JP2012054180A - Photovoltaic power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an overvoltage applied to a power conditioner due to thunderbolt by a simple configuration at a low cost, and to prevent failure or malfunction of the power conditioner due to overvoltage.SOLUTION: Each side of a structure 100 on which a photovoltaic panel is installed is configured of a plurality of conductors. A power conditioner 41 which converts DC power generated by the photovoltaic panel into AC power is disposed in the internal space surrounded by these conductors, and conductors such as conductor meshes are arranged to cover the structure 100 partially or entirely.

Description

  The present invention relates to a solar power generation device applied to a mega solar power plant (large-scale solar power plant), and more particularly to a solar power generation device that protects a power conditioner from an overvoltage caused by a lightning strike. .

  The construction of a mega solar power plant requires a large amount of land, and there are often few high buildings around the power plant in order to obtain more solar energy. For this reason, even if the mega solar power plant itself is not a very high building, it is easy to become a lightning strike target, and lightning damage countermeasures using a lightning rod, a surge protection device (SPD), etc. are indispensable.

Here, for example, in Patent Document 1, it is detected that lightning has occurred in the vicinity of a solar power generation device linked to an electric power system, the solar power generation device is disconnected, and an internal electric circuit is connected from the lightning surge. A control device for a solar power generation device, a lightning surge protection system for the solar power generation device, and a lightning surge protection method are described.
In summary, this prior art obtains the generated power value of the photovoltaic power generation apparatus linked to the power system, and when the occurrence of lightning is detected, the generated power value is smaller than a preset value. In this case, an instruction for disconnecting the photovoltaic power generation apparatus is given.

JP 2007-116857 A (paragraphs [0070] to [0142], FIGS. 1 to 3, etc.)

According to the prior art related to Japanese Patent Application Laid-Open No. 2007-116857, it is possible to prevent a lightning surge from entering the photovoltaic power generation device from the power system during a lightning strike, and to convert the DC generated power by the solar panel into AC power. It is possible to protect an internal electric circuit such as a power conditioner that converts to lightning surge.
However, in the above-described conventional technology, there are problems such as a complicated circuit configuration such as a switch and a control device for disconnecting the photovoltaic power generation device, which leads to an increase in the size of the device and an increase in cost.

  Therefore, the problem to be solved by the present invention is to provide a photovoltaic power generation apparatus that can reduce overvoltage applied to the power conditioner at the time of a lightning strike with a simple configuration and low cost, and prevents failure and malfunction of the power conditioner due to overvoltage. It is to provide.

  In order to solve the above-mentioned problem, the invention according to claim 1 is configured such that each side of a structure for installing a solar panel is constituted by a plurality of conductors, and the sunlight is contained in an internal space surrounded by these conductors. A power conditioner for converting DC generated power generated by the panel into AC power is disposed, and a conductor such as a conductor mesh is disposed so as to cover a part or all of the structure.

According to the present invention, in a mega solar power plant or the like, a power conditioner is disposed in the internal space of the structure of the solar power generation device, and a conductor such as a conductor mesh is covered over part or all of the structure. By arranging, overvoltage applied to the power conditioner during a lightning stroke can be suppressed, and failure or malfunction of the power conditioner can be prevented.
In particular, since a disconnection switch and control device are not required as in the prior art, the circuit configuration can be simplified and the cost can be reduced.

It is a block diagram which shows the principal part of the overvoltage analysis model of the solar power generation device which concerns on embodiment of this invention. FIG. 2 is a waveform diagram of a pseudo lightning current injected into the overvoltage analysis model of FIG. 1. FIG. 3 is a waveform diagram of voltages V ₁ and V ₂ when the lightning current of FIG. 2 is injected into points A to F of FIG. 1. FIG. 3 is a waveform diagram of voltages V ₁ and V ₂ when a conductor mesh is arranged at a predetermined position and the lightning current of FIG. 2 is injected at point A in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, in the present invention, an overvoltage generated when a lightning strike occurs in a photovoltaic power generation apparatus is analyzed using a FDTD (Finite-Difference Time-Domain) method which is one of numerical electromagnetic field analysis methods. Note that the FDTD method (also called time domain difference method, finite difference time domain method, etc.) is an analysis method that calculates Maxwell's equations by discretely dividing space and time, and alternately calculating an electric field and a magnetic field. “Electromagnetic field and antenna analysis by FDTD method” (issued by Corona, 1998) and the like.

FIG. 1 is a configuration diagram showing a main part of an analysis model of a solar power generation device constructed based on an existing mega solar power plant.
In FIG. 1, 100 is a structure on which a solar panel is installed, 11, 12, and 15 are long and horizontal conductors parallel to each other, and 13 and 14 are horizontal conductors that connect the conductors 11 and 12 to each other. 16, 17 are vertical conductors connecting the conductors 12, 15 to each other, and 18, 19 are oblique conductors connecting the conductors 11, 15 to each other.
Here, the rectangular slope formed by the conductors 11, 15, 18, and 19 forms a light receiving surface on which a solar panel (not shown) is installed.

The conductors 11, 12, and 15 have a length of 130 [m], the conductors 13, 14, 16, and 17 have a length of 5 [m], and the conductors 11 to 14 have a height of 1 [m] from the ground surface. Is installed.
Furthermore, 21 is 28 conductive foundation piles embedded at a depth of 15 [m], and these foundation piles are fixed to the ground (resistivity: 100 [Ωm], relative dielectric constant: 10). Has been.

Reference numerals 31 to 33 are lightning rods installed behind the structure 100, and the ground height is 11 [m], and the distance from the structure 100 is 2 [m].
Reference numeral 41 denotes a power conditioner that converts direct-current power generated by the solar panel into alternating-current power. The power conditioner 41 is disposed in the inner space of the structure 100 at substantially the center in the longitudinal direction of the conductors 11, 12, and 15. Reference numerals 51 and 52 denote power lines (the length is 63 [m]) for connecting the power conditioner 41 and the solar panel.
Note that the shape and structure of the structure 100, the dimensions of each part, and the position of the power conditioner 41 in the structure 100 are not limited to the above example.

Next, FIG. 2 shows a pseudo lightning current waveform (crest value 1 [A], wavefront length about 1 [μs]) injected into the analysis model.
Although not shown, a power source in which a current source and a resistor (500 [Ω]) are connected in parallel is installed immediately above the points A to F in FIG. It was decided to inject the lightning current of FIG.
Here, points A to C are points on the conductor 15, and points D to F are tip portions of the lightning rods 31 to 33.

Usually, when a structure supporting a solar panel or a lightning rod in the vicinity thereof receives a lightning strike, an induced voltage is generated in the power line due to a current flowing through the lightning path or the structure. Due to this induced voltage, an overvoltage is applied to the power conditioner to which the power line is connected, and the power conditioner may break down or malfunction.
Since the main lightning accident at the mega solar power plant is expected to be a failure of the power conditioner, in this embodiment, the power lines 51 and 52 and the power conditioner 41 of FIG. The voltage between the casing (voltage generated on the DC side of the power conditioner 41) V ₁ and V ₂ was calculated by the FDTD method and examined.

3A to 3F show calculation results of the voltages V ₁ and V ₂ when the lightning current of FIG. 2 is injected at points A to F in FIG.
Table 1 summarizes the maximum overvoltage (absolute value) based on these analysis results. In Table 1, A ^* is data when a lightning current is injected at point A using a conductor mesh as will be described later.

For example, the overvoltage generated during a lightning strike due to a general lightning current (crest value 24 [kA]) may be obtained by multiplying the voltages V ₁ and V ₂ shown in Table 1 by 24 × 10 ³ . In addition, when it is desired to study at different wavefront lengths, it is necessary to perform the calculation using the FDTD method again.

As is clear from FIG. 3C, when there is a lightning strike in the vicinity of the power conditioner 41 (when a lightning current is injected from the point C), the maximum values of the voltages V ₁ and V ₂ are the largest. . When these maximum values are converted when a general lightning current (peak value 24 [kA]) flows, the maximum value reaches 460 [kV].

As shown in FIG. 1, when the power lines 51 and 52 are disposed inside the structure 100, the structure 100 is covered with a conductor such as a conductor mesh, and a Faraday gauge is configured by the structure 100 and the conductor. By doing so, it is considered that the voltages V ₁ and V ₂ can be suppressed from becoming excessive.

As an example, the back surface of the structure 100 (between the lightning rods 31 to 33 and the power lines 51 and 52) and the side surface of the structure 100 (conductors 13, 16, 18 and conductors 14, 17, 19, respectively) FIG. 4 shows a calculation result when a conductor mesh is inserted into the portion (ii) and a pseudo lightning current is injected from the point A. Further, the maximum values of V ₁ and V ₂ at this time are as shown in Table 1 as A ^* .
When the conductor mesh is arranged as described above, it is possible to suppress the overvoltage maximum value to about 25% compared to the case without the conductor mesh although the complete Faraday gauge is not configured. is there.

  As described above, according to this embodiment, the power conditioner 41 is disposed in the internal space of the structure 100 of the photovoltaic power generator, and a conductor such as a conductor mesh is covered over part or all of the structure. By disposing the power conditioner 41, an overvoltage applied between the casing of the power conditioner 41 and the power line can be suppressed, and a failure or malfunction of the power conditioner 41 can be prevented.

11-19: Conductor 21: Foundation pile 31-33: Lightning rod 41: Power conditioner 51, 52: Power line 100: Structure

Claims (1)

  A power conditioner for converting each side of a structure for installing a solar panel with a plurality of conductors, and converting the DC power generated by the solar panel into AC power in an internal space surrounded by the conductors. And a conductor such as a conductor mesh is disposed so as to cover part or all of the structure.

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