Inverter output power single-phase independent control method, energy storage inverter and system

Abstract

The invention relates to a single-phase independent control method for inverter output power, an energy storage inverter and a system. A U phase, a V phase and a W phase of the energy storage inverter are connected with a power grid through a measuring electricity meter, and the U phase, the V phase and the W phase can be independently connected with single-phase loads. Acquiring the output power of a first target phase and the electricity buying power of the first target phase acquired by the measurement electricity meter in real time; when the electricity buying power of the first target phase is not zero, the output power of the first target phase is increased until the electricity buying power is zero, and the first target phase is at least one of the U phase, the V phase and the W phase. By adopting the method, the independent control of different phases of the energy storage inverter on the power purchasing power of the power grid is realized, the energy storage inverter is enabled to adaptively adjust the output power, the power is not purchased from the power grid at an unnecessary moment, and the working benefit of the energy storage inverter is improved.

Description

Technical Field

[0001] The present application relates to the technical field of inverters, and in particular to a single-phase independent control method of inverter output power, an energy storage inverter and a system. Background Art

[0002] As new energy power generation systems represented by photovoltaic power generation have been widely used, the demand for intelligent household electricity consumption is getting higher and higher. However, when using the current photovoltaic storage system, it is impossible to achieve accurate control of the purchase and sale of power on the grid according to the tiered rate electricity price system and the time-of-use electricity price system for each of the three phases of the energy storage inverter, which can easily lead to over-buying and under-selling of electricity, causing economic losses to users. Summary of the invention

[0003] Based on this, it is necessary to provide a single-phase independent control method, energy storage inverter and system that can enable the energy storage inverter to adaptively adjust the single-phase output power and achieve inverter output power without static error regulation.

[0004] In a first aspect, a single-phase independent control method for inverter output power is provided, which is applied to an energy storage inverter, wherein the U phase, V phase, and W phase of the energy storage inverter are connected to a power grid through a measuring meter, and the U phase, V phase, and W phase of the energy storage inverter can be independently connected to a single-phase load, and the energy storage inverter is connected to a photovoltaic module, wherein the photovoltaic module is used to provide energy for the energy storage inverter and the single-phase load, and the measuring meter is used to collect the power purchased by the U phase, V phase, and W phase of the energy storage inverter from the power grid, and the method comprises:

[0005] When the energy storage inverter works in the grid feeding mode to supply power to each of the single-phase loads, the output power of the first target phase and the purchased power of the first target phase collected by the measuring electric meter are obtained in real time;

[0006] When the purchased power of the first target phase is not zero, the output power corresponding to the first target is increased until the purchased power is zero, and the first target phase is at least one of the U phase, the V phase and the W phase.

[0007] In one embodiment, when the purchased power of the first target phase is not zero, increasing the output power corresponding to the first target until the purchased power is zero includes:

[0008] If the purchased power of the first target phase is not zero, the phase current output on the first target phase is controlled to increase so as to increase the output power of the first target phase until the purchased power of the first target phase is zero.

[0009] In one embodiment, the measurement electric meter is further configured to collect the power sold from each of the U-phase, V-phase, and W-phase of the energy storage inverter to the power grid; the method further includes:

[0010] When the energy storage inverter operates in the grid feeding mode to supply power to each of the single-phase loads, the output power of the second target phase and the power sold from the second target phase collected on the measurement electric meter are acquired in real time;

[0011] When the power sold from the second target phase is less than the reference grid feeding power of the second target phase, the output power of the second target phase is increased until the power sold is equal to the reference grid feeding power of the second target phase. The second target phase is at least one of the U-phase, V-phase, and W-phase, and the reference grid feeding power of the second target phase changes in real time according to the power supply state of the energy storage inverter.

[0012] In one embodiment, the step of increasing the output power of the second target phase until the power sold is equal to the reference grid feeding power of the second target phase when the power sold from the second target phase is less than the reference maximum grid feeding power of the second target phase includes:

[0013] If the power sold from the second target phase is less than the reference grid feeding power of the second target phase, then the phase current output on the second target phase is controlled to increase so as to increase the output power of the second target phase until the power sold is equal to the reference grid feeding power of the second target phase.

[0014] In one embodiment, the energy storage inverter is connected to a battery, and the method further includes:

[0015] When the energy storage inverter operates in the battery charging mode, the reference grid feeding power of the third target phase of the energy storage inverter and the output power of the third target phase are acquired in real time. The third target phase is at least one of the U-phase, V-phase, and W-phase;

[0016] Calculate the power error between the reference grid feeding power of the third target phase and the output power of the third target phase;

[0017] Based on the power error, the output power of the energy storage inverter is controlled to increase or decrease so as to control the energy storage inverter to buy or sell power from the power grid until the power error is zero.

[0018] In one embodiment, the step of controlling the energy storage inverter to buy or sell power from the power grid until the power error is zero based on the power error includes:

[0019] If the reference grid-fed power of the third target phase is less than zero, the output power of the third target phase is less than zero and the power error is negative, then the current charging power of the battery is less than the preset maximum charging power of the battery;

[0020] The phase current output on the third target phase is controlled to increase in the reverse direction, and the output power of the energy storage inverter is reduced, thereby controlling the energy storage inverter to buy electricity from the power grid until the power error is zero.

[0021] In one embodiment, controlling the energy storage inverter to buy or sell electricity from the power grid based on the power error until the power error is zero further includes:

[0022] If the reference grid-fed power of the third target phase is greater than zero, the output power of the third target phase is greater than zero and the power error is negative, the current charging power of the battery is equal to the preset maximum charging power of the battery, and there is unused energy in the photovoltaic module;

[0023] The phase current output on the third target phase is controlled to increase, and the output power of the energy storage inverter is increased, so as to control the energy storage inverter to sell electricity to the power grid until the power error is zero.

[0024] In a second aspect, an energy storage inverter is provided, the energy storage inverter comprising a control unit, the control unit being used to implement the single-phase independent control method of the inverter output power as described in any one of the first aspects above.

[0025] In a third aspect, a single-phase independent control system of an inverter output power is provided, the system comprising an energy storage inverter, a measuring meter, a photovoltaic module, a battery and a single-phase load, at least one of the U phase, V phase and W phase of the energy storage inverter is connected to the grid through the measuring meter, the photovoltaic module and the battery are respectively connected to the energy storage inverter, and the U phase, V phase and W phase of the energy storage inverter can be independently connected to the single-phase load;

[0026] Among them, the measuring electric meter is used to collect the power purchased by the U phase, V phase and W phase of the energy storage inverter from the power grid; the energy generated by the photovoltaic module is used to provide energy for the energy storage inverter, the battery and the single-phase load; the energy storage inverter is used to implement the single-phase independent control method of the inverter output power as described in any one of the first aspects above.

[0027] In one of the embodiments, the measuring electric meter is also used to collect the power sold by the U phase, V phase, and W phase of the energy storage inverter to the power grid.

[0028] The above-mentioned single-phase independent control method of the inverter output power, energy storage inverter and system, when the energy storage inverter works in the feeding mode to supply power to each single-phase load, obtains the output power of the first target phase and the corresponding purchased power collected on the measuring meter in real time; when the purchased power of the first target phase is not zero, the output power corresponding to the first target is increased until the purchased power is zero, thereby realizing the independent control of the purchased power of the energy storage inverter to the grid for different phases, meeting the different load requirements, feeding power requirements and purchased power requirements of different phases, allowing the energy storage inverter to adaptively adjust the output power, not to purchase electricity from the grid when it is not necessary, and improving the efficiency of the energy storage inverter when it is working. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 This is an application scenario diagram of a single-phase independent control method of inverter output power according to an embodiment;

[0031] Figure 2 It is a flow chart of output power regulation when the energy storage inverter has purchased power in one embodiment;

[0032] Figure 3 is a working principle diagram of a power control loop in one embodiment;

[0033] Figure 4 It is a flow chart of output power regulation when the energy storage inverter has selling power in one embodiment;

[0034] Figure 5 It is a flow chart of an energy storage inverter in an embodiment when it works in a battery charging mode;

[0035] Figure 6 The figure is a flow chart of calculating the preset maximum grid feeding power in one embodiment. DETAILED DESCRIPTION

[0036] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] In one embodiment, a single-phase independent control method for the output power of an inverter is provided, which is applied to an energy storage inverter as shown in Figure 1 . At least one of the U-phase, V-phase, and W-phase of the energy storage inverter 10 is connected to the power grid through a measuring meter 20. The energy storage inverter 10 is respectively connected to the photovoltaic module 30 and the battery 40. The U-phase, V-phase, and W-phase of the energy storage inverter 10 can all be independently connected to a single-phase load load. The measuring meter 20 is used to collect the power sold to or bought from the power grid by the U-phase, V-phase, and W-phase of the energy storage inverter 10 respectively. On the measuring meter 20, if the measured power Pmeter is positive, it represents selling power to the power grid; if the measured power Pmeter is negative, it represents buying power from the power grid. The photovoltaic module is used to provide energy for the energy storage inverter and the battery.

[0039] As shown in Figure 2 , the single-phase independent control method for the output power of the inverter provided in this embodiment specifically includes the following steps 101 to step 102:

[0040] Step 101, when the energy storage inverter is operating in the power feeding mode to supply power to each single-phase load, the output power of the first target phase and the power bought from the power grid collected on the measuring meter are obtained in real time.

[0041] Step 102, when the power bought from the power grid of the first target phase is not zero, increase the output power corresponding to the first target phase until the power bought from the power grid is zero. The first target phase is at least one of the U-phase, V-phase, and W-phase.

[0042] First, the energy supplied by the photovoltaic module 30 to the energy storage inverter 10 will be used to charge the battery 40. If there is a connected single-phase load, it can also supply power to the single-phase load. Further, if there is still excess energy under the condition of satisfying battery energy storage and load carrying, power can be sold to the power grid (i.e., power feeding). When the power generation of the photovoltaic module is sufficient, such as during the day, power feeding can be performed at a preset maximum power feeding value. In this embodiment, the state of feeding the excess power in the photovoltaic system to the power grid and selling power to the power grid is called the power feeding mode. In the power feeding mode, it is necessary to avoid buying power.

[0043] In order to improve the overall benefits of the photovoltaic system, it is necessary to adjust when the energy storage inverter 10 sells electricity and when it buys electricity. For example, in the peak electricity price range, the photovoltaic module generates a large amount of electricity. The energy storage inverter can sell electricity to the grid with the maximum grid-feeding power when basic needs are met to maximize benefits. In the valley electricity price range, the photovoltaic system has insufficient production capacity, which makes the energy storage inverter 10 insufficient to supply power to the battery or insufficient to carry load. In this case, it will give priority to buying electricity from the grid to obtain electricity at a lower price and store it in the battery.

[0044] In the grid-feeding mode, if there is excess energy in the energy storage inverter, it will sell electricity to the grid, and minimize the power purchased from the grid. However, sometimes, in the grid-feeding mode, in order to prevent the occurrence of reverse flow, that is, the energy storage inverter sells electricity to the grid, the maximum grid-feeding power of the energy storage inverter needs to be set to zero. At this time, although the energy storage inverter 10 is working in the grid-feeding mode, since the maximum grid-feeding power is zero, that is, the reference grid-feeding power is zero, if the single-phase load load is connected to the first target phase of the energy storage inverter 10, the measuring meter 20 will show that the measured power Pmeter of the first target phase is negative, and the purchased power is generated. In order not to buy electricity from the grid in the grid-feeding mode, the present application controls the energy storage inverter 10 to increase the output power of the first target phase to compensate for the negative part of the measuring meter until the purchased power is zero, thereby avoiding the energy storage inverter from buying electricity from the grid in the grid-feeding mode.

[0045] In detail, the energy storage inverter 10 adjusts the phase current of the target phase through the power control loop to adjust the output power of the target phase. The working principle of the power control loop is as follows: Figure 3 As shown, Pfeed represents the feedback power. In the grid-feeding mode, the feedback power value is the measured power Pmeter of the measuring meter. Pref represents the reference grid-feeding power. Error represents the difference between the reference grid-feeding power and the feedback power. PI represents PI regulation. Limit represents the limiting condition. Ipwr represents the phase current. The limit limiting condition is the maximum forward current Imax and the maximum reverse current -Imax that the machine can withstand, which are determined by the machine hardware design. Both of them are fixed.

[0046] Specifically, when the energy storage inverter works in the grid feeding mode to supply power to each of the single-phase loads, and the maximum grid feeding power of the energy storage inverter is set to zero, if the purchased power of the first target phase is not zero, that is, the measured power Pmeter < 0, the energy storage inverter 10 controls the phase current output on the first target phase to increase through the power control loop to increase the output power of the first target phase until the purchased power of the first target phase is zero and the output power of the first target phase is stable. Among them, the phase current output on the first target phase is greater than zero.

[0047] In one embodiment, as Figure 4 shown, when the preset maximum feed network power is not zero, that is, when the anti-backflow needs not be considered, if the energy storage inverter 10 is operating in the feed network mode to supply power to the single-phase load load of the second target phase and there is excess energy, it means that in addition to supplying power to the single-phase load load, the energy storage inverter 10 also needs to feed the excess energy into the grid and sell electricity to the grid. At this time, the measured power Pmeter of the second target phase on the measurement meter 20 is positive, and the selling power is collected. The method further includes the following steps 201 to step 202:

[0048] Step 201, when the energy storage inverter is operating in the feed network mode to supply power to each of the single-phase loads, obtain the output power of the second target phase and the selling power of the second target phase collected on the measurement meter in real time.

[0049] Step 202, when the selling power of the second target phase is less than the reference feed network power of the second target phase, increase the output power on the second target phase until the selling power is equal to the reference feed network power of the second target phase, and the second target phase is at least one of the U phase, V phase, and W phase.

[0050] Among them, the reference feed network power of the second target phase changes in real time with the power supply state of the energy storage inverter. Specifically, when the energy storage inverter is operating in the feed network mode to supply power to each of the single-phase loads, if the selling power at this time is less than the reference feed network power of the second target phase of the energy storage inverter 10, it means that the excess energy of the energy storage inverter has not been fully supplied to the feed network at this time. Then, the energy storage inverter controls the phase current output on the second target phase to increase through the Figure 3 power control loop shown in the figure to increase the output power on the second target phase until the selling power is equal to the reference feed network power of the second target phase.

[0051] When the energy storage inverter is operating in the feed network mode and supplying power to the single-phase load and there is excess energy, in the Figure 3 power control loop shown in the figure, at this time, the reference feed network power Pref of the second target phase = (Ppv - Pbatcharge) / 3 - Pload, where Ppv is the power generated by the photovoltaic module, Pbatcharge is the maximum charging power allowed by the current SOC of the battery, and Pload is the single-phase load power. Among them, 0 <= Pref <= Pset, 0 <= Pset + Pload <= Pmax, and the measured power Pmeter represented by Pfeed is the selling power, that is, Pmeter > 0. Among them, Pset is the externally set single-phase maximum feed network power, and Pmax is the maximum output power allowed for a single phase of the energy storage inverter determined by the hardware design circuit.

[0052] Preferably, if the power Ppv generated by the photovoltaic module is greater than the sum of the battery charging power Pbatcharge and the total single-phase load power, the result of 1 / 3Ppv-(1 / 3Pbatcharge+Pload) is added to the reference grid feed power Pref calculated for the second target phase, otherwise it is not added. The purpose of this is to use the energy of the photovoltaic module for battery charging, load carrying and grid feeding as much as possible when there is surplus energy in the photovoltaic module, to maximize the effective use of all the energy of the photovoltaic module, and to allow the battery energy to store energy as much as possible for use with load when the photovoltaic module energy is insufficient. When the battery is discharging, it is necessary to reduce the energy discharged by the battery to ensure that all the energy generated by the photovoltaic module can be effectively utilized without consuming battery energy.

[0053] In this embodiment, when grid feeding is required, the grid feeding power is automatically adjusted according to the power generation power of the photovoltaic module. After ensuring that the output load can be met and no electricity is purchased from the grid, the excess energy is used to charge the battery to ensure that the battery stores enough energy. After that, the remaining energy of the photovoltaic module is automatically fed back to the grid to sell electricity to the grid for subsequent use, thereby maximizing benefits.

[0054] In one embodiment, if Figure 5 As shown, the method further includes the following steps 301 to 303:

[0055] Step 301, when the energy storage inverter operates in a battery charging mode, real-time acquisition of a reference grid-fed power of a third target phase of the energy storage inverter and an output sampling power of the third target phase, wherein the third target phase is at least one of the U phase, the V phase, and the W phase.

[0056] Step 302: Calculate the power error between the reference grid-fed power of the third target phase and the output sampled power of the third target phase.

[0057] Step 303: Based on the power error, control the output power of the energy storage inverter to increase or decrease, so as to control the energy storage inverter to buy or sell electricity from the power grid until the power error is zero.

[0058] Specifically, when the energy storage inverter works in the battery charging mode, the supplied load is not considered, the battery is fully charged, and the purchase of electricity from the power grid to charge the battery is required as little as possible. If the energy generated by the photovoltaic module 30 is sufficient to meet the battery charging and has surplus, it will automatically output the load and feed the grid. However, when the energy generated by the photovoltaic module 30 is not enough to charge the battery, the energy storage inverter 10 will have the need to buy electricity from the grid to charge the battery. Therefore, it is necessary to obtain the reference grid-fed power and the output sampled power of the third target phase when the energy storage inverter is charging the battery, and determine the required purchase power or sale power by calculating the power error between the reference grid-fed power of the third target phase and the output sampled power of the third target phase, so as to control the output power of the energy storage inverter to increase or decrease until the power error is zero.

[0059] Among them, when the energy generated by the photovoltaic module 30 is insufficient to charge the battery, the reference grid-fed power of the third target phase is less than zero, the output sampling power of the third target phase is less than zero and the power error between the two is negative, indicating that the current charging power of the battery is less than the preset maximum charging power of the battery; by Figure 3 The power control loop shown controls the phase current output on the third target phase to increase in the reverse direction, so as to control the energy storage inverter to buy electricity from the power grid, and the input power of the third target phase of the energy storage inverter increases until the power error is zero. Optionally, when the power Ppv of the photovoltaic module gradually increases to exceed the maximum charging power allowed by the battery as the lighting conditions improve, the power flow direction of the inverter is automatically adjusted from the power grid buying direction to the power grid selling direction, and the power of the photovoltaic module Ppv greater than the maximum charging power of the battery is automatically output and loaded until it is fed to the grid, reducing the energy of the load driven by the power grid buying electricity, until it actively sells electricity to the grid to make up for the previous power purchase loss.

[0060] Among them, when the energy generated by the photovoltaic module 30 is sufficient to charge the battery, the reference grid-feeding power of the third target phase is greater than zero, the output sampling power of the third target phase is greater than zero and the power error between the two is negative, indicating that the current charging power of the battery is equal to the preset maximum charging power of the battery, and the photovoltaic module has excess energy for load and grid feeding; the energy storage inverter 10 controls the phase current output on the third target phase to increase through the power control loop to control the energy storage inverter to sell electricity to the power grid, and the output power of the energy storage inverter increases until the power error is zero, thereby realizing zero-static error control.

[0061] Preferably, when the energy storage inverter operates in the battery charging mode, Figure 3In the power control loop shown, the reference grid-connected power Pref' of the third target phase = (Ppv - Pbatcharge) / 3, where Ppv is the power generated by the photovoltaic module and Pbatcharge is the maximum charging power allowed by the current SOC of the battery. At this time, -Pmax <= Pref' <= Pload + Pset, and Pload + Pset <= Pmax, where -Pmax is the maximum input power allowed for a single phase of the energy storage inverter determined by the hardware design circuit. Pfeed represents the feedback power, and at this time, the value of Pfeed is the output sampling power of the third target phase of the energy storage inverter.

[0062] In this embodiment, through the single-phase independent control of the energy storage inverter, different phase loadings, grid-connected powers, and purchased power requirements can be satisfied, realizing the control of unbalanced three-phase power output. The response speed and stability of the output power of the target phase are precisely controlled through a closed-loop power control loop, achieving static error-free control, and the power output is faster and smoother.

[0063] As Figure 6 shown, a flowchart for calculating the reference grid-connected power Pref of the target phase in the grid-connected mode of the energy storage inverter or the reference grid-connected power Pref' of the third target phase in the battery charging mode is provided. The reference grid-connected power changes in real time with the operating mode of the energy storage inverter, the single-phase load power, and the maximum charging power of the battery.

[0064] In one embodiment, an energy storage inverter is provided. The energy storage inverter includes a control unit, and the control unit is used to implement the single-phase independent control method of the inverter output power as described in any one of the above embodiments.

[0065] In one embodiment, a single-phase independent control system for the inverter output power is provided. The system block diagram is as Figure 1 shown, and it includes an energy storage inverter 10, a measuring meter 20, a photovoltaic module 30, a battery 40, and a single-phase load load. The U phase, V phase, and W phase of the energy storage inverter 10 are connected to the power grid through the measuring meter 20. The energy storage inverter 10 is connected to the battery 40, and the U phase, V phase, and W phase of the energy storage inverter can be independently connected to the single-phase load load.

[0066] Among them, the measuring meter 20 is used to collect the purchased power of the U phase, V phase, and W phase of the energy storage inverter to the power grid respectively. The energy generated by the photovoltaic module 30 is used to provide energy for the energy storage inverter 10, the battery 40, and the single-phase load load.

[0067] In one embodiment, the energy storage inverter is used to: when the energy storage inverter works in the grid feeding mode to supply power to each of the single-phase loads, obtain the output power of the first target phase and the purchased power of the first target phase collected by the measuring electric meter in real time. When the purchased power of the first target phase is not zero, increase the output power corresponding to the first target until the purchased power is zero, and the first target phase is at least one of the U phase, V phase and W phase.

[0068] In one embodiment, the energy storage inverter is also used to: if the purchased power of the first target phase is not zero, control the phase current output on the first target phase to increase so as to increase the output power of the first target phase until the purchased power of the first target phase is zero.

[0069] In one of the embodiments, the measuring electric meter is also used to collect the power sold by the U phase, V phase, and W phase of the energy storage inverter to the power grid.

[0070] In one of the embodiments, the energy storage inverter is also used for: when the energy storage inverter operates in the grid feeding mode to supply power to each of the single-phase loads, obtaining in real time the output power of the second target phase and the corresponding selling power collected on the measuring meter; when the selling power of the second target phase is less than the reference grid feeding power of the second target phase, increasing the output power of the second target phase until the selling power is equal to the reference grid feeding power of the second target phase, the second target phase is at least one of the U phase, V phase and W phase, and the reference grid feeding power of the second target phase changes in real time with the power supply status of the energy storage inverter.

[0071] In one of the embodiments, the energy storage inverter is also used to: if the electricity selling power of the second target phase is less than the reference grid feeding power of the second target phase, control the phase current output on the second target phase to increase so as to increase the output power on the second target phase until the electricity selling power is equal to the reference grid feeding power of the second target phase.

[0072] In one of the embodiments, the energy storage inverter is also used for: when the energy storage inverter operates in a battery charging mode, obtaining in real time a reference grid-fed power of a third target phase of the energy storage inverter and an output sampled power of the third target phase, wherein the third target phase is at least one of the U phase, the V phase, and the W phase; calculating a power error between the reference grid-fed power of the third target phase and the output sampled power of the third target phase; and based on the power error, controlling the output power of the energy storage inverter to increase or decrease, so as to control the energy storage inverter to buy or sell electricity to the power grid until the power error is zero.

[0073] In one of the embodiments, the energy storage inverter is also used for: if the reference grid-fed power of the third target phase is less than zero, the output sampling power of the third target phase is less than zero and the power error is negative, then the current charging power of the battery is less than the preset maximum charging power of the battery; controlling the phase current output on the third target phase to increase in the reverse direction, and reducing the output power of the energy storage inverter, thereby controlling the energy storage inverter to buy electricity from the power grid until the power error is zero.

[0074] In one embodiment, the energy storage inverter is also used for: if the reference grid-fed power of the third target phase is greater than zero, the output sampling power of the third target phase is greater than zero and the power error is negative, then the current charging power of the battery is equal to the preset maximum charging power of the battery, and there is unused energy in the photovoltaic module; controlling the phase current output on the third target phase to increase, and the output power of the energy storage inverter to increase, thereby controlling the energy storage inverter to sell electricity to the power grid until the power error is zero.

[0075] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0076] It can be understood that the “connection” in the above embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0077] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least part of an element” means part or all of an element.

[0078] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0079] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic description of the above terms does not necessarily refer to the same embodiment or example.

[0080] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0081] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A single-phase independent control method for inverter output power, applied to an energy storage inverter, wherein the U phase, V phase, and W phase of the energy storage inverter are connected to the power grid through a measuring meter, and the U phase, V phase, and W phase of the energy storage inverter can be independently connected to a single-phase load, and the energy storage inverter is connected to a photovoltaic module, wherein: The photovoltaic module is used to provide energy for the energy storage inverter and the single-phase load, and the measuring electric meter is used to collect the power purchased by the U phase, V phase, and W phase of the energy storage inverter from the power grid. The method includes: When the energy storage inverter operates in the grid feeding mode to supply power to each of the single-phase loads, the output power of the first target phase and the purchased power of the first target phase collected by the measuring electric meter are obtained in real time; When the purchased power of the first target phase is not zero, the output power of the first target phase is increased until the purchased power is zero, and the first target phase is at least one of the U phase, the V phase and the W phase.

2. The single-phase independent control method of inverter output power according to claim 1, characterized in that: When the purchased power of the first target phase is not zero, increasing the output power corresponding to the first target until the purchased power is zero includes: If the purchased power of the first target phase is not zero, the phase current output on the first target phase is controlled to increase so as to increase the output power of the first target phase until the purchased power of the first target phase is zero.

3. The single-phase independent control method of inverter output power according to claim 1, characterized in that: The measuring electric meter is also used to collect the power sold by the U phase, V phase, and W phase of the energy storage inverter to the power grid; the method also includes: When the energy storage inverter operates in the grid feeding mode to supply power to each of the single-phase loads, the output power of the second target phase and the selling power of the second target phase collected by the measuring electric meter are obtained in real time; When the electricity selling power of the second target phase is less than the reference grid feeding power of the second target phase, the output power of the second target phase is increased until the electricity selling power is equal to the reference grid feeding power of the second target phase, the second target phase is at least one phase among the U phase, V phase and W phase, and the reference grid feeding power of the second target phase changes in real time with the power supply status of the energy storage inverter.

4. The single-phase independent control method of inverter output power according to claim 3, characterized in that: When the electricity selling power of the second target phase is less than the reference grid feeding power of the second target phase, increasing the output power on the second target phase until the electricity selling power is equal to the reference grid feeding power of the second target phase includes: If the electricity selling power of the second target phase is less than the reference grid feeding power of the second target phase, the phase current output on the second target phase is controlled to increase so as to increase the output power on the second target phase until the electricity selling power is equal to the reference grid feeding power of the second target phase.

5. The single-phase independent control method of inverter output power according to claim 1, characterized in that: The energy storage inverter is connected to a battery, and the method further comprises: When the energy storage inverter operates in a battery charging mode, a reference grid-fed power of a third target phase of the energy storage inverter and an output sampling power of the third target phase are acquired in real time, wherein the third target phase is at least one of the U phase, the V phase, and the W phase; Calculating a power error between a reference grid-fed power of the third target phase and an output sampled power of the third target phase; Based on the power error, the output power of the energy storage inverter is controlled to increase or decrease, so as to control the energy storage inverter to buy or sell electricity from the power grid until the power error is zero.

6. The single-phase independent control method of inverter output power according to claim 5, characterized in that: The step of controlling the energy storage inverter to buy or sell electricity from the power grid based on the power error until the power error is zero includes: If the reference grid-fed power of the third target phase is less than zero, the output sampled power of the third target phase is less than zero and the power error is negative, then the current charging power of the battery is less than the preset maximum charging power of the battery; The phase current output on the third target phase is controlled to increase in the reverse direction, and the output power of the energy storage inverter is reduced, thereby controlling the energy storage inverter to buy electricity from the power grid until the power error is zero.

7. The single-phase independent control method of inverter output power according to claim 5, characterized in that: The step of controlling the energy storage inverter to buy or sell electricity from the power grid based on the power error until the power error is zero further includes: If the reference grid-fed power of the third target phase is greater than zero, the output sampled power of the third target phase is greater than zero and the power error is negative, the current charging power of the battery is equal to the preset maximum charging power of the battery, and there is unused energy in the photovoltaic module; The phase current output on the third target phase is controlled to increase, and the output power of the energy storage inverter is increased, so as to control the energy storage inverter to sell electricity to the power grid until the power error is zero.

8. An energy storage inverter, characterized in that: It comprises a control unit, which is used to implement the single-phase independent control method of the inverter output power according to any one of claims 1 to 7.

9. A single-phase independent control system for inverter output power, characterized in that: The system comprises the energy storage inverter as claimed in claim 8, a measuring meter, a photovoltaic module, a battery and a single-phase load, at least one of the U phase, V phase and W phase of the energy storage inverter is connected to the power grid through the measuring meter, the photovoltaic module and the battery are respectively connected to the energy storage inverter, and the U phase, V phase and W phase of the energy storage inverter can be independently connected to the single-phase load; Among them, the measuring electric meter is used to collect the power purchased by the U phase, V phase and W phase of the energy storage inverter from the power grid; the energy generated by the photovoltaic module is used to provide energy for the energy storage inverter, the battery and the single-phase load; the energy storage inverter is used to implement the single-phase independent control method of the inverter output power as described in any one of claims 1 to claim 7.

10. The single-phase independent control system of the inverter output power according to claim 9, characterized in that: The measuring electric meter is also used to collect the power sold by the U phase, V phase and W phase of the energy storage inverter to the power grid.

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