JP2012143102A - Photovoltaic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic power generation system capable of reducing a power loss in a connection cable for an AC output of photovoltaic power generation units, even when solar cell units are successively installed in longitudinal direction for a long distance.SOLUTION: A photovoltaic power generation system 10 includes a plurality of photovoltaic power generation units 11, each unit comprises: a solar cell unit 15 configured by high voltage output solar cell modules connected in parallel, or parallelly connected strings of high voltage output solar cell modules connected in series; a conversion part 16 for converting a DC current being output from the solar cell unit 15 to an AC current; and a primary power transformer 17 for pressure rising an AC current being output from the conversion part 16 to an AC current at a suitable voltage. The photovoltaic power generation system 10 includes a high voltage cable 12, which is juxtaposed in a plurality of photovoltaic power generation units 11, and to which each of the plurality of photovoltaic power generation units 11 is connected.

Description

  The present invention relates to a photovoltaic power generation system, and more particularly to a type of photovoltaic power generation system that is configured by a plurality of solar cell modules and that generates power by being installed along a transmission line, and a configuration of substation equipment in the transmission system.

  The solar power generation system is generally of a type that generates power by installing a plurality of solar cell modules in an array on one land. In recent years, a large-scale power generation system in which a large amount of this solar cell array is spread over a vast land has been attracting attention, and MW (megawatt) class power generation systems have been installed in various parts of the world.

  As described above, when a plurality of solar cell modules are installed in an array on a single land to generate power, the larger the power generation, the larger the land required, making it difficult to secure the land. For example, in the case of a system of about 10 MW, a vast land of approximately 400 m × 700 m is required.

  On the other hand, a solar power generation system of a type that generates power by installing a solar cell unit constituted by a plurality of solar cell modules along an expressway or the like has been proposed. For example, Patent Document 1 discloses a configuration in which an output of a PCS (power conditioner system) is connected to a distribution line for an existing road illumination lamp.

  Patent Document 2 discloses a photovoltaic power generation system capable of reducing power loss due to an increase in the length of a cable connecting a solar cell unit and a PCS in an array structure that is elongated in the horizontal direction. According to this system configuration, by using a solar cell unit in which high-voltage output solar cell modules are connected in parallel, the connection cable can be reduced and the power loss of the cable can be reduced.

JP-A-8-326019 JP 2010-98797 A

  The photovoltaic power generation system of Patent Document 2 includes a plurality of photovoltaic power generation units each having a solar cell unit, a PCS that converts a direct current output from the solar cell unit into an alternating current, and a load such as an indicator lamp. . In the plurality of photovoltaic power generation units, the longitudinal direction of the solar cell unit is arranged along a sound insulation wall of an expressway, for example.

  In this photovoltaic power generation system, AC400V outputs from PCS arranged one by one for a plurality of solar cell units are connected in parallel using a PCS output cable. Moreover, the rated capacity of 150 kVA is obtained by transforming the voltage from the PCS output cable side to a high voltage and supplying it to the high voltage transmission line, and conversely transforming the voltage from the high voltage transmission line to 400 V AC and supplying it to the PCS output cable. Equipped with a transformer. The high voltage transmission line here is intended for power transmission to a remote place such as AC6600V or AC22kV.

  Moreover, each solar cell unit in the photovoltaic power generation system of Patent Document 2 includes 75 high-voltage output thin-film solar cell modules having an open circuit voltage of 240 V or more, and 75 of these are connected in parallel. The parallel direction is the longitudinal direction of the solar cell unit. And the solar cell unit and PCS are connected by the PCS input cable.

  In the case of such a configuration, the power generation capacity of each photovoltaic power generation unit is about 10 kW because 75 pieces of 140 W are used. The rated capacity of each PCS is also 10 kW. Furthermore, since each photovoltaic power generation unit is connected in parallel and then input to a 150 kVA transformer, a total of 15 photovoltaic power generation units are connected in parallel. In this case, the total length of the solar cell unit is 75 m, and the installation interval of each PCS is also 75 m. If a transformer is installed in the center of these 15 photovoltaic power generation units, the distance from the outermost PCS to the transformer is about 350 m. In the case of AC400V, the power transmission loss for such a distance is not particularly problematic.

  By the way, as described above, there is an installation example of a MW class power generation system, and a solar power generation system installed on a highway is also in the direction of considering a large capacity. If, for example, an attempt is made to construct a 10 MW power generation system with the configuration as in Patent Document 2, it will lead to cost increase if 10 kW PCSs are arranged one by one for every 10 kW. It is reasonable to use PCS. Therefore, the solar cell unit is similarly arranged to be 250 kW.

  Here, when a system is constructed by selecting a specification that inputs a string in which two 140 W thin-film solar cell modules are connected in series as a specification of 250 kW PCS, a solar cell unit of 2 series × 1000 parallels is obtained. Since 1000 modules are installed in a horizontal row, the total length of the solar cell unit is 1000 m. Therefore, the PCS installation interval is similarly 1000 m.

  Next, when a plurality of these PCSs are connected in parallel as in Patent Document 2, the number of PCSs × 1000 m is connected in parallel. Therefore, the total length of the PCS output cable becomes a considerably long distance, causing a problem that power loss increases. When a 10 MW power generation system is grid-connected, it is necessary to link to an extra high voltage such as 66 kV because it is necessary to link to a special high voltage instead of 6600 V as in Patent Document 2. For example, when considering a configuration in which the number of parallel PCSs is increased to 6600V with the primary transformer and further boosted to 66kV with the transformer after 10 parallels, the power generation system for 1 MW Assuming that the primary transformer is installed in the center, the distance from the outermost PCS to the primary transformer is 2000 m. If AC 400 V is supplied to this, power loss cannot be ignored. In addition, it is thought that the distance which can be transmitted with AC400V is at most 500m.

  An object of the present invention is to provide a solar power generation system that can reduce power loss in a connection cable for AC output of a solar power generation unit even when solar cell units are continuously installed in a lateral direction for a long distance. To do.

  In order to achieve the above object, the present invention provides a solar cell unit in which high-voltage output solar cell modules are connected in parallel, or strings in which the high-voltage output solar cell modules are connected in series are connected in parallel, and output from the solar cell unit. A plurality of photovoltaic power generation units each having a conversion unit that converts a direct current to be converted into an alternating current and a primary transformer that boosts the alternating current output from the conversion unit to an alternating current of an appropriate voltage. The solar power generation system includes a high voltage cable that is provided in the solar power generation unit and connected to each of the plurality of solar power generation units.

  According to this structure, the installation distance of a conversion part and a primary transformer can be shortened.

  When the solar power generation system is installed on an expressway or the like, it is preferable that the high voltage output solar cell module is arranged in parallel with the high voltage cable.

  In the above solar power generation system, it is preferable that the high voltage output solar cell modules are arranged in parallel and connected in parallel. By arranging in this way, parallel connection of solar cell units is completed with only the connector for parallel connection, and it is only necessary to connect the cable at one end of the solar cell unit to the conversion unit. The connection box and the DC current collection box that are necessary in the above can be omitted.

  Moreover, in said solar power generation system, it is preferable to install the said conversion part and the said primary transformer adjacently.

  In the solar power generation system described above, it is preferable that the converter and the primary transformer are provided in a metal box.

  The solar power generation system preferably includes a secondary transformer that boosts an alternating current output from the high voltage cable to an alternating current having an appropriate voltage.

  In the above solar power generation system, it is preferable to include a transmission line for transmitting an alternating current output from the secondary transformer.

  In the above solar power generation system, it is preferable that the high voltage output solar cell module is arranged in parallel with the power transmission line. Thereby, the length of a power transmission line becomes the minimum necessary, and the cost increase can be suppressed.

  The solar power generation system may further include a mount for installing the solar cell unit. The mount may have an attachment portion, and the high voltage cable and / or the power transmission line may be supported by the attachment portion. Further, the high voltage cable and / or the power transmission line may be supported by the attachment portion in a state of being accommodated in a pipeline. Thereby, the installation method of the high voltage cable and / or the transmission line is the same regardless of whether the road to be installed is elevated or on land, and the length can be further suppressed.

  According to the present invention, since the installation distance between the conversion unit and the primary transformer can be shortened, even when the solar cell unit is continuously installed in a long distance as a MW class ultra-large-scale photovoltaic power generation system, The power loss in the cable connecting the primary transformer can be reduced. Therefore, an efficient power generation facility can be provided.

  In addition, according to the present invention, it is possible to supply power to a non-electrified village where infrastructure is not established. Furthermore, by installing the photovoltaic power generation system of the present invention on an expressway, it is not necessary to use a vast and cohesive land, and it is easy to install on an existing expressway. do not do.

It is a figure which shows schematic structure of the solar energy power generation system which concerns on 1st Embodiment. It is a single wire connection diagram of the alternating current circuit part in FIG. 1A. It is a figure which shows the connection relation of the photovoltaic power generation unit of 1st Embodiment. It is a figure which shows the structure connected in series and parallel in FIG. 2A. It is a perspective view which shows the example of installation of the solar energy power generation system which concerns on 1st Embodiment. It is sectional drawing of FIG. 3A. It is a figure which shows schematic structure of the solar energy power generation system which concerns on 2nd Embodiment. It is a perspective view which shows the example of installation of the solar energy power generation system which concerns on 3rd Embodiment. It is a perspective view which shows the example of installation of the solar energy power generation system which concerns on 3rd Embodiment.

  FIG. 1A shows a schematic configuration of the photovoltaic power generation system according to the first embodiment of the present invention. Here, the case where the power generation capacity of the solar power generation system is 10 MW will be described. The photovoltaic power generation system 10 includes a plurality of photovoltaic power generation units 11, a high voltage cable 12 that is attached to the plurality of photovoltaic power generation units 11, and is connected to each of the plurality of photovoltaic power generation units 11. A secondary transformer 13 that boosts the output AC current to an AC current of an appropriate voltage, and a special high-voltage transmission line 14 that transmits the AC current output from the secondary transformer 13 are provided. Actually, a plurality of units including a plurality of photovoltaic power generation units 11, high voltage cables 12, and secondary transformers 13 are connected to the special high voltage transmission line 14.

  The solar power generation unit 11 includes a solar cell unit 15, a conversion unit 16 that converts a direct current output from the solar cell unit 15 into an alternating current, and an alternating current output from the conversion unit into an alternating current of an appropriate voltage. And a primary transformer 17 for boosting the voltage. Here, 40 photovoltaic power generation units 11 are provided. The solar power generation unit 11 is installed, for example, so that the longitudinal direction of the solar cell unit 15 is along the sound insulation wall of the highway.

  The solar cell unit 15 is an array unit in which high voltage output solar cell modules are connected in parallel, or strings in which high voltage output solar cell modules are connected in series are connected in parallel. The solar cell unit 15 will be described in detail separately.

  The conversion unit 16 is a PCS (power conditioner system) such as an inverter device, and converts a direct current output from the solar cell unit 15 into an alternating current. Here, the rated capacity of the PCS is assumed to be 250 kW and converted to AC400V.

  Here, the primary transformer 17 has a rated capacity of 250 kVA, and boosts AC400V output from the converter 16 to AC6600V. And it is preferable to install the conversion part 16 and the primary transformer 17 adjacent in the same solar power generation unit 11. FIG. For example, if the conversion unit 16 and the primary transformer 17 are installed in one metal box, a cable of several tens of centimeters can be used, or can be provided without using a cable. As a material of the metal box, iron, aluminum, stainless steel or the like can be used. By shortening the installation distance between the converter 16 and the primary transformer 17, it is possible to reduce power loss in the cable connecting the converter 16 and the primary transformer 17.

  The high voltage cable 12 is a cable for connecting output power from the primary transformer 17 of each photovoltaic power generation unit 11 in parallel, and is arranged in parallel with the photovoltaic power generation unit 11 along the longitudinal direction of the solar cell unit 15.

The secondary transformer 13 is installed at an intermediate point (intermediate point of the high voltage cable 12) of the 40 photovoltaic power generation units 11 provided side by side, and the high voltage (AC6600V in this case) output from the high voltage cable 12 is extra high. The voltage is boosted to 66 kV here.
The

  The special high voltage transmission line 14 is installed along a highway, for example, and transmits the special high voltage output from each secondary transformer 13. Here, a plurality of units including 40 photovoltaic power generation units 11, high voltage cables 12, and secondary transformers 13 are continuously installed, so that each secondary transformer 13 is continuously connected to a special height. It is connected to the voltage transmission line 14.

  FIG. 1B shows a single-line connection diagram of an AC circuit portion in the photovoltaic power generation system 10 having such a configuration. One feature is that one primary transformer 17 is installed for each converter 16.

  In the above embodiment, when a load such as an illuminating lamp is installed along the highway, the special high voltage transmission line 14 is connected to the power company system, and the solar power generation system 10 generates power, the solar power generation When power is supplied from the system to the load and there is no power generation by the solar power generation system 10 (nighttime or the like), power may be supplied from the power company to supply power to the load.

  Next, the configuration of the solar cell unit 15 will be described with reference to FIGS. 2A and 2B. As shown in FIG. 2A, the solar cell unit 15 includes, for example, two strings of high voltage output solar cell modules (for example, thin film type solar cell modules) 20 having an output of 140 W connected in series, and 1000 strings are connected in parallel. It is a thing.

  Further, as shown in FIG. 2B, in order to connect two high voltage output solar cell modules 20 in series, the plus terminal of the terminal box 24 of one high voltage output solar cell module 20 and the other high voltage output solar cell module 20 The negative terminal of the 20 terminal box 24 is connected by a cable 22 to form a string. In order to sequentially connect the strings in parallel, the pluses and minuses of the remaining two cables 21 and 25 are repeatedly connected via the connector 23 for parallel connection. A backflow prevention diode 26 is installed between the parallel connection connectors 23 that connect the pluses in parallel. The backflow prevention diode 26 has a role of preventing a current from flowing back when a part of the solar cell module 20 is shaded or the power generation amount of the module is insufficient due to some trouble.

  Then, two sets of two series strings as shown in FIG. 2A arranged in parallel in the horizontal direction and arranged in parallel are installed, and a DC current is connected from each to the input terminal of the converter 16 by the cable 27. Enter. In this way, the solar power generation unit 11 including the solar cell unit 15 in which 2000 high-voltage output solar cell modules are connected in 2 series × 1000 parallel, the conversion unit 16, and the primary transformer 17 is formed. .

  By adopting such a connection structure, parallel connection can be made only by the parallel connection connector 23, and a generally used connection box or DC current collection box is not necessary.

  The solar power generation unit 11 as described above has a length of about 2.8 m × width of about 1000 m when a general module of 1.4 m × 1 m is used as the high voltage output solar cell module 20. The photovoltaic power generation system 10 in which 40 photovoltaic power generation units 11 are continuously installed in the lateral direction has a total length of 40 km and is arranged in parallel with the photovoltaic power generation system 10 (in other words, in the high voltage output solar cell module 20). The length of the high voltage cable 12 (which is arranged in parallel) is also 40 km. If the alternating current is 6600 V, the power loss is not a problem in practice even if it is passed through a 40 km cable.

  In the present embodiment, the power generation capacity of 10 MW is set, but the power generation capacity, that is, the number of parallel solar power generation units 11 may be increased up to the upper limit of the length of the high voltage cable 12. The upper limit value can be determined in accordance with the technical standards of electric facilities in consideration of power loss and the like, and there is no problem as long as it is normally up to 50 km.

  When the high-voltage cable 12 and the special high-voltage transmission line 14 are installed on the expressway, as shown in FIGS. 3A and 3B, each is housed in a dedicated conduit 30 (see FIGS. 3A and 3B). If the road is overlaid, install it under the road, and if the road is overland, install it under the side. That is, the high voltage output solar cell module 20 is arranged in parallel with the high voltage cable 12 and the special high voltage transmission line 14.

  The special high-voltage transmission line 14 is arranged along the road. For example, when three 40-km solar power generation systems 10 are continuously installed, the total high-voltage transmission line 14 has a total length of 120 km, and the generated power 30 MW flows here. The photovoltaic power generation system 10 does not need to be installed continuously. If the length of the 66 kV extra high-voltage transmission line 14 is within a practical distance range, the photovoltaic power generation system 10 is installed separately. It doesn't matter. Moreover, the upper limit in each of the length of the special high voltage power transmission line 14 and the number of installed photovoltaic power generation systems 10 (power generation capacity) is determined in accordance with the technical standards of the power equipment and the laws and regulations at the installation location.

  Moreover, in FIG. 3, the solar cell unit 15 is installed in the mount frame 31 provided along the road. One pedestal 31 is provided with one array in which three strings are connected in parallel.

  Next, a solar power generation system according to the second embodiment will be described. In the solar power generation system 10 of the first embodiment, the case where the extra high voltage transmission line 14 is installed along the expressway to collect the generated power has been described, but in the second embodiment, the extra high voltage transmission line 14 is installed. It is assumed that the output power from the secondary transformer 13 is directly connected to an electric power system such as an electric power company.

  As shown in FIG. 4, the photovoltaic power generation system 40 according to the second embodiment is connected to a 66 kV power system 42 using a connection cable 41. Since the configuration of the solar power generation system 40 is the same as that of the solar power generation system 10 of the first embodiment except that the extra high voltage transmission line 14 is omitted, detailed description thereof is omitted.

  The second embodiment can be implemented in the case where an electric power system exists near the expressway, and the case where power is supplied to a non-electrified village where infrastructure is not established is described in the first embodiment. The distribution line is connected to the special high-voltage transmission line 14, and it is installed and supplied to the demand area.

  In the case of the second embodiment, since it is preferable to install the secondary transformer 13 in a place connectable to the power system, the installation location of the secondary transformer 13 does not have to be an intermediate point of the photovoltaic power generation system 40. .

  Next, a solar power generation system according to the third embodiment will be described. In the first embodiment, the case where the high-voltage cable 12 and the special high-voltage transmission line 14 are embedded under the highway or underground is described. However, if the high-voltage cable 12 and the special high-voltage transmission line 14 are installed on the mount 31, the highway is elevated. Regardless of whether it is on land or not, it is possible to continuously install the gantry 31 having the same specification, and to continuously install the pipeline 30 and the like. Therefore, even if it is a land laying location, the construction for burying the pipe line 30 is not necessary, and the installation cost can be reduced.

  As shown in FIG. 5A and FIG. 5B, a mounting portion (not shown) is provided on the gantry 31 of the solar power generation system 50, and the pipe line 30 is supported by the mounting portion. In addition, the pipe line 30 is not necessarily required, and the high voltage cable 12 and / or the special high voltage transmission line 14 may be directly supported by the attachment portion.

  In the third embodiment, it is assumed that the mount 31 for installing the solar cell unit 15 is laid on the highway. In many cases, there are no side walls on highways around the world, and it is often necessary to install the gantry 31. Therefore, the configuration in which the pipe line 30 and the like are installed on the gantry 31 as in the third embodiment is effective. It is.

  The present invention is not limited to the above description, and various modifications can be made without departing from the spirit of the invention. For example, the technical scope of the present invention also includes a configuration in which a storage battery is installed in a solar power generation system and a part of the electric power generated during the daytime is stored and consumed at night or when the sun is insufficient.

10, 40, 50 Photovoltaic power generation system 11 Photovoltaic power generation unit 12 High voltage cable 13 Secondary transformer 14 Special high voltage transmission line (transmission line)
DESCRIPTION OF SYMBOLS 15 Solar cell unit 16 Conversion part 17 Primary transformer 20 High voltage output solar cell module 31 Mounting frame

Claims (11)

A solar cell unit in which high voltage output solar cell modules are connected in parallel, or a string in which the high voltage output solar cell modules are connected in series, and a DC current output from the solar cell unit is converted into an AC current. A plurality of photovoltaic power generation units, and a primary transformer that boosts the alternating current output from the converter to an alternating current of an appropriate voltage,
A solar power generation system comprising a high voltage cable that is attached to a plurality of the solar power generation units and connected to each of the plurality of solar power generation units.   The solar power generation system according to claim 1, wherein the high-voltage output solar cell module is juxtaposed with the high-voltage cable.   The solar power generation system according to claim 1 or 2, wherein the high voltage output solar cell modules are arranged in parallel and connected in parallel.   The photovoltaic power generation system according to any one of claims 1 to 3, wherein the converter and the primary transformer are installed adjacent to each other.   The photovoltaic power generation system according to any one of claims 1 to 4, wherein the converter and the primary transformer are provided in a metal box.   The solar power generation system according to claim 1, further comprising a secondary transformer that boosts an alternating current output from the high-voltage cable to an alternating current having an appropriate voltage.   The photovoltaic power generation system according to claim 6, further comprising a power transmission line that transmits an alternating current output from the secondary transformer.   The solar power generation system according to claim 7, wherein the high voltage output solar cell module is juxtaposed with the power transmission line.   The solar power generation system according to claim 1, further comprising a mount on which the solar cell unit is installed.   The solar power generation system according to claim 9, wherein the mount has an attachment portion, and the high-voltage cable and / or the power transmission line is supported by the attachment portion.   The solar power generation system according to claim 10, wherein the high voltage cable and / or the power transmission line is supported by the attachment portion in a state of being accommodated in a pipeline.

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