KR20210055311A - Adaptive partial shading determinant mehtod for solar array system and photovoltaic power generation device using the method thereof - Google Patents

Abstract

The present invention relates to an adaptive partial shading detection method for a photovoltaic array system, which includes the steps of: performing global peak scanning (GPS) on a photovoltaic array including a plurality of photovoltaic panels; identifying a plurality of areas divided according to at least one reference voltage on a voltage versus power graph for the photovoltaic array; and determining whether to re-perform the global peak scanning based on an area in which the photovoltaic array currently operates among the areas and the calculated reference power. Thus, the downtime of maximum power point tracking (MPPT) is minimized, so that the power generation performance of the photovoltaic array is improved.

Description

An adaptive partial shading detection method for a solar panel array system, and a photovoltaic power generation device using the method.

The present invention relates to a photovoltaic panel array system, and more particularly, to an adaptive partial shadow detection method and a photovoltaic device for a photovoltaic panel array system.

Photovoltaic (PV) power generation is a representative technology of renewable energy with little environmental pollution. In order to make the most of the solar panel array (hereinafter referred to as the solar array), a maximum power point tracking (MPPT) algorithm is used, and the MPPT algorithm is an operating point at which the output power is maximized on a characteristic curve. ) Is always maintained.

However, in an actual environment, the phenomenon of insolation shadows of the solar array occurs entirely or partially cannot be avoided. In particular, in the case of a solar array in which a plurality of solar panels are connected in series, it is known that the power generation performance of the entire solar system is deteriorated due to the effect of partial shading in which the amount of solar radiation between some panels is uneven.

In order to prevent such performance degradation, a structure in which bypass diodes are connected in parallel in a solar panel is common. However, during partial shading, multiple local maximum power points may occur in the PV curve (power versus voltage curve) of the solar array due to the selective conduction of these reverse diodes, and thus the operating point is the global maximum power point. If not rearranged, the achievable output power may not be maximized. This is a local MPPT algorithm that does not work properly when there are multiple maximum points because a typical MPPT algorithm assumes one maximum point within a given range and tracks the power point.

What is needed in this case is the global MPPT algorithm. The global MPPT algorithm periodically or intermittently stops the local MPPT, re-scans the entire operating voltage range, and resets the operating range to a section where the highest power point is likely to exist, and then the local MPPT algorithm is used. It is a series of algorithms that resume and keep track of the maximum power point in real time. However, in general, it takes a relatively large amount of time (e.g., 4 seconds) to scan the global peak, and the tracking of the maximum power point is temporarily suspended during this scanning process, so this is a technology that calls the scanning process only when necessary. Is required.

[Document 1] Korean Patent Registration No. 10-1260880 A junction box having an MPPT control function individually embedded in a solar cell module and a driving method thereof (Han Yoon-hee) 2013.04.29.

Therefore, it is an object of the present invention to perform unnecessary global peak scanning (GPS) in the solar array system only when necessary, thereby further improving the performance of the solar array, adaptive partial shading for the solar panel array system. It is to provide a detection (PSD, partial shading detection) method and a photovoltaic device using the method.

In order to achieve the above object, the present invention includes the steps of performing Global Peak Scanning on a solar array; Comparing the open circuit voltage (Voc) and the operating voltage (V _received ) of the unit module of the solar array to check area information in which the current operating point is located in the solar array; And determining whether to re-perform the global peak scanning based on a current operating region of the solar array and a reference power (P _{r) set in the operating region according to the region information.} An adaptive partial shadow detection method is provided.

According to the present embodiment, when the operating point is located in a region with the highest voltage, a threshold power level adaptively set according to the _{currently measured generated power P received} and the reference power P _r P _th ) is compared to selectively perform the global peak scanning.

According to the present embodiment, the threshold power level P _th is calculated by the following equation according to the region of the measured power generation power P _received.

According to the present embodiment, when the operating point is located in a region having the highest voltage, checking the number of peaks; If the number of peaks is a single peak, updating the _{generated power P received} to the reference power P _{r; Calculating a threshold power level (P th} ) of a corresponding region in which the peak exists and executing a maximum power point tracking (MPPT); And performing the global peak scanning only when the generation power P _received is less than the threshold power level P _th , and updating the _{reference power P r when the power generation power P received is less than the threshold power level P th.}

According to the present embodiment, if the number of peaks is two or more _{, updating the reference power P r} based on the peak level of the leftmost region; Calculating a threshold power level (P _th ) of the updated area information and executing a maximum power point tracking (MPPT); And performing the global peak scanning only when the generation power P _received is less than the threshold power level P _th , and updating the _{reference power P r when the power generation power P received is less than the threshold power level P th.}

으로 계산된다. 여기서, 상기

은

이다.According to this embodiment, the reference power (P _r ) of the leftmost region is the equation

Is calculated as. Where, above

silver

to be.

According to the present embodiment, when the operating point is located in a region other than the region with the highest voltage, the maximum power point tracking (MPPT) is repeatedly performed according to a set time, or the global peak scanning is called to check other peaks. It is characterized by that.

According to another feature of the present invention, a solar array including a plurality of solar panels; And a control module that determines whether to execute Global Peak Scanning according to an area in which an operating point of the solar array is located among a plurality of operation areas analyzed based on the PV curve of the solar array. It provides a solar power generation device.

According to the present embodiment, when the operating point is located in a region other than the region with the highest voltage, the control module repeatedly performs the MPPT tracking or global peak scanning according to a set time. Scanning) is called periodically.

According to the present embodiment, if the operating point is located in a region with the highest voltage and a single peak, the control module _{updates the generated power P received} to the reference power P _r , and the threshold power level P _{th of the corresponding region is updated.} ) Is calculated, and the global peak scanning is performed or the reference power P _r is updated again _{according to a result of comparing the generated power P received} and the critical power level P _th.

According to the present embodiment, if the operating point is located in the region with the highest voltage and has two or more peaks, the control module _{updates the reference power P r} based on the peak level of the leftmost region, and the update After calculating the critical power level (P _th ) of the area information, the global peak scanning is performed or the reference power (P _r ) is calculated according to the comparison result between the generated power (P _received ) and the critical power level (P _{th ).} Try to update again.

According to the present embodiment, the control module performs the global peak scanning only when the _{threshold power level (P th} ) is greater than the generated power (P _received ), and in the opposite case, updates _{the reference power (P r ).} do.

로 계산된다. According to the present embodiment, the threshold power level (P _th ) is determined according to the region of the measured generated power (P _received).

Is calculated as

으로 계산된다. 여기서, 상기

은

이다.According to this embodiment, the reference power (P _r ) of the leftmost region is the equation

Is calculated as. Where, above

silver

to be.

According to the present embodiment, after the threshold power level P _th is calculated, maximum power point tracking (MPPT) is further performed.

According to the present invention, if the present invention is applied even when partial shading occurs in a solar array system to which a plurality of solar panels are connected, the maximum power is performed only when global peak scanning (GPS) is required. There is an effect that can further improve the power generation performance of the solar array by minimizing the interruption time of the point tracking (MPPT).

1 is a typical flow diagram of a Global MPPT technique for a solar array system.
2A is a diagram showing a state in which global shading occurs in a solar array composed of two modules connected in series.
2B is a diagram illustrating a state in which partial shading occurs in a solar array composed of two modules connected in series.
3A is a graph showing PV and IV curves when global shading occurs in a solar array composed of two modules connected in series.
3B is a graph showing PV and IV curves when partial shading occurs in a solar array composed of two modules connected in series.
4 is a graph showing a PV curve of a solar array composed of three modules connected in series.
5A is a flowchart illustrating a method of determining partial shadows for a solar array system based on a power difference.
5B is a flowchart illustrating an adaptive partial shadow detection method according to the present invention.
6 is a circuit diagram for simulation for verifying the performance of the solar power generation device to which the adaptive partial shade detection method according to the present invention is applied.
7A to 7D are graphs comparing simulation results to which the prior art and the present invention are applied according to a smooth insolation change pattern.
8A to 8D are graphs comparing simulation results to which the prior art and the present invention are applied according to a sharp insolation change pattern.
9 to 12 are measurement graphs comparing the results of hardware experiments according to the prior art and the present invention.

Hereinafter, specific details for carrying out the present invention will be described based on embodiments with reference to the drawings. These embodiments are described in detail sufficient to enable a person skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different from each other, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention in relation to one embodiment. In addition, it should be understood that the location or arrangement of individual components in each disclosed embodiment may be changed without departing from the spirit and scope of the present invention. Accordingly, the detailed description to be described below is not intended to be taken in a limiting sense, and the scope of the present invention, if properly described, is limited only by the appended claims, along with all scopes equivalent to those claimed by the claims. Like reference numerals in the drawings refer to the same or similar functions over several aspects.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used with meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.

An embodiment of the present invention proposes a core element technology of a global maximum power point tracking (MPPT) algorithm in a partial shading condition. In other words, in a typical solar panel array system formed by a plurality of solar panels connected in series and each panel is divided by a bypass diode connected in parallel, when partial shading occurs, on the power vs. voltage curve that misleads the usual local MPPT algorithm. Complex peak patterns are formed. Accordingly, various types of global MPPT algorithms have been studied. These global MPPT algorithms are generally three algorithms: Partial Shading Detection (PSD), Global Peak Search (GPS), and local MPPT. It consists of. That is, if a partial shadow is detected while performing the local MPPT function continuously, power peak scanning is performed, and then the local MPPT function is again performed.

However, since the conventional partial shadow detection algorithm uses a uniform criterion, global peak scanning is performed too frequently and the local MPPT is stopped for a long time, so that the maximum power point cannot be tracked, or vice versa. There is a problem in that the achievable power is reduced because the operating point cannot be moved to the maximum power point because the global peak scanning cannot be performed properly.

Therefore, in order to improve this, a more effective partial shadow detection algorithm is essential for efficient use of the solar energy source.

The present invention proposes a new partial shadow detection technique that uses a reference power value that changes adaptively using information of a current operating point. The conventional method is too sensitive to some sharp shading patterns and calls for unnecessary global peak scanning, or insensitive to some soft shading patterns, so that the required global peak scanning cannot be called. Regardless of the shape of the shadow pattern, since it always shows the best partial shadow detection performance, the maximum power point tracking performance can be maximized and the solar power generation efficiency can be improved.

Hereinafter, an intelligent partial shadow detection method according to an embodiment of the present invention will be described.

1 is a typical flow diagram of a global maximum power point tracking (MPPT) technique for a solar array system. Referring to FIG. 1, a general global MPPT is a global peak scanning (GPS) 120, a local MPPT 130, partial shading detection (PSD) after initialization 110. It may proceed in the order of (140). For example, in step 140, if the preset PDS criterion is satisfied, the local MPPT operation is stopped and the GPS operation in step 120 is again performed. If the preset PDS criterion is not satisfied in step 140, the GPS operation is not performed again. While repeating the local MPPT operation of step 130, the operating point is always located at the maximum power point.

Several types of conventional partial shadow detection algorithms have been studied. The simplest example is a method in which only timer interrupts are used to call GPS. That is, a method of performing GPS after stopping MPPT at a predetermined time. In this case, a separate partial shadow detection method is not performed.

A more advanced method is a method of determining whether to call the global peak scanning based on the current generated power value and the generated power value stored immediately before. For example, when the increment of the power value is ΔP and the current output power value is P, the ratio of the two power values, such as when ΔP/P is more than a certain value, such as 10%, stops the local MPPT and calls the global peak scanning. . In a similar way, an artificial neural network (ANN)-based algorithm has been proposed. Even in this case, the standard using ΔP as described above is used for the PSD.

However, in all of the above conventional PSD methods, too frequent detection impedes the maximum power tracking function, generates a significant ripple in the current, hinders the optimal operation of the photovoltaic power generation system, and lowers the photovoltaic power generation efficiency.

Therefore, it is clear that the partial shadow detection algorithm plays an important role in the overall performance of the global MPPT. This is because once the global peak scanning starts, it takes time for the local MPPT to position the operating point at the maximum power point again, and whether or not the global peak is scanned depends on the PSD algorithm. As will be explained in the following figures, if you analyze the type of PV curve in case of partial shade, even if the pattern of partial shade changes, the position of the maximum power point does not change significantly in a specific PV curve region. It can be seen that the number of times can be greatly reduced.

In detail, the solar array is involved in different types of shades as shown in Figs. 2A and 2B. FIG. 2A is a diagram illustrating a state in which global shading has occurred in the solar array, and FIG. 2B is a diagram illustrating a state in which partial shading has occurred in the solar array. 2A and 2B show a case where two solar panels 210 and 220 are connected in series. In general, bypass diodes 211 and 221 are connected in parallel to each of the solar panels in preparation for non-uniform solar radiation.

The global shading 230 of FIG. 2A is a state in which the entire solar array is exposed to a uniform amount of insolation, which may occur due to a change in fog, fog, or sunlight. On the other hand, as shown in FIG. 2B, a phenomenon in which a part of the solar array is exposed to different amounts of insolation due to natural light blocking due to clouds or artificial light blocking due to the shadow of a building is referred to as partial shading 241, 242. do. In a real environment, the PSD algorithm must be able to distinguish between two different shading conditions.

3A and 3B show the P-V and I-V curves of a solar array with two identical modules connected in series as shown in FIGS. 2A and 2B. 3A is a graph showing P-V and I-V curves when global shading occurs in a solar array, and FIG. 3B is a graph showing P-V and I-V curves when partial shading occurs in a solar array.

When global shading occurs, the array output decreases without activating the bypass diode as shown in Fig. 3A, and the operating point is successfully determined by the local MPPT. However, in partial shading, the behavior of the characteristic curve changes differently as shown in FIG. 3B. In the P-V curve, two peaks appear as a left peak (LP) and a right peak (RP). At this time, the local MPPT may not be able to discern different peaks of the P-V curve, and thus may be continuously fixed to the current peak, and if the other peaks produce a larger maximum power, it fails to follow the global maximum power point.

Therefore, it is necessary to check whether another peak exists through Global Peak Scanning (GPS), and the PSD algorithm determines whether to call the GPS algorithm.

The current flowing through the photovoltaic module is determined by whether the operating point is operated at the right peak or the left peak. For example, when RP is selected as the operating point, the heavily shadowed module of the two modules determines the total amount of array current, so the array current decreases, but the array voltage is determined by the sum of the two PV module voltages and increases. Both modules will contribute to the array power supply. On the contrary, when LP is selected as the operating point, the module with heavy shadows is bypassed through the diode and does not operate, and the array current and voltage are determined only by the module with bright shadows. Generated only by modules with bright shades.

However, since the sizes of these two peaks differ from each other according to the state of the shadow, the higher of the two peaks should always be selected. According to the principle of the characteristic curve described above, the height of the RP (power produced by RP) is mainly influenced by the darkest shading module, while the height of the LP (power produced by LP) is always determined by the lightest shading module. Of course, at this time, there is also a temperature effect due to the change in shade, but it is assumed that this is negligible.

This concept can be extended to multiple arrays of serial modules as well as two. For example, a three-module array (number of serial connections of modules, N _S = 3) is illustrated in FIG. 4. 4 is a graph showing a PV curve of a solar array composed of three solar modules. In this case, the module operation in the global shading condition shows a single peak, but in the case of partial shading, there may be two or three peaks. It can be seen that the number of possible peaks is determined by the number of modules (bypass diodes) of the PV array connected in series.

To analyze the principle in which peaks occur _{, it is useful to divide the operating voltage region by the N S} part, which is the number of modules connected in series, where “region n” (1 ≤ n ≤ NS) is (n-1)V _oc to nV _Represents the voltage band up to oc. In this case, Voc is the open-circuit voltage of one module, and it is assumed that all modules are the same. ) Of the remaining regions are on the left, so the peak in any region n is referred to as LPn.

If an array of three modules connected in series is covered with two types of different insolation levels, two scenarios can be identified. One scenario includes only two peaks, LP2 and RP, where LP2 is generated by two light shade modules and RP is generated by one dark shade module. In another scenario, peaks appear only in LP1 and RP, where LP1 is caused by one light shade module and RP is caused by two dark shade modules.

On the other hand, when an array of three modules connected in series is covered with three different levels of insolation, three peaks, LP1, LP2, and RP, appear. LP1 and LP2 appear due to the lightest shade module and the second lightest shade module. As previously defined, LPn reflects the left peak in the n-th region. RP always occurs when the array current is dominated by the dark shaded module.

According to the above analysis, the maximum output of LPn is closely related to the global shading level as shown in Equation 1 below.

Here, N _S is the number of solar modules connected in series, and P _r is a virtual power value, which is the output power calculated assuming that all modules are entirely covered with only the brightest shade of the current shade level. In the invention, it is referred to as reference power. P _r is the main information of the proposed algorithm and can be calculated by deferring the information of the current operating point of the solar array and the derivation equation given from the measured value of the output power.

5A is a flowchart illustrating a conventional partial shadow detection method, and FIG. 5B is a flowchart illustrating an adaptive partial shadow detection method according to the present invention.

5A, the global MPPT is a global peak scanning (GPS) 511, a local maximum power tracking (MPPT) 512, partial shadow detection (PSD, Partial) after initialization. Shading Detection) may be performed in the order of 513 and 514. For example, in steps 513 and 514, if the preset PDS criterion is satisfied, the GPS operation of step 511 is again performed, and if the preset PDS criterion in steps 513 and 514 is not satisfied, the GPS operation is not performed again, and step 512 The local MPPT operation of is performed repeatedly.

As shown in FIG. 5A, the existing partial shadow detection algorithm monitors the rate of change between two consecutive powers. For example, if it exceeds the threshold value used as 0.1, the GPS is called. However, P/P can be quite high in a sudden change in insolation, so it can be called erratically even in a global shading situation. Conversely, there is a possibility that this method may fail to call the GPS, especially in soft shading patterns with low insolation levels.

In summary, there are three disadvantages to the conventional algorithm as shown in FIG. 5A. First, when the system reaches the leftmost peak, it is no longer possible to monitor the peak value of the RP on the right, so it is not easy to return to another peak point. Second, if the solar radiation increases during operation at an operating point other than the leftmost peak, the partial shadow is released, so a GPS call is not necessary, but a GPS call is attempted based on the judgment criteria. Third, since the judgment criterion depends on the rate of change of the output power, it is too sensitive to sudden change in shadow pattern, and insensitive to soft change in shadow pattern.

5B is a flowchart illustrating an adaptive partial shading determination method for a solar array system according to the present invention. Referring to FIG. 5B, it is possible to optimize the GPS call because the GPS call uses a method that simultaneously considers the reference power value reflecting the virtual global shading state in the current shaded state and information of the current operating point. Do.

First, the GPS is called 521 once for initialization, and the number of local peaks is checked (522). By comparing the open circuit voltage (Voc) of the unit module with the measured operating voltage (V _received ), it is possible to know the area number "n" in which the current operating point is located. For this purpose, the following <Equation 2> is used.

If, in the determination of step 523, the current operating point is in the left peak (LPn), not the region with the highest voltage, every time the local MPPT is executed (531), the other peak must be checked regularly. Will be called. This periodic call of GPS is implemented with a _{timer T count} and a set time T _{set (522).} That is, in step 532, if the timer T _count is less than or equal to the set time T _set , the local MPPT is repeatedly executed 531 in real time, and if the timer T _count is greater than the set time T _set , the GPS is called and executed ( 521).

On the other hand, in the determination of step 523, when the current operating point is in the right peak RP, which is the region with the highest voltage, it is divided into two possible scenarios. First, in step 524, the number of peaks checked through the GPS is used. As a result of determining the number of peaks, when the number of peaks is two or more, the reference power P _r should be updated based on the leftmost peak level in step 527. In the current situation, since the value of the leftmost region n is known through Equation 2, P _r is recalculated using _{P LPn} in this region by the following <Equation 3>.

In the judgment of step 524, if there is only a single peak in the PV curve, it is reflected that the system is in a global shading state, and that the measured power can be directly used as the reference power. Therefore, P _r is updated by Equation 4 below in step 526.

On the other hand, using Equation 1 above, it is possible to calculate all the expected power magnitudes when a peak exists in each region through the currently calculated reference power, where n=1,... Ns, and for convenience, it is defined as _{P LPNs} = P _RP = P _r. After calculating the expected power magnitudes of all peaks through Equation 1, in the next step 528, the threshold power level P _th is determined according to which power region the currently measured generated power (Preceived) belongs to. It is set differently. That is, the threshold power may be calculated differently according to the section in which the currently measured amount of generated power (Preceived) of the solar array belongs.

Where m = 1, 2,... , (N _S -1). After the local MPPT is executed in step 529, the calling criterion for GPS in step 530 is given by Equation 6, which compares the current generation power and critical power.

When the condition of Equation 6 is satisfied, the GPS is called. If this condition is not satisfied, it is determined that the amount of insolation increases compared to the previous one, and in step 525, P _r is upwardly updated _{by the following <Equation 7>, and P th} is updated again by the above <Equation 5>.

Thereafter, in step 529, the local MPPT is repeated, and in step 530, the GPS call criterion is tested again.

On the other hand, in order to compare the performance of the existing ΔP/P algorithm and the algorithm proposed according to the present invention through a simulation, the circuit simulation block as shown in FIG. 6 was implemented.

6 is a circuit diagram for simulation for verifying the performance of a photovoltaic device to which the adaptive partial shade detection method according to the present invention is applied. 6, a solar device according to an embodiment of the present invention includes a solar array 610, a control module 620, a boost DC/DC converter 630, a sensor circuit 640, an appropriate resistive load ( 650).

Any local MPPT algorithm for performance comparison is possible, but in this simulation, the P & O (perturb & observation) algorithm with duty change set to △-D = 0.007 was used as the local MPPT algorithm, and the control module 620 It was coded as a C program inside the DLL block, and both the local MPPT, GPS algorithm, and GPS algorithm were coded together in the control module 620.

In the schematic diagram of FIG. 6, two solar modules 210 and 220 (eg, SCM 60 modules) are connected in series as an array, and two bypass diodes are connected respectively, and the boost converter circuit 630 is actually Current and voltage are extracted from the solar array according to the set operating point according to the conventional MPPT algorithm. Two signals are input from each solar panel module, insolation (S) and temperature (T).

In this simulation test, a random pattern was injected for the amount of insolation, and the temperature was fixed at room temperature 25°C. Observation probes P1 and P2 are values that monitor the ideal maximum power that can be obtained from a given insolation from each module, and the currently generated output power is calculated by the product of the solar array output voltage and current and assigned to the _{probe P received.}

To test the partial shade detection performance for the partial shade pattern, in the case of the solar panel 1 feed the shadow pattern (Irr_P1) to change the tooth and the sinusoidal wave pattern, and when the solar panel 2 uniform irradiation pattern of 1000W / m ² ( Irr_P2). Irradiation was gradually changed between 1000W / m ² and 200W / m ² in the first test shown in Figure 7a, in Test 2 shown in Figure 8a was changed suddenly to 500W / m ² at 1000W / m ^2.

First, when only the local MPPT algorithm without the GMPPT function is used, the output power (Preceived) that can be generated by a given solar array is shown in FIGS. 7B and 8B. As mentioned above, FIG. 7B is for a gentle insolation pattern, and FIG. 8B is for a rapid change in insolation.

Now, the results of adopting the conventional partial shadow detection algorithm to the global MPPT algorithm in which the GPS algorithm is added to the local MPPT are shown in FIGS. 7C and 8C, respectively. Similarly, FIG. 7C is for a gentle insolation pattern, and FIG. 8C is for a sudden change in insolation. Comparing with FIGS. 7B and 8B, it can be seen that the generated power has increased considerably, but it can be confirmed that the generation power is still wasted due to an incorrect judgment. Here, GPS_flag is a flag indicating whether global park scanning is called, and a logically high value, that is, "1" indicates a GPS call event. The highlighted area shows the solar power wasted by improper GPS triggering.

Now, output power generated after applying the adaptive partial shadow detection algorithm proposed according to an embodiment of the present invention instead of the conventional partial shadow detection algorithm is shown in FIGS. 7D and 8D. Compared with the above FIGS. 7C and 8C, the proposed method proves that a greater amount of power generation can be obtained from a given insolation pattern by reducing unnecessary GPS calls for a sudden change in insolation without losing judgment on a gentle change in insolation. The main observations of the simulation are summarized in Table 1 below.

Sensed power(W) Detection criterion PSD flag Comments P _{received .old} P _received dp/p p _th Conventional Proposed Conventional Proposed 255 225 0.12 127.5 One 0 Unnecessary detection Proper detection 130 120 0.08 127.5 0 One Detection failure Proper detection

On the other hand, in addition to the simulation, the improved result can be verified by an experiment composed of real hardware. The experiment set can be performed with an experiment consisting of a PV hardware simulator, a boost converter and an electrical load. As the setting value of the PV hardware simulator, the solar panel data value of the SCM60 product of'Solar Center', a single crystal silicon panel, was used, and the two were set to be connected in series. The main solar panel specifications are described in Table 2 below together with the specifications of the hardware production of the boost converter.

Category Parameter Value Item Value PV
panel
SCM 60 P _max 60W DSP TMS320F28377S Vmpp 19.0V I _mpp 3.16A Electric load
Prodigit 3314F V _OC 23.0V I _SC 3.30A Power
circuit C _i 22μF C 22μF L 56μH V, I sensor LT1366 Vo 48V Diode FYPF201 f _sw 100 kHz Mosfet 11NM60

Due to the limitation of the performance of the PV hardware simulator, the experiment was performed under the assumption that a slew rate of less than ^{100W/m 2} ·s ^{1 was assumed to be a gentle change in the insolation pattern.}

In Fig. 9, the operation result is performed on the gentle partial shading patterns. Figure 9a shows the initial condition of two irradiation levels of the PV curve distribution of the solar array when kept at 800W / m ^2, and 360W / m ^2. At this time, since RP is higher than LP, the operating point should be located on the RP (35.8V, 1.34A) preferably by the global maximum power tracking algorithm. Figure 9b is a solar radiation level S1 is 800W / m while being kept in a ^2, a level S2 is to 360W / m ² in the case when the fall to 320W / m ^2, now LP is higher preferably at the operating point jyeoteumeuro than RP It should be changed to LP (16.6V, 2.79A).

However, due to a small power change (P/P <0.1), the conventional method cannot detect such partial shadows as shown in FIG. 10A, and does not make a GPS call, so the operating point remains at the RP (output power 43.5W). ). On the contrary, in the proposed method, the GPS is called and the operating point is relocated to the preferred location, LP, and shows a desirable maximum power (output power 46W) as shown in FIG. 10B.

Likewise, such a difference in performance can be confirmed even in the case of a sudden change in insolation. In the initial condition of two modules solar radiation level to as Figure 11a of the irradiation level of the module 1 while kept the same as 800W / m ^2, S1 has as one of modules 2, solar radiation S2 is a 11b maintained in conventional 800W / m ² It dropped from 800W/m ² to 650W/m ^2. In this case, there is only one power peak of RP at first, but after the change of insolation, the peak is divided into two, but since the output of LP is still lower than that of RP, the GPS call becomes unnecessary.

However, since the conventional PSD algorithm in FIG. 12A detects this power difference (P/P> 0.1), it calls GPS to waste time and returns to the current peak (RP). On the contrary, the proposed method does not unnecessarily call the GPS as shown in FIG. 12B and allows the operating point to continue to operate in the RP. In other words, it was verified that by removing unnecessary GPS calls, defects in voltage and current waveforms were eliminated to increase the amount of generated power that can be obtained from the solar array.

In the present invention, a new partial shading detection algorithm is proposed. The existing PSD algorithm called GPS by relying only on information about the rate of change of power generation. However, in the present invention, by analyzing the pattern of the PV curve in detail, the global shading level information inferred through the shading state of each module is updated to the reference power information, and a threshold power value that determines whether or not a GPS call is made based on this. Is set adaptively. By using this concept, not only can you make the necessary GPS calls in a timely manner even under the conditions of gentle insolation change. In the conditions of rapid insolation change, energy waste due to unnecessary GPS can be reduced.

Through this, the proposed algorithm provides efficient utilization of the solar array. The greater the number of panels connected in series, the greater this advantage, so this technology is expected to further increase the power generation efficiency in large-capacity solar power generation such as Solar Farm.

The present invention has been described above with the purpose of method steps representing the performance of specific functions and their relationships. The boundaries and order of these functional components and method steps have been arbitrarily defined herein for convenience of description. Alternative boundaries and orders may be defined as long as the specific functions and relationships are properly performed. Any such alternative boundaries and sequences are therefore within the scope and spirit of the claimed invention. In addition, the boundaries of these functional components have been arbitrarily defined for convenience of description. Alternative boundaries can be defined as long as certain important functions are performed properly. Likewise, flowchart blocks may also have been arbitrarily defined herein to indicate any significant functionality. For extended use, the flow diagram block boundaries and order may have been defined and still perform some important function. Alternative definitions of both functional elements and flowchart blocks and sequences are therefore within the scope and spirit of the claimed invention.

The present invention may also have been described, at least in part, in terms of one or more embodiments. Embodiments of the invention are used herein to represent the invention, its aspects, its features, its concepts, and/or examples thereof. A physical embodiment of an apparatus, article of manufacture, machine, and/or process embodying the present invention refers to one or more aspects, features, concepts, examples, etc. described with reference to one or more embodiments described herein. Can include. Moreover, in the entire drawing, embodiments may incorporate the same or similarly named functions, steps, modules, etc., which may use the same or different reference numbers, and as such, the functions, Steps, modules, etc. may be the same or similar functions, steps, modules, etc. or others.

As described above, in the present invention, specific matters such as specific components, etc., and limited embodiments and drawings have been described, but these are provided only to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments. , If a person of ordinary skill in the field to which the present invention belongs, various modifications and variations are possible from these descriptions.

Therefore, the spirit of the present invention is limited to the described embodiments and should not be defined, and all things that are equivalent or equivalent to the claims as well as the claims to be described later belong to the scope of the present invention. .

210: first solar panel 211: first diode
220: second solar panel 221: second diode
230: global shading 241: first partial shading
242: second partial shading 610: solar array
611: first solar panel 612: second solar panel
620: control module 630: boost converter circuit
640: sensor circuit 650: load resistance

Claims (15)

Performing global peak scanning on the solar array;
Comparing the open circuit voltage (Voc) and the operating voltage (V _received ) of the unit module of the solar array to check area information in which the current operating point is located in the solar array; And
For a solar array system comprising the step of determining whether to re-perform the global peak scanning based on the current operating region of the solar array and the reference power (P _{r) set in the operating region according to the region information} Adaptive partial shadow detection method. The method of claim 1,
When the operating point is located in the region with the highest voltage,
It characterized in that the global peak scanning is selectively performed by comparing the currently measured generation power (P _received ) of the solar array and a threshold power level (P _th ) adaptively set by the reference power (P _{r ).} Adaptive partial shade detection method for solar array system. The method of claim 2,
The threshold power level (P _th ) is,
An adaptive partial shadow detection method for a solar array system, characterized in that it is calculated by the following equation according to the region of the measured generation power (P _received).

The method of claim 2,
When the operating point is located in the region with the highest voltage,
Checking the number of peaks;
If the number of peaks is a single peak, updating the _{generated power P received} to the reference power P _{r;
Calculating a threshold power level (P th} ) of a corresponding region in which the peak exists and executing a maximum power point tracking (MPPT); And
And performing the global peak scanning only when the generated power P _received is less than the threshold power level P _th , and updating the _{reference power P r when the power generation P received is less than the threshold power level P th.} Adaptive partial shadow detection method for the system. The method of claim 4,
If the number of peaks is 2 or more,
Updating the reference power P _r based on the peak level of the leftmost region;
Calculating a threshold power level (P _th ) of the updated area information and executing a maximum power point tracking (MPPT); And
And performing the global peak scanning only when the generated power P _received is less than the threshold power level P _th , and updating the _{reference power P r when the power generation P received is less than the threshold power level P th.} Adaptive partial shadow detection method for the system. The method of claim 5,
The reference power (P _r ) of the leftmost region is the equation

(here,

silver

An adaptive partial shade detection method for a solar array system, characterized in that calculated as ). The method of claim 1,
When the operating point is located in a region other than the region with the highest voltage,
An adaptive partial shadow detection method for a solar array system, characterized in that repeating maximum power point tracking (MPPT) according to a set time or calling the global peak scanning to check other peaks. A solar array including a plurality of solar panels; And
Including a control module for determining whether to execute Global Peak Scanning according to a region in which an operating point of the solar array is located among a plurality of operating regions analyzed based on the PV curve of the solar array. Solar power device. The method of claim 8,
When the operating point is located in a region other than the region with the highest voltage,
The control module is a photovoltaic device, characterized in that it repeatedly performs the maximum power point tracking (MPPT) according to a set time or periodically calls a global peak scanning (Global Peak Scanning). The method of claim 8,
If the operating point is located in the region with the highest voltage and a single peak,
The control module,
The generated power (P _received ) is updated to the reference power (P _r ), the critical power level (P _th ) of the corresponding region is calculated, and the result of comparison between the generated power (P _received ) and the critical power level (P _th) Accordingly, the photovoltaic device, characterized in that performing the global peak scanning or _{updating the reference power (P r) again.} The method of claim 8,
If the operating point is located in the region with the highest voltage and has two or more peaks,
The control module,
_{The reference power (P r} ) is updated based on the peak level of the leftmost region, the threshold power level (P _th ) of the updated region information is calculated, and then the generated power (P _received ) and the threshold power level (P) are calculated. _th ) A photovoltaic device, characterized in that _{performing the global peak scanning or updating the reference power (P r} ) again according to a result of comparison with th ). The method of claim 10 or 11,
The control module,
A photovoltaic device, characterized in that the global peak scanning is performed only when the threshold power level (P _th ) is greater than the generated power (P _{received ), and the reference power (P r) is updated in the opposite case.} The method of claim 12,
The threshold power level (P _th ) is,
According to the area of the measured generation power (P _received)

Solar power generation device, characterized in that calculated as. The method of claim 11,
The reference power (P _r ) of the leftmost region is the equation

(here,

silver

Im) photovoltaic device, characterized in that calculated as. The method of claim 10 or 11,
After the critical power level (P _th ) is calculated, a maximum power point tracking (MPPT) is further performed.

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