CN114865690A - Three-phase micro inverter device, system and control method thereof - Google Patents
Three-phase micro inverter device, system and control method thereof Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/40—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation wherein a plurality of decentralised, dispersed or local energy generation technologies are operated simultaneously
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
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Abstract
The invention provides a three-phase micro inverter device, a three-phase micro inverter system and a control method thereof, wherein the three-phase micro inverter is composed of three single-phase micro inverters in N groups, if N is 1, when the m-th single-phase micro inverter in the three-phase micro inverter is detected to meet the closing condition, the m-th single-phase micro inverter is closed; if N is larger than 1, when the situation that the nth single-phase micro inverter in the x group of three-phase micro inverters meets the closing condition is detected, the nth single-phase micro inverter is closed, the three-phase micro inverter device can keep three-phase power balance after the nth single-phase micro inverter is closed is detected, power compensation is carried out on the phase to be compensated corresponding to the nth single-phase micro inverter through the residual three-phase micro inverters, compensation of the phase with lower power is achieved, and therefore the three-phase unbalance degree of the photovoltaic grid connection is reduced.
Description
Technical Field
The invention relates to the technical field of power conversion, and particularly provides a three-phase micro inverter, a three-phase micro inverter system and a control method of the three-phase micro inverter system.
Background
The micro inverter is a key device for photovoltaic power generation grid connection, can realize maximum power tracking of each photovoltaic module, and effectively improves solar energy conversion efficiency.
In general, most users use a single-phase micro inverter to access a three-phase power grid to supply power to the three-phase power grid. However, the single-phase micro-inverter has different grid-connected power, which easily causes power imbalance of a three-phase power grid, thereby causing poor power quality of the power grid and reducing reliability of power supply.
Disclosure of Invention
In order to overcome the above defects, the present invention is proposed to provide a three-phase micro inverter, a system and a control method thereof, which solve or at least partially solve the technical problems of poor power quality of a power grid and low reliability of power supply.
In a first aspect, the present invention provides a control method of a three-phase micro-inverter apparatus including N sets of three-phase micro-inverters and a system controller; each group of three-phase micro-inverters comprises three single-phase micro-inverters; each single-phase micro inverter comprises a main circuit, a control module, a power supply module and a communication module; n is an integer greater than or equal to 1;
the control module and the communication module are respectively electrically connected with the power supply module; the main control module and the main circuit are respectively electrically connected with the communication module; the main circuit is electrically connected with an alternating current power grid; the main control module is also electrically connected with the system controller;
the method comprises the following steps:
if N is equal to 1, when the mth single-phase micro-inverter in the three-phase micro-inverters is detected to meet the shutdown condition, shutting down the mth single-phase micro-inverter; wherein m is more than or equal to 1 and less than or equal to 3;
if N is more than 1, when detecting that the nth single-phase micro inverter in the x group of three-phase micro inverters meets the closing condition, closing the nth single-phase micro inverter, and detecting whether the three-phase micro inverter device can keep three-phase power balance after closing the nth single-phase micro inverter; wherein x is more than 1 and less than or equal to N, and N is more than or equal to 1 and less than or equal to 3;
if the three-phase micro inverter device can keep three-phase power balance, performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter by using the remaining three-phase micro inverters; wherein the remaining three-phase micro-inverters are three-phase micro-inverters other than the group X three-phase micro-inverter.
Further, in the above method for controlling a three-phase micro-inverter, detecting whether the three-phase micro-inverter can maintain three-phase power balance after the nth single-phase micro-inverter is turned off includes:
detecting whether the three-phase micro inverter device meets a preset compensation constraint condition after the nth single-phase micro inverter is closed;
if the three-phase micro inverter device meets the preset compensation constraint condition, determining that the three-phase micro inverter device can keep three-phase power balance;
if the three-phase micro inverter device does not meet the preset compensation constraint condition, determining that the three-phase micro inverter device cannot keep three-phase power balance;
wherein, the constraint function corresponding to the compensation constraint condition is:
wherein, the P' ai Represents the maximum active power of the single-phase micro-inverter corresponding to the compensation in the ith group of three-phase micro-inverters, P B Representing the active power of a first uncompensated phase of said three-phase micro-inverter device, said P C Representing the active power of a second uncompensated phase of said three-phase micro-inverter device, said P avg And the mean value of the three-phase active power of the three-phase micro inverter is represented, and the delta represents a preset threshold value.
Further, in the control method of the three-phase micro-inverter, the performing power compensation on the phase to be compensated corresponding to the nth single-phase micro-inverter by using the remaining three-phase micro-inverters includes:
constructing a target function based on a pre-constructed three-phase unbalance degree constraint function, a phase modulation switch action time function and a phase modulation switch line loss reduction function;
solving the objective function to obtain a three-phase micro inverter combination corresponding to the optimal solution;
and performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter based on the three-phase micro inverter combination.
Further, in the control method of the three-phase micro-inverter device, the power compensation of the phase to be compensated corresponding to the nth single-phase micro-inverter based on the combination of the three-phase micro-inverters includes:
and performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter by using a power difference value between the maximum active power and the actual internet access power of each phase of each three-phase micro inverter in the three-phase micro inverter combination.
Further, in the control method of the three-phase micro inverter, a target function is constructed based on a pre-constructed three-phase unbalance constraint function, a phase modulation switch action frequency function, and a phase modulation switch line loss reduction function, and the method includes:
normalizing the three-phase unbalance degree constraint function, the phase modulation switch action time function and the phase modulation switch reduced line loss function to obtain a dimensionless three-phase unbalance degree constraint function, a dimensionless phase modulation switch action time function and a dimensionless phase modulation switch reduced line loss function;
dividing each dimensionless function by the corresponding reference value and multiplying the dimensionless function by the corresponding weighting coefficient, and summing to obtain the target function; the non-dimensional function comprises a non-dimensional three-phase unbalance degree constraint function, a non-dimensional phase modulation switch action time function or a non-dimensional phase modulation switch line loss reduction function.
Further, in the control method of the three-phase micro inverter, the sum of the weighting coefficients corresponding to each dimensionless function is 1.
Further, in the control method of the three-phase micro inverter, the shutdown condition includes:
the available output power of any one single-phase micro inverter is smaller than a preset power threshold value, or the photovoltaic power generation equipment corresponding to any one single-phase micro inverter breaks down.
In a second aspect, the present invention provides a three-phase micro inverter device, comprising N sets of three-phase micro inverters and a system controller; each group of three-phase micro-inverters comprises three single-phase micro-inverters; each micro inverter comprises a main circuit, a control module, a power supply module and a communication module; n is an integer greater than or equal to 1;
the control module and the communication module are respectively electrically connected with the power supply module; the main control module and the main circuit are respectively electrically connected with the communication module; the main circuit is electrically connected with an alternating current power grid; the main control module is also electrically connected with the system controller;
the system controller is used for executing the control method of the three-phase micro inverter device.
In a third aspect, the present invention provides a three-phase micro-inverter system, comprising a network transmission device, a monitoring management device and the three-phase micro-inverter device as described above;
the three-phase micro inverter is connected with the monitoring management device through the network transmission device.
One or more technical schemes of the invention at least have one or more of the following beneficial effects:
in the technical scheme for implementing the invention, three single-phase micro-inverters form a group of three-phase micro-inverters, so that each three single-phase micro-inverters can be independently operated, and when only one group of three-phase micro-inverters exist, when the m-th single-phase micro-inverter in the three-phase micro-inverters is detected to meet the shutdown condition, the m-th single-phase micro-inverter is shut down. When a plurality of groups of three-phase micro inverters exist, if it is detected that the nth single-phase micro inverter in the xth group of three-phase micro inverters meets the closing condition, when the nth single-phase micro inverter is closed, whether the three-phase micro inverter device can keep three-phase power balance or not needs to be detected after the nth single-phase micro inverter is closed, if the three-phase micro inverter device can keep three-phase power balance, the remaining three-phase micro inverters are used for carrying out power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter, and therefore compensation on the phase with lower power is achieved, and the three-phase unbalance degree of photovoltaic grid connection is reduced.
Drawings
The disclosure of the present invention will become more readily understood with reference to the accompanying drawings. As is readily understood by those skilled in the art: these drawings are for illustrative purposes only and are not intended to constitute a limitation on the scope of the present invention. Moreover, in the drawings, like numerals are used to indicate like parts, and in which:
fig. 1 is a schematic view of a structure of a three-phase micro inverter according to an embodiment of the present invention;
fig. 2 is a flowchart of a control method of a three-phase micro inverter according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of an embodiment of a three-phase micro inverter system according to the present invention.
Detailed Description
Some embodiments of the invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only for explaining the technical principle of the present invention, and are not intended to limit the scope of the present invention.
In the description of the present invention, a "module" or "processor" may include hardware, software, or a combination of both. A module may comprise hardware circuitry, various suitable sensors, communication ports, memory, may comprise software components such as program code, or may be a combination of software and hardware. The processor may be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and/or signal processing functionality. The processor may be implemented in software, hardware, or a combination thereof. Non-transitory computer readable storage media include any suitable medium that can store program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random-access memory, and the like. The term "a and/or B" denotes all possible combinations of a and B, such as a alone, B alone or a and B. The term "at least one A or B" or "at least one of A and B" means similar to "A and/or B" and may include only A, only B, or both A and B. The singular forms "a", "an" and "the" may include the plural forms as well.
Referring to fig. 1, fig. 1 is a schematic diagram illustrating a structure of a three-phase micro inverter according to an embodiment of the present invention.
As shown in fig. 1, the three-phase micro-inverter apparatus of the present embodiment may include N sets of three-phase micro-inverters 1 and a system controller (not shown in the drawing); each group of three-phase micro-inverters 1 comprises three single-phase micro-inverters 11; each single-phase micro-inverter 11 comprises a main circuit 111, a control module 112, a power module 113 and a communication module 114; and N is an integer greater than or equal to 1. In fig. 1, a 2-bank three-phase microinverter 1 is shown. It is understood that the control module 112 may include a voltage current sampling unit, a maximum power tracking unit, a PWM modulation unit, a circuit unit and a control strategy unit, etc., which are not shown in the drawing.
In a specific implementation process, the control module 112 and the communication module are electrically connected to the power module 113 respectively; the main control module and the main circuit 111 are respectively electrically connected with the communication module; the main circuit 111 is respectively electrically connected with the photovoltaic module and the alternating current power grid; the main control module is also electrically connected with the system controller. The communication module 114 includes an LoRa wireless communication module 114, so that stable data transmission is ensured, and plug and play can be realized.
Fig. 2 is a flowchart of a control method of a three-phase micro inverter according to an embodiment of the present invention. As shown in fig. 2, the control method of the three-phase micro inverter of the present embodiment may specifically include the following steps:
102, when detecting that the nth single-phase micro inverter 11 in the xth group of three-phase micro inverters 1 meets the closing condition, closing the nth single-phase micro inverter 11, and detecting whether the three-phase micro inverter device can keep three-phase power balance after closing the nth single-phase micro inverter 11;
in a specific implementation process, when there are multiple groups of three-phase micro-inverters 1, when it is detected that the nth single-phase micro-inverter 11 in the xth group of three-phase micro-inverters 1 meets the shutdown condition, the nth single-phase micro-inverter 11 may be shutdown, which is that the phase power corresponding to the nth single-phase micro-inverter 11 decreases, which may affect the three-phase power balance, and therefore, it may be further detected whether the three-phase micro-inverter apparatus can maintain the three-phase power balance after the nth single-phase micro-inverter 11 is shut down. Wherein x is more than 1 and less than or equal to N, and N is more than or equal to 1 and less than or equal to 3.
Specifically, it may be detected whether the three-phase micro-inverter device satisfies a preset compensation constraint condition after the nth single-phase micro-inverter 11 is turned off; if the three-phase micro inverter device meets the preset compensation constraint condition, determining that the three-phase micro inverter device can keep three-phase power balance; and if the three-phase micro inverter does not meet the preset compensation constraint condition, determining that the three-phase micro inverter cannot keep three-phase power balance.
Wherein, the constraint function corresponding to the compensation constraint condition is:
wherein, the P a ′ i Represents the maximum active power of the single-phase micro-inverter 11 corresponding to the compensation in the i-th group of three-phase micro-inverters 1, P B Presentation instrumentActive power of a first uncompensated phase in the three-phase micro inverter device, P C Representing the active power of a second uncompensated phase of said three-phase micro-inverter device, said P avg And the delta represents a preset threshold value. In a specific implementation process, in the normal operation process of the three-phase micro inverter, the calculation formula of the active power of each item on the internet actually is as follows:
wherein, the P A Representing the active power corresponding to the compensation in the three-phase micro inverter device, the Pai representing the actual active power of the single-phase micro inverter 11 corresponding to the compensation in the i-th group of three-phase micro inverters 1, and the P bi Representing the actual active power of the single-phase micro-inverter 11 of the i-th group of three-phase micro-inverters 1 corresponding to the first uncompensated phase, said P ci Representing the actual active power of the single-phase microinverter 11 of the i-th group of three-phase microinverters 1 corresponding to the second uncompensated phase.
In one particular implementation of the process of the present invention,
in one specific implementation, the shutdown condition may include: the available output power of any one single-phase micro-inverter 11 is smaller than a preset power threshold, or a photovoltaic power generation device corresponding to any one single-phase micro-inverter 11 fails. When the ratio of the difference between the active power of the three phases and the mean value is smaller than a set value, the three-phase micro-inverter device satisfies three-phase balance, and when a certain phase changes and the ratio of the difference between the active power of the three phases and the mean value is greater than or equal to the set value, it is indicated that the available output power of the corresponding single-phase micro-inverter 11 is smaller than a preset power threshold value, or the photovoltaic power generation equipment corresponding to the corresponding single-phase micro-inverter 11 fails, and the corresponding single-phase micro-inverter 11 satisfies a shutdown condition, and at this time, it may be further detected whether the three-phase micro-inverter device can maintain three-phase power balance after the nth single-phase micro-inverter 11 is shut down.
103, if the three-phase micro inverter device can keep three-phase power balance, performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter 11 by using the remaining three-phase micro inverter 1;
in a specific implementation, the remaining three-phase microinverters 1 are three-phase microinverters 1 other than the group X three-phase microinverters 1. This step may be specifically performed as follows:
(1) constructing a target function based on a pre-constructed three-phase unbalance degree constraint function, a phase modulation switch action time function and a phase modulation switch line loss reduction function;
in a specific implementation process, normalization processing may be performed on the three-phase unbalancing degree constraint function, the phase modulation switch action time function, and the phase modulation switch reduced line loss function, so as to obtain a dimensionless three-phase unbalancing degree constraint function, a dimensionless phase modulation switch action time function, and a dimensionless phase modulation switch reduced line loss function; dividing each dimensionless function by the corresponding reference value and multiplying the dimensionless function by the corresponding weighting coefficient, and summing to obtain the target function; the dimensionless quantity function comprises a dimensionless three-phase unbalance degree constraint function, a dimensionless phase modulation switch action time function or a dimensionless phase modulation switch line loss reduction function, so that a multi-objective optimization problem can be converted into a single-objective optimization problem, and a subsequent solving process is simpler. Wherein the sum of the weighting coefficients corresponding to each dimensionless function is 1.
In one specific implementation, the three-phase imbalance constraint function is:
minε＝maxε z ，z＝A,B,C
wherein ε represents the degree of unbalance of three phases, ε z The degree of unbalance of each phase is represented,
the phase modulation switch action times function is:
wherein Q represents the total action times of the phase modulation switch, Q i The number of switching operations of the i-th group three-phase micro-inverter 1 is shown.
The phase modulation switch reduces the line loss function as follows:
minL＝∑L nj
wherein minL represents a minimum distance value, L nj And the distance between the grid-connected point of the phase to be compensated and the grid-connected point of the active compensation phase is represented.
The objective function is specifically:
wherein ε' represents a reference value corresponding to the three-phase unbalance, w 1 Weight coefficient corresponding to three-phase unbalance degree, Q' represents reference value corresponding to total action times of phase modulation switch, and w 2 A weighting coefficient corresponding to the total number of phase modulation switch operations, L' a reference value corresponding to the minimum distance, and w 3 Indicating the weighting factor corresponding to the minimum distance.
(2) Solving the objective function to obtain a three-phase micro inverter 1 combination corresponding to the optimal solution;
in a specific implementation process, the objective function may be solved by using a genetic algorithm to obtain a three-phase micro-inverter 1 combination corresponding to an optimal solution. For the specific process of the genetic algorithm, reference may be made to the basic steps of the genetic algorithm in the related art, and details are not described herein.
(3) And performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter 11 based on the combination of the three-phase micro inverters 1.
In a specific implementation process, a power difference between a maximum active power of each phase of each three-phase micro-inverter 1 in the three-phase micro-inverter 1 combination and an actual grid power may be used to perform power compensation on a phase to be compensated corresponding to the nth single-phase micro-inverter 11.
And 104, when the m single-phase micro-inverter 11 in the three-phase micro-inverter 1 is detected to meet the shutdown condition, shutting down the m single-phase micro-inverter 11.
In a specific implementation process, when there is only one set of three-phase micro-inverters 1, if it is detected that the mth single-phase micro-inverter 11 in the three-phase micro-inverters 1 meets the shutdown condition, the mth single-phase micro-inverter 11 is directly shut down, and the remaining two single-phase micro-inverters 11 are reserved, so that the three-phase micro-inverter device is switched from the three-phase operation mode to the two-phase operation mode. Wherein m is more than or equal to 1 and less than or equal to 3.
In a specific implementation process, if the three-phase micro-inverter device cannot maintain three-phase power balance, the remaining two single-phase micro-inverters 11 in the x-th group of three-phase micro-inverters 1 may be turned off.
In the control method of the three-phase micro-inverter according to the embodiment, three single-phase micro-inverters 11 are combined into one group of three-phase micro-inverters 1, so that each three single-phase micro-inverters 11 can be operated independently, and when only one group of three-phase micro-inverters 1 is provided, when it is detected that the mth single-phase micro-inverter 11 in the three-phase micro-inverters 1 meets the shutdown condition, the mth single-phase micro-inverter 11 is shut down. When a plurality of groups of three-phase micro-inverters 1 exist, if it is detected that the nth single-phase micro-inverter 11 in the xth group of three-phase micro-inverters 1 meets the shutdown condition, when the nth single-phase micro-inverter 11 is shutdown, it is also required to detect whether the three-phase micro-inverter device can keep three-phase power balance after the nth single-phase micro-inverter 11 is shutdown, and if the three-phase micro-inverter device can keep three-phase power balance, power compensation is performed on the phase to be compensated corresponding to the nth single-phase micro-inverter 11 by using the remaining three-phase micro-inverters 1, so that compensation on the phase with lower power is realized, and the three-phase unbalance degree of photovoltaic grid connection is reduced.
It should be noted that, although the foregoing embodiments describe each step in a specific sequence, those skilled in the art will understand that, in order to achieve the effect of the present invention, different steps do not necessarily need to be executed in such a sequence, and they may be executed simultaneously (in parallel) or in other sequences, and these changes are all within the protection scope of the present invention.
Fig. 3 is a schematic structural diagram of an embodiment of a three-phase micro-inverter system according to the present invention, and as shown in fig. 3, the three-phase micro-inverter system of the present embodiment may include a network transmission device 200, a monitoring management device 300, and the three-phase micro-inverter device 100 of the above embodiment. The three-phase micro inverter device 100 is connected to the monitoring management device 300 through the network transmission device 200.
In a specific implementation process, the control module 112 in the three-phase micro inverter device 100 packages and sends data such as voltage, frequency, output power, input power, phase state, temperature, fault state, and the like to the communication module 114, and sends the data upwards to the network transmission device 200(LoRa gateway) through the LoRa wireless communication mode; meanwhile, the LoRa communication module 114 in the three-phase micro inverter device 100 receives the scheduling command of the network transmission device 200 and adjusts the power of the network.
The network transmission device 200 is mainly a LoRa gateway, and is used as a relay for the photovoltaic micro inverter and a display interface, receives data of the acquisition layer, uploads the data to the monitoring management device 300 for display and storage, and simultaneously sends a scheduling instruction of the monitoring management device 300 to the photovoltaic micro inverter.
The monitoring management device 300 is used for realizing the display and storage of data and the scheduling management of the system, and a user can realize the monitoring and scheduling management of the whole photovoltaic micro-inversion system through various forms such as a mobile phone APP, a micro-communication applet, a PC (personal computer) end monitoring interface and a Web interface.
In the embodiment of the control method for implementing the three-phase micro-inverter 100 of the above embodiment, the technical principles, the solved technical problems, and the generated technical effects of the two embodiments are similar, and it can be clearly understood by those skilled in the art that, for convenience and simplicity of description, the specific working process and related descriptions of the three-phase micro-inverter system may refer to the content described in the embodiment of the control method for the three-phase micro-inverter 100, and no further description is given here.
It will be understood by those skilled in the art that all or part of the flow of the method according to the above-described embodiment may be implemented by a computer program, which may be stored in a computer-readable storage medium and used to implement the steps of the above-described embodiments of the method when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable storage medium may include: any entity or device capable of carrying said computer program code, media, usb disk, removable hard disk, magnetic diskette, optical disk, computer memory, read-only memory, random access memory, electrical carrier wave signals, telecommunication signals, software distribution media, etc. It should be noted that the computer readable storage medium may contain content that is subject to appropriate increase or decrease as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable storage media that does not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
Further, it should be understood that, since the configuration of each module is only for explaining the functional units of the apparatus of the present invention, the corresponding physical devices of the modules may be the processor itself, or a part of software, a part of hardware, or a part of a combination of software and hardware in the processor. Thus, the number of individual modules in the figures is merely illustrative.
Those skilled in the art will appreciate that the various modules in the apparatus may be adaptively split or combined. Such splitting or combining of specific modules does not cause the technical solutions to deviate from the principle of the present invention, and therefore, the technical solutions after splitting or combining will fall within the protection scope of the present invention.
So far, the technical solutions of the present invention have been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can fall into the protection scope of the invention.
Claims (10)
1. The control method of the three-phase micro inverter is characterized in that the three-phase micro inverter comprises N groups of three-phase micro inverters and a system controller; each group of three-phase micro-inverters comprises three single-phase micro-inverters; each single-phase micro inverter comprises a main circuit, a control module, a power supply module and a communication module; n is an integer greater than or equal to 1;
the control module and the communication module are respectively electrically connected with the power supply module; the main control module and the main circuit are respectively electrically connected with the communication module; the main circuit is electrically connected with an alternating current power grid; the main control module is also electrically connected with the system controller;
the method comprises the following steps:
if N is equal to 1, when the m-th single-phase micro-inverter in the three-phase micro-inverters is detected to meet the closing condition, closing the m-th single-phase micro-inverter; wherein m is more than or equal to 1 and less than or equal to 3;
if N is more than 1, when detecting that the nth single-phase micro inverter in the x group of three-phase micro inverters meets the closing condition, closing the nth single-phase micro inverter, and detecting whether the three-phase micro inverter device can keep three-phase power balance after closing the nth single-phase micro inverter; wherein x is more than 1 and less than or equal to N, and N is more than or equal to 1 and less than or equal to 3;
if the three-phase micro inverter device can keep three-phase power balance, performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter by using the remaining three-phase micro inverters; wherein the remaining three-phase micro-inverters are three-phase micro-inverters other than the group X three-phase micro-inverter.
2. The method of claim 1, wherein the detecting whether the three-phase micro-inverter apparatus can maintain three-phase power balance after turning off the nth single-phase micro-inverter includes:
detecting whether the three-phase micro inverter device meets a preset compensation constraint condition after the nth single-phase micro inverter is closed;
if the three-phase micro inverter device meets the preset compensation constraint condition, determining that the three-phase micro inverter device can keep three-phase power balance;
if the three-phase micro inverter device does not meet the preset compensation constraint condition, determining that the three-phase micro inverter device cannot keep three-phase power balance;
wherein, the constraint function corresponding to the compensation constraint condition is:
wherein, the P' ai Represents the maximum active power of the single-phase micro-inverter corresponding to the compensation in the ith group of three-phase micro-inverters, P B Representing the active power of a first uncompensated phase of said three-phase micro-inverter device, said P C Representing the active power of a second uncompensated phase of said three-phase micro-inverter device, said P avg And the delta represents a preset threshold value.
3. The method for controlling a three-phase micro-inverter according to claim 1, wherein the power compensation of the phase to be compensated corresponding to the nth single-phase micro-inverter by using the remaining three-phase micro-inverters comprises:
constructing a target function based on a pre-constructed three-phase unbalance degree constraint function, a phase modulation switch action time function and a phase modulation switch line loss reduction function;
solving the objective function to obtain a three-phase micro inverter combination corresponding to the optimal solution;
and performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter based on the three-phase micro inverter combination.
4. The method of claim 3, wherein the step of performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter based on the combination of the three-phase micro inverters comprises:
and performing power compensation on the phase to be compensated corresponding to the nth single-phase micro inverter by using a power difference value between the maximum active power and the actual internet access power of each phase of each three-phase micro inverter in the three-phase micro inverter combination.
5. The method for controlling a three-phase micro inverter according to claim 3, wherein constructing an objective function based on a pre-constructed three-phase unbalance degree constraint function, a phase modulation switch action time function and a phase modulation switch line loss reduction function comprises:
normalizing the three-phase unbalance degree constraint function, the phase modulation switch action time function and the phase modulation switch reduced line loss function to obtain a dimensionless three-phase unbalance degree constraint function, a dimensionless phase modulation switch action time function and a dimensionless phase modulation switch reduced line loss function;
dividing each dimensionless function by the corresponding reference value and multiplying the dimensionless function by the corresponding weighting coefficient, and summing to obtain the target function; the non-dimensional function comprises a non-dimensional three-phase unbalance degree constraint function, a non-dimensional phase modulation switch action time function or a non-dimensional phase modulation switch line loss reduction function.
6. The control method of a three-phase micro inverter according to claim 5, wherein the sum of the weighting coefficients corresponding to each dimensionless function is 1.
7. The control method of a three-phase micro inverter device according to claim 1, wherein the turn-off condition includes:
the available output power of any one single-phase micro inverter is smaller than a preset power threshold value, or the photovoltaic power generation equipment corresponding to any one single-phase micro inverter breaks down.
8. A three-phase micro inverter is characterized by comprising N groups of three-phase micro inverters and a system controller; each group of three-phase micro-inverters comprises three single-phase micro-inverters; each micro inverter comprises a main circuit, a control module, a power supply module and a communication module; n is an integer greater than or equal to 1;
the control module and the communication module are respectively electrically connected with the power supply module; the main control module and the main circuit are respectively electrically connected with the communication module; the main circuit is electrically connected with an alternating current power grid; the main control module is also electrically connected with the system controller;
the system controller is used for executing a control method of the three-phase micro inverter device according to any one of claims 1 to 7.
9. The three-phase micro inverter of claim 8, wherein the communication module comprises a LoRa wireless communication module.
10. A three-phase micro-inverter system comprising network transmission means, monitoring and management means and a three-phase micro-inverter device according to claim 8 or 9;
the three-phase micro inverter is connected with the monitoring management device through the network transmission device.
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