JP2019022370A - Power generator - Google Patents

Abstract

To provide a power generator using renewable energy, capable of achieving highly efficient power generation.SOLUTION: A power generator 10 includes: a power generation part 12 for generating electric power using renewable energy; an inverter 14 for inverting a first voltage output from the power generation part 12 into a second voltage; and an auxiliary power supply part 16 for outputting an auxiliary voltage for assisting a first voltage so that an input voltage input into the inverter 14 is not less than a threshold voltage value which makes a conversion efficiency of the inverter 14 become a desired conversion efficiency.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power generator.

  In Patent Document 1, by connecting a plurality of solar panels in parallel, when the voltage of sunlight on one side decreases, the voltage on the other side is compensated to make it more than the optimum starting voltage of the inverter. A solar power generation system that achieves high efficiency of the entire system by performing is disclosed.

  Patent Document 2 discloses a wind power generation system that restricts the output to a certain level or less with an impedance load or the like in order to suppress the influence on the power system to which the power of the wind power generation is supplied when the output of the wind power generation becomes unstable. Is disclosed.

  It is known that conversion efficiency of inverters mounted on solar power generation systems and wind power generation systems using renewable energy is generally greatly reduced at low output (low voltage). Further, when the voltage of the solar power generation system or the wind power generation system is equal to or lower than the minimum starting voltage of the inverter, it is not converted into AC power, so that the power at the corner is wasted.

  Thus, for example, a method of boosting the inverter efficiency by using the system power at the time of low output (low voltage) of the photovoltaic power generation system can be considered, but it is not appropriate because it leads to instability of the system power.

JP 2013-137752 A JP 2004-15905 A

  An object of the present invention is to provide a power generation device capable of generating power with high efficiency in a power generation device using renewable energy.

  To achieve the above object, a power generation device of the present invention includes a power generation unit that generates power using renewable energy, an inverter that converts a first voltage output from the power generation unit into a second voltage, An auxiliary power supply unit that outputs an auxiliary voltage for assisting the first voltage so that an input voltage input to the inverter is equal to or higher than a predetermined threshold voltage at which the conversion efficiency of the inverter becomes a desired conversion efficiency; .

  According to the present invention, it is possible to generate power with high efficiency in a power generation device using renewable energy.

It is a block diagram of a power generator. It is a diagram showing the characteristic of the conversion efficiency of an inverter. It is a flowchart which shows the process routine of an electric power generation process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As illustrated in FIG. 1, the power generation apparatus 10 according to the present embodiment includes a power generation unit 12, an inverter 14, an auxiliary power supply unit 16, a detection unit 18, and a control unit 20.

The power generation unit 12 is a power generation device that generates power using renewable energy. Examples of the renewable energy include sunlight, solar heat, wind power, hydropower, geothermal, biomass, heat using water as a heat source, snow / ice heat, ocean temperature difference, wave power, tidal current (sea current), tide, and the like. That is, the renewable energy in the present embodiment includes power generation by so-called energy harvesting technology, and includes, for example, the renewable energy described in the following references.
(References)
"NEDO Renewable Energy Technology White Paper 2nd Edition", New Energy and Industrial Technology Development Organization

  The inverter 14 converts the first voltage output from the power generation unit 12 into a second voltage. Here, the first voltage is, for example, a DC voltage. The second voltage is, for example, an alternating voltage.

  The auxiliary power supply unit 16 outputs an auxiliary voltage that assists the first voltage so that the first voltage is equal to or higher than a predetermined threshold voltage.

  In the present embodiment, the auxiliary power supply unit 16 includes a fuel cell 22 and a fuel supply unit 24 as an example.

  In the present embodiment, a pure hydrogen fuel cell is used as the fuel cell 22 as an example. This is because the pure hydrogen fuel cell has high efficiency, high load followability, and short startup time compared to other fuel cells.

  The fuel supply unit 24 supplies hydrogen as fuel to the fuel cell 22.

  Note that the auxiliary power supply unit 16 is not limited to a fuel cell, and may be a power generation device used with, for example, a gas engine or a gas turbine, or a storage battery.

  The detection unit 18 detects the first voltage (voltage value) output from the power generation unit 12.

  When the first voltage detected by the detection unit 18 is less than the threshold voltage, the control unit 20 determines that the input voltage input to the inverter 14 is a predetermined threshold at which the conversion efficiency of the inverter 14 becomes a desired conversion efficiency. The auxiliary power supply unit 16 is controlled so as to output the auxiliary voltage from the auxiliary power supply unit 16 so as to be equal to or higher than the voltage.

  Here, the threshold voltage is set to a voltage at which the conversion efficiency of the inverter 14 becomes a desired conversion efficiency, for example, a voltage corresponding to a lower limit value of an allowable range permitted as the conversion efficiency of the inverter 14.

  For example, assume that the conversion efficiency characteristic of the inverter 14 is as shown in FIG. Here, the horizontal axis in FIG. 2 is the input voltage (V) input to the inverter 14, and the vertical axis is the conversion efficiency (%) of the inverter 14. In this case, as shown in FIG. 2, when the desired conversion efficiency of the inverter 14 is equal to or higher than L (%), the voltage TH corresponding to L (%) is set as the threshold voltage. Note that L is set to, for example, a value of 90% or more (for example, 95%), but is not limited thereto.

  In this way, by setting the voltage corresponding to the desired conversion efficiency of the inverter 14 to the threshold voltage TH, even if the first voltage output from the power generation unit 12 is a low voltage, the auxiliary power supply unit 16 The input voltage input to the inverter 14 is maintained at the threshold voltage TH or higher by the auxiliary voltage output from. That is, the conversion efficiency of the inverter 14 is maintained at or above the desired conversion efficiency.

  Specifically, when the first voltage detected by the detection unit 18 is less than the threshold voltage TH, the control unit 20 controls the fuel supply unit so that the voltage input to the inverter 14 is equal to or higher than the threshold voltage TH. The amount of hydrogen supplied from the fuel cell 22 to the fuel cell 22 is controlled by, for example, PLC (Programmable Logic Controller) control.

  Next, as an operation of the present embodiment, power generation processing executed by the control unit 20 will be described with reference to a flowchart shown in FIG.

  First, in step S100, the first voltage (voltage value) detected by the detection unit 18 is captured.

  In step S102, it is determined whether or not the first voltage acquired in step S100 is less than the threshold voltage TH. If the first voltage is less than the threshold voltage TH, the process proceeds to step S104. On the other hand, if the first voltage is equal to or higher than the threshold voltage TH, the process returns to step S100.

  In step S <b> 104, the fuel supply unit 24 is controlled so that an auxiliary voltage that causes the voltage input to the inverter 14 to be equal to or higher than the threshold voltage TH is output to the inverter 14. For example, a differential voltage between the first voltage captured in step S100 and the threshold voltage TH is calculated, and the amount of hydrogen corresponding to the calculated differential voltage is obtained using, for example, an arithmetic expression or table data. Then, the fuel supply unit 24 is controlled so that the determined amount of hydrogen is supplied to the fuel cell 22. Thereby, the voltage input to the inverter 14 is maintained at the threshold voltage TH or higher, and the conversion efficiency of the inverter is maintained at a desired conversion efficiency.

  Thus, in the present embodiment, when the first voltage output from the power generation unit 12 is less than the threshold voltage TH, the fuel cell 22 is configured so that the voltage input to the inverter 14 is equal to or higher than the threshold voltage TH. Control the amount of hydrogen supplied. Thereby, even if it is a case where the 1st voltage output from the electric power generation part 12 is less than threshold voltage TH in which the conversion efficiency of the inverter 14 falls, the inverter 14 can be operated with high efficiency.

  In the present embodiment, the case where the amount of hydrogen supplied to the fuel cell 22 is controlled according to whether or not the first voltage is less than the threshold voltage TH has been described. The auxiliary voltage set in advance may be output so that the input voltage input to the inverter 14 is equal to or higher than the threshold voltage TH even when the first voltage fluctuates.

  In this case, a fluctuation range of the first voltage is obtained in advance, and even if the first voltage fluctuates within the fluctuation range, an auxiliary voltage is provided so that the input voltage input to the inverter 14 is always equal to or higher than the threshold voltage TH. The amount of hydrogen supplied from the fuel supply unit 24 to the fuel cell 22 is set in advance so as to be output to the inverter 14. Thereby, it is not necessary to detect the first voltage and control the amount of hydrogen supplied to the fuel cell 22, and the detection unit 18 can be omitted.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. Nor.

DESCRIPTION OF SYMBOLS 10 Power generator 12 Power generation part 14 Inverter 16 Auxiliary power supply part 18 Detection part 20 Control part 22 Fuel cell 24 Fuel supply part

Claims (5)

A power generation unit that generates power using renewable energy;
An inverter that converts the first voltage output from the power generation unit into a second voltage;
An auxiliary power supply unit that outputs an auxiliary voltage for assisting the first voltage so that an input voltage input to the inverter is equal to or higher than a predetermined threshold voltage at which the conversion efficiency of the inverter becomes a desired conversion efficiency; ,
A power generator with A detection unit for detecting the first voltage;
A control unit that performs control to output the auxiliary voltage from the auxiliary power supply unit so that the input voltage is equal to or higher than the threshold voltage when the first voltage detected by the detection unit is less than the threshold voltage. When,
The power generation device according to claim 1, comprising: The power generator according to claim 1, wherein the auxiliary power supply unit outputs a preset auxiliary voltage so that an input voltage input to the inverter is equal to or higher than the threshold voltage even if the first voltage fluctuates. . The power generator according to claim 1, wherein the auxiliary power supply unit includes a pure hydrogen fuel cell. The renewable energy is any one of sunlight, solar heat, wind power, hydropower, geothermal, biomass, heat using water as a heat source, snow / ice heat, ocean temperature difference, wave power, tidal current, and tide. The power generation device according to any one of the above.