CN113725900A - Grid-connected control method, terminal and storage medium for photovoltaic inverter - Google Patents
Grid-connected control method, terminal and storage medium for photovoltaic inverter Download PDFInfo
- Publication number
- CN113725900A CN113725900A CN202110970766.2A CN202110970766A CN113725900A CN 113725900 A CN113725900 A CN 113725900A CN 202110970766 A CN202110970766 A CN 202110970766A CN 113725900 A CN113725900 A CN 113725900A
- Authority
- CN
- China
- Prior art keywords
- grid
- current
- photovoltaic
- photovoltaic output
- target value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 59
- 238000004590 computer program Methods 0.000 claims description 15
- 230000002596 correlated effect Effects 0.000 claims description 3
- 230000004044 response Effects 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 11
- 230000006870 function Effects 0.000 description 7
- 238000004088 simulation Methods 0.000 description 7
- 238000010248 power generation Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000008859 change Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- 230000000875 corresponding effect Effects 0.000 description 3
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 230000003044 adaptive effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000005286 illumination Methods 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004422 calculation algorithm Methods 0.000 description 1
- 238000011217 control strategy Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- 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
-
- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
- H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
-
- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
-
- 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
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
-
- 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
-
- 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
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
- H02J2300/26—The renewable source being solar energy of photovoltaic origin involving maximum power point tracking control for photovoltaic sources
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
- Control Of Electrical Variables (AREA)
Abstract
The invention relates to the technical field of photovoltaic, in particular to a grid-connected control method of a photovoltaic inverter, a terminal and a storage medium, wherein the method comprises the following steps: acquiring photovoltaic output data, an active power target value, grid-connected parameters and a direct current target voltage value; determining the duty ratio of a boost circuit according to the photovoltaic output data and the active power target value; and determining the duty ratio of the inverter circuit according to the grid-connected parameter and the direct current target voltage value. According to the implementation mode of the grid-connected control method of the photovoltaic inverter, the photovoltaic output power can track the upper-level command power more quickly. The response speed of the photovoltaic can be improved to a greater extent when the constant power tracking control is operated in the grid-connected state of the photovoltaic inverter, the risk of grid disconnection of the photovoltaic inverter due to the out-of-limit grid-connected point voltage is avoided, the stability of a power grid is improved, and the method has a strong engineering application value.
Description
Technical Field
The invention relates to the technical field of photovoltaic, in particular to a grid-connected control method of a photovoltaic inverter, a terminal and a storage medium.
Background
Energy shortage and environmental pollution become serious problems in countries all over the world, and renewable energy sources such as photovoltaic energy, wind power energy and the like are widely applied due to the advantages of being green, clean and renewable. Among them, solar energy is widely used in distributed photovoltaic grid-connected power generation as a main renewable energy source.
Photovoltaic power generation has the stochastic, intermittent, and fluctuating characteristics typical of new energy sources, and typically outputs maximum power through maximum power tracking techniques. When the external environment changes, the output power of the photovoltaic system fluctuates, even the power flow distribution of the power distribution network is changed, and the uncertainty of the power flow of the power distribution network is increased.
Therefore, although the maximum power tracking technology can maximize the photovoltaic power generation amount, the problems of out-of-limit and power fluctuation of the grid-connected point voltage and the like can be caused, and even the problems of serious deviation of the bus voltage from the standard, large-area photovoltaic grid disconnection and the like can be caused in severe cases, so that the application of the photovoltaic power generation technology is hindered, and therefore the active support function of the photovoltaic is realized, the schedulability of the photovoltaic inverter is improved, and the trend gradually becomes new.
Aiming at the problems in the photovoltaic power generation grid connection process, a photovoltaic inverter control method needs to be developed and designed for optimizing the grid connection performance of the photovoltaic inverter.
Disclosure of Invention
The embodiment of the invention provides a grid-connected control method, a terminal and a storage medium of a photovoltaic inverter, which are used for solving the problem of poor grid-connected performance of the photovoltaic inverter in the prior art.
In a first aspect, an embodiment of the present invention provides a photovoltaic inverter grid-connected control method, including:
the method comprises the following steps of obtaining photovoltaic output data, an active power target value, grid-connected parameters and a direct current target voltage value, wherein the photovoltaic output data comprise: the photovoltaic output voltage and the photovoltaic output current, the active power target value is an active power target value, and the grid-connected parameters include: the direct current target voltage value is an inverse circuit direct current side voltage target value;
determining the duty ratio of a boost circuit according to the photovoltaic output data and the active power target value;
and determining the duty ratio of the inverter circuit according to the grid-connected parameter and the direct current target voltage value.
In one possible implementation manner, the determining a duty cycle of a boost circuit according to the photovoltaic output data and the active power target value includes:
determining a photovoltaic output voltage target value according to the photovoltaic output data and the active power target value;
determining a photovoltaic output current target value according to the photovoltaic output voltage target value and the photovoltaic output voltage;
and determining the duty ratio of the boost current according to the photovoltaic output current target value and the photovoltaic output current.
In one possible implementation manner, the determining a photovoltaic output voltage target value according to the photovoltaic output data and the active power target value includes:
determining a photovoltaic output voltage target value according to the photovoltaic output data, a first formula and an active power target value, wherein the first formula is as follows:
wherein, UpvrefFor photovoltaic output voltage target value, Kp_pAs a power loop proportional control coefficient, Ki_pFor integrating the control coefficient, P, for the power looppvFor photovoltaic output power value, PpvrefIs the active power target value.
In a possible implementation manner, the power loop integral control coefficient is positively correlated with a power coefficient ratio, and the power coefficient ratio is a ratio of the active power target value to the photovoltaic maximum output power.
In one possible implementation, the determining a photovoltaic output current target value according to the photovoltaic output voltage target value and the photovoltaic output voltage includes:
determining a photovoltaic output current target value according to the photovoltaic output voltage target value, a second formula and the photovoltaic output voltage, wherein the second formula is as follows:
wherein, IpvrefFor photovoltaic output current target value，Kp_uFor proportional control coefficient of voltage loop, Ki_uFor voltage loop integral control coefficient, UpvIs the photovoltaic output voltage.
In one possible implementation, the determining a duty cycle of a boost current according to the photovoltaic output current target value and the photovoltaic output current includes:
determining a duty cycle of a boost current according to the photovoltaic output current target value, a third formula and the photovoltaic output current, wherein the third formula:
wherein u isboost_gIs the duty cycle of the boost circuit, Kp_iAs a current loop proportional control coefficient, Ki_iFor the current loop integral control coefficient, IpvTo photovoltaic output current.
In a possible implementation manner, the determining a duty ratio of the inverter circuit according to the grid-connected parameter and the dc target voltage value includes:
acquiring a direct-axis component of the grid-connected current of the inverter circuit and a quadrature-axis component of the grid-connected current of the inverter circuit according to the grid-connected parameters;
and obtaining the duty ratio of the inverter circuit according to the direct current target voltage value, the direct axis component of the inverter circuit grid-connected current and the alternating axis component of the inverter circuit grid-connected current.
In one possible implementation manner, the obtaining the duty ratio of the inverter circuit according to the dc target voltage value, the direct component of the inverter circuit grid-connected current, and the alternating component of the inverter circuit grid-connected current includes:
determining a direct-axis component of the grid-connected target current according to the direct-current target voltage value, the direct-current side voltage of the inverter circuit and a fourth formula, wherein the fourth formula comprises the following steps:
wherein, IdrefFor the direct component of the grid-connected target current, kpIs the inverse voltage loop proportionality coefficient, kiFor the integral coefficient of the inverter voltage ring, UdcrefIs a direct current target voltage value;
determining that the quadrature-axis component of the grid-connected target current is zero;
and obtaining the duty ratio of the inverter circuit according to the grid-connected target current direct-axis component, the grid-connected target current quadrature-axis component, the inverter circuit grid-connected current direct-axis component and the inverter circuit grid-connected current quadrature-axis component.
In a second aspect, an embodiment of the present invention provides a photovoltaic inverter grid-connected control device, including:
the data acquisition module is used for acquiring photovoltaic output data, an active power target value, grid-connected parameters and a direct current target voltage value, wherein the photovoltaic output data comprises: the photovoltaic output voltage and the photovoltaic output current, the active power target value is an active power target value, and the grid-connected parameters include: the direct current target voltage value is an inverse circuit direct current side voltage target value;
the boost circuit control module is used for determining the duty ratio of the boost circuit according to the photovoltaic output data and the active power target value; and the number of the first and second groups,
and the inverter circuit control module is used for determining the duty ratio of the inverter circuit according to the grid-connected parameter and the direct-current target voltage value.
In a third aspect, an embodiment of the present invention provides a terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor implements the steps of the method according to the first aspect or any one of the possible implementation manners of the first aspect when executing the computer program.
In a fourth aspect, the present invention provides a computer-readable storage medium, which stores a computer program that, when executed by a processor, implements the steps of the method as described in the first aspect or any one of the possible implementations of the first aspect.
Compared with the prior art, the implementation mode of the invention has the following beneficial effects:
according to the implementation mode of the grid-connected control method of the photovoltaic inverter, the photovoltaic output power can track the upper-level command power more quickly. The response speed of the photovoltaic can be improved to a greater extent when the constant power tracking control is operated in the grid-connected state of the photovoltaic inverter, the risk of grid disconnection of the photovoltaic inverter due to the out-of-limit grid-connected point voltage is avoided, the stability of a power grid is improved, and the method has a strong engineering application value.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.
Fig. 1 is a schematic diagram of a photovoltaic inverter provided by an embodiment of the present invention;
fig. 2 is a flowchart of a photovoltaic inverter grid-connected control method provided by the embodiment of the invention;
FIG. 3 is a block diagram of the control function of the boost circuit provided by the embodiment of the invention;
fig. 4 is a functional block diagram of an inverter circuit according to an embodiment of the present invention;
FIG. 5 is a first graph of a MATLAB/Simulink simulation provided by an embodiment of the present invention;
FIG. 6 is a second graph of a MATLAB/Simulink simulation provided by an embodiment of the present invention;
fig. 7 is a functional block diagram of a photovoltaic inverter grid-connected control device according to an embodiment of the present invention;
fig. 8 is a functional block diagram of a terminal according to an embodiment of the present invention.
Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made with reference to the accompanying drawings.
Aiming at the problems that the maximum power tracking technology may cause the voltage of a grid-connected point to be out of limit, power fluctuation and the like, the prior art provides a grid-connected active support type photovoltaic inverter with self-adaptive adjustment of power loop parameters. In the current research, an active power control strategy of a photovoltaic system mainly includes a constant power point tracking method based on a disturbance observation method and a constant power tracking method based on a power loop. However, the constant power point tracking method based on the disturbance observation method needs to balance the influence of the step length on the tracking speed and the steady-state fluctuation, and the tracking speed is slow. However, currently, the commonly used constant power tracking control based on the power loop mostly adopts fixed parameters, and when the characteristic change of a photovoltaic power-voltage curve does not take different power instructions into consideration, namely near a maximum power point, the power change caused by the voltage change of a photovoltaic port is small; under light load conditions, the power variation caused by the photovoltaic port voltage variation is severe. When the two areas adopt fixed control parameters, the problems of slow tracking and adjusting speed, large oscillation amplitude and the like can occur, and certain defects exist.
The main circuit of the photovoltaic inverter disclosed by the patent application of the invention is shown in a schematic diagram in fig. 1 and mainly comprises a photovoltaic array, a boost circuit, an inverter circuit, a filter, a load and a power grid side. The direct current voltage output by the photovoltaic array is boosted through the boost circuit, and then is connected with the power grid side in parallel through the inverter circuit and the filter to jointly supply power to the three-phase load. The photovoltaic inverter tracks an externally given power command value, and adopts power loop and voltage and current dual-loop control of self-adaptive adjustment parameters, so that photovoltaic is controlled to track the upper-level command power in real time. In order to achieve the purpose, the patent application method provides a new technical scheme.
The following is a detailed description of the embodiments of the present invention, which is implemented on the premise of the technical solution of the present invention, and the detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the following embodiments.
Fig. 2 is a flowchart of a photovoltaic inverter grid-connected control method according to an embodiment of the present invention.
As shown in fig. 2, it shows an implementation flowchart of a photovoltaic inverter grid-connected control method provided by the embodiment of the present invention, and details are as follows:
in step 201, photovoltaic output data, an active power target value, a grid-connected parameter, and a dc target voltage value are obtained.
Wherein the photovoltaic output data comprises: the photovoltaic output voltage and the photovoltaic output current, the active power target value is an active power target value, and the grid-connected parameters include: the direct current target voltage value is the direct current side voltage target value of the inverter circuit.
Illustratively, the photovoltaic output data is output data of the photovoltaic array, and are actually sampled data values, the photovoltaic output voltage is a sampled value of the output voltage of the photovoltaic array, and the photovoltaic output current is a sampled value of the output current of the photovoltaic array.
The active power target value is an external control power value received by the photovoltaic inverter. The grid-connected parameter is a parameter of grid connection of the inverter circuit and a power grid, the grid-side voltage of the grid connection of the inverter circuit is the voltage of the grid-connected power grid, the grid-side frequency of the grid connection of the inverter circuit is the frequency of the grid-connected power grid, the direct-current side voltage of the inverter circuit is the voltage value of the direct-current side of the inverter circuit, and the output current of the grid connection of the inverter circuit is the current value output by the inverter circuit to the grid-connected power grid.
In step 202, a duty cycle of a boost circuit is determined according to the photovoltaic output data and the active power target value.
In some possible embodiments, step 202 includes:
determining a photovoltaic output voltage target value according to the photovoltaic output data and the active power target value;
determining a photovoltaic output current target value according to the photovoltaic output voltage target value and the photovoltaic output voltage;
and determining the duty ratio of the boost current according to the photovoltaic output current target value and the photovoltaic output current.
In some possible embodiments, the determining a photovoltaic output voltage target value according to the photovoltaic output data and the active power target value includes:
determining a photovoltaic output voltage target value according to the photovoltaic output data, a first formula and an active power target value, wherein the first formula is as follows:
wherein, UpvrefFor photovoltaic output voltage target value, Kp_pAs a power loop proportional control coefficient, Ki_pFor integrating the control coefficient, P, for the power looppvFor photovoltaic output power value, PpvrefIs the active power target value.
In some possible embodiments, the power loop integral control coefficient is positively correlated with a power coefficient ratio, where the power coefficient ratio is a ratio of the active power target value to the photovoltaic maximum output power.
In some possible embodiments, the determining a photovoltaic output current target value according to the photovoltaic output voltage target value and the photovoltaic output voltage includes:
determining a photovoltaic output current target value according to the photovoltaic output voltage target value, a second formula and the photovoltaic output voltage, wherein the second formula is as follows:
wherein, IpvrefFor photovoltaic output current target value, Kp_u is the proportional control coefficient of the voltage loop, Ki_uFor voltage loop integral control coefficient, UpvIs the photovoltaic output voltage.
In some possible embodiments, the determining the duty cycle of the boost current according to the photovoltaic output current target value and the photovoltaic output current includes:
determining a duty cycle of a boost current according to the photovoltaic output current target value, a third formula and the photovoltaic output current, wherein the third formula:
wherein u isboost_gIs the duty cycle of the boost circuit, Kp_iAs a current loop proportional control coefficient, Ki_iFor the current loop integral control coefficient, IpvTo photovoltaic output current.
Illustratively, fig. 3 shows a control functional block diagram of the boost circuit, which is obtained by multiplying the sampled photovoltaic output voltage and photovoltaic output current, and is expressed by the formula:
Ppv＝Upv*Ipv，
wherein, UpvFor photovoltaic output voltage, IpvTo photovoltaic output current.
Then, the active power target value P is determinedpvrefAnd a photovoltaic output power value UpvSending the data to a power loop PI regulator, and selecting a proper K by the PI regulator through a PI parameter self-adaptive modulep_p、Ki_p。
The self-adaptive module adopted by the embodiment of the invention is a module for determining the power loop integral control coefficient according to the ratio of the active power target value to the photovoltaic maximum output power, and the photovoltaic maximum output power is the maximum output power under the current illumination intensity.
And the last output value of the power loop PI regulator is the photovoltaic output voltage target value.
The power loop PI regulator is formulated as:
wherein, UpvrefFor photovoltaic output voltage target value, Kp_pAs a power loop proportional control coefficient, Ki_pFor integrating the control coefficient, P, for the power looppvFor photovoltaic output power value, PpvrefThe PI parameter adaptive module is based on U as the target value of active powerpvrefAnd integral control coefficient K of photovoltaic maximum output power selection power loopi_p。
Target value U of photovoltaic output voltagepvrefAnd photovoltaic output voltage U obtained by samplingpvThe difference value of the voltage loop PI regulator is used for generating a photovoltaic output current target value IpvrefExpressed by the formula:
finally, the photovoltaic output current target value IpvrefAnd the photovoltaic output current IpvThe difference value of (2) generates duty ratio through a current loop PI regulator, PWM pulse output by the boost circuit is modulated, and the on and off of IGBT of the boost circuit are controlled, wherein the current loop P regulator is expressed by a formula as follows:
in step 203, the duty ratio of the inverter circuit is determined according to the grid-connected parameter and the direct current target voltage value.
In some possible embodiments, step 203 comprises:
acquiring a direct-axis component of the grid-connected current of the inverter circuit and a quadrature-axis component of the grid-connected current of the inverter circuit according to the grid-connected parameters;
and obtaining the duty ratio of the inverter circuit according to the direct current target voltage value, the direct axis component of the inverter circuit grid-connected current and the alternating axis component of the inverter circuit grid-connected current.
In some possible embodiments, the obtaining the duty ratio of the inverter circuit according to the dc target voltage value, the direct component of the inverter circuit grid-connected current, and the quadrature component of the inverter circuit grid-connected current includes:
determining a direct-axis component of the grid-connected target current according to the direct-current target voltage value, the direct-current side voltage of the inverter circuit and a fourth formula, wherein the fourth formula comprises the following steps:
wherein, IdrefFor the direct component of the grid-connected target current, kpIs the inverse voltage loop proportionality coefficient, kiThe integral coefficient of the inverter voltage loop is obtained;
determining that the quadrature-axis component of the grid-connected target current is zero;
and obtaining the duty ratio of the inverter circuit according to the grid-connected target current direct-axis component, the grid-connected target current quadrature-axis component, the inverter circuit grid-connected current direct-axis component and the inverter circuit grid-connected current quadrature-axis component.
Illustratively, the control function block diagram of the inverter circuit is shown in fig. 4, first, the voltage u on the power grid side is sampledabcObtaining the grid-side frequency, a possible way to achieve is to obtain the grid-side frequency ω through a phase-locked loopg. Using park transformation to convert grid-connected point current iabcConversion to grid-side frequency omegagOn the rotating dq coordinate system, obtaining the direct-axis component I of the grid-connected current of the inverter circuit respectivelydQuadrature component I of grid-connected current of sum-inverter circuitq. The specific calculation formula is as follows:
then, the target value U of the voltage on the DC side of the inverter currentdcrefThe actually measured DC side voltage U of the photovoltaic inverterdcAnd a DC target voltage value UdcrefSending the voltage into an inverter voltage PI regulator to generate a direct-axis component I of a grid-connected target currentdref. Given grid-connected target current quadrature axis component IqrefIs 0, expressed by the formula:
Iqref＝0
direct component I of grid-connected target currentdrefQuadrature component I of grid-connected target currentqrefDirect component I of current connected to inverter circuitdGrid-connected current quadrature component I of inverter circuitqAnd respectively carrying out difference making, obtaining the duty ratio of the inverter circuit through inverse park transformation, modulating to obtain the PWM pulse of the inverter circuit, and controlling the on-off of the IGBT of the photovoltaic inverter.
The following is an achievable example which is merely an explanation of the method according to the invention and does not constitute a limitation of the method according to the invention.
A possible embodiment comprises the following specific implementation steps:
first, generating the duty ratio of the boost circuit
First, the photovoltaic output voltage U is sampledpvAnd photovoltaic output current IpvCalculating to obtain the photovoltaic output power Ppv：
Ppv＝Upv×Ipv
Then, obtaining the target value P of the active powerpvrefSelecting a corresponding power loop K according to the PI self-adaptive modulei_pThe values are specifically chosen as shown in the following formula:
Kp_p＝0.001
wherein, PpvmaxThe maximum photovoltaic output power is the maximum output power under the current illumination intensity.
Then, the photovoltaic output power P is calculated according to the calculation result of the formulapvAnd an active power target value PpvrefAn input power loop PI regulator for generating a voltage target value Upvref。
Then, for the voltage target value UpvrefAnd the obtained photovoltaic output voltage UpvMaking difference, and generating a photovoltaic output current target value I through a voltage loop PI regulatorpvref。
Finally, the target value I of the photovoltaic output current is obtainedpvrefAnd photovoltaic output current IpvAnd (4) performing difference, generating a duty ratio through a current loop PI regulator, and modulating to obtain a PWM pulse of the boost current.
Generating the duty ratio of the inverter circuit
Firstly, the voltage u on the network side is sampledabcObtaining the grid side frequency omega through a phase-locked loopgUsing park transformation to convert the grid-connected point current iabcConversion to angular frequency omegagRespectively obtaining the direct-axis component I of the grid-connected current of the inverter circuit on a rotating dq coordinate systemdQuadrature component I of grid-connected current of sum-inverter circuitq。
Then, a voltage target value U on the direct current side of the photovoltaic inverter is obtaineddcrefSampling the DC side voltage U of the photovoltaic inverterdcThe target voltage and the target value UdcrefAnd a DC side voltage UdcInput PI regulator for generating grid-connected target current direct-axis component Idref。
Then, the direct-axis component I of the grid-connected target current isdrefDirect component I of current connected to inverter circuitdMaking a difference between the grid-connected target current quadrature-axis component 0 and the grid-connected current quadrature-axis component I of the inverter circuitqMaking difference, obtaining the duty ratio of the inverter circuit by inverse park transformation based on the two difference values, modulating to obtain the PWM pulse of the inverter circuit,and controlling the on and off of the IGBT of the photovoltaic inverter.
Aiming at the embodiment, simulation of grid connection of the photovoltaic inverter is built in MATLAB/Simulink.
The overall structure diagram of the photovoltaic inverter running with load is shown in fig. 1, and a photovoltaic array is connected with a power grid side in parallel through a boost circuit and an inverter circuit to jointly supply power to a three-phase load. Parameters of a photovoltaic power loop controller are changed through a PI parameter self-adaptive module, photovoltaic output power is tracked to upper-level instruction power in real time through voltage and current double-loop control, and grid-connected active support is achieved.
Using a fixed parameter Kp_p＝0.001，K i_p2 and Kp_p＝0.001，Ki_pThe power tracking control and PI parameter adaptation module control method of 40 simulates the case where the command power is 8000W to 2000W, and the simulation result is shown in fig. 5. As can be seen from the figure, in the power tracking control using fixed parameters, when K isp_p＝0.001，Ki_pAt 40, the oscillation amplitude is too large and even unstable when the upper command power is 2000W.
Using a fixed parameter Kp_p＝0.001，K i_p2 and Kp_p＝0.001，Ki_pThe power tracking control and power loop parameter adaptive adjustment control method of 25 simulates the case where the command power is from 4000W to 6000W, and the simulation result is shown in fig. 6. In power tracking control with fixed parameters, when Kp_p＝0.001，Ki_pWhen the upper level command power is 6000W, the tracking speed is too slow.
The simulation result can be obtained, when fixed parameters are adopted, the change of the working point of the photovoltaic inverter easily causes the problem of too low tracking speed or instability, and the photovoltaic inverter is not favorable for providing an active supporting function.
Therefore, a control mode of power loop parameter self-adaptive adjustment is provided, and as can be seen from simulation results, the photovoltaic inverter grid-connected control technology adopting the method can realize rapid tracking under various instruction power conditions, and the tracking speed and stability are obviously improved compared with a control method of fixed parameters.
According to the implementation mode of the grid-connected control method of the photovoltaic inverter, the photovoltaic output power can track the upper-level command power more quickly. The response speed of the photovoltaic can be improved to a greater extent when the constant power tracking control is operated in the grid-connected state of the photovoltaic inverter, the risk of grid disconnection of the photovoltaic inverter due to the out-of-limit grid-connected point voltage is avoided, the stability of a power grid is improved, and the method has a strong engineering application value.
It should be understood that the sequence numbers of the steps in the above embodiments do not mean the execution sequence, and the execution sequence of each process should be determined by the function and the inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
The following are apparatus embodiments of the invention, and for details not described in detail therein, reference may be made to the corresponding method embodiments described above.
Fig. 7 is a functional block diagram of a photovoltaic inverter grid-connected control device according to an embodiment of the present invention, and referring to fig. 7, the photovoltaic inverter grid-connected control device includes: a data acquisition module 710, a boost circuit control module 720, and an inverter circuit control module 730.
The data obtaining module 710 is configured to obtain photovoltaic output data, an active power target value, a grid-connected parameter, and a dc target voltage value, where the photovoltaic output data includes: the photovoltaic output voltage and the photovoltaic output current, the active power target value is an active power target value, and the grid-connected parameters include: the direct current target voltage value is the direct current side voltage target value of the inverter circuit.
And a boost circuit control module 720, configured to determine a duty cycle of the boost circuit according to the photovoltaic output data and the active power target value.
And the inverter circuit control module 730 is used for determining the duty ratio of the inverter circuit according to the grid-connected parameter and the direct-current target voltage value.
Fig. 8 is a functional block diagram of a terminal according to an embodiment of the present invention. As shown in fig. 8, the terminal 8 of this embodiment includes: a processor 800, a memory 801 and a computer program 802 stored in said memory 801 and executable on said processor 800. The processor 800, when executing the computer program 802, implements the steps of the above-described pv inverter grid-connection control method and pv inverter grid-connection control method embodiments, such as the steps 201 to 203 shown in fig. 2.
Illustratively, the computer program 802 may be partitioned into one or more modules/units that are stored in the memory 801 and executed by the processor 800 to implement the present invention.
The terminal 8 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal 8 may include, but is not limited to, a processor 800, a memory 801. It will be appreciated by those skilled in the art that fig. 8 is only an example of a terminal 8 and does not constitute a limitation of the terminal 8, and that it may comprise more or less components than those shown, or some components may be combined, or different components, for example the terminal may further comprise input output devices, network access devices, buses, etc.
The Processor 800 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
The memory 801 may be an internal storage unit of the terminal 8, such as a hard disk or a memory of the terminal 8. The memory 801 may also be an external storage device of the terminal 8, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), and the like, provided on the terminal 8. Further, the memory 801 may also include both an internal storage unit and an external storage device of the terminal 8. The memory 801 is used for storing the computer programs and other programs and data required by the terminal. The memory 801 may also be used to temporarily store data that has been output or is to be output.
It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit, and the integrated unit may be implemented in a form of hardware, or may be implemented in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the above embodiments, the description of each embodiment is focused on, and for parts that are not described or illustrated in detail in a certain embodiment, reference may be made to the description of other embodiments.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal and method may be implemented in other manners. For example, the above-described apparatus/terminal embodiments are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.
In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method according to the above embodiment may be realized by a computer program, which may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the steps of the embodiments of the pv inverter grid-connected control method and the pv inverter grid-connected control apparatus may be realized. 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 medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media which may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.
The above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may be modified or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.
Claims (10)
1. A grid-connected control method for a photovoltaic inverter is characterized by comprising the following steps:
the method comprises the following steps of obtaining photovoltaic output data, an active power target value, grid-connected parameters and a direct current target voltage value, wherein the photovoltaic output data comprise: photovoltaic output voltage and photovoltaic output current, the parameter of being incorporated into the power networks includes: the direct current target voltage value is an inverse circuit direct current side voltage target value;
determining the duty ratio of a boost circuit according to the photovoltaic output data and the active power target value;
and determining the duty ratio of the inverter circuit according to the grid-connected parameter and the direct current target voltage value.
2. The grid-connected control method for the photovoltaic inverter according to claim 1, wherein the determining the duty ratio of the boost circuit according to the photovoltaic output data and the active power target value comprises:
determining a photovoltaic output voltage target value according to the photovoltaic output data and the active power target value;
determining a photovoltaic output current target value according to the photovoltaic output voltage target value and the photovoltaic output voltage;
and determining the duty ratio of the boost current according to the photovoltaic output current target value and the photovoltaic output current.
3. The grid-connected control method for the photovoltaic inverter according to claim 2, wherein the step of determining the target photovoltaic output voltage according to the photovoltaic output data and the target active power value comprises the steps of:
determining a photovoltaic output voltage target value according to the photovoltaic output data, a first formula and an active power target value, wherein the first formula is as follows:
wherein, UpvrefFor photovoltaic output voltage target value, Kp_pAs a power loop proportional control coefficient, Ki_pFor integrating the control coefficient, P, for the power looppvFor photovoltaic output power value, PpvrefIs the active power target value.
4. The grid-connected control method for the photovoltaic inverter according to claim 3, wherein the power loop integral control coefficient is positively correlated with a power coefficient ratio, and the power coefficient ratio is a ratio of the active power target value to the photovoltaic maximum output power.
5. The pv inverter grid-connection control method according to claim 2, wherein the determining the pv output current target value according to the pv output voltage target value and the pv output voltage includes:
determining a photovoltaic output current target value according to the photovoltaic output voltage target value, a second formula and the photovoltaic output voltage, wherein the second formula is as follows:
wherein, IpvrefFor photovoltaic output current target value, Kp_uFor proportional control coefficient of voltage loop, Ki_uFor voltage loop integral control coefficient, UpvIs the photovoltaic output voltage.
6. The grid-connected control method for the photovoltaic inverter according to claim 2, wherein the determining the duty ratio of the boost current according to the target value of the photovoltaic output current and the photovoltaic output current comprises:
determining a duty cycle of a boost current according to the photovoltaic output current target value, a third formula and the photovoltaic output current, wherein the third formula:
wherein u isboost_gIs the duty cycle of the boost circuit, Kp_iAs a current loop proportional control coefficient, Ki_iFor the current loop integral control coefficient, IpvTo photovoltaic output current.
7. The grid-connected control method for the photovoltaic inverter according to any one of claims 1 to 6, wherein the determining the duty ratio of the inverter circuit according to the grid-connected parameter and the DC target voltage value comprises:
acquiring a direct-axis component of the grid-connected current of the inverter circuit and a quadrature-axis component of the grid-connected current of the inverter circuit according to the grid-connected parameters;
and obtaining the duty ratio of the inverter circuit according to the direct current target voltage value, the direct axis component of the inverter circuit grid-connected current and the alternating axis component of the inverter circuit grid-connected current.
8. The pv inverter grid-connection control method according to claim 7, wherein obtaining the duty ratio of the inverter circuit according to the dc target voltage value, the dc-to-grid current direct-axis component, and the ac-to-grid current quadrature-axis component comprises:
determining a direct-axis component of the grid-connected target current according to the direct-current target voltage value, the direct-current side voltage of the inverter circuit and a fourth formula, wherein the fourth formula comprises the following steps:
wherein, IdrefFor the direct component of the grid-connected target current, kpIs the inverse voltage loop proportionality coefficient, kiFor the integral coefficient of the inverter voltage ring, UdcrefIs a direct current target voltage value;
determining that the quadrature-axis component of the grid-connected target current is zero;
and obtaining the duty ratio of the inverter circuit according to the grid-connected target current direct-axis component, the grid-connected target current quadrature-axis component, the inverter circuit grid-connected current direct-axis component and the inverter circuit grid-connected current quadrature-axis component.
9. A terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of the preceding claims 1 to 8 when executing the computer program.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 8.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110970766.2A CN113725900A (en) | 2021-08-23 | 2021-08-23 | Grid-connected control method, terminal and storage medium for photovoltaic inverter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110970766.2A CN113725900A (en) | 2021-08-23 | 2021-08-23 | Grid-connected control method, terminal and storage medium for photovoltaic inverter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113725900A true CN113725900A (en) | 2021-11-30 |
Family
ID=78677503
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110970766.2A Pending CN113725900A (en) | 2021-08-23 | 2021-08-23 | Grid-connected control method, terminal and storage medium for photovoltaic inverter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113725900A (en) |
-
2021
- 2021-08-23 CN CN202110970766.2A patent/CN113725900A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| de Oliveira et al. | Grid‐tied photovoltaic system based on PSO MPPT technique with active power line conditioning | |
| Patel et al. | Photovoltaic system operation as DSTATCOM for power quality improvement employing active current control | |
| Singh et al. | Single‐phase solar grid‐interfaced system with active filtering using adaptive linear combiner filter‐based control scheme | |
| Gupta et al. | Power quality improvement of single phase weak grid interfaced hybrid solar PV and wind system using double fundamental signal extracter‐based control | |
| CN112671232B (en) | LLC resonant circuit control method and device and terminal equipment | |
| CN111130372B (en) | Three-level grid-connected inverter bus midpoint potential adjusting method and terminal equipment | |
| Patel et al. | Optimised PI‐4VPI current controller for three‐phase grid‐integrated photovoltaic inverter under grid voltage distortions | |
| WO2017103697A1 (en) | Power sharing for dc microgrids | |
| CN111130123A (en) | Self-adaptive control method of parallel active power filter | |
| CN110521077B (en) | Power supply system with inverter input voltage control | |
| CN109995078B (en) | Photovoltaic grid-connected electromechanical transient simulation device | |
| CN112600405B (en) | Control method and device of unidirectional PFC circuit and terminal equipment | |
| CN111162539A (en) | Controllable phase shifter site selection method and system considering wind power generation uncertainty | |
| CN113725900A (en) | Grid-connected control method, terminal and storage medium for photovoltaic inverter | |
| CN110061646A (en) | A kind of method, equipment and the storage medium of three-level inverter neutral balance | |
| CN115589031A (en) | Permanent magnet direct-drive wind mechanism network type control method and device, terminal and storage medium | |
| CN113482852B (en) | Control method, terminal and storage medium for permanent magnet direct-drive wind power generation converter | |
| CN111416377B (en) | Flexible direct current control method and device for improving transient stability of power grid | |
| Fuyin et al. | Research on UPQC harmonic control strategy based on optimized QPIR controller of beetle antennae search algorithm in microgrid | |
| CN111555353A (en) | Distributed control method and device for micro-grid system and storage medium | |
| CN111555354B (en) | Control method and device for autonomous renewable micro-grid system and storage medium | |
| CN110048431B (en) | Reactive power optimization method, device, equipment and storage medium for power distribution network | |
| CN110320958A (en) | Maximum power tracking method, system and terminal device based on Taylor's formula | |
| CN111082454B (en) | Method and system for obtaining oscillation risk quantitative index of power system | |
| CN108155676B (en) | New energy power generation field harmonic suppression method and device, controller and storage medium |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |