KR101274632B1  Optimized power allocation method of inverter in photovoltaic power generating system  Google Patents
Optimized power allocation method of inverter in photovoltaic power generating system Download PDFInfo
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 KR101274632B1 KR101274632B1 KR1020110055132A KR20110055132A KR101274632B1 KR 101274632 B1 KR101274632 B1 KR 101274632B1 KR 1020110055132 A KR1020110055132 A KR 1020110055132A KR 20110055132 A KR20110055132 A KR 20110055132A KR 101274632 B1 KR101274632 B1 KR 101274632B1
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 Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSSSECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSSREFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
 Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
 Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
 Y02E10/00—Energy generation through renewable energy sources
 Y02E10/50—Photovoltaic [PV] energy
 Y02E10/56—Power conversion electric or electronic aspects
 Y02E10/58—Maximum power point tracking [MPPT] systems
Abstract
Description
The present invention relates to a power allocation method of an inverter in a photovoltaic system for improving the efficiency of the photovoltaic system.
The photovoltaic power generation system is a power generation device that converts sunlight directly into electrical energy, and is composed of an overpower converter (inverter) consisting of receiving sunlight to generate electricity.
The power converter converts direct current electricity generated from solar cells into alternating current electricity and supplies it to the power system, and occupies the largest share except for solar cells in photovoltaic power generation systems.
In addition, one of the main obstacles to the practical application of solar power generation technology is the low efficiency of the solar power system.
The efficiency of photovoltaic arrays usually suffers from the loss of 30% power converters, resulting in low system efficiency despite the high installation costs.
Thus, the best way to increase the overall efficiency of the solar system is to improve the efficiency of the solar array itself, but that requires more time and effort.
Since much effort has already been made in this area, the energy generated by photovoltaic arrays is improving the efficiency of power transformers to the maximum extent possible, so we must look for a variety of ways to improve the overall efficiency of photovoltaic systems.
Therefore, the technical problem to be solved by the present invention is to adopt an optimal power allocation method for allocating the power optimized for the high efficiency conditions of the photovoltaic system to the inverter according to the situation.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular embodiments that are described. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, There will be.
In order to achieve the above object, an optimal power allocation method allocated to an inverter of a photovoltaic system according to the present invention includes: a first step of calculating an output power sum of photovoltaic arrays; A second step of comparing the output power sum with the maximum power capacity of the inverter; And a third step of allocating the output power to each inverter according to the power allocation efficiency of the inverter.
In the second step, when the maximum power capacity of the inverter is less than the sum of the output powers, the efficiency when allocating the average power to each inverter and the efficiency when allocating the maximum efficiency power to each inverter are obtained.
In addition, the efficiency when allocating the average power to the inverter is preferably expressed as a ratio of the power allocated to each inverter and the maximum power capacity of the inverter when the total output power is divided by the number of inverters.
In addition, the efficiency at the time of assigning the maximum efficiency power to the inverter, the total output power is assigned to each inverter as the maximum efficiency power, the remaining output power is assigned to the unassigned inverter, and then the output power total and the assigned It is preferable to express the ratio of the power according to the number of inverters and the maximum power capacity of the inverter.
In addition, if the efficiency when allocating the average power to the inverter is greater than the efficiency when allocating the maximum efficiency power to the inverter, the average power is allocated to each inverter or the maximum efficiency power is allocated to each inverter.
The method of allocating the maximum efficiency power to the inverter further comprises: allocating the maximum efficiency power to the first inverter; Allocating maximum efficiency power to a next inverter if the sum of the output powers is greater than the output power of the photovoltaic array; And allocating the maximum efficiency power to each inverter in the total output power and allocating the remaining power to the next inverter when the remaining output power is less than the output power.
Also, in the second step, if the maximum power capacity of the inverter is greater than the sum of the output powers, only one inverter is used.
According to the characteristics of the present invention, the present invention has an effect of maximizing the efficiency of the inverter by increasing the selective power allocation method according to the efficiency.
1 is a flowchart illustrating a power allocation method of an inverter in a solar power generation system according to the present invention.
2 is a flowchart illustrating a method of allocating a maximum efficiency power to an inverter of the power allocation method of the inverter in the solar power generation system according to the present invention.
3 is a graph showing the efficiency of the 3Kw inverter according to an embodiment of the present invention.
4 to 6 are simulation cases showing the efficiency of the power allocation method of the inverter in the solar power generation system according to an embodiment of the present invention.
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like elements in the figures are denoted by the same reference numerals wherever possible. In the following description, wellknown functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.
1 is a power allocation method of the inverter in the photovoltaic power generation system according to the invention, and calculates the first, aspect total output power (P _{total)} of the PV array (S10). In this case, the total output power P _{total} may be expressed as in Equation 1 below.
[Equation 1]
Here, k means the number of the photovoltaic array, P _{1} represents the output power of the photovoltaic array.
In addition, the output power P _{l} of the photovoltaic array may be obtained through Equation 2 below.
&Quot; (2) "
Here, v _{sl} denotes the output voltage of the solar array, and i _{sl} denotes the current output solar array.
Next, the total output power and the maximum power capacity of the inverter are compared (S20). At this time, if the sum of the output powers is greater than the maximum power capacity of the inverter, the efficiency (η _{ave} ) when allocating the average power to each inverter and the efficiency (η _{MEP} ) when allocating the maximum efficiency power to each inverter are obtained. (S30).
In addition, if the sum of the output power is less than the maximum power capacity of the inverter, it is allocated to the inverter of the photovoltaic system using only one inverter (S40).
Here, the efficiency η _{ave} when allocating the average power to the inverter is expressed by the ratio of the power allocated to each inverter and the maximum power capacity of the inverter when the total output power is divided by the number of inverters.
In addition, the efficiency (η _{MEP} ) when allocating the maximum efficiency power to the inverter is the sum of the output power as the maximum efficiency power to each inverter and the remaining output power to the unassigned inverter. It is expressed as the ratio of the average power and the maximum power capacity of the inverter according to the number of assigned inverters.
Finally, output power is allocated to each inverter according to the power allocation efficiency of the inverter.
That is, when the efficiency when allocating the maximum efficiency power to the inverter is greater than the efficiency when allocating the average power to the inverter (S50), the efficiency when allocating the maximum efficiency power (S60) and making the average power to the inverter becomes If greater than the efficiency when allocating the maximum efficiency power to the inverter, the average power is allocated (S70).
Here, the method when allocating the maximum efficiency power is as follows.
First, the maximum efficiency power is allocated to the first inverter of the total output power (S81).
Subsequently, maximum efficiency power is allocated to the next inverter until Equation 3 below is satisfied (S82).
&Quot; (3) "
Here, Pn means power allocated to each inverter, that is, n means the number of inverters installed.
Finally, if the maximum efficiency power is allocated to each inverter in the total output power and the remaining output power is less than the output power, the remaining power is allocated to the next inverter (S83).
An example will be described based on the abovedescribed contents.
Assuming that the solar inverter should be designed with the same capacity and know the efficiency characteristic data of the inverter in advance, the maximum efficiency of the inverter is 2.4kw in any graph showing the efficiency of the inverter with a maximum power capacity of 3kw as shown in FIG. Let's say 90% and 1.8kw is 86%.
Further, suppose that the solar power generation array of the solar power generation system is provided with five inverters in the module configuration of the solar power generation system to generate 9Kw.
In the case of adopting a method of allocating average power to inverters, the same power is allocated to each inverter by dividing 9 kw generated by the photovoltaic array by the number of inverters, 5, respectively. That is, the efficiency of the inverter becomes 86% by allocating five inverters of 1.8 kw.
On the contrary, when adopting a method of allocating the maximum efficiency power to the inverters, the maximum efficiency of the inverter is assigned to each inverter by 2.4kw, but by assigning 2.4kw to each of the five inverters, the photovoltaic array exceeds 9kw. As they stand, they allocate 2.4 kw to three inverters on the line that are no more than 9 kw, and the remaining 1.8 kw to other inverters. At this time, since four inverters are used, one may maintain an off state.
Here, looking at the efficiency of the inverter it can be seen that the average efficiency of the four inverters used in 9kw used is 88%.
In other words, the efficiency of 2% can be obtained by adopting a method of allocating the maximum efficiency power to the inverter. Here, 2% may be a small number, but as the power is increased, the efficiency for the power corresponding to 2% is increased, thereby increasing the power efficiency substantially in a large capacity solar power generation system.
In addition, the efficiency may be further increased according to the maximum efficiency power of the inverter and the average power according to the number of inverters.
4 to 6, the power allocation method allocated to the inverter selects another allocation method according to the efficiency.
As shown in FIG. 4, when the efficiency (83.60%) of the maximum efficiency power allocation is greater than the efficiency (81.32%) of the average power allocation, the maximum efficiency power allocation method is adopted to allocate power of the inverter's maximum efficiency to each inverter. Is assigned to the next inverter and processed.
In this case, when the maximum efficiency power is allocated, the inverter does not need to be generated, thereby extending the life of the inverter, and each inverter used has the advantage of increasing the use efficiency of the inverter by allocating the maximum efficiency to the power.
As shown in FIG. 5, when the efficiency (82.67%) of the maximum efficiency power allocation is greater than the efficiency (82.68%) of the average power allocation, the average power is allocated to each inverter and processed.
However, it is desirable that the previously adopted allocation method is the maximum efficiency power allocation method and that the previously adopted allocation method can be adopted if the efficiency of both does not differ significantly.
In addition, when the efficiency (84.00%) of the maximum efficiency power allocation is the same as the efficiency (84.00%) of the average power allocation as shown in FIG. 6, power is allocated while maintaining the previously adopted allocation method.
In other words, when power is previously allocated to the inverter using the maximum efficiency power allocation method, the power is allocated by maintaining the maximum efficiency power allocation method, and when power is previously allocated to the inverter using the average power allocation method, the average power allocation method is selected. It is desirable to maintain and allocate power.
It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined by the appended claims. It will be possible. The scope of the present invention is defined by the appended claims, and all differences within the scope of the claims are to be construed as being included in the present invention.
Claims (7)
 Calculating a sum of output power of the photovoltaic arrays;
A second step of comparing the sum of the output powers with a maximum power capacity of inverters; And
And a third step of allocating output power to each inverter according to power allocation efficiency of the inverters.
In the second step, if the maximum power capacity of the inverters is less than the sum of the output power, the efficiency of allocating the average power to each inverter and the efficiency of allocating the maximum efficiency power to each inverter is calculated. Method of power allocation of inverters in power generation systems.
 delete
 The method according to claim 1,
In the photovoltaic power generation system, the efficiency in allocating the average power to each inverter is represented by the ratio of the maximum power capacity and the power allocated to each inverter when the total output power of the photovoltaic arrays is divided by the number of inverters. How to allocate power of the inverter.
 The method according to claim 1,
The efficiency in allocating the maximum efficiency power to each inverter is determined by assigning the total output power of the photovoltaic arrays as the maximum efficiency power to each inverter and allocating the remaining output power to the unassigned inverter. A method of allocating power in an inverter in a solar power system, expressed as a ratio of the average of the power according to the sum and the number of assigned inverters and the maximum power capacity of the inverter.
 The method according to claim 1,
If the efficiency when allocating the average power to each inverter is greater than the efficiency when allocating the maximum efficiency power to each inverter, the average power is allocated to each inverter or the maximum efficiency power is allocated to each inverter. Method of power allocation of inverters in power generation systems.
 The method according to claim 5,
The method of allocating maximum efficiency power to the inverter comprises: assigning maximum efficiency power to a first inverter;
Allocating maximum efficiency power to a next inverter if the sum of the output powers is greater than the output power of the photovoltaic array; And
Allocating the maximum efficiency power to each inverter in the sum of the output powers and allocating the remaining power to the next inverter when the remaining output power is less than the output power.
 The method according to claim 1,
In the second step, if the maximum power capacity of the inverter is greater than the sum of the output power, the power allocation method of the inverter in the solar power system using only one inverter.
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