmetrical output, the surplus photovoltaic power is redistributed, dynamically responding to the power demand of each phase of the load, and effectively improving energy utilization efficiency.

[0125] In some embodiments, when at least two single-phase metered powers are both 0, the target power reference value for each output phase is the second power output value.

[0126] In this embodiment, the first power output value is used as input, and the target power reference value of each output phase is obtained by sequentially passing through the first cumulative power, the second power output value, and the second cumulative power limit. After the grid connection point power control is performed according to the target power reference value, when the single-phase metering power of all output phases is 0, it indicates that all photovoltaic surplus power has been absorbed by the target electrical load 540. At this time, the target electrical load 540 can reach the maximum available power, effectively improving energy utilization efficiency.

[0127] For example, the power conversion device 520 includes three output phases. For phase x (x=a, b, c) of the power conversion device 520, the single-phase power consumption is... Single-phase metering power is With the first power output value As input, it sequentially passes through the first accumulated power Second power output value and the second cumulative power The limiting is used to obtain the target power reference value. .

[0128] In this embodiment, the target power reference value for each output phase is obtained according to the calculation logic shown in Figure 4, as follows:

[0129] After controlling the grid connection point power according to the target power reference value, the following relationship exists:

[0130] All single-phase metered power is 0, meaning the reverse current power at the three-phase grid connection point is 0.

[0131] It is understandable that photovoltaic and photovoltaic energy storage systems can be connected to ordinary loads in addition to the target power load 540. The target power load 540 operates in photovoltaic surplus power supply mode, which means that the target power load 540 is only allowed to use the photovoltaic surplus power remaining after the photovoltaic power generation device 510 has met the power demand of the ordinary load.

[0132] The following is a specific example.

[0133] As shown in Figure 5, the photovoltaic system includes a photovoltaic power generation device 510, a power conversion device 520, a target electrical load 540, and a general load (not shown in the figure). The input terminal of the power conversion device 520 is connected to the photovoltaic power generation device 510, and the output terminal of the power conversion device 520 is connected to the target electrical load 540 and the general load at the grid connection point. The power conversion device 520 is a three-phase inverter.

[0134] A three-phase inverter consists of three output phases. The sum of the power consumption of ordinary loads on phase x (x=a, b, c) is... The sum of the power consumption of the target electrical load 540 on phase x is .

[0135] When the target electrical load 540 is a three-phase electrical load, the power consumption of the target electrical load 540 in phases a, b, and c is balanced. .

[0136] The following section uses the target electrical load 540 as an example, which is a three-phase electrical load, to specifically explain the control strategy of the embodiments of this application and the control strategy of related technologies.

[0137] Assume the actual usable photovoltaic power of the system is ,and The single-phase metering power sampled by the power sensor at the grid connection point is Record the metered power of each phase at the grid connection point, sorted from largest to smallest, as follows: , and .

[0138] One requirement for photovoltaic surplus power supply mode is that there can be no purchased power at the grid connection point; that is, the maximum available power at the grid connection point is... The target electrical load is 540. In related technologies, the photovoltaic power generation is evenly distributed across the three phases. After the intelligent load power stabilizes, the actual three-phase metering power at the grid connection point is... , and At this time, some of the photovoltaic power will be fed back to the grid 530, which cannot be utilized by the smart load.

[0139] In this embodiment of the application, after the target electrical load 540 is started, the power consumption of the target electrical load 540 can be gradually increased to make full use of the surplus photovoltaic power.

[0140] As shown in Figure 2, the first power output value is obtained through controller 1. The first power feedback value of phase x First power reference value In this scenario, the role of controller 1 is to control the output power of the photovoltaic system to cover the power consumption of ordinary loads.

[0141] As shown in Figure 3, the second power output value is obtained through controller 2. The second power feedback value of phase x First power reference value In this scenario, the role of controller 2 is to control the output power of the photovoltaic system to cover the power consumption of ordinary loads and target power load 540.

[0142] Simultaneously, output through residual power calculation module 1 ,when When the rated output power is reached, the output value of the residual power calculation module 1 remains constant, while the residual power calculation module 2 begins to output. .

[0143] As shown in Figure 4, for phase x, the first power output value of controller 1 is... As input, the first accumulated power output by the residual power calculation module 1 is... The first power reference value is obtained by using the first power reference lower limit as input and performing the first power output value. As the upper limit of the power reference, a second limiting is performed to obtain the second power reference value; finally, using the second power reference value as input, the residual power calculation module 2 outputs the second cumulative power. As the lower limit of the power reference, a third limiting is performed to obtain the target power reference value for phase x. It is used for output power control of phase x in power conversion device 520.

[0144] like The single-phase power consumption of each output phase is less than or equal to the minimum value of all single-phase metering power, and the surplus photovoltaic power of each phase can meet the power consumption of the smart load. At this time, the following relationship exists:

[0145] in, The actual usable photovoltaic power of the system, and the target power reference value for each phase at this time. .

[0146] like The surplus photovoltaic power of the phase with the lowest metering power at the grid connection point cannot meet the power consumption of ordinary loads and smart loads. The phase with the lowest power at the grid connection point begins to consume electricity. After implementing grid connection point power control, the following relationship exists:

[0147] As can be seen from the above formula, the three-phase output power of the power conversion device 520 is unbalanced at this time. According to the law of conservation of energy, we have:

[0148] As can be seen, compared with the control strategies in related technologies, the target electrical load 540 in this embodiment has a larger available power.

[0149] When the three-phase metering power at the grid connection point is 0, it indicates that all surplus photovoltaic power in the system has been absorbed by the target load 540. At this time, the target load 540 reaches its maximum available power, satisfying the following mathematical relationship:

[0150] It should be noted that in the above mathematical relationship, each character can be understood in two parts: the first part represents the power. Indicates the power measured at the grid connection point. Indicates the target power reference value. This indicates the second power output value. This indicates the power consumption of a typical load. The first part represents the power consumption of the target electrical load of 540. The second part is the meaning of the output phase: min represents the output phase corresponding to the minimum value among the three power values, mid represents the output phase corresponding to the middle value among the three power values, and max represents the output phase corresponding to the maximum value among the three power values.

[0151] Understandably, the target power reference value for each output phase is calculated independently. For the target electrical load 540 with unbalanced three-phase power, the power consumption of the target electrical load 540 can be gradually increased after startup. By utilizing the unbalanced control capability of the power conversion device 520, the surplus photovoltaic power can be redistributed, making full use of the surplus photovoltaic power, dynamically responding to the power demand of the load, and effectively improving energy utilization efficiency.

[0152] The control method for the power conversion device 520 provided in this application embodiment can be executed by the control device of the power conversion device 520. This application embodiment uses the example of the control device of the power conversion device 520 executing the control method of the power conversion device 520 to illustrate the control device of the power conversion device 520 provided in this application embodiment.

[0153] This application embodiment also provides a control device for a power conversion device 520. The input terminal of the power conversion device 520 is connected to a photovoltaic power generation device 510, and the output terminal of the power conversion device 520 is connected to a target electrical load 540 at a grid connection point. The output terminal of the power conversion device 520 includes at least two output phases.

[0154] As shown in Figure 7, the control device of the power conversion device 520 includes: a first processing module 710, used to acquire the current metering power of the grid connection point and the current power consumption of the target electrical load 540 when the target electrical load 540 is operating in photovoltaic surplus power supply mode, wherein the current metering power includes at least two single-phase metering powers corresponding to at least two output phases, and the current power consumption includes at least two single-phase power consumption corresponding to at least two output phases; and a second processing module 720, used to take the difference between the single-phase metering power and the single-phase power consumption of the output phase as the first power feedback value of the output phase, and to determine the first power of the output phase based on the first power feedback value and the first power reference value of the output phase. The output value; the third processing module 730 is used to take the single-phase metering power corresponding to the output as the second power feedback value of the output phase, and determine the second power output value of the output phase based on the second power feedback value and the second power reference value of the output phase; the fourth processing module 740 is used to obtain the target cumulative power of the photovoltaic power generation device 510, the target cumulative power is determined based on the photovoltaic power limiting power of the power conversion device 520 and the preset power increment; the fifth processing module 750 is used to determine the target power reference value of the output phase based on the first power output value corresponding to the output, the second power output value corresponding to the output and the target cumulative power as the power reference limit value, and control the output power of the output phase based on the target power reference value.

[0155] According to the control device of the power conversion device 520 provided in the embodiments of this application, by acquiring the first power output value, the second power output value and the target cumulative power of each output phase, using the first power output value as the input value, and using the corresponding second power output value and the target cumulative power as power reference limits, the first power output value is limited to determine the target power reference value of each output phase, and the output power of each output phase is controlled. This is applicable to the case where the target electrical load 540 is operating in the photovoltaic surplus power supply mode. By utilizing the unbalance control capability of the power conversion device 520, the photovoltaic surplus power is redistributed, making full use of the photovoltaic surplus power, dynamically responding to the power demand of the load, and effectively improving energy utilization efficiency.

[0156] In some embodiments, the target cumulative power includes a first cumulative power and a second cumulative power; the fourth processing module 740 is used to obtain the target cumulative power of the photovoltaic power generation device 510, including: obtaining the first cumulative power; and obtaining the second cumulative power when the first cumulative power reaches the rated output power of the power conversion device 520, wherein the first cumulative power is the rated output power of the power conversion device 520.

[0157] In some embodiments, the fifth processing module 750 is configured to determine a target power reference value for the output phase based on a first power output value corresponding to the output, and using a second power output value corresponding to the output and a target cumulative power as power reference limits, including: determining a first power reference value based on the first power output value and using the first cumulative power as a power reference lower limit; determining a second power reference value based on the first power reference value and using the second power output value as a power reference upper limit; and determining a target power reference value based on the second power reference value and using the second cumulative power as a power reference lower limit.

[0158] In some embodiments, when the single-phase power consumption of each output phase is less than or equal to the minimum of at least two single-phase metered power values, the target power reference value for each output phase is determined to be the second cumulative power.

[0159] In some embodiments, when the single-phase power consumption of the first output phase is greater than the single-phase metering power, the target power reference value of the first output phase is the second power output value, and the target power reference value of the second output phase is the second cumulative power.

[0160] The first output phase is the output phase corresponding to the minimum value of at least two single-phase metered power, and the second output phase is the output phase other than the first output phase among the at least two output phases.

[0161] In some embodiments, when at least two single-phase metered powers are both 0, the target power reference value for each output phase is the second power output value.

[0162] In some embodiments, the first cumulative power and the second cumulative power are calculated by the surplus power calculation module, which performs the following steps: when it is determined that the power reference value for the photovoltaic power generation device 510 to perform maximum power point tracking is greater than the power output value, the photovoltaic power limiting power is accumulated; the output power of the power conversion device 520 is increased by a preset power increment at preset time intervals until the output power of the power conversion device 520 reaches the rated output power; and the target cumulative power output by the surplus power calculation module is determined based on the photovoltaic power limiting power and the preset power increment.

[0163] In some embodiments, the first power reference value is 0, and the second power reference value is 0.

[0164] The control device of the power conversion device 520 in this embodiment can be an electronic device or a component in an electronic device, such as an integrated circuit or a chip.

[0165] The control device of the power conversion device 520 provided in this application embodiment can realize the various processes implemented in the above-described control method embodiment of the power conversion device 520. To avoid repetition, it will not be described again here.

[0166] This application also provides a power conversion device 520.

[0167] As shown in Figure 5, the input terminal of the power conversion device 520 is connected to the photovoltaic power generation device 510, and the output terminal of the power conversion device 520 is connected to the target electrical load 540 at the grid connection point. The output terminal of the power conversion device 520 includes at least two output phases.

[0168] In this embodiment, the power conversion device 520 also includes a control device as described above. The control device can control the output power of each output phase according to the target power reference value of each output phase.

[0169] In some embodiments, the target electrical load 540 includes at least one target sub-load, which is a single-phase electrical load or a multi-phase electrical load.

[0170] According to the power conversion device 520 provided in the embodiments of this application, by acquiring the first power output value, the second power output value, and the target cumulative power of each output phase, using the first power output value as the input value, and using the corresponding second power output value and the target cumulative power as power reference limits, the first power output value is limited to determine the target power reference value of each output phase and control the output power of each output phase. This is applicable to the case where the target electrical load 540 is operating in a photovoltaic surplus power supply mode. By utilizing the unbalance control capability of the power conversion device 520, the photovoltaic surplus power is redistributed, making full use of the photovoltaic surplus power, dynamically responding to the power demand of the load, and effectively improving energy utilization efficiency.

[0171] In some embodiments, the output phase of the power conversion device 520 is connected to one phase of the grid connection point of the single-phase power converter.

[0172] It is understood that the output of the power conversion device 520 includes at least two output phases, and the power conversion device 520 is a multi-phase power conversion device with unbalanced output capability; a single-phase power converter is a power conversion device with only one phase.

[0173] In this embodiment, the multiphase power conversion device 520 can be paralleled with the single-phase power converter. By utilizing the unbalanced output capability of the power conversion device 520, the output power of each output phase of the power conversion device 520 can be controlled by the control device to transfer the excess photovoltaic power of the single-phase power converter.

[0174] Taking the power conversion device 520 as a three-phase inverter and the single-phase power converter as a single-phase inverter as an example.

[0175] As shown in Figure 6, single-phase inverter 1 is connected to phase A, single-phase inverter 2 is connected to phase B, and single-phase inverter n is connected to phase C.

[0176] In related technologies, the smart load uses photovoltaic surplus power control. When the phase of the single-phase inverter connected to the grid 530 is inconsistent with the phase of the smart load connected to the grid 530, the photovoltaic surplus power output by the single-phase inverter cannot be transferred to the smart load due to the limitations of the actual physical wiring.

[0177] The embodiments of this application can utilize the unbalanced output capability of a three-phase inverter to transfer the surplus photovoltaic power of a single-phase inverter, thereby maximizing the utilization of surplus photovoltaic power.

[0178] In practice, the power sensor at the grid connection point can collect the active power (i.e., metered power) of each phase at the grid connection point. The active power of each phase can reflect the residual photovoltaic power of the single-phase inverter from the side. There is no need to establish communication with the single-phase inverter or obtain the specific information of the single-phase inverter's connected phase.

[0179] Assume the photovoltaic system consists of a three-phase inverter and a single-phase inverter connected in parallel. The photovoltaic-storage system is connected to several ordinary loads and several target power loads (540). The sum of the power consumption of the ordinary loads on phase x (x=a, b, c) is... The sum of the power consumption of the target electrical load 540 on phase x is .

[0180] The target electrical load 540 operates in photovoltaic surplus power supply mode. For the sake of simplicity, it is assumed that the three-phase inverter is not connected to the photovoltaic power generation device 510 or the photovoltaic power generation device 510 has no photovoltaic surplus power.

[0181] In this configuration, a single-phase inverter is connected to phase A of the three-phase inverter, the target electrical load 540 is connected to phase B of the three-phase inverter, and the power of the ordinary load is 0. A relationship exists. .

[0182] Assume the output power of the single-phase inverter is When the target electrical load 540 is not started, the power sensor samples the three-phase active power at the grid connection point as follows: .

[0183] After the target electrical load of 540 starts, phase A shows power selling and phase B shows power buying.

[0184] For controller 1, the control objective is to control the grid connection point power to be 0, and the first power feedback value is... The first power output value of phases A, B, and C is .

[0185] For controller 2, the control objective is to control the grid connection point power to be 0, and the second power feedback value... The second power output values ​​of phases A, B, and C are .

[0186] Following the calculation logic shown in Figure 4, the target power reference values ​​for each phase of the three-phase inverter are obtained. .

[0187] when At that time, the target power reference value for phases A, B, and C is The output power of the single-phase inverter on phase A can be transferred to phase B for use by the target electrical load 540 on phase B. At this time, the target electrical load 540 can absorb all the output power of the single-phase inverter.

[0188] when At that time, the target power reference value for phases A, B, and C is The output power of the single-phase inverter on phase A can be transferred to phase B to supply the target electrical load 540 on phase B, at which point the target electrical load 540 reaches its maximum power consumption.

[0189] In this embodiment, the first power output value is used as the input value, and the corresponding second power output value and the target cumulative power are used as the power reference limit. The first power output value is limited, and the target power reference value for each output phase is determined. The unbalanced control capability of the power conversion device 520 is used to redistribute the photovoltaic surplus power, transfer the photovoltaic surplus power of the single-phase inverter, maximize the utilization of photovoltaic surplus power, and effectively improve energy utilization efficiency.

[0190] In some embodiments, as shown in FIG8, this application embodiment also provides an electronic device 800, including a processor 801, a memory 802, and a computer program stored in the memory 802 and executable on the processor 801. When the program is executed by the processor 801, it implements the various processes of the control method embodiment of the power conversion device 520 described above and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0191] It should be noted that the electronic devices in the embodiments of this application include the mobile electronic devices and non-mobile electronic devices described above.

[0192] This application also provides a non-transitory computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the various processes of the control method embodiment of the power conversion device 520 described above and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0193] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0194] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the control method of the power conversion device 520 described above.

[0195] The processor is the processor in the electronic device described in the above embodiments. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk.

[0196] This application embodiment also provides a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run programs or instructions to implement the various processes of the control method embodiment of the power conversion device 520 described above, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0197] It should be understood that the chip mentioned in the embodiments of this application may also be referred to as a system-on-a-chip, system chip, chip system, or system-on-a-chip, etc.

[0198] It should be noted that, in this document, 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 comprises a list of elements includes not only those elements but also 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. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0199] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the related technology, can be embodied in the form of a computer software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0200] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

[0201] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0202] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A control method for a power conversion device, characterized in that, The input terminal of the power conversion device is connected to the photovoltaic power generation device, and the output terminal of the power conversion device is connected to the target electrical load at the grid connection point. The output terminal of the power conversion device includes at least two output phases. The method includes: when the target electrical load is operating in the photovoltaic surplus power supply mode, obtaining the current metering power of the grid connection point and obtaining the current electrical power consumption of the target electrical load, wherein the current metering power includes at least two single-phase metering powers corresponding one-to-one with the at least two output phases, and the current electrical power consumption includes at least two single-phase electrical power consumptions corresponding one-to-one with the at least two output phases; using the difference between the single-phase metering power and the single-phase electrical power consumption of the output phase as the first power feedback value of the output phase, and based on the output phase... The first power feedback value and the first power reference value are used to determine the first power output value of the output phase; the single-phase metering power corresponding to the output is used as the second power feedback value of the output phase, and the second power output value of the output phase is determined based on the second power feedback value and the second power reference value of the output phase; the target cumulative power of the photovoltaic power generation device is obtained, and the target cumulative power is determined based on the photovoltaic power limiting power of the power conversion device and the preset power increment; based on the first power output value corresponding to the output, the second power output value corresponding to the output and the target cumulative power are used as power reference limits to determine the target power reference value of the output phase, and the output power of the output phase is controlled based on the target power reference value.

2. The control method for the power conversion device according to claim 1, characterized in that, The target cumulative power includes a first cumulative power and a second cumulative power; obtaining the target cumulative power of the photovoltaic power generation device includes: obtaining the first cumulative power; and obtaining the second cumulative power when the first cumulative power reaches the rated output power of the power conversion device, wherein the first cumulative power is taken as the rated output power of the power conversion device.

3. The control method for the power conversion device according to claim 2, characterized in that, The step of determining the target power reference value of the output phase based on the first power output value corresponding to the output, and using the second power output value corresponding to the output and the target cumulative power as power reference limits, includes: determining a first power reference value based on the first power output value and using the first cumulative power as a power reference lower limit; determining a second power reference value based on the first power reference value and using the second power output value as a power reference upper limit; and determining the target power reference value based on the second power reference value and using the second cumulative power as a power reference lower limit.

4. The control method for the power conversion device according to claim 3, characterized in that, When the single-phase power consumption of each output phase is less than or equal to the minimum of the at least two single-phase metered power values, the target power reference value for each output phase is determined to be the second cumulative power.

5. The control method for the power conversion device according to claim 3, characterized in that, When the single-phase power consumption of the first output phase is greater than the single-phase metered power, the target power reference value of the first output phase is the second power output value, and the target power reference value of the second output phase is the second cumulative power. The first output phase is the output phase corresponding to the minimum value of the at least two single-phase metered power, and the second output phase is the output phase other than the first output phase among the at least two output phases.

6. The control method for the power conversion device according to claim 3, characterized in that, When the power of at least two single-phase meters is 0, the target power reference value for each output phase is the second power output value.

7. The control method for the power conversion device according to claim 2, characterized in that, The first cumulative power and the second cumulative power are calculated by the surplus power calculation module, which performs the following steps: when the power reference value for the photovoltaic power generation device to perform maximum power point tracking is greater than the power output value, the photovoltaic power limiting power is accumulated; the output power of the power conversion device is increased by the preset power increment at preset time intervals until the output power of the power conversion device reaches the rated output power; based on the photovoltaic power limiting power and the preset power increment, the target cumulative power output by the surplus power calculation module is determined.

8. The control method for the power conversion device according to any one of claims 1-7, characterized in that, The first power reference value is 0, and the second power reference value is 0.

9. A control device for a power conversion device, characterized in that, The input terminal of the power conversion device is connected to the photovoltaic power generation device, and the output terminal of the power conversion device is connected to the target electrical load at the grid connection point. The output terminal of the power conversion device includes at least two output phases. The control device includes: a first processing module, used to obtain the current metering power of the grid connection point and the current electrical power consumption of the target electrical load when the target electrical load is operating in the photovoltaic surplus power supply mode. The current metering power includes at least two single-phase metering powers corresponding to the at least two output phases, and the current electrical power consumption includes at least two single-phase electrical power consumptions corresponding to the at least two output phases; a second processing module, used to take the difference between the single-phase metering power and the single-phase electrical power consumption of the output phase as the first power feedback value of the output phase, and based on the first power feedback value of the output phase... A first power output value for the output phase is determined using a power feedback value and a first power reference value; a third processing module is used to take the single-phase metering power corresponding to the output as the second power feedback value of the output phase, and determine the second power output value of the output phase based on the second power feedback value and the second power reference value of the output phase; a fourth processing module is used to obtain the target cumulative power of the photovoltaic power generation device, the target cumulative power being determined based on the photovoltaic power limiting power of the power conversion device and a preset power increment; a fifth processing module is used to determine the target power reference value of the output phase based on the first power output value corresponding to the output, using the second power output value corresponding to the output and the target cumulative power as power reference limits, and control the output power of the output phase based on the target power reference value.

10. A power conversion device, characterized in that, The input terminal of the power conversion device is connected to the photovoltaic power generation device, and the output terminal of the power conversion device is connected to the target electrical load at the grid connection point. The output terminal of the power conversion device includes at least two output phases. The power conversion device includes the control device of the power conversion device as described in claim 9.

11. The power conversion device according to claim 10, characterized in that, The target electrical load includes at least one target sub-load, which can be a single-phase electrical load or a multi-phase electrical load.

12. The power conversion device according to claim 10, characterized in that, The output phase of the power conversion device is connected to one phase of the single-phase power converter at the grid connection point.

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