POWER GENERATION PLANT AND METHOD FOR PLANNING A POWER GENERATION PLANT

Abstract

Power generation plant, including: - a large number of parallel-connected power generation units; - a power collector device for collecting electrical power from a multitude of power generating units; and - Lines for connecting the multiple power generating units and the power collector device, where a ratio of a conductor diameter to a predetermined length of each of the conductors is defined as a reference ratio, wherein a value obtained by multiplying the reference ratio, a number of conductors and a loss resulting from a specific conductor connection is subtracted from a value obtained by multiplying a predetermined number of tuning conductors by a ratio of a conductor diameter to a length of the specific conductor, and where the sum of the ratios of the conductor diameters to the lengths of the predetermined number of conductors for adjustment is determined as a value that is smaller than the subtracted value.

Description

PRIORITY CLAIM

[0001] The present application claims priority over Japanese patent application JP 2013 - 201 847 filed on September 27, 2013, the contents of which are hereby incorporated into the present application by reference. BACKGROUND OF THE INVENTION

[0002] The present invention relates to a power generation plant and a method for planning the power generation plant.

[0003] In general, a photovoltaic power generation system consists of numerous strings of solar cells, formed by connecting many solar modules in series, connected in parallel within a junction box to create a power generation unit. Furthermore, multiple power generation units are connected in parallel via a collector rack and controlled by a power conditioner to feed power into a grid.

[0004] The distances between the solar cell strings and the junction box, as well as the distances between the junction boxes and the power collector rack, vary depending on the location of the power collector rack and the installation locations of the junction boxes. Therefore, when connecting with the same type of electrical cables, the resistance values ​​of the electrical cables will differ depending on the distances.

[0005] In JP 2012-256092A, which represents the state of the art in this field, a photovoltaic power generation system is disclosed in which a large number of solar cell generation units are connected in parallel and some or all of the cable lengths of the extension cables from the solar cell generation units to the parallel connection points differ. In this case, the electrical resistance values ​​of the power transmission paths from the solar cell generation units to the parallel connection points are controlled to be approximately equal by using a variety of different types of extension cables that differ from each other at least in either electrical resistance or conductor cross-section.

[0006] Document US 2010 / 0295383A1 describes an embodiment of a power plant electrical system architecture in which a solar energy concentrator in the form of an inflated reflector focuses the light onto a high-concentration photovoltaic receiver. A number of these concentrators are combined into a series-connected cluster that shares control electronics and a support structure.

[0007] Furthermore, the JIS standard (JIS C 8907) recommends that the loss (arrangement circuit correction coefficient) of a connecting line, i.e. the loss in a DC circuit with an electrical line and a diode provided in a terminal box, should each be within 3%. BRIEF SUMMARY OF THE INVENTION

[0008] The loss in the DC circuit of the large photovoltaic power plant arises from line resistance between the solar cell string and the junction box, a reverse current inhibitor diode within the junction box, and line resistance between the junction box and the current collector rack. The JIS standard (JIS C 8907) recommends that the sum of these losses (arrangement correction coefficient) be controlled within 3.0%. For example, if the loss due to the reverse current diode in the junction box is 1.0%, the design can be chosen such that the line resistance between the solar cell string and the junction box is limited to 1.0%, and the line resistance between the junction box and the current collector rack is also limited to 1.0%.For this reason, the cable thickness must be adjusted during the planning phase so that the voltage drop, calculated by multiplying the solar cell's rated current by the conductor resistance, is limited to 1.0%, depending on the distances of the solar cell string to the junction box and the distances of the junction boxes to the power collector rack. Specifically, large-diameter cables are used for cabling over long distances from the solar cells to the junction box and from the junction boxes to the power collector rack. By applying the technology from JP 2012-256092A, the conductor resistance values ​​are standardized by using electrical cables with different resistances or conductor diameters.In any case, the large conductor diameter, low electrical resistance, and long length of electrical cables inevitably lead to increased costs. Therefore, one objective of the present invention is to create a power generation plant in which, with regard to the design of the cables in a large power plant, the thickness of cables over a long distance from the solar cell string to a junction box and the thickness of a cable over a long distance between the junction box and a power collector rack are reduced to the necessary level, and a method for manufacturing such a plant.

[0009] A representative invention disclosed in the present application is outlined below. A power generating plant is provided comprising: a plurality of parallel-connected power generating units; a power collector device for collecting the electrical power from the plurality of power generating units; and conductors for connecting the plurality of power generating units to the power collector device. A ratio of a conductor diameter to a predetermined length of each cable is defined as the reference ratio. A value obtained by multiplying the reference ratio, a number of conductors, and a loss resulting from a specific conductor is subtracted from a value obtained by multiplying a predetermined number of conductors by a ratio of a conductor diameter to a length of the specific conductor.The sum of the ratios of the conductor diameters to the lengths of the predetermined number of conductors for adjustment is defined as a value that is less than the subtracted value.

[0010] As explained above, according to a representative embodiment of the invention, the electrical conductor can be selected with a suitable thickness depending on the length of the conductor extending from the solar cell string, thus avoiding the cost increase for the electrical conductor. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention will be understood by the following description with reference to the figures. They show: Fig. 1 a diagram illustrating a configuration of a photovoltaic power generation plant according to a first embodiment of the invention; Fig. 2 a diagram showing the interconnections of a solar cell string, a junction box and a current collector rack of the photovoltaic power generation plant according to the first embodiment, Fig. 3 a diagram illustrating configurations of a solar cell, a solar cell module and the solar cell string according to the first embodiment; Fig. 4 a diagram showing currents flowing from the power generation units to the power collector rack according to the first embodiment; Fig. 5 a diagram showing the voltage drop across the resistance of a line arrangement of the power generation unit according to the first embodiment; Fig. 6 a diagram illustrating a voltage and current in the solar cell string provided in the power generation unit according to the first embodiment; Fig. 7 a diagram illustrating a configuration of the photovoltaic power generation plant according to a first embodiment; Fig. 8 a diagram illustrating a configuration of a photovoltaic power generation plant according to a second embodiment of the invention; Fig. 9 a diagram illustrating a configuration of a photovoltaic power generation plant according to a third embodiment of the invention; Fig. 10 a diagram illustrating a configuration of a computer according to a fourth embodiment of the invention; and Fig. 11 a flowchart illustrating a planning procedure according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED VERSIONS First Version

[0012] Fig. Figure 1 is a diagram illustrating a configuration of a photovoltaic power generation plant according to a first embodiment of the invention.

[0013] The photovoltaic power generation system according to the first embodiment of the invention comprises a solar cell string (power generation unit) 11a, which is formed by connecting a plurality of solar cell modules in series. The plurality of solar cell strings 11a are connected in parallel in a terminal box 1f, thereby forming the power generation units (solar cell arrangement) 1a, 1b, ... 1e. Lines between the solar cell strings 11a and the terminal box 1f have resistances R1_1, R1_2, ... R1_20. Similarly, the lines between the solar cell strings and the terminal box 1f of the other power generation units have resistances R2_1, R2_2, ... R2_20, ... R5_1, R5_2, ... R5_20. The lengths of these cables are determined according to the installation locations of the solar cell strings11a and the installation locations of the connection boxes1f, which is why the resistance values ​​of the cables differ from each other.

[0014] A number of power generation units 1a, 1b, ... 1e are connected in parallel via the power collector rack 1g. The lines from the power generation units 1a, 1b, ... 1e to the power collector rack 1g have resistances Ra1, Ra2, ... and Ra5, respectively. The lengths of these lines are determined according to the installation locations of the connection boxes 1f and the power collector rack 1g, which is why the resistance values ​​of the lines differ.

[0015] The electrical energy collected in the power collector rack 1g is controlled by a power conditioner 1h and then fed into a system. The power conditioner 1h features Maximum Power Point Tracking (MPPT) and DC / AC converter (inverter) functionality.

[0016] Next follows a description of a current flowing through the solar cell string 11a of the photovoltaic power generation plant of the first embodiment.

[0017] Fig. Figure 2 is a diagram showing the interconnections of a solar cell string 11a, the connection box 1f and the current collector rack 1g of the photovoltaic power generation system according to the first embodiment.

[0018] A large number of solar cell modules are connected in series, forming the solar cell string 11a. In the junction box 1f, the multiple solar cell strings 11a are connected in parallel via the reverse current prevention diodes 11b. The resistance values ​​of the lines between the solar cell strings 11a and the junction box 1f are determined according to the installation locations of the solar cell strings 11a and the installation location of the junction box 1f. Therefore, the resistance values ​​of the lines R1_1, R1_2, R1_3, R1_4, ..., R1_20 differ from one another. Furthermore, the resistance values ​​of the lines between the junction boxes 1f and the current collector rack 1g are determined according to the installation locations of the junction boxes 1f and the installation location of the current collector rack 1g. Therefore, the resistance values ​​of the lines Ra1, Ra2, ..., Ra5 differ from one another.

[0019] Fig. Figure 3 is a diagram illustrating configurations of a solar cell 3f, a solar cell module 3g and the solar cell string 11a according to the first embodiment.

[0020] In solar cell module 3g, a plurality of solar cells 3f are connected in series. These series-connected solar cells 3f are separated by a bypass diode 3e. The bypass diode 3e is attached to solar cell module 3g to prevent the reverse flow of current through the solar cells 3f when a reverse bias is applied to solar cell module 3g. Furthermore, a plurality of solar cell modules 3g are connected in series to form solar cell string 11a. The solar cell 3f can be represented by an equivalent circuit with a current source 3a, a pn junction diode 3b, a parallel resistor 3c, and a series resistor 3d. The current source 3a outputs a current proportional to the solar irradiance.

[0021] Fig. Figure 4 is a diagram showing currents flowing from the power generation units 1a, 1b, ..., 1e to the power collector rack 1g. Fig. Figure 5 is a diagram showing the voltage drop across the resistance of the lines of the power generating unit 1a. Furthermore, Fig. Figure 6 shows a diagram illustrating the voltage and current in the solar cell string 11a in the power generation unit 1a.

[0022] If the operating current of the entire photovoltaic power generation system is Idc and the operating voltage of the entire photovoltaic power generation system, controlled by the power conditioner, is Vdc, as in Fig. As shown in Figure 4, the operating current Idc of the entire photovoltaic power generation system is expressed by a sum of the currents that are caused to flow from the power generation units 1a, 1b, ... 1e to the power collector rack 1g. Idc=Iarray1+Iarray2+Iarray3+Iarray4+Iarray5

[0023] If, as in Fig. 5 If the voltage drop caused by the resistance of the lines from the terminal box 1f to the current collector rack 1g in the power generation unit 1a is -Vra1, and the voltage drop caused by the backflow prevention diode 11b is -Vf, then an operating voltage Varray 1 of the power generation unit (solar cell arrangement) 1a can be specified by expression (2). Varray1−Vral−Vf=Vdc

[0024] Furthermore, the current of the solar cell arrangement Iarray1 can be expressed by the sum of the currents that are caused to flow from the solar cell strings 11a to the terminal box 1f. Iarray1=Istring1+Istring2+Istring3+Istring4+…+Istring20

[0025] Furthermore, as in Fig. 6 the voltage Varray1 applied to an arrangement is the same as in the other arrangements, therefore, taking into consideration that a resistance value of the parallel resistor 3c is large enough, a voltage Varray1 applied to the solar cell string 11a using the current of the solar cell arrangement Iarray1 can be specified by expression (4). Varray1=Ncell⋅(nf⋅k⋅TqIn(Isc−Istring1Is))−VR1_1=Ncell⋅(nf⋅k⋅TqIn(Isc−Istring1Is))−Istring1⋅R1_1

[0026] In expression (4), Ncell is the number of solar cells forming the solar cell string 11a, Is is a saturated reverse current [A], Isc is a short-circuit current [A], T is the absolute temperature [K] of a solar cell element, k is the Boltzmann constant [J / K], q is the charge [C] of an electron, and nf is a junction constant.

[0027] Similarly, the voltage Varray1 applied to another solar cell string 11a connected in parallel with the solar cell string 11a can be specified using a current Istring2 flowing through the solar cell string 11a using expression (5). Varray1=Ncell⋅(nf⋅k⋅TqIn(Isc−Istring2Is))Istring2−R1_2

[0028] Combining expressions (4) and (5), it is clear that the current Istring2 is expressed in terms of the current Istring1. This relationship holds true for all solar cell strings connected in parallel. In other words, if the current Istring1 flowing through the first solar cell string has been determined, the currents flowing through other solar cell strings can also be determined. If the currents Istring flowing through other solar cell strings are expressed as functions of the current Istring1 flowing through the first solar cell string—in other words, in the form Istring2 = I2 [Istring1], Istring3 = I3 [Istring1], ..., Istring20 = I20 [Istring1], as shown in expression (6)—then the current of the array Iarray1 can be expressed as a function of Istring1. Iarray1=Istring1+I2[Istring1]+I3[Istring1]+…+I20[Istring1]

[0029] With regard to the arrangement currents Iarray1 and Iarray2, since the operating voltage Vdc is the same for all arrangements, the relationship is similar to that in expression (4) and expression (5). Therefore, each of the currents Iarray2 to Iarray5 can be expressed as a function of the arrangement current Iarray1.

[0030] For simplification, the case is considered in which the total voltage drop is limited to less than 2.0%, taking into account only the voltage drop caused by the resistances of the lines from the solar cell strings to the junction box; in other words, a method to ensure the nominal power Po from expression 7. Varray1⋅Iarray1>0.98⋅Po

[0031] Specifically, the current Istring1 is first determined as a reference value using expression (4), from which the voltage Varray, at which the solar cell string is to be operated, is derived. If the loss of string 1 is 4.0%, expression 8 applies, and the voltage Varray can be expressed by expression (9), which is a modification of expression (8). Varray1=10.96⋅(Ncell⋅(nf⋅k⋅TqIn(Isc−Istring1Is))−Istring1−R1_1)>0.98⋅(PoIarray1) Ncell⋅(nf⋅k⋅TqIn(Isc−Istring1Is))−Istring1⋅R1_1>0.98⋅(PoIarray)⋅0.96

[0032] At this point, the same current as that for the first solar cell string flows through each of the (n-1) strings in the power generation unit 1a. In order for the loss of electrical power from the n strings, including the first solar cell string, to be less than 2% in this case, expression (10) must be satisfied. n⋅Ncell⋅(nf⋅k⋅TqIn(Isc−Istring1Is))−Istring1⋅(R1_1+⋯+R1_n)n>0.98⋅(PoIarray1)

[0033] It should be mentioned that it is desirable to define a power loss of less than 2% as a planning target with a margin so that the power loss is 3% or below, as regulated in the JIS standard described above. Furthermore, if expression (9) is multiplied by n and then subtracted from expression (10), the resulting expression (9) can be transformed into expression (11). (n−1)⋅Istring1⋅R1_1−Istring1⋅(R1_2+⋯+R1_n)>n⋅0.98⋅(PoIarray1)⋅(1−0.96)

[0034] If Varray1=0.98xPo / Iarrayl is set as the design target as in expression (7), Varray1 / Istring1 becomes the nominal resistance Rt of the solar cell string. If this nominal resistance value Rt is used, expression (12) can replace expression (11). (R1_2+⋯+R1_n)<(n−1)⋅R1_1−n⋅(1−0.96)⋅Rt

[0035] In other words, it is only necessary that the sum of the line resistance values ​​of the other (n-1) strings in the power generation unit 1a is adjusted such that expression (12) is satisfied. The electrical resistances p of all cables are equal, the cable lengths are L1_1, L1_2, ... L1_n, the cable diameters are S1_1, S1_2, ..., S1_n, a cable length necessary to keep the current loss below 2% is Lt, and a conductor diameter (in the cross-sectional area of ​​the conductor) of the cable is St. Under these conditions, the line resistance of the first solar cell string can be expressed in the form px(L1-1 / S1-1). Therefore, expression (13) can be replaced by expression (12). (L1_2S1_2+L1_3S1_3+⋯+L1_nS1_n)<(n−1)⋅L1_1S1_1−n⋅(1−0.96)⋅LtSt

[0036] Next, an example of the specific resistance value of the conductors in the photovoltaic power generation system of the first embodiment is described. In the photovoltaic power generation system of the first embodiment, a specific example is described in which two solar cell strings are used. Then, if the voltage drop in one solar cell string reaches, for example, 4%, the voltage drop in the other solar cell string is calculated to compensate for this loss, and the conductors in the solar cell string located at a greater distance from the junction box 1f are adjusted to the appropriate thickness.

[0037] Fig. Figure 7 is a diagram illustrating the configuration of the photovoltaic power generation system according to the first embodiment and showing the ratio between the length and the conductor diameter of the line extending from the solar cell string 11a, which is connected to the terminal box 1f. In the example of the photovoltaic power generation system configuration from Fig. 7 The resistance value of the lines is calculated using the expression (13) described above.

[0038] The in Fig. The specific example given in Figure 7 specifies the ratio between the lengths and conductor diameters of 20 solar cell strings that form the power generation unit 1a. The nominal resistance of the solar cell string is Rt. The line resistance loss R1_1 of the first solar cell string, which is furthest from the terminal box 1f, is 4.0%, and the line resistance losses R1_2, R1_3, ... R1_20 of the solar cell strings from the second to the 20th solar cell string are each 2.0%. Using the nominal resistance L / S set as a reference value, the 4.0% line resistance loss R1_1 can be expressed as 1.04 L / S, and the 2.0% loss of each of the line resistances R1_2, R1_3, ... R1_20 can be expressed as 1.02 L / S. If it is desired that the entire voltage drop be calculated using the 20thIf the solar cell string is to be reduced to below 2.0% when n=2 is substituted into expression (13), expression (13) can be replaced by expression (14). (LR1_20SR1_20)<1.04⋅LS−2⋅(1−0.96)⋅LS=0.96⋅LS

[0039] Expression 14 makes it clear that in the photovoltaic power generation system according to the first embodiment, it is only necessary that the line resistance value of the 20th solar cell string is set below px0.96x(L / S).

[0040] As described above, in the first embodiment, the appropriate thickness of the conductors between the solar cell string 11a and the junction box 1f in the photovoltaic power generation system can be calculated. Furthermore, the conductors can have a suitable thickness even if the distance between the solar cell string 11a and the junction box 1f is large. As described above for the first embodiment, the solar cell string is also individually selected to compensate for the conductor resistance. This reduces the number of solar cell strings exposed to this influence and thus simplifies the conceptual design. Second embodiment

[0041] Next, a photovoltaic power generation plant according to a second embodiment of the invention will be illustrated.

[0042] In the photovoltaic power generation system according to the second embodiment, a specific example is described in which, if the voltage drop in a solar cell string reaches, for example, 4%, in order to compensate for this loss, the voltage drop in all 20 solar cell strings, which form the power generation unit 1a, is calculated using all solar cell strings, and the conductors of the solar cell string with a large distance to the connection box 1f are adjusted to the appropriate thickness.

[0043] It should be noted that in the second embodiment, expression (13) from the first embodiment is used as the expression with which the specific resistance value of the lines is calculated.

[0044] Fig. Figure 8 is a diagram illustrating the configuration of the photovoltaic power generation system according to the second embodiment and showing the ratio between the length and conductor diameter of the lines extending from the solar cell string 11a, which is connected to the terminal box 1f. In the example of the photovoltaic power generation system configuration from Fig. 8 The resistance value of the lines is calculated using the same expression as expression (13) in the first embodiment.

[0045] The loss of the line resistance R1_1 of the first solar cell string, which is furthest from the terminal box 1f, is 4.0%.

[0046] If the total voltage drop using the second to 20th solar cell string is to be reduced to below 2.0%, expression (13) can be replaced by expression (15) when n=20 is substituted into expression (13). If the length and conductor diameter of the line resistance in expression (15) are determined, the loss of the line resistance R1_1 of the first solar cell string can be compensated. (LR1_2SR1_2+LR1_3SR1_3+⋯+LR1_20SR1_20)<19⋅1.04⋅LS−20⋅(1−0.96)⋅LS=18.96⋅LS

[0047] Expression (15) shows that the sum of the conduction resistance values ​​of the second to 20th solar cell strings is less than px(18.96L / S), and if the sum is divided into equal parts which are in turn assigned to other solar cell strings, it is only required that the conduction resistance value of each of the solar cell strings is less than (0.997L / S).

[0048] As described above, in the second embodiment, the appropriate thickness of the conductors between the solar cell string 11a and the junction box 1f in the photovoltaic power generation system can be calculated. Furthermore, the conductors can have a suitable thickness even if the distance between the solar cell string 11a and the junction box 1f is large. In addition, as described for the second embodiment, the conductor resistances are balanced by all other solar cell strings. This allows for the development of a suitable design even when a solar cell string is located far away. Third embodiment

[0049] Next, a photovoltaic power generation plant according to a third embodiment of the invention will be illustrated.

[0050] In the photovoltaic power generation system according to the third embodiment, a specific example is described in which, in order to compensate for the loss of the lines between the connection box 1f and the power collector rack 1g, the lines of the connection box 1f, wherein the lines of the connection box 1f have a large distance to the power collector rack 1g, are adjusted to the appropriate thickness.

[0051] It should be noted that in the third embodiment, expression (13) from the first embodiment is used as the expression with which the specific resistance value of the lines is calculated.

[0052] Fig. Figure 9 is a diagram illustrating the configuration of the photovoltaic power generation system according to the third embodiment and showing the relationship between the lengths and conductor diameters of the lines extending from the power generation units 1a, 1b, 1c, 1d, and 1e, which are connected to the power collector rack 1g. The example of the photovoltaic power generation system configuration from Fig. 9 The resistance value of the lines is calculated using the same expression as expression (13) in the first embodiment described above.

[0053] The resistance loss R1 of the first power generation unit, which is furthest from the power collector rack 1g, is 4.0%. If the total voltage drop is to be reduced to less than 2.0%, expression (13) can be replaced by expression (16) when n=5 is substituted into expression (13). By adjusting the length and diameter of the resistance line in expression (16), the resistance loss R1 of the first power generation unit can be compensated. (LR2SR2)<4⋅1.04⋅L10⋅S−5⋅(1−0.96)⋅L10⋅S=3.96⋅L10⋅S

[0054] Expression (16) shows that the sum of the line resistance values ​​of the second to fifth power generation units is less than px(3.96L / 10S), and if the sum is divided into equal parts which in turn are allocated to other power generation units, it is only required that the line resistance value of each of the power generation units is less than (0.99L / S).

[0055] As described above, in the third embodiment, the appropriate thickness of the cables between the junction box 1f and the power collector rack 1g in the photovoltaic power generation plant can be calculated. Furthermore, the long cables between the junction box 1f and the power collector rack 1g can be adjusted to have the appropriate thickness. Fourth embodiment

[0056] Next, a calculation method (planning method) is described which uses a computer (planning system) to calculate the thickness of the conductors of the photovoltaic power generation system using the method described so far according to a fourth embodiment of the invention.

[0057] Fig. Figure 10 is a block diagram showing a hardware configuration of the computer for calculating the thickness of the conductors of the photovoltaic power generation plant according to the fourth embodiment of the invention.

[0058] The computer according to the fourth embodiment is a computer with a processor 101, an input device 102, an output device 103, a storage device 104 and a communication interface 105.

[0059] The processor 101 comprises a CPU (Central Processing Unit) for executing a program, a ROM as a non-volatile memory element, and a RAM as a volatile memory element. The ROM stores an immutable program (for example, a BIOS) or the like. The RAM is a fast, volatile memory element, such as Dynamic Random Access Memory (DRAM). Furthermore, the RAM temporarily stores the program stored in the memory device 104 and the data used during the execution of the program.

[0060] The input device 102 is a keyboard, a mouse, or the like, and an interface that receives input from a user. The output device 103 is a display device, a printer, or the like, and outputs a calculation result in a form that can be visually recognized by the user.

[0061] Memory device 104, for example, is a large, non-volatile storage device, such as a magnetic storage device or flash memory. Furthermore, memory device 104 stores a program that is executed by the CPU of processor 101 and data used during the execution of the program. In other words, the program is read from memory device 104 to be loaded into RAM and executed by the processor's CPU.

[0062] The communication interface 105 is a network interface device for controlling communication with another device according to a predefined protocol.

[0063] A program to be executed by the CPU of processor 101 is provided to each server via a removable medium (for example, a CD-ROM or flash memory) or a network and subsequently stored in a non-volatile storage device as a non-temporary storage medium. For this reason, it is preferred that the computer system have an interface through which data can be read from a removable medium.

[0064] The system according to the fourth embodiment is a computer system that is physically configured on a computer or on a plurality of logical or physical computers. Furthermore, the system from the fourth embodiment can be operated on separate threads on the same computer or on a virtual computer created on a plurality of physical computer resources.

[0065] Fig.Figure 11 is a block diagram showing the method for calculating the thickness of the conductors of the photovoltaic power generation system according to the fourth embodiment of the invention.

[0066] First, the conductor diameter L1_1 / S1_1 of the lines connected to the first terminal box, which exhibit the greatest loss, and the loss x of these lines are set (step S1), and the number n of lines to compensate for the losses is set (step S2). If a line length required to achieve a current loss below the target value is Lt and the conductor diameter (in the cross-section of the conductor) of the cable is St, the calculation is performed using the value on the right-hand side of expression (13) as the threshold (step S3). Subsequently, the conductor diameters of the lines to compensate for the losses are determined such that the sum of the ratios of the conductor diameters to the line lengths does not exceed the threshold calculated in step S3 (step S4).By performing the processing from steps S1 to S4, the total loss through the lines connected to the first connection box can be reduced below the target value.

[0067] Processing steps S1 to S4 are performed for all connection boxes 1f. In parallel with the processing from steps S1 to S4, the conductor diameter Lal_1 / Sa 1_1 of the line that has the greatest loss among the lines between the connection boxes 1f and the current collector rack 1g is set (step S5) and the number na of lines to compensate for the losses is set (step S6).

[0068] After the calculation of the conductor diameters of the cables for all connection boxes 1f is completed, the cables between the connection boxes 1f and the power collector rack 1g are optimized.

[0069] First, the largest loss xa in the first to fifth terminal boxes is subtracted from the results of steps S1 to S4 (step S7), and the calculation is performed using the value of the right-hand side of expression (13) as the threshold (step S8). Then, the conductor diameters of the lines are determined to compensate for the losses such that the sum of the ratios of the conductor diameters to the line lengths does not exceed the threshold calculated in step S8 (step S9).

[0070] The present invention is not limited to the embodiments described above, but includes various modifications. The embodiments described above have been discussed for a better understanding of the invention and are not limited to them with all the configurations described above. A part of the configuration of one embodiment can be replaced by that of another embodiment; the configuration of one embodiment can be incorporated into the configuration of another embodiment. A part of the configuration of each embodiment can be added to, omitted from, or replaced by that of another configuration.

[0071] The configurations, functions, processing modules, and processing facilities described above can be implemented entirely or partially by hardware, for example, by an integrated circuit. The configurations and functions described above can also be implemented by software; that is, a processor interprets and executes programs that provide the functions.

[0072] The information from the programs, tables and files used to implement the functions can be stored in a storage device, such as memory, a hard disk or SSD (Solid State Drive), or a storage medium such as an IC card or an SD card.

[0073] The drawings depict control and information lines deemed necessary for explanation, but do not show all control or information lines in the products. It can be assumed that almost all components are interconnected.

Claims

[1] Power generating plant, comprising: - a large number of parallel-connected power generation units; - a power collector device for collecting electrical power from a multitude of power generating units; and - Lines for connecting the multiple power generating units and the power collector device, where a ratio of a conductor diameter to a predetermined length of each of the conductors is defined as a reference ratio, wherein a value obtained by multiplying the reference ratio, a number of conductors and a loss resulting from a specific conductor connection is subtracted from a value obtained by multiplying a predetermined number of tuning conductors by a ratio of a conductor diameter to a length of the specific conductor, and where the sum of the ratios of the conductor diameters to the lengths of the predetermined number of conductors for adjustment is determined as a value that is smaller than the subtracted value. [2] Power generation plant according to claim 1, further comprising a connection device between at least one of the plurality of power generation units and the power collector device, wherein the at least one of the plurality of power generation units is connected to the connection device, wherein each of the lines is contained in either a first line group between the power collector device and the connection device or a second line group between the connection device and the plurality of power generating units, and the specific line and the lines for adjustment are included in the first line group. [3] Power generation plant according to claim 1, further comprising a connection device which is provided between at least one of the plurality of power generation units and the power collector device, wherein at least one of the multiple power generation units is connected to the connection device, wherein each of the lines is contained in either a first line group between the power collector device and the connection device or a second line group between the connection device and the plurality of power generating units, and the specific line and the lines for adjustment are included in the second line group. [4] Method for planning a power generation plant with a plurality of parallel connected power generation units, a power collector device for collecting electrical power from the plurality of power generation units and lines for connecting the plurality of power generation units and the power collector device, the procedure includes the following steps: - Determining a reference ratio as a ratio of a conductor diameter to a predetermined length of each of the conductors; - Subtracting a value obtained by multiplying the reference ratio, a number of conductors, and a loss resulting from a specific conductor connection from a value obtained by multiplying a predetermined number of adjustment conductors by a ratio of a conductor diameter to a length of the specific conductor; and - Determining a sum of the ratios of the conductor diameters to the lengths of the predetermined number of conductors for adjustment such that it is smaller than the subtracted value. [5] Method for planning a power generation plant according to claim 4, wherein the power generation plant further comprises a connection device which is provided between at least one of the plurality of power generation units and the power collector device, wherein the at least one of the plurality of power generation units is connected to the connection device, wherein each of the lines is contained in either a first line group between the power collector device and the connection device or a second line group between the connection device and the plurality of power generating units, and the procedure further includes the step of determining the specific line and lines to be set up, which are contained in the first line group. [6] Method for planning a power generation plant according to claim 4, wherein the power generation plant further comprises a connection device which is provided between at least one of the plurality of power generation units and the power collector device, wherein the at least one of the plurality of power generation units is connected to the connection device, wherein the conductors are contained in either a first conductor group between the power collector device and the connection device or a second conductor group between the connection device and the plurality of power generating units, and the procedure further includes the step of determining the specific management and the managers to be appointed in the second management group.

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