CN112379720B - Photovoltaic array maximum power point tracking controller for photovoltaic power generation system - Google Patents
Photovoltaic array maximum power point tracking controller for photovoltaic power generation system Download PDFInfo
- Publication number
- CN112379720B CN112379720B CN202011030144.3A CN202011030144A CN112379720B CN 112379720 B CN112379720 B CN 112379720B CN 202011030144 A CN202011030144 A CN 202011030144A CN 112379720 B CN112379720 B CN 112379720B
- Authority
- CN
- China
- Prior art keywords
- maximum power
- power point
- photovoltaic
- photovoltaic array
- voltage
- 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.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/66—Regulating electric power
- G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
-
- 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
-
- 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
Abstract
A photovoltaic array maximum power point tracking controller for a photovoltaic power generation system comprises a voltage/current detection and processing module, an array maximum power point curve family register, a first sub-controller and a second sub-controller. The controller firstly searches the intersection points of the output current-voltage curve of the photovoltaic array system and the maximum power point curve family of the array, then selects the best intersection point (namely the intersection point with the maximum power) from all the intersection points, and finally finds the global maximum power point of the photovoltaic array system on the basis of the best intersection point. The invention has accurate and rapid global maximum power point tracking capability.
Description
Technical Field
The invention relates to a photovoltaic power generation system, in particular to a photovoltaic array maximum power point tracking controller and a photovoltaic array maximum power point tracking method suitable for the photovoltaic power generation system.
Background
When an array form is adopted, the photovoltaic module can realize the capacity expansion. When shading conditions are different, Maximum Power Points (MPP) of the same photovoltaic array system show different distribution conditions. That is, the maximum power point of the photovoltaic array system is different under no-shadow, static-shadow and dynamic-shadow conditions. Moreover, under the static and dynamic shadow conditions, the output P-V (i.e., power-voltage) curve of the photovoltaic array system presents a multi-peak value, the output I-V (i.e., current-voltage) curve of the photovoltaic array system presents a monotonous region, and the existence of the local maximum power point increases the difficulty of tracking the global maximum power point.
In order to obtain the electric energy of the photovoltaic array system to the maximum extent, the existing MPPT (maximum power point tracking) control method includes a disturbance observation method, a conductance increment method, a simulated annealing method, a big data statistical algorithm, and the like. Wherein, the disturbance observation method and the conductance incremental method are easy to fall into a local maximum power point and deviate from a global maximum power point; the simulated annealing method and the big data statistical method cannot lock the global maximum power point hundred percent, and the possibility of finding a secondary large power point exists.
In order to improve accuracy while achieving rapidity, the MPPT control method needs to be further improved.
Disclosure of Invention
In order to overcome the defect that the existing MPPT control method is easy to fall into a local maximum power point or has the possibility of finding a secondary high power point, the invention provides a photovoltaic array maximum power point tracking controller for a photovoltaic power generation system, which can assist a power converter to quickly and accurately lock the global maximum power point of the photovoltaic array system and transmit the electric energy of the photovoltaic array system to a load for use as much as possible.
Embodiments of the present invention provide a photovoltaic array maximum power point tracking controller for a photovoltaic power generation system, wherein the photovoltaic power generation system includes a photovoltaic array system having a plurality of photovoltaic modules, and a power converter coupled to an output of the photovoltaic array system. The photovoltaic array maximum power point tracking controller comprises: the voltage/current detection and processing module is used for detecting the output voltage and the output current of the photovoltaic array system and converting the output voltage and the output current into a digital voltage signal and a digital current signal; the array maximum power point curve family register is internally stored with a plurality of photovoltaic array maximum power point curve functions, the plurality of photovoltaic array maximum power point curve functions correspond to a plurality of photovoltaic array maximum power point curves, and a plurality of intersection points exist between the plurality of photovoltaic array maximum power point curves and an output current-voltage curve of a photovoltaic array system; the first sub-controller finds the intersection points by adjusting the working state of an electronic switch in the power converter according to the digital voltage signal, the digital current signal and the curve function of the maximum power point of the photovoltaic arrays; and the second sub-controller identifies the optimal intersection point with the maximum power in the plurality of intersection points, and enables the photovoltaic array system to operate at the global maximum power point by adjusting the working state of an electronic switch in the power converter on the basis of the optimal intersection point.
In one embodiment, the photovoltaic array maximum power point tracking controller further comprises: the third sub-controller monitors whether the global maximum power point changes or not, and if the global maximum power point changes, the first sub-controller and the second sub-controller are triggered again to search for a new global maximum power point; otherwise, the working state of an electronic switch in the power converter is maintained so as to keep the photovoltaic array system to operate at the global maximum power point.
In one embodiment, the photovoltaic array maximum power point tracking controller further comprises: an intersection register which stores voltage values and current values of the plurality of intersections; and the global maximum power point register is used for storing the voltage value and the current value of the global maximum power point and the working state of an electronic switch in the power converter corresponding to the global maximum power point.
In one embodiment, the array maximum power point curve family register stores n × m photovoltaic array maximum power point curve functions Irefij ═ j × fref (Vin/(m +1-i)), where n is the total column number of photovoltaic modules in the photovoltaic array system, m is the total row number of photovoltaic modules in the photovoltaic array system, Vin is a function input variable, Irefij is a function output variable, fref () is a function containing information of maximum power points of single photovoltaic modules under different illumination conditions, the value range of i is 1 to m, and the value range of j is 1 to n; the maximum power point curve function of the n x m photovoltaic arrays corresponds to the maximum power point curve of the n x m photovoltaic arrays, and the maximum power point curve of the n x m photovoltaic arrays and the output current-voltage curve of the photovoltaic array system have n x m intersection points.
The function fref () may be a fitted curve function of the maximum power point of a single photovoltaic module under different lighting conditions, or a fitted curve function of the maximum power point of a single photovoltaic module under different lighting conditions of superimposed voltage or current boundary conditions.
In one embodiment, the voltage/current detection and processing module includes a voltage detection circuit, a current detection circuit, an analog-to-digital conversion circuit, and an average calculator or digital filter.
In one embodiment, the first sub-controller comprises: the function arithmetic unit extracts a curve function of the maximum power point of the photovoltaic array from the curve family register of the maximum power point of the array, enables a function input variable to be equal to a digital voltage signal, and solves a function output variable to serve as a current reference value; the intersection point judger compares the current reference value with the magnitude of the digital current signal to judge whether to find the intersection point of the photovoltaic array maximum power point curve corresponding to the current photovoltaic array maximum power point curve function and the output current-voltage curve of the photovoltaic array system; a first reference voltage generator for adjusting a first voltage reference value according to the judgment result of the intersection point judger; and the first hysteresis comparator compares the first voltage reference value with the digital voltage signal and generates a control signal according to the comparison result so as to adjust the working state of an electronic switch in the power converter.
When the first sub-controller is operating, the function operator may sequentially extract the plurality of pv array maximum power point curve functions from the array maximum power point curve family register in a sequential or reverse order to find the plurality of intersection points between the plurality of pv array maximum power point curves and the output current-voltage curve of the pv array system.
In one embodiment, the second sub-controller comprises: an optimum intersection locator which finds an optimum intersection having the maximum power by calculation from the plurality of intersections; the global maximum power point judger judges whether to find the global maximum power point on the basis of the optimal intersection point; the second reference voltage generator adjusts a second voltage reference value according to the judgment result of the optimal intersection point and the global maximum power point judger; the second hysteresis comparator compares the second voltage reference value with the digital voltage signal and generates a control signal according to the comparison result so as to adjust the working state of an electronic switch in the power converter; and the frequency meter is used for calculating the working frequency and the duty ratio of an electronic switch in the power converter corresponding to the global maximum power point.
The embodiment of the invention also provides a photovoltaic array maximum power point tracking method for a photovoltaic power generation system, which comprises the following steps: detecting the output voltage and the output current of the photovoltaic array system; generating a plurality of photovoltaic array maximum power point curves based on the output characteristics of a single photovoltaic assembly; searching an intersection point between an output voltage-current curve of the photovoltaic array system and the maximum power point curves of the photovoltaic arrays; finding out the best intersection point with the maximum power from the intersection points; and on the basis of the optimal intersection point, the photovoltaic array system is enabled to operate at the global maximum power point by adjusting the working state of an electronic switch in the power converter.
The beneficial effects of the embodiment according to the invention are mainly expressed in that: the interference of a local maximum power point to a global maximum power point can be avoided by utilizing the intersection point and the optimal intersection point of the photovoltaic array system output current-voltage curve and the array maximum power point curve family; the global maximum power point optimizing process or tracking process based on the optimal intersection point is fast and accurate; the method can cope with the working conditions of no shadow, static shadow, dynamic shadow and the like, and has the capability of tracking the global maximum power point.
Drawings
Fig. 1 is a schematic block diagram of a photovoltaic power generation system to which an embodiment of the present invention is applicable.
Fig. 2 shows a block diagram of a photovoltaic array maximum power point tracking controller for a photovoltaic power generation system according to an embodiment of the present invention.
Fig. 3 is a block diagram of the voltage/current detection and processing module of fig. 2 according to an embodiment of the present invention.
Fig. 4 is a block diagram of the sub-controller 1 of fig. 2 according to an embodiment of the present invention.
Fig. 5 is a block diagram of the sub-controller 2 of fig. 2 according to an embodiment of the present invention.
Fig. 6 is a block diagram of a structure of the sub-controller 3 of fig. 2 according to an embodiment of the present invention.
Fig. 7 is a static schematic diagram of an output I-V curve, an array MPP curve family Irefij and a global maximum power point MPPg of the photovoltaic array system under the illumination condition 1 in the embodiment of the present invention (I takes 1 to 2, j takes 1 to 2).
Fig. 8 is a static schematic diagram of an output P-V curve of the photovoltaic array system under the illumination condition 1, power Prefij of an array MPP family curve, and a global maximum power point MPPg in the embodiment of the present invention (i takes 1 to 2, j takes 1 to 2).
Fig. 9 is a static schematic diagram of an output I-V curve, an array MPP curve family Irefij and a global maximum power point MPPg of the photovoltaic array system under the illumination condition 2 in the embodiment of the present invention (I takes 1 to 2, j takes 1 to 2).
Fig. 10 is a static diagram of the output P-V curve of the photovoltaic array system under the illumination condition 2, the power of the array MPP curve group prefix, and the global maximum power point MPPg in the embodiment of the present invention (i takes 1 to 2, j takes 1 to 2).
Fig. 11 is a dynamic schematic diagram of the photovoltaic array system under the illumination conditions 1 to 2 including the output voltage vin, the output current iin, the intersection crossj, the optimal intersection and the global maximum power point MPPg in the embodiment of the present invention (i takes 1 to 2, j takes 1 to 2).
Fig. 12 is a dynamic schematic diagram of the photovoltaic array system under the illumination conditions 1 to 2 including the output power pin, the intersection crossj, the optimal intersection, and the global maximum power point MPPg at the switching time in the embodiment of the present invention (i takes 1 to 2, j takes 1 to 2).
Detailed Description
The invention is further described below with reference to the accompanying drawings. It should be noted that the embodiments described herein are only for illustration and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be understood by those of ordinary skill in the art that these specific details are not required in order to practice the present invention. In other instances, well-known circuits, materials, or methods have not been described in detail in order to avoid obscuring the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the figures provided herein are for illustrative purposes, and wherein like reference numerals refer to like elements throughout. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present.
Fig. 1 is a schematic block diagram of a photovoltaic power generation system including a photovoltaic array system having n x m photovoltaic modules, a DC/DC converter having an electronic switch, and a photovoltaic array maximum power point tracking controller for the photovoltaic power generation system to which embodiments of the present invention are applicable. The DC/DC converter is a power converter that receives the output voltage vin and the output current iin of the photovoltaic array system and converts them into an output voltage Vo to be supplied to the DC bus to drive a load connected to the DC bus.
Referring to fig. 1, a pv array maximum power point tracking controller for a pv power generation system detects an output voltage vin and an output current iin of the pv array system, outputs a control signal vdriving to control an electronic switch in a DC/DC converter, and finally operates at a global maximum power point MPPg by adjusting a working state of the electronic switch in the DC/DC converter. The DC/DC converter can adopt a DC/DC converter with continuous input and output currents, such as: a Super-Boost converter, a Super-Buck converter, a Cuk converter and the like.
The technical idea of the embodiment of the invention is as follows: based on the output characteristics of a single photovoltaic assembly, a family of array maximum power point curves are generated through methods such as curve fitting. A method for searching the global maximum power point MPPg is designed by means of an array maximum power point curve family, and comprises the following steps: firstly, finding out the intersection points of a photovoltaic array system output current-voltage curve and an array maximum power point curve family, then selecting the optimal intersection point (namely the intersection point with the maximum power) from all the intersection points, and finally finding out the overall maximum power point MPPG on the basis of the optimal intersection point. The array maximum power point curve family obtained by adopting the curve fitting method can contain the information of the maximum power point MPP of a single photovoltaic module under different illumination conditions. The interference of a local maximum power point to a global maximum power point MPPg can be avoided by utilizing the intersection point and the optimal intersection point of the photovoltaic array system output current-voltage curve and the array maximum power point curve family; the MPPG optimizing process or tracking process of the global maximum power point based on the optimal intersection point is rapid and accurate; the method can cope with the working conditions of no shadow, static shadow, dynamic shadow and the like, and has the capability of tracking the global maximum power point.
Referring to fig. 2, the photovoltaic array maximum power point tracking controller for a photovoltaic power generation system includes a voltage/current detection and processing module, an array maximum power point family register (i.e., an array MPP family register), an intersection register, a global maximum power point register (i.e., an MPPg register), and first to third sub-controllers (i.e., sub-controllers 1 to 3). The voltage/current detection and processing module detects the output voltage vin and the output current iin of the photovoltaic array system and converts the output voltage vin and the output current iin into a digital voltage signal vin (k) and a digital current signal iin (k), wherein k is an integer. The array MPP curve family register is internally stored with n multiplied by m photovoltaic array maximum power point curve functions (namely photovoltaic array MPP curve functions): the maximum power point MPP curve function of the single photovoltaic module under different illumination conditions corresponds to the maximum power point MPP curve (namely the MPP curve) of the n multiplied by m photovoltaic arrays, the MPP curve of the n multiplied by m photovoltaic arrays and the output current-voltage curve (namely the output I-V curve of the photovoltaic array system) of the photovoltaic array system have n multiplied by m intersection points Crossij, the value range of I is 1 to m, and the value range of j is 1 to n. The fref () is a fitting curve function of the maximum power point MPP of the single photovoltaic assembly under different illumination conditions, or is a fitting curve function of the maximum power point MPP of the single photovoltaic assembly under different illumination conditions of the boundary conditions of superposed voltage or current. Superimposing voltage or current boundary conditions can speed up the speed of finding the intersection. The fitted curve function includes an exponential function, a polynomial function, a polyline function, and the like. The voltage boundary conditions comprise that Vin is more than or equal to 0 and less than or equal to m multiplied by Voc, the current boundary conditions comprise that Irefij is more than or equal to 0 and less than or equal to j multiplied by Isc, and Voc and Isc are open-circuit voltage and short-circuit current of a single photovoltaic module under the maximum illumination condition. The intersection register internally stores voltage values Vin _ Cross11 to Vin _ Cross and current values Iin _ Cross11 to Iin _ Cross of n × m intersections Cross11 to Cross. The MPPg register stores a voltage value Vin _ MPPg and a current value Iin _ MPPg of a global maximum power point MPPg, and also stores a working state of an electronic switch in the DC/DC converter corresponding to the global maximum power point MPPg, for example: switching frequency f _ MPPg, duty ratio D _ MPPg, on-time, off-time, voltage reference value, hysteresis width and the like.
And information interaction exists among the voltage/current detection and processing module, the array MPP curve family register, the intersection point register, the MPPG register, the sub-controllers 1 to 3.
In order to deal with various working conditions such as no shadow, static shadow, dynamic shadow and the like, the sub-controllers 1 to 3 output control signals vdriving in sequence in a time-sharing working mode, and the operation is repeated; the task of the sub-controller 1 is to generate a current reference value by using a photovoltaic array MPP curve function Iref11 ═ fref (Vin/m) to Irefmn ═ n × fref (Vin), find intersection points Cross11 to Cross n by adjusting the operating state of electronic switches in the DC/DC converter, i.e. the photovoltaic array system operates from intersection point Cross11 to Cross, when the photovoltaic array system operates from intersection point Cross, Vin (k) ═ Vin _ Cross, Iin (k) ═ Iin _ Cross, i ranges from 1 to m, j ranges from 1 to n; the task of the sub-controller 2 is to find a global maximum power point MPPg by adjusting the operating state of the electronic switches in the DC/DC converter on the basis of the intersection points Cross11 to Cross smn, that is, to make the photovoltaic array system operate at the global maximum power point MPPg, when the photovoltaic array system operates at the global maximum power point MPPg, Vin (k) ═ Vin _ MPPg, and Iin (k) ═ Iin _ MPPg; the task of the sub-controller 3 is to monitor whether the global maximum power point MPPg changes, if the global maximum power point MPPg changes, that is, Vin (k) ≠ Vin _ MPPg or Iin (k) ≠ Iin _ MPPg or Vin (k) × Iin (k) ≠ Vin _ MPPg × Iin _ MPPg, the sub-controller 1 is called again to the sub-controller 3 to find the global maximum power point MPPg, otherwise, the working state of an electronic switch in the DC/DC converter is maintained, that is, the photovoltaic array system is kept running at the global maximum power point MPPg.
The voltage/current detection and processing module, the array MPP curve family register, the intersection point register, the MPPG register and the sub-controllers 1 to 3 can adopt special integrated chips, such as: LM6152 and S29GL128P, programmable devices such as: TMS320F 28027.
Further, referring to fig. 3, the voltage/current detecting and processing module includes a voltage detecting circuit, a current detecting circuit, an analog-to-digital converting circuit and an average calculator or a digital filter, the voltage detecting circuit detects an output voltage vin of the photovoltaic array system, the current detecting circuit detects an output current iin of the photovoltaic array system, the analog-to-digital converting circuit respectively converts analog detection results of the voltage detecting circuit and the current detecting circuit into an original digital voltage signal vin (k) and an original digital current signal iin (k), the average calculator obtains an average value of the original digital voltage signal vin (k) and the original digital current signal iin (k), that is, a digital voltage signal vin (k) and a digital current signal iin (k), and the average algorithm may use an equation
And
or
And
y is a positive integer; the original digital voltage signal vin (k) and the original digital current signal iin (k) may also be filtered by a digital filter, which may be a low-pass digital filter or a band-pass digital filter, into a digital voltage signal vin (k) and a digital current signal iin (k). Both the mean calculator and the digital filter function to reduce the noise of the original digital signal.
Referring to fig. 4, the sub-controller 1 includes a function operator, a cross point judger, a first reference voltage generator (i.e., the reference voltage generator 1), and a first hysteresis comparator (i.e., the hysteresis comparator 1), the function operator extracts a photovoltaic array MPP curve function Irefij (j) × fref (Vin/(m +1-i)) from the array MPP family register, makes the function input variable Vin equal to the digital voltage signal Vin (k), finds the function output variable Irefij, makes the current reference value Irefij (k) equal to the function output variable Irefij, i has a range of 1 to m, and j has a range of 1 to n. The intersection judger compares the current reference value Irefij (k) with the digital current signal Iin (k), if the absolute value of the difference value Delta I between the digital current signal Iin (k) and the current reference value Irefij (k) is smaller than an allowable error, the intersection crossj is judged to be found, and corresponding Vin (k) and Iin (k) are stored into an intersection register as the voltage value Vin _ crossj and the current value Iin _ crossj of the intersection crossj, and meanwhile, the reference voltage generator 1 is enabled to keep the voltage reference value vref1 unchanged, so that the photovoltaic array system operates at the intersection crossj; otherwise, it is determined that "the intersection crossj is not found", and the reference voltage generator 1 is made to adjust the first voltage reference vref1 according to the difference Δ I between the digital current signal iin (k) and the current reference irefij (k), if the difference Δ I >0, the first voltage reference vref1 is increased, otherwise, the first voltage reference vref1 is decreased. The hysteretic comparator 1 compares the first voltage reference vref1 with the digital voltage signal vin (k), if vin (k) > vref1+ Δ vref1, the control signal vdriving is set to high level, if vin (k) < vref1- Δ vref1, the control signal vdriving is set to low level, otherwise, the control signal vdriving is kept unchanged, and Δ vref1 is the hysteretic width of the hysteretic comparator 1. When the sub-controller 1 works, the function arithmetic unit sequentially extracts the photovoltaic array MPP curve function Irefij (j) multiplied by fref (Vin/(m +1-i)) from the array MPP curve family register in sequence or reverse sequence, wherein the value range of i is 1 to m, and the value range of j is 1 to n. And a hysteresis comparator is adopted, so that a rapid intersection point searching process can be realized.
Referring to fig. 5, the sub-controller 2 comprises an optimum Cross point locator, a global maximum power point determiner (i.e. MPPg determiner), a frequency meter, a second reference voltage generator (i.e. reference voltage generator 2) and a second hysteresis comparator (i.e. hysteresis comparator 2), the optimum Cross point locator and the MPPg determiner working in sequence with time sharing, the task of the optimum Cross point locator being to find the Cross point corresponding to MAX (Vin _ Cross11 x Iin _ Cross11, …, Vin _ Cross x Iin _ Cross) from the Cross points Cross11 to Cross, i.e. the optimum Cross point, MAX () being a function of the maximum value, the task of the MPPg determiner being to find the global maximum power point MPPg on the basis of the optimum Cross point. When the optimal intersection point locator works, the optimal intersection point locator extracts voltage values Vin _ Cross11 to Vin _ Cross and current values Iin _ Cross11 to Iin _ Cross of the intersection points Cross11 to Cross from the intersection point register, finds the optimal intersection point through calculation, and simultaneously makes the voltage reference value vref2 output by the reference voltage generator 2 equal to the voltage value of the optimal intersection point, the hysteresis comparator 2 compares the second voltage reference value vref2 with the magnitude of the digital voltage signal Vin (k), if Vin (k) is greater than vref2+ Δ vref2, the control signal vdriving is made high, if Vin (k) is smaller than vref2- Δ vref2, the control signal vdriving is made low, otherwise, the control signal vdriving is kept unchanged, so that the photovoltaic array system operates at the optimal intersection point, and Δ vref2 is the hysteresis width of the hysteresis comparator 2.
When the MPPG judger works, the MPPG judger judges whether a global maximum power point MPPG is found by adopting a disturbance observation method or a conductance increment method, if the MPPG is judged to be found, corresponding Vin (k) and Iin (k) are taken as a voltage value Vin _ MPPG and a current value Iin _ MPPG of the global maximum power point MPPG and stored in an MPPG register, a frequency meter is called to calculate a working frequency f _ MPPG and a duty ratio D _ MPPG of an electronic switch in a DC/DC converter corresponding to the global maximum power point MPPG, the working frequency f _ MPPG and the duty ratio D _ MPPG are also stored in the MPPG register together, and a reference voltage generator 2 is also made to keep a voltage reference value vref2 unchanged, so that a photovoltaic array system runs at the global maximum power point MPPG; if the determination is that the global maximum power point MPPg is not found, the reference voltage generator 2 is made to generate a second voltage reference value vref2 by using a disturbance observation method or a conductance increment method, the hysteresis comparator 2 compares the second voltage reference value vref2 with the digital voltage signal vin (k), if vin (k) > vref2+ Δ vref2, the control signal vdriving is made to be at a high level, if vin (k) < vref2- Δ vref2, the control signal vdriving is made to be at a low level, otherwise, the control signal vdriving is kept unchanged, and Δ vref2 is the hysteresis width of the hysteresis comparator 2. And a hysteresis comparator is adopted, so that the rapid overall maximum power point MPPG searching process can be realized.
Referring to fig. 6, the sub-controller 3 includes a global maximum power point change determiner (i.e., MPPg change determiner), the MPPg change judger extracts a voltage value Vin _ MPPg and a current value Iin _ MPPg of the global maximum power point MPPg from the MPPg register, compares the magnitude of the digital voltage signal Vin (k) and Vin _ MPPg, or comparing the digital current signals Iin (k) and Iin _ MPPg, or comparing the values of Vin (k) xIin (k) and Vin _ MPPg xIin _ MPPg, if the absolute value of the difference between Vin (k) and Vin _ MPPg is larger than the allowable error, or the absolute value of the difference between Iin (k) and Iin _ MPPg is larger than the allowable error, or the absolute value of the difference between Vin (k) x Iin (k) and Vin _ MPPg x Iin _ MPPg is larger than the allowable error, judging that the global maximum power point MPPG changes, otherwise, judging that the global maximum power point MPPG does not change. The sub-controller 3 further comprises a PWM modulator, the PWM modulator extracts the working frequency f _ MPPg and the duty ratio D _ MPPg of an electronic switch in the DC/DC converter corresponding to the global maximum power point MPPg from the MPPmpg register, and outputs a control signal vdriving according to the information of the f _ MPPg and the D _ MPPmpg, so that the photovoltaic array system is kept to operate at the global maximum power point MPPmpg. The PWM modulator has the function of fixing the working frequency of the DC/DC converter, and is more beneficial to monitoring whether the global maximum power point MPPg changes or not compared with a hysteresis comparator.
Examples of m-2 and n-2 are provided to further illustrate the simulation of the embodiments of the present invention. As shown in fig. 1, the photovoltaic array system consists of 2 rows and 2 columns of photovoltaic modules, 4 bypass diodes and 2 reverse blocking diodes. Taking array MPP curve function
Wherein Isc is the short circuit current of a single photovoltaic module under maximum lighting conditions. Lighting conditions 1 and 2 were taken as 2 different typical static shadow conditions. As can be seen from fig. 7 to 10, the output I-V curve of the pv array system in both cases exhibits multiple monotonic regions, and the output P-V curve thereof also exhibits multiple peaks.
Further, as shown in fig. 7, the output I-V curve of the photovoltaic array system under the illumination condition 1 has 4 intersections with the array MPP curve family Irefij; referring again to fig. 8, it can be seen that the intersection of the photovoltaic array system output I-V curve and the array MPP curve Iref11 is the optimal intersection, very close in power to the global maximum power point MPPg. As shown in fig. 9, the output I-V curve of the photovoltaic array system under the illumination condition 2 and the array MPP curve family Irefij also have 4 intersections; referring again to fig. 10, it can be seen that the intersection of the photovoltaic array system output I-V curve and the array MPP curve Iref22 is the optimal intersection, very close in power to the global maximum power point MPPg.
Meanwhile, an existing scheme is selected for comparison, that is, an ideal Isc-Voc curve (when Vin is 2 × Voc, the current value corresponding to the curve is 2 × Isc) is provided as a comparison curve. As can be seen from fig. 7 to 10, the optimal intersection point of the embodiment of the present invention is closer to the global maximum power point MPPg than the intersection point of the output I-V curve of the photovoltaic array system and the ideal Isc-Voc curve. Under the illumination condition 1, the global maximum power point MPPG is searched from the intersection point of the I-V curve output by the photovoltaic array system and the ideal Isc-Voc curve, and the MPPG is easy to be trapped in the local maximum power point. This shows that it is faster and more accurate to look for the global maximum power point MPPg from the optimal intersection point than the intersection point of the photovoltaic array system output I-V curve and the ideal Isc-Voc curve.
Fig. 11 is a dynamic schematic diagram of the photovoltaic array system under the illumination conditions 1 to 2 including the output voltage vin, the output current iin, the intersection crossj, the optimal intersection, and the global maximum power point MPPg at the switching time. Fig. 12 is a dynamic schematic diagram of the output power pin, the intersection crossj, the optimal intersection and the global maximum power point MPPg of the photovoltaic array system in the lighting conditions 1 to 2 including the switching time. Fig. 11 and 12 both show the optimization process or tracking process of "first crossing, then best crossing, and finally MPPg" under the static shadow and the dynamic shadow, which illustrates that the embodiment of the present invention has the global maximum power point tracking capability.
The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but rather by the equivalents thereof as may occur to those skilled in the art upon consideration of the present inventive concept. Although in the foregoing embodiments, the DC/DC converter is coupled to the output end of the photovoltaic array system, the photovoltaic array MPPT controller adjusts the operating state of the electronic switch in the DC/DC converter, so that the photovoltaic array system finally operates at the global maximum power point MPPg. It will be appreciated by those skilled in the art that the aforementioned DC/DC converter may be replaced by other power converters that convert voltage or current from the photovoltaic array system to drive a load such as a grid, battery or motor. Besides, in addition to the disturbance observation method and the conductance increment method, other MPPT control methods, such as an analog annealing method, a big data statistical algorithm, a current scanning method, and the like, may be adopted according to the embodiment of the present invention to determine and search the global maximum power point MPPg. The sub-controllers 1 to 3 may also adopt other suitable control modes besides the hysteresis control and the PWM control according to the actual application requirements. None of these variants goes beyond the scope of protection of the present invention.
Claims (10)
1. A photovoltaic array maximum power point tracking controller for a photovoltaic power generation system, wherein the photovoltaic power generation system includes a photovoltaic array system having a plurality of photovoltaic modules, and a power converter coupled to an output of the photovoltaic array system, the photovoltaic array maximum power point tracking controller comprising:
the voltage/current detection and processing module is used for detecting the output voltage and the output current of the photovoltaic array system and converting the output voltage and the output current into a digital voltage signal and a digital current signal;
the array maximum power point curve family register is internally stored with a plurality of photovoltaic array maximum power point curve functions, the plurality of photovoltaic array maximum power point curve functions correspond to a plurality of photovoltaic array maximum power point curves, and a plurality of intersection points exist between the plurality of photovoltaic array maximum power point curves and an output current-voltage curve of a photovoltaic array system;
the first sub-controller finds the intersection points by adjusting the working state of an electronic switch in the power converter according to the digital voltage signal, the digital current signal and the curve function of the maximum power point of the photovoltaic arrays; and
and the second sub-controller identifies the optimal intersection point with the maximum power in the plurality of intersection points, and enables the photovoltaic array system to operate at the global maximum power point by adjusting the working state of an electronic switch in the power converter on the basis of the optimal intersection point.
2. The photovoltaic array maximum power point tracking controller of claim 1, further comprising:
the third sub-controller monitors whether the global maximum power point changes or not, and if the global maximum power point changes, the first sub-controller and the second sub-controller are triggered again to search for a new global maximum power point; otherwise, the working state of an electronic switch in the power converter is maintained so as to keep the photovoltaic array system to operate at the global maximum power point.
3. The photovoltaic array maximum power point tracking controller of claim 1, further comprising:
an intersection register which stores voltage values and current values of the plurality of intersections; and
and the global maximum power point register stores the voltage value and the current value of the global maximum power point and the working state of an electronic switch in the power converter corresponding to the global maximum power point.
4. The pv array maximum power point tracking controller of claim 1, wherein the array maximum power point curve family register stores n × m pv array maximum power point curve functions Irefij j × fref (Vin/(m +1-i)), where n is the total number of columns of pv devices in the pv array system, m is the total number of rows of pv devices in the pv array system, Vin is a function input variable, Irefij is a function output variable, fref () is a function containing information of maximum power points of individual pv devices under different illumination conditions, i ranges from 1 to m, and j ranges from 1 to n; the maximum power point curve function of the n x m photovoltaic arrays corresponds to the maximum power point curve of the n x m photovoltaic arrays, and the maximum power point curve of the n x m photovoltaic arrays and the output current-voltage curve of the photovoltaic array system have n x m intersection points.
5. The photovoltaic array maximum power point tracking controller of claim 4, wherein the function fref () is a fitted curve function of the maximum power point of a single photovoltaic module under different lighting conditions or a fitted curve function of the maximum power point of a single photovoltaic module under different lighting conditions with superimposed voltage or current boundary conditions.
6. The photovoltaic array maximum power point tracking controller of claim 1, wherein the voltage/current detection and processing module comprises a voltage detection circuit, a current detection circuit, an analog-to-digital conversion circuit, and an average calculator or a digital filter.
7. The photovoltaic array maximum power point tracking controller of claim 1, wherein the first sub-controller comprises:
the function arithmetic unit extracts a curve function of the maximum power point of the photovoltaic array from the curve family register of the maximum power point of the array, enables a function input variable to be equal to a digital voltage signal, and solves a function output variable to serve as a current reference value;
the intersection point judger compares the current reference value with the magnitude of the digital current signal to judge whether to find the intersection point of the photovoltaic array maximum power point curve corresponding to the current photovoltaic array maximum power point curve function and the output current-voltage curve of the photovoltaic array system;
a first reference voltage generator for adjusting a first voltage reference value according to the judgment result of the intersection point judger; and
and the first hysteresis comparator compares the first voltage reference value with the digital voltage signal and generates a control signal according to the comparison result so as to adjust the working state of an electronic switch in the power converter.
8. The pv array mppt controller of claim 7, wherein when the first sub-controller is operating, the function operator sequentially extracts the pv array mppt functions from the array mppt family register in a sequential or reverse order to find the intersections between the pv array mppt curves and the output current-voltage curve of the pv array system.
9. The photovoltaic array maximum power point tracking controller of claim 1, the second sub-controller comprising:
an optimum intersection locator which finds an optimum intersection having the maximum power by calculation from the plurality of intersections;
the global maximum power point judger judges whether to find the global maximum power point on the basis of the optimal intersection point;
the second reference voltage generator adjusts a second voltage reference value according to the judgment result of the optimal intersection point and the global maximum power point judger;
the second hysteresis comparator compares the second voltage reference value with the digital voltage signal and generates a control signal according to the comparison result so as to adjust the working state of an electronic switch in the power converter; and
and the frequency meter is used for calculating the working frequency and the duty ratio of an electronic switch in the power converter corresponding to the global maximum power point.
10. A photovoltaic array maximum power point tracking method for a photovoltaic power generation system, wherein the photovoltaic power generation system includes a photovoltaic array system having a plurality of photovoltaic modules, and a power converter coupled to an output of the photovoltaic array system, the photovoltaic array maximum power point tracking method comprising:
detecting the output voltage and the output current of the photovoltaic array system;
generating a plurality of photovoltaic array maximum power point curves based on the output characteristics of a single photovoltaic assembly;
searching an intersection point between an output voltage-current curve of the photovoltaic array system and the maximum power point curves of the photovoltaic arrays;
finding out the best intersection point with the maximum power from the intersection points; and
and on the basis of the optimal intersection point, the photovoltaic array system is enabled to operate at the global maximum power point by adjusting the working state of an electronic switch in the power converter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011030144.3A CN112379720B (en) | 2020-09-27 | 2020-09-27 | Photovoltaic array maximum power point tracking controller for photovoltaic power generation system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011030144.3A CN112379720B (en) | 2020-09-27 | 2020-09-27 | Photovoltaic array maximum power point tracking controller for photovoltaic power generation system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112379720A CN112379720A (en) | 2021-02-19 |
| CN112379720B true CN112379720B (en) | 2022-02-18 |
Family
ID=74579876
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011030144.3A Active CN112379720B (en) | 2020-09-27 | 2020-09-27 | Photovoltaic array maximum power point tracking controller for photovoltaic power generation system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112379720B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113760036B (en) * | 2021-09-26 | 2023-05-12 | 中机国能电力工程有限公司 | Component optical power tracking circuit |
| CN115309195A (en) * | 2022-09-06 | 2022-11-08 | 合肥仁卓智能科技有限公司 | Control method and device of photovoltaic tracking axis and photovoltaic tracking system |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2655007C (en) * | 2009-02-20 | 2017-06-27 | Queen's University At Kingston | Photovoltaic cell inverter |
| EP2503427A1 (en) * | 2011-03-23 | 2012-09-26 | ABB Research Ltd. | Method for searching global maximum power point |
| CN105515047B (en) * | 2016-01-12 | 2018-04-06 | 上海电力学院 | A kind of voltage control method of photovoltaic cell |
| CN106684912B (en) * | 2016-12-23 | 2019-10-25 | 上海致远绿色能源股份有限公司 | A kind of control method of the solar power system of multiple module paralleling operation |
| CN106647921B (en) * | 2017-01-19 | 2017-12-01 | 南通大学 | Mitigate the improvement MPPT algorithm that local shades influence on photovoltaic system |
-
2020
- 2020-09-27 CN CN202011030144.3A patent/CN112379720B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN112379720A (en) | 2021-02-19 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Boztepe et al. | Global MPPT scheme for photovoltaic string inverters based on restricted voltage window search algorithm | |
| JP5412575B2 (en) | Solar power generation system and control system | |
| Ahmed et al. | A novel maximum power point tracking for photovoltaic applications under partially shaded insolation conditions | |
| AU2011245033B2 (en) | Maximum power point tracking for a power generator | |
| Hohm et al. | Comparative study of maximum power point tracking algorithms | |
| Boukenoui et al. | Experimental assessment of Maximum Power Point Tracking methods for photovoltaic systems | |
| CN112379720B (en) | Photovoltaic array maximum power point tracking controller for photovoltaic power generation system | |
| Luo et al. | Synchronous buck converter based low-cost and high-efficiency sub-module DMPPT PV system under partial shading conditions | |
| KR101550368B1 (en) | Solar photovoltaic power generation system and method for controlling connection of solar cell array | |
| Kang et al. | A Novel MPPT Control of photovoltaic system using FLC algorithm | |
| CN112187168B (en) | MPPT controller suitable for photovoltaic module series system | |
| Li | A MPPT control strategy with variable weather parameter and no DC/DC converter for photovoltaic systems | |
| Shao et al. | A multi-stage MPPT algorithm for PV systems based on golden section search method | |
| Mahmoud et al. | A comparative study of four widely-adopted mppt techniques for pv power systems | |
| Septya et al. | Design and implementation soft-switching MPPT SEPIC converter using P&O algorithm | |
| CN112104323B (en) | MPPT controller suitable for photovoltaic module parallel system | |
| Shao et al. | A new maximum power point tracking method for photovoltaic arrays using golden section search algorithm | |
| Drıs et al. | Comparative study of algorithms (MPPT) applied to photovoltaic systems | |
| A Elbaset et al. | A modified perturb and observe algorithm for maximum power point tracking of photovoltaic system using buck-boost converter | |
| CN113359940B (en) | Maximum power point tracking method and system of photovoltaic array | |
| CN109885123B (en) | Maximum power point tracking system and tracking method for photovoltaic module | |
| Ghasemi et al. | Fast maximum power point tracking for PV arrays under partial shaded conditions | |
| Tawiah-Mensah et al. | An improved Perturb and Observe Maximum Power Point Tracking Algorithm with the capability of drift avoidance in PV systems | |
| Hajighorbani et al. | Novel hybrid maximum power point tracking algorithm for PV systems under partially shaded conditions | |
| Marti-Arbona et al. | PV panel power optimization using sub-panel MPPT |
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 | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |