CN110515418B - Method for determining and tracking global maximum power point of photovoltaic system - Google Patents
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Abstract
The embodiment of the invention provides a method for determining and tracking a global maximum power point of a photovoltaic system, which comprises the following steps: acquiring a highest local peak point in a power voltage curve of a preset photovoltaic system; the photovoltaic system is preset to be a photovoltaic array formed by photovoltaic cells made of the same materials; obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point; the parameters in the power per unit value comprise the position of the highest local peak point and the number of the local peak points; and determining a global maximum power point of the preset photovoltaic system based on the power per unit value of the highest local peak point. The method comprises the steps of obtaining a local peak point of a power voltage curve, solving a power per unit value for the local peak point, finding a local highest peak point from the local peak points to determine a global maximum power point in the photovoltaic system, combining formula calculation, simplifying the process of obtaining the global maximum power point, and improving the tracking speed of the photovoltaic global maximum power.
Description
Technical Field
The invention relates to the technical field of photovoltaic power generation, in particular to a method for determining a global maximum power point of a photovoltaic system and a tracking method.
Background
The Laser Power Transfer (LPT) technology is a way to realize wireless energy Transfer by using Laser as an energy carrier and utilizing photovoltaic effect. And the LPT technology has the advantages of high energy density and long energy transmission distance, and is suitable for application occasions for supplying power to mobile electric equipment such as aircrafts and the like. However, the transmission efficiency of the conventional LPT system is only about 10%, and the low efficiency of the photovoltaic array caused by the uneven laser irradiation is the main reason of low transmission efficiency. Because the power-voltage output characteristic curve of the photovoltaic array presents a 'multimodal' characteristic due to the nonuniformity of laser irradiation, the traditional maximum power tracking algorithms such as an Incremental conductance method (incorporated), a disturbance observation method (P & O) and the like are easy to fall into a Local Maximum Power Point (LMPP), the output power of the photovoltaic system can not be accurately tracked, and the efficiency of converting the photovoltaic system into solar energy is seriously influenced.
In the prior art, aiming at the problem that the traditional maximum power is easy to fall into a local maximum power point according to an algorithm, a Global Maximum Power Point Tracking (GMPPT) algorithm can be obtained by improving the traditional incremental conductance method, so that the probability of tracking GMPP is improved, and the efficiency of a photovoltaic system is improved. However, the improved algorithm often adopts a full-segment search mode in which the photovoltaic module increments the output voltage from 0 to the open-circuit voltage when tracking the GMPP. The tracking speed of the photovoltaic battery is slowed down when the number of the photovoltaic battery monomers in series connection is larger or the voltage value corresponding to the global maximum power point is larger.
Disclosure of Invention
In view of this, the embodiment of the present invention provides a method for determining a global maximum power point of a photovoltaic system and a tracking method, so as to solve the problem of a slow tracking speed of the global maximum power point of the photovoltaic system.
According to a first aspect, an embodiment of the present invention provides a method for determining a global maximum power point of a photovoltaic system, including:
acquiring a highest local peak point in a power voltage curve of a preset photovoltaic system; the preset photovoltaic system is a photovoltaic array formed by photovoltaic cells made of the same material;
obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point; wherein the parameters in the power per unit value include the position of the highest local peak point and the number of the local peak points;
and determining the global maximum power point of the preset photovoltaic system based on the power per unit value corresponding to the highest local peak point.
The method comprises the steps of obtaining a local peak point of a power voltage curve, solving a power per unit value for the local peak point, finding a local highest peak point from the local peak points to determine a global maximum power point in the photovoltaic system, combining formula calculation, simplifying the process of obtaining the global maximum power point, and improving the tracking speed of the photovoltaic global maximum power.
With reference to the first aspect, in a first implementation manner of the first aspect, the obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point includes:
obtaining the open-circuit voltage and the short-circuit current of the photovoltaic cell monomer through measurement;
calculating the product of the open-circuit voltage and the short-circuit current of the photovoltaic cell monomer to obtain a power per unit value corresponding to the local peak point; and extracting the power per unit value corresponding to the highest local peak point from the power per unit values of the corresponding local peak point pairs.
With reference to the first aspect, in a second implementation manner of the first aspect, a product of an open-circuit voltage and a short-circuit current of the photovoltaic cell is calculated to obtain a per unit power value corresponding to the local peak point; extracting a power per unit value corresponding to the highest local peak point from the power per unit values corresponding to the corresponding local peak points; the method comprises the following steps: when the current reference value and the voltage reference value corresponding to the first local peak point are both 1; wherein, the voltage per unit value and the current per unit value of the nth local peak point are respectively expressed by the following formulas:
Vpn＝2n-1
and expressing the power per unit value corresponding to the highest local peak point by adopting the following formula:
Ppn＝Ipn*Vpn
wherein k is the number of local peak points; n is the local peak point position.
With reference to the first aspect, in a third implementation manner of the first aspect, the determining a global maximum power point of the preset photovoltaic system based on the power per unit value corresponding to the highest local peak point includes:
determining a parameter which enables the power per unit value corresponding to the highest local peak point to be maximum by utilizing the power per unit value corresponding to the highest local peak point;
rounding the determined parameters to obtain two integers adjacent to the parameters; wherein the two integers respectively represent the positions of the two local peak points;
calculating two power per unit values corresponding to the positions of the two local peak points;
and comparing the two power per unit values, and determining the local peak point with the maximum power per unit value as the global maximum power point.
With reference to the first aspect, in a fourth implementation manner of the first aspect, a parameter that causes a power per unit value corresponding to the highest local peak point to take a maximum value is expressed by the following formula:
and determining the power per unit value to be equal to the maximum global power point obtained by the current per unit value by defining the maximum value of the power per unit value.
The number of the photovoltaic cells is obtained, a per unit power value is obtained through calculation, the per unit power value is compared to obtain a global maximum power point, operation of calibrating the global maximum power is simplified, the global maximum power tracking speed of the photovoltaic is improved, and the accuracy of the global maximum power of the photovoltaic can be improved through comparison.
According to a second aspect, an embodiment of the present invention provides a tracking method for a global maximum power point of a photovoltaic system, where a global maximum power point in a power voltage curve of a preset photovoltaic system is obtained; the global maximum power point is determined by performing the method for determining the global maximum power point of the photovoltaic system described in any one of the embodiments of the first aspect;
extracting a voltage value corresponding to the global maximum power point to use the voltage value as a tracked voltage reference value;
adjusting the output voltage value of the preset photovoltaic system based on the voltage reference value so that the preset photovoltaic system tracks the global maximum power point.
With reference to the second aspect, in a first implementation manner of the second aspect, before the step of extracting the voltage value corresponding to the global maximum power point to use the voltage value as a tracked voltage reference value, the method further includes:
judging whether the number of local peak points in the power voltage curve of the preset photovoltaic system is greater than or equal to a preset value or not;
when the number of local peak points in the power voltage curve of the preset photovoltaic system is smaller than a preset value, acquiring the open-circuit voltage of the preset photovoltaic system;
calculating the voltage reference value based on the open circuit voltage and the number of local peak points;
and when the number of the local peak points in the power voltage curve of the preset photovoltaic system is greater than or equal to a preset value, executing a step of extracting a voltage value corresponding to the global maximum power point to use the voltage value as a tracked voltage reference value.
With reference to the second aspect, in a second implementation manner of the second aspect, the calculating the voltage reference value based on the open-circuit voltage and the number of local peak points includes:
Vref＝(2k-1)*C*Vocwherein C is a proportionality coefficient, and the value of C depends on the multiple relation of adjacent peak values;
wherein, VocAnd 2k-1 is an open-circuit voltage and a photovoltaic cell string.
With reference to the second aspect, in a third implementation manner of the second aspect, the adjusting the output voltage value of the preset photovoltaic system based on the voltage reference value so that the preset photovoltaic system tracks the global maximum power point includes:
potential proportional-integral-derivative control is carried out on the photovoltaic system, the output voltage of the photovoltaic system is controlled and adjusted to change the voltage flowing through the converter, and the duty ratio is changed to enable the voltage value of the output voltage to approach the actual voltage value;
and carrying out fine adjustment on the output voltage by using an incremental conductance method to obtain a global maximum power point.
Aiming at tracking the global maximum power point under different conditions, corresponding modes are different, the per unit value comparison is needed finally to obtain a more accurate global maximum power point, the obtained global maximum power point also needs to be subjected to fine adjustment in practical application to ensure the correctness of the obtained global maximum power point, and in the whole tracking process, only one-time manual fine adjustment is carried out to ensure that the global maximum power point can be quickly tracked.
According to a third aspect, an embodiment of the present invention provides an electronic device, including: the photovoltaic system global maximum power point determination method comprises a memory and a processor, wherein the memory and the processor are connected with each other in a communication mode, the memory stores computer instructions, and the processor executes the computer instructions to execute the photovoltaic system global maximum power point determination method in any one of the embodiments of the first aspect and the second aspect, and/or the photovoltaic system global maximum power point tracking method in any one of the embodiments of the first aspect and the second aspect.
According to a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, which stores computer instructions for causing a computer to execute the method for determining a global maximum power point of a photovoltaic system according to any one of the first and second aspects or execute the method for tracking a global maximum power point of a photovoltaic system according to any one of the first and second aspects.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
Fig. 1 is a flow chart of a method for determining a global maximum power point of a photovoltaic system according to an embodiment of the present invention;
FIG. 2 is a flowchart of a method for obtaining per unit power of a local peak point by a photovoltaic system according to an embodiment of the present invention;
fig. 3 is a flowchart for obtaining a global maximum power point of a preset photovoltaic system according to an embodiment of the present invention;
fig. 4 is a flowchart 1 of a tracking method of a global maximum power point of a photovoltaic system according to an embodiment of the present invention;
fig. 5 is a flowchart 2 of a tracking method of a global maximum power point of a photovoltaic system according to an embodiment of the present invention;
fig. 6 is a flowchart a of a photovoltaic system global maximum power point determination method and tracking method according to a preferred embodiment of the present invention;
fig. 7 is a schematic structural diagram of a method for determining a global maximum power point of a photovoltaic system and a method for tracking the global maximum power point of the photovoltaic system according to an embodiment of the present invention;
FIG. 8 is a schematic diagram of the connection of a string of cells of a photovoltaic array according to an embodiment of the present invention;
fig. 9 is a flowchart B of a photovoltaic system global maximum power point determination method and tracking method according to a preferred embodiment of the present invention;
fig. 10 is a flowchart C of a photovoltaic system global maximum power point determination method and tracking method according to a preferred embodiment of the present invention;
FIG. 11 is a photovoltaic array P-V characteristic according to a preferred embodiment of the present invention;
fig. 12 is a schematic diagram of a hardware structure of an electronic device according to an embodiment of the present invention.
Reference numerals
71-a processor; 72-a bus; 73-a communication interface; 74-memory.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention provides a method for determining a global maximum power point of a photovoltaic system, which comprises the following steps as shown in fig. 1:
s1, acquiring the highest local peak point in a power voltage curve of a preset photovoltaic system; the preset photovoltaic system is a photovoltaic array formed by photovoltaic cells made of the same material;
s2, obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point; wherein the parameters in the power per unit value include the position of the highest local peak point and the number of the local peak points;
and S3, determining the global maximum power point of the preset photovoltaic system based on the power per unit value corresponding to the highest local peak point.
Specifically, the a x b array is formed by connecting the photovoltaic cells made of the same material of the photovoltaic array in series and parallel.
Specifically, the open-circuit voltage and the short-circuit current of a photovoltaic cell monomer of the photovoltaic array are obtained through measurement, then the local maximum power voltage and the power theoretical value are calculated one by one through parameters of the photovoltaic cell monomer, and the current local maximum power voltage and the previous local maximum power voltage are compared to determine the global maximum power voltage theoretical value. And then, the output voltage of the photovoltaic array is quickly adjusted to the theoretical value of the global maximum power voltage through PID control, and finally, the actual global maximum power value is finely adjusted through a traditional incremental conductance method.
The method comprises the steps of obtaining a local peak point of a power voltage curve, solving a power per unit value for the local peak point, finding a local maximum peak point from the local peak point to determine a global maximum power point in the photovoltaic system, combining formula calculation, simplifying the process of obtaining the global maximum power point, and improving the tracking speed of the photovoltaic global maximum power.
An embodiment of the present invention provides a specific implementation manner, where obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point, as shown in fig. 2, includes:
s10, obtaining the open-circuit voltage and the short-circuit current of the photovoltaic cell monomer through measurement;
s11, calculating the product of the open-circuit voltage and the short-circuit current of the photovoltaic cell monomer to obtain a power per unit value corresponding to the local peak point; and extracting the power per unit value corresponding to the highest local peak point from the power per unit values corresponding to the local peak points.
Specifically, when the current reference value and the voltage reference value corresponding to the first local peak point are both 1; wherein, the voltage per unit value and the current per unit value of the nth local peak point are respectively expressed by the following formulas:
Vpn＝2n-1
and expressing the power per unit value corresponding to the highest local peak point by adopting the following formula:
Ppn＝Ipn*Vpn
wherein k is the number of local peak points; n is the local peak point position.
Optionally, determining the global maximum power point of the preset photovoltaic system based on the power per unit value corresponding to the highest local peak point, as shown in fig. 3, includes:
s20, determining a parameter which enables the power per unit value corresponding to the highest local peak point to be maximum by utilizing the power per unit value corresponding to the highest local peak point;
s21, rounding the determined parameters to obtain two integers adjacent to the parameters; wherein the two integers respectively represent the positions of the two local peak points;
s22, calculating two power per unit values corresponding to the positions of the two local peak points;
and S23, comparing the two power per unit values, and determining the local peak point with the maximum power per unit value as the global maximum power point.
Specifically, a parameter that maximizes the power per unit value corresponding to the highest local peak point is expressed by the following formula:
and determining the power per unit value to be equal to the maximum global power point obtained by the current per unit value by defining the maximum value of the power per unit value.
The number of the photovoltaic cells is obtained, a per unit power value is obtained through calculation, the per unit power value is compared to obtain a global maximum power point, operation of calibrating the global maximum power is simplified, the global maximum power tracking speed of the photovoltaic is improved, and the accuracy of the global maximum power of the photovoltaic can be improved through comparison.
The embodiment of the invention provides a tracking method of a global maximum power point of a photovoltaic system, which comprises the steps of acquiring the global maximum power point in a power voltage curve of a preset photovoltaic system as shown in figure 4; the method for determining the global maximum power point of the photovoltaic system comprises the following steps:
s30, extracting a voltage value corresponding to the global maximum power point, and taking the voltage value as a tracked voltage reference value;
s31, adjusting the output voltage value of the preset photovoltaic system based on the voltage reference value, so that the preset photovoltaic system tracks the global maximum power point.
Specifically, before the step of extracting the voltage value corresponding to the global maximum power point to use the voltage value as the tracked voltage reference value, as shown in fig. 5, the method further includes:
s301, judging whether the number of local peak points in the power voltage curve of the preset photovoltaic system is larger than or equal to a preset value;
s302, when the number of local peak points in the power voltage curve of the preset photovoltaic system is smaller than a preset value, acquiring the open-circuit voltage of the preset photovoltaic system;
s303, calculating the voltage reference value based on the open circuit voltage and the number of the local peak points;
s304, when the number of the local peak points in the power voltage curve of the preset photovoltaic system is larger than or equal to a preset value, a step of extracting a voltage value corresponding to the global maximum power point is performed, and the voltage value is used as a tracked voltage reference value.
Optionally, the calculating the voltage reference value based on the open-circuit voltage and the number of local peak points includes:
Vref＝(2k-1)*C*Vocwherein C is a proportionality coefficient, and the value of C depends on the multiple relation of the upper peak value and the lower peak value;
wherein, VocAnd 2k-1 is an open-circuit voltage and a photovoltaic cell string.
Specifically, the adjusting the output voltage value of the preset photovoltaic system based on the voltage reference value to enable the preset photovoltaic system to track the global maximum power point includes: carrying out potential PID control on the photovoltaic system to adjust and preset the output voltage of the photovoltaic system so as to change the voltage flowing through the converter and change the duty ratio to make the voltage value of the output voltage tend to the actual voltage value;
and carrying out fine adjustment on the output voltage by using an incremental conductance method to obtain a global maximum power point.
Aiming at tracking the global maximum power point under different conditions, corresponding modes are different, the per unit value comparison is needed to be carried out finally to obtain the more accurate global maximum power point, the obtained global maximum power point also needs to be subjected to fine adjustment in practical application to ensure the correctness of the obtained global maximum power point, and only one-time manual fine adjustment is needed in the whole tracking process to ensure that the global maximum power point can be quickly tracked.
The embodiment of the invention provides a tracking method of a global maximum power point of a photovoltaic system, as shown in fig. 6, the tracking method further includes:
s40, measuring the open-circuit voltage and the short-circuit current of the photovoltaic cells forming the photovoltaic array;
s41, calculating the voltage and the theoretical power value of the local power point at two sides of the highest point of the P-V characteristic curve by the serial number of the photovoltaic cell monomers;
s42, comparing the sizes of the two local power points, and taking the larger local power point as a global maximum power point, thereby determining a voltage theoretical value of the global maximum power point;
and S43, rapidly adjusting the output voltage of the photovoltaic array to the theoretical value of the voltage of the global maximum power point through PID control, and finally finely adjusting the output voltage of the photovoltaic array to the actual global maximum power point through a traditional incremental conductance method.
Optionally, the number of the photovoltaic cells forming the photovoltaic array is measured to be at least 2.
Optionally, local power values are obtained by using the open-circuit voltage and the short-circuit current of the photovoltaic cells of the photovoltaic array, and the local power value with the maximum local power value is selected from the local power values and set as the local maximum power point.
A preferred embodiment, as shown in FIG. 7;
when the photovoltaic array is connected to a photovoltaic converter, the converter is a Boost converter, and the output voltage of the photovoltaic array is controlled by changing the duty ratio of the converter.
Optionally, Voc and Isc are open circuit voltage and short circuit current of the photovoltaic cell.
As shown in fig. 8, a cell string S of a photovoltaic array0Composed of (2k-1) photovoltaic cellsThe cell is composed of a single cell, and when the center of a light spot is coincident with the geometric center of the photovoltaic string, the photovoltaic string has k different illumination intensities.
Specifically, as shown in fig. 9, in the a × b array (a is an odd number), the number of the photovoltaic cells in each photovoltaic string is a.
S50, there are k local maximum power points on the power voltage curve of the photovoltaic string:
s51, judging the k value;
s52, when k is 2, calculating the voltage of the global maximum power point: vref＝3*0.8VαAnd set as a reference voltage Vref；
S53, when k is larger than or equal to 3, calculating the power per unit values of two local maximum power points:
before calculating the power per unit values of the two local maximum power points, the value of the maximum power point m needs to be determined according to the following formula:
s54, comparing the power per unit values of the two local maximum power points:
s55, when
Calculating PmThe photovoltaic array global maximum power voltage theoretical value is set as a reference voltage:
Vref＝(2m-1)*0.8Voc
s56, when P ispm≤Pp(m+1)Calculating Pm+1The photovoltaic array global maximum power voltage theoretical value is set as a reference voltage:
Vref＝(2m+1)*0.8Voc
and S57, performing PID control by using the set reference voltage, adjusting the corresponding duty ratio of the converter, and quickly adjusting the output voltage of the photovoltaic array to the theoretical value of the global maximum power voltage.
And S58, adjusting the output voltage of the photovoltaic array after the duty ratio is adjusted to be close to the actual value of the global maximum power voltage, and finely adjusting the output voltage of the photovoltaic array to the actual value of the global maximum power voltage by a traditional Inccond method.
In particular, VocAnd IscRespectively representing the open-circuit voltage and short-circuit current of a photovoltaic cell monomer and the current I of a maximum power pointmAnd voltage VmCan be approximately expressed as:
Im＝0.9Isc
Vm≈0.8Voc
taking the irradiation intensity on the photovoltaic cell with the coordinate (0,0) as a reference 1, when calculating from 0, the per unit value G of the laser irradiation intensity on the photovoltaic cell with the coordinate (0, j)jCan be expressed as
Starting from 1, marking the current of the first local maximum power point as reference 1, and then obtaining the current per unit value I of the nth local maximum power pointpnCan represent that:
individual local peaks of photovoltaic array under non-uniform illuminationPoint voltages all equal to about 0.8VocInteger multiples of. The voltage of the first local maximum power point is recorded as reference 1, and then the voltage per unit value V of the nth local maximum power pointpnCan be expressed as:
Vpn＝2n-1
according to the open-circuit voltage V of the photovoltaic cellocAnd short-circuit current IscIt can be known that the power of the first local maximum power point on the P-V line of the photovoltaic cell string can be approximately expressed as:
Pp1≈0.8Voc*0.9Isc
the power P of the first local maximum power pointp1Reference 1 is made. According to the current per unit value I of the nth local maximum power pointpnAnd voltage per unit value V of nth local maximum power pointpnIt can be known that the output power per unit value P of the nth local MPPpnCan be expressed as
Per unit value P of output power for nth local MPPpnTaking the derivative, when k is 2, the derivative is positive, indicating PpnThe second local maximum power point, namely the global maximum power point, is increased along with the increase of n; when k is more than or equal to 3, the derivative is positive or negative along with the increase of n, and P is in the defined fieldpnWith a maximum, let the derivative be 0:
if the value of the above formula is an integer, then the nth. If the value of the above formula is not an integer, there must be a positive integer m that satisfies the following formula:
m＜n＜m+1
the formula shows that the maximum power point is between Pm and Pm +1, so that two points of power need to be calculated separately, and the maximum power point is obtained by comparison.
ComparisonSetting the voltage of the local maximum power point with larger power as a reference voltage VrefAnd adopts PID control. The power-voltage characteristic of the photovoltaic array is formed by superposing the power-voltage characteristics of the photovoltaic strings, so that the monotonous interval of the power-voltage characteristic of the photovoltaic array and the monotonicity in the monotonous interval are consistent with the photovoltaic strings, the difference between a theoretical calculation value and an actual value is considered, and when the output voltage of the photovoltaic array reaches a reference voltage VrefAnd then, accurately tracking the GMPP by adopting an incremental conductance method.
By applying the optimal implementation mode, the global maximum power point of the photovoltaic system under laser irradiation is quickly tracked, and the problem that the existing maximum power tracking method is not suitable for the photovoltaic system under laser irradiation and the searching speed of all improved maximum power tracking methods is influenced by the series connection number of photovoltaic cells and the voltage value corresponding to the global maximum power point is solved.
A preferred embodiment, as shown in FIG. 10;
taking 5 x 5 photovoltaic array as an example, let the center of the light spot coincide with the geometric center of the photovoltaic array, VocAnd IscThe open-circuit voltage and the short-circuit current of the photovoltaic cell. The corresponding P-V characteristic is shown in FIG. 11, and it can be seen that the P-V curve has three local peak points.
Specifically, the photovoltaic array is formed by firstly connecting photovoltaic cells made of the same material in series into a photovoltaic string, and then the photovoltaic string is connected in parallel to form a 5 x 5 photovoltaic array, so that global maximum power point tracking is performed:
s60, calculating the k value,
k＝3；
and S61, calculating the value of m,
s62, calculating PpmThe value of the one or more of,
s63, calculating Pp(m+1)The value of the one or more of,
s64, when P ispm>Pp(m+1)When is, PpmThe corresponding voltage is the global maximum power voltage;
s65, calculating a photovoltaic array global maximum power voltage theoretical value, and setting the theoretical value as a reference voltage:
Vref＝(2m-1)*0.8Voc＝2.4Voc；
s66, determining a reference voltage VrefAnd then, the corresponding duty ratio of the Boost converter is obtained through PID control, and the output voltage of the photovoltaic array is quickly adjusted to the global maximum power voltage theoretical value (reference voltage).
And S67, the regulated output voltage of the photovoltaic array is located near the actual value of the global maximum power voltage, and the regulated output voltage is finely adjusted to the actual value of the global maximum power voltage through a traditional IncCond method, so that the global maximum power point tracking is completed.
The tracking method can deal with the multi-peak phenomenon of the P-V characteristic of the photovoltaic array due to the Gaussian characteristic of the laser spot, and accurately track the global maximum power point, so that the conversion efficiency of the photovoltaic system is improved;
through the adjustment process only involving hardware once, by utilizing PID control and an incremental conductance method, the tracking time is greatly reduced, so that the maximum power point is prevented from being tracked according to the searching direction of the photovoltaic module output voltage from 0 incremental to the open-circuit voltage, and the tracking time is saved.
An embodiment of the present invention further provides an electronic device, as shown in fig. 12, the electronic device may include a processor 71 and a memory 74, where the processor 71 and the memory 74 may be connected by a bus 72 or in another manner, and fig. 12 illustrates the connection by the bus.
The processor 71 may be a Central Processing Unit (CPU). The Processor 71 may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory 74, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the PIDs in the embodiments of the present invention. The processor 71 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions and modules stored in the memory 74, that is, the determination method and the tracking method of the photovoltaic system global maximum power point in the above method embodiments are implemented.
The memory 74 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor 71, and the like. Further, the memory 74 may include high speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory 74 may optionally include memory located remotely from the processor 71, and such remote memory may be connected to the processor 71 via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
The one or more modules are stored in the memory 74 and, when executed by the processor 71, perform the method of determining and tracking the global maximum power point of the photovoltaic system in the embodiment shown in fig. 1-10.
The above specific details can be understood by referring to the corresponding descriptions and effects in the embodiments shown in fig. 1 to fig. 10, and are not described herein again.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD), a Solid State Drive (SSD), or the like; the storage medium may also comprise a combination of memories of the kind described above.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (11)
1. A method for determining a global maximum power point of a photovoltaic system is characterized by comprising the following steps:
acquiring a highest local peak point in a power voltage curve of a preset photovoltaic system; the preset photovoltaic system is a photovoltaic array formed by photovoltaic cells made of the same material;
obtaining a power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point; wherein the parameters in the power per unit value include the position of the highest local peak point and the number of the local peak points;
and determining the global maximum power point of the preset photovoltaic system based on the power per unit value corresponding to the highest local peak point.
2. The method according to claim 1, wherein obtaining the power per unit value corresponding to the highest local peak point according to the photovoltaic array and the highest local peak point comprises:
obtaining the open-circuit voltage and the short-circuit current of the photovoltaic cell monomer through measurement;
calculating the product of the open-circuit voltage and the short-circuit current of the photovoltaic cell monomer to obtain a power per unit value corresponding to the local peak point; and extracting the power per unit value corresponding to the highest local peak point from the power per unit values corresponding to the local peak points.
3. The method according to claim 2, wherein the product of the open-circuit voltage and the short-circuit current of the photovoltaic cell is calculated to obtain a per unit power value corresponding to the local peak point; extracting a power per unit value corresponding to the highest local peak point from the power per unit values corresponding to the local peak points; the method comprises the following steps:
when the current reference value and the voltage reference value corresponding to the first local peak point are both 1; wherein, the voltage per unit value and the current per unit value of the nth local peak point are expressed by the following formulas:
Vpn＝2n-1
and expressing the power per unit value corresponding to the highest local peak point by adopting the following formula:
Ppn＝Ipn*Vpn
wherein k is the number of local peak points; n is the local peak point position.
4. The method according to any one of claims 1-3, wherein determining the global maximum power point of the preset photovoltaic system based on the power per unit value corresponding to the highest local peak point comprises:
determining a parameter which enables the power per unit value corresponding to the highest local peak point to be maximum by utilizing the power per unit value corresponding to the highest local peak point;
rounding the determined parameters to obtain two integers adjacent to the parameters; wherein the two integers respectively represent two preset highest local peak point positions;
calculating two power per unit values corresponding to the positions of the two preset highest local peak points;
and comparing the two power per unit values, and determining the local peak point with the maximum power per unit value as the global maximum power point.
5. The method according to claim 4, characterized in that the parameter that maximizes the power per unit value corresponding to the highest local peak point is expressed by the following formula:
and determining the maximum value by defining the power per unit value, so that the power per unit value is equal to the maximum global power point determined by the current per unit value.
6. A tracking method of a global maximum power point of a photovoltaic system is characterized in that,
acquiring a global maximum power point in a power voltage curve of a preset photovoltaic system; the global maximum power point is determined according to the determination method of the photovoltaic system global maximum power point in any one of claims 1-5;
extracting a voltage value corresponding to the global maximum power point to use the voltage value as a tracked voltage reference value;
adjusting the output voltage value of the preset photovoltaic system based on the voltage reference value so that the preset photovoltaic system tracks the global maximum power point.
7. The method according to claim 6, wherein before the step of extracting the voltage value corresponding to the global maximum power point to use the voltage value as a tracked voltage reference value, the method further comprises:
judging whether the number of local peak points in the power voltage curve of the preset photovoltaic system is greater than or equal to a preset value or not;
when the number of local peak points in the power voltage curve of the preset photovoltaic system is smaller than a preset value, acquiring the open-circuit voltage of the preset photovoltaic system;
calculating the voltage reference value based on the open circuit voltage and the number of local peak points;
and when the number of the local peak points in the power voltage curve of the preset photovoltaic system is greater than or equal to a preset value, executing a step of extracting a voltage value corresponding to the global maximum power point to use the voltage value as a tracked voltage reference value.
8. The method of claim 7, wherein calculating the voltage reference based on the open circuit voltage and the number of local peak points comprises:
Vref＝(2k-1)*C*Vocwherein C is a proportionality coefficient, and the value of C depends on the multiple relation of the upper peak value and the lower peak value;
wherein, VocAnd 2k-1 is an open-circuit voltage and a photovoltaic cell string.
9. The method of claim 8, wherein adjusting the output voltage value of the preset photovoltaic system based on the voltage reference value to cause the preset photovoltaic system to track the global maximum power point comprises:
potential proportional-integral-derivative control is carried out on the photovoltaic system, the output voltage of the photovoltaic system is controlled and adjusted to change the voltage flowing through the converter, and the duty ratio is changed to enable the voltage value of the output voltage to approach the actual voltage value;
and (4) finely adjusting the output voltage by using an incremental conductance method to obtain a global maximum power point.
10. An electronic device, comprising:
a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform a method for determining a global maximum power point of a photovoltaic system according to any one of claims 1 to 5 or a method for tracking a global maximum power point of a photovoltaic system according to any one of claims 6 to 9.
11. A computer-readable storage medium, wherein the computer-readable storage medium stores computer instructions for causing the computer to execute the method for determining the global maximum power point of the photovoltaic system according to any one of claims 1 to 5 or the method for tracking the global maximum power point of the photovoltaic system according to any one of claims 6 to 9.
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