KR101079404B1 - Photovoltaic and fuel cell hybrid generation system using single converter and single inverter, and control method of the same - Google Patents

Abstract

The present invention relates to a photovoltaic-fuel cell combined cycle power generation system using a single converter and a single inverter, and a control method thereof. A DC / DC converter 200 for converting the FC output voltage VFC from 110 into a preset voltage; The output terminal of the solar cell 120 for converting sunlight into electrical energy and the output terminal of the DC / DC converter 200 are connected in common, and the PV output voltage (VPV) from the solar cell 120 and the DC A DC link unit 300 linking the converted FC output voltage VFC from the / DC converter unit 200 to generate a DC voltage VDC; And a DC / AC inverter unit 400 for converting the DC voltage VDC from the DC link unit 300 into a predetermined AC voltage Vac.

In addition, a method for controlling the photovoltaic-fuel cell combined cycle power generation system is proposed.

Solar cell, fuel cell, combined cycle, DC / DC conversion, DC / AC conversion

Description

Photovoltaic-fuel cell hybrid power generation system and control method using single converter and single inverter {PHOTOVOLTAIC AND FUEL CELL HYBRID GENERATION SYSTEM USING SINGLE CONVERTER AND SINGLE INVERTER, AND CONTROL METHOD OF THE SAME}

The present invention relates to a photovoltaic-fuel cell combined cycle power generation system and a control method thereof, and more particularly, to a photovoltaic-fuel cell combined cycle power generation system using a single converter and a single inverter that can reduce the number of expensive converters and inverters and control thereof. It is about a method.

Since the end of the 20th century, there has been an increase in the development and demand of renewable energy sources due to the depletion of fossil fuels, environmental pollution caused by carbon dioxide, NOx and SOx, and the seriousness of global warming. The demand and demand for technology development are increasing rapidly due to the full-scale burden and rising oil prices. As a result, the problem of modern energy resources is directly related to the national security problem, and the will and technology for reducing carbon dioxide emission are recognized as the national competitiveness.

In addition, despite the shortcomings of low efficiency in the recent domestic market of various renewable energy sources, solar cells (PV) with advantages that are consistent with domestic semiconductor technology continues to expand the market. Overseas, solar cell (PV) power generation system has been commercialized under the leadership of Japan and Germany based on long-term accumulated technology and funding.

By the way, solar cell (PV) can be generated only in the daytime with sunlight, intermittent power source dependent on environmental conditions such as cloud and rain, and has the disadvantage of very low efficiency of 10 to 15%. It is developed as a solar cell only during the day and is used as a way of receiving power from commercial systems in the case of night and environmental constraints.

To solve these shortcomings, hybrid power systems such as PV-batteries, PV-wind power, PV-diesel, or PV-fuel cells are being researched and developed around technology leaders. In Korea, such hybrid power systems are also being developed. Technology and market preoccupation for systems are recognized as important issues.

In the case of PV-batteries, batteries are secondary batteries, not generators, which have a short lifespan and eventually cause pollution during manufacturing and disposal. In the case of PV-wind, the wind power source is also an intermittent power source dependent on environmental conditions, and in the case of home use, there are many problems such as installation space and noise. In the case of PV-diesel, fossil fuels must be used, so there is a limit to developing the ultimate future power generation system.

In addition, PV-fuel cells use hydrogen and oxygen as fuels, which is an infinite clean energy source in line with the hydrogen economy that the government is aiming for, and has high generation efficiency (35% to 80%-cogeneration) In case of CHP: Combined Heat and Power), it is expected to be the most competitive source of combined power generation in the future as it uses fuel cells that can generate power at all times. Power generation of the fuel cell (FC) at all times is responsible for the basic load, and can be supplied to the system by utilizing the power of PV during the day, and in the future, by generating electricity hydrogen by electrolyzing water with the surplus power of PV, It has the advantage of being able to use the ultimate pollution-free infinite energy source used as fuel.

However, due to the different output characteristics of solar cells (PV) and fuel cells (FC), to date, converters and inverters for solar cells (PV), converters and inverters for fuel cells (FC) Inverter) and two converters and two inverters (2CON-2INV) structure, there is a problem that the manufacturing cost is increased and the size is large to implement a practical complex power generation system.

The present invention has been proposed to solve the above problems of the prior art, the object of which is to implement a complex power generation system using a solar cell and a fuel cell using a single converter and a single inverter, The present invention provides a photovoltaic-fuel cell combined cycle power generation system and a control method using a single converter and a single inverter, which can reduce the number of uses, thereby reducing the size and manufacturing cost, and enable an efficient system configuration.

The first technical aspect of the present invention for achieving the above object of the present invention, DC / DC converter unit for converting the FC output voltage from the fuel cell for converting chemical energy into electrical energy to a predetermined voltage; The output terminal of the solar cell converting sunlight into electrical energy and the output terminal of the DC / DC converter part are connected in common, thereby linking the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter part. A direct current link unit for generating a direct current voltage; And a DC / AC inverter unit for converting the DC voltage from the DC link unit into a predetermined AC voltage.

In addition, the second technical aspect of the present invention, the DC / DC converter unit for converting the FC output voltage from the fuel cell for converting chemical energy into electrical energy to a predetermined voltage; The output terminal of the solar cell converting sunlight into electrical energy and the output terminal of the DC / DC converter part are connected in common, thereby linking the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter part. A direct current link unit for generating a direct current voltage; A DC / AC inverter unit converting a DC voltage from the DC link unit into a predetermined AC voltage; A voltage / current detector for detecting a voltage and a current generated by each of the fuel cell, the solar cell, and the DC / AC inverter unit; And a combined power generation control unit controlling the operation of the DC / DC converter unit and the DC / AC inverter unit based on the plurality of voltages and currents detected by the voltage / current detection unit. Suggest.

In the first and second technical aspects of the present invention, the DC link unit includes a capacitor connected between a common connection node and a ground in which the output terminal of the solar cell and the output terminal of the DC / DC converter unit are connected to each other in common. It is done.

The DC / AC inverter unit may include: a DC / AC inverter for converting a DC voltage from the DC link unit into a pulse voltage; And a filter for converting the voltage of the pulse form of the DC / AC inverter into the AC voltage. And a system transfer unit configured to transfer the AC voltage from the filter to the system.

In the second technical aspect of the present invention, the voltage / current detection unit, FC output voltage and current of the fuel cell, PV output voltage and current of the solar cell, AC voltage and output current of the DC / AC inverter unit, and The grid voltage of the commercial power system is characterized in that each detection.

The combined power generation control unit may include a converter controller controlling the operation of the DC / DC converter unit using the grid voltage, the FC output voltage, and the current; And an inverter controller for controlling the operation of the DC / AC inverter unit based on the PV output voltage and current from the voltage / current detector.

Each of the converter controller and the inverter controller, in a grid-connected operation mode, determines the solar power generation state according to the PV power by the PV output voltage and the current of the solar cell, and the first preset power according to the determination result of the solar power generation. And a second grid linkage-control mode, wherein the first grid linkage-control mode is a control mode without solar power generation in the grid linkage operation mode, and the second grid linkage-control mode includes: The grid-connected operation mode is characterized in that the control mode with solar power.

The converter controller may include: a first calculator configured to calculate a first control error value for constant power control of the DC / DC converter in the first grid-control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And a first PWM controller configured to generate a PWM converter control signal using the converter control value compensated by the first control value compensator and to control an operation of the DC / DC converter unit using the PWM converter control signal. It is characterized by.

The inverter controller may include: a second calculator configured to calculate a second control error value for DC link, grid connection, and output current control with respect to the DC / AC inverter in the first grid connection-control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And a second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and control the operation of the DC / AC inverter using the PWM inverter control signal. It is characterized by.

In addition, a third technical aspect of the present invention, the DC / DC converter unit for converting the FC output voltage from the fuel cell to a predetermined voltage, the PV output voltage from the solar cell and the conversion from the DC / DC converter unit Method for controlling a photovoltaic-fuel cell combined cycle power generation system comprising a DC link unit for linking the FC output voltage to generate a DC voltage, and a DC / AC inverter unit for converting the DC voltage from the DC link unit to a predetermined AC voltage A system start step of detecting the voltage and current required for grid connection determination and solar power generation determination; When the grid voltage is normal, the grid-connected operation mode is performed by comparing the PV power calculated from the PV output voltage and the output current of the solar cell with a predetermined minimum PV power to determine the solar power generation status. step; In the grid-connected solar determination step, when there is no solar power generation in the grid-connected operation mode, a converter control step of controlling the electrostatic power for the DC / DC converter unit, DC link, grid-linked for the DC / AC inverter And a first grid linkage-control step of performing a first grid linkage-operation mode having an inverter control step of controlling the output current. And a converter control step of controlling electrostatic power for the DC / DC converter unit when there is solar power in the grid-connected operation mode, and tracking the maximum power point for the DC / AC inverter in the grid-connected solar determination step. Proposes a control method of a photovoltaic-fuel cell combined cycle power generation system comprising a second grid linkage-control step of performing a second grid linkage-operation mode having an inverter control step of controlling a direct current link, grid linkage, and output current. do.

In addition, the fourth technical aspect of the present invention, the DC / DC converter unit for converting the FC output voltage from the fuel cell to a predetermined voltage, the PV output voltage from the solar cell and the conversion from the DC / DC converter unit Method for controlling a photovoltaic-fuel cell combined cycle power generation system comprising a DC link unit for linking the FC output voltage to generate a DC voltage, and a DC / AC inverter unit for converting the DC voltage from the DC link unit to a predetermined AC voltage A system start step of detecting the voltage and current required for grid connection determination and solar power generation determination; An operation mode determination step of determining whether the system-linked operation mode or the independent operation mode is based on the system voltage; A grid connection-sun determination step of determining a solar power generation state by comparing the PV power calculated from the PV output voltage and the output current of the solar cell with a predetermined minimum PV power when the grid connection operation mode is performed; An independent-sun determination step of determining a solar power generation state by comparing the PV power of the solar cell with a preset minimum PV power when the independent operation mode is performed; In the grid-connected solar determination step, when there is no solar power generation in the grid-connected operation mode, a converter control step of controlling the electrostatic power for the DC / DC converter unit, DC link, grid-linked for the DC / AC inverter And a first grid linkage-control step of performing a first grid linkage-operation mode having an inverter control step of controlling the output current. In the grid-connected solar determination step, if there is solar power in grid-connected operation mode, the converter control step of controlling the electrostatic power for the DC / DC converter unit, tracking the maximum power point for the DC / AC inverter, A second grid linkage-control step of performing a second grid linkage-operation mode having an inverter control step of controlling the DC link, the grid linkage and the output current; In the independent-sun determination step, when there is solar power in the independent operation mode, the converter control step of controlling the current for the DC / DC converter unit, the maximum power point tracking, DC link and A first independent control step of performing a first independent operation mode having an inverter control step of controlling an output constant voltage; And a converter control step of controlling a DC link to the DC / DC converter unit when there is no solar power in the independent operation mode, and an inverter controlling an output constant voltage to the DC / AC inverter in the independent-sun determination step. A control method of a solar-fuel cell combined cycle power generation system including a second independent control step of performing a second independent operation mode having a control step is proposed.

In the third and fourth technical aspects of the present invention, the system start step, operation mode determination step, grid connection-sun determination step, independent-sun determination step, first grid connection-control step and second grid connection-control In each step, the FC output voltage and current of the fuel cell, the PV output voltage and current of the solar cell, the AC voltage and output current of the DC / AC inverter unit, and the grid voltage in the system of the commercial power supply, respectively,

Each of the first independent-control step and the first independent-control step,

The FC output voltage and current of the fuel cell, the PV output voltage and current of the solar cell, AC voltage and output current of the DC / AC inverter unit is detected.

The converter control step of the first grid linkage-control step may include: a first calculation step of calculating a first control error value for constant power control for the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And a first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step, and controlling the operation of the DC / DC converter unit using the PWM converter control signal. Characterized in that.

The inverter control step of the first grid linkage-control step may include: a second calculation step of calculating a second control error value for DC link, grid linkage, and output current control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And a second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal. Characterized in that.

The converter control step of the second grid linkage-control step may include: a first calculation step of calculating a first control error value for constant power control for the DC / DC converter; A first control value compensation step of compensating a converter control value using a first control error value from the first operation step; And a first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step, and controlling the operation of the DC / DC converter unit using the PWM converter control signal. Characterized in that.

The inverter control step of the second grid linkage-control step may include: a second calculation step of calculating a second control error value for maximum power point tracking, DC link, grid linkage, and output current control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And a second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal. Characterized in that.

In a fourth technical aspect of the present invention, the converter control step of the first independent control step includes: a first calculation step of calculating a first control error value for current control for the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And a first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step, and controlling the operation of the DC / DC converter unit using the PWM converter control signal. Characterized in that.

The inverter control step of the first independent control step includes: a second calculation step of calculating a second control error value for the maximum power point tracking, the DC link, and the output constant voltage control for the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And a second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal. Characterized in that.

The converter control step of the second independent control step may include: a first calculating step of calculating a first control error value for DC link control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And a first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step, and controlling the operation of the DC / DC converter unit using the PWM converter control signal. Characterized in that.

The inverter control step of the second independent control step may include: a second calculation step of calculating a second control error value for output constant voltage control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And a second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal. Characterized in that.

According to the solar-fuel cell combined cycle power generation system of the present invention, by implementing a complex power generation system using a solar cell and a fuel cell using a single converter and a single inverter, the number of expensive converters and inverters can be reduced Therefore, the size and manufacturing cost can be reduced.

In addition, in the solar-fuel cell combined cycle power generation system of the present invention, it is possible to perform the optimal control mode among a plurality of preset control mode according to whether the grid connection or solar power generation, so that the Power control is also possible.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is not limited to the embodiments described, and the embodiments of the present invention are used to assist in understanding the technical spirit of the present invention. In the drawings referred to in the present invention, components having substantially the same configuration and function will use the same reference numerals.

1 is a circuit block diagram illustrating a solar-fuel cell combined cycle power generation system using a single converter and a single inverter according to a first embodiment of the present invention.

Referring to FIG. 1, in the solar-fuel cell combined cycle power generation system according to the first embodiment of the present invention, a FC output voltage (VFC) from a fuel cell 110 for converting chemical energy into electrical energy is preset. The solar cell is connected to the DC / DC converter 200 for converting the voltage, and the output terminal of the solar cell 120 for converting sunlight into electrical energy and the output terminal of the DC / DC converter 200 in common, A DC link unit 300 linking the PV output voltage VPV from 120 and the converted FC output voltage VFC from the DC / DC converter unit 200 to generate a DC voltage VDC; The DC / AC inverter unit 400 may convert the DC voltage VDC from the DC link unit 300 into a predetermined AC voltage Vac.

Here, the fuel cell 110 converts chemical energy into electrical energy having a predetermined size and outputs the same by using a redox reaction of hydrogen and oxygen.

The solar cell 120 is divided into a time when there is sunlight, such as daytime and no time such as night time, solar power is performed at the time of the solar light to generate a valid PV power by solar power generation and However, in the event that solar power generation is not carried out, no valid PV power can be generated. As described above, the solar cell 120 does not have constant solar power generation according to the presence or absence of solar light, and thus, the maximum power point tracking (MPPT) is used to track the maximum power point among the power generated by the solar cell 120. Maximum power point tracking should be controlled to generate maximum power.

2 is a circuit block diagram illustrating a solar-fuel cell combined cycle power generation system using a single converter and a single inverter according to a second embodiment of the present invention. Referring to FIG. 2, in the solar-fuel cell combined cycle power generation system according to the second embodiment of the present invention, an FC output voltage VFC from a fuel cell 110 that converts chemical energy into electrical energy is preset. The DC / DC converter 200 for converting the solar cell and the output terminal of the solar cell 120 for converting sunlight into electrical energy and the output terminal of the DC / DC converter 200 are connected in common to each other. A DC link unit 300 linking the PV output voltage VPV from 120 and the converted FC output voltage VFC from the DC / DC converter 200 to generate a DC voltage VDC; DC / AC inverter unit 400 for converting the DC voltage VDC from the DC link unit 300 into a predetermined AC voltage Vac, the fuel cell 110, the solar cell 120, and DC / AC. A voltage / current detector 700 that detects the voltage and current generated by each of the inverter units 400 and the voltage / current detector 700. Based on the plurality of voltage and current to the detection may include a combined cycle power generation control unit 800 that controls the operation of the DC / DC converter 200 and the DC / AC inverter section (400).

1 and 2, in the first and second embodiments of the present disclosure, the DC link unit 300 may include an output terminal of the solar cell 120 and the DC / DC converter unit 200. The output terminal of may include a common connection node (NC) connected in common with each other and a capacitor (Cdc) connected between the ground.

The DC / AC inverter unit 400 may include a DC / AC inverter 410 for converting the DC voltage VDC from the DC link unit 300 into a voltage in a pulse form, and the DC / AC inverter 410. It may include a filter 420 for converting the voltage of the pulse form into the AC voltage (Vac).

In addition, the DC / AC inverter unit 400 transmits an AC voltage Vac from the filter 420 to a grid when grid connection is required to supply power to the commercial power supply 600. A system delivery unit 430 may be further included.

In this case, the system transmission unit 430 may operate under the control of the combined power generation controller 800 to transmit the AC voltage Vac from the filter 420 to the grid.

Referring to FIG. 2, in the second embodiment of the present disclosure, the voltage / current detector 700 may include the FC output voltage VFC and the current IFC of the fuel cell 110, and the solar cell 120. PV output voltage (VPV) and current (IPV) of the, AC voltage (Vac) and output current (Iout) of the DC / AC inverter unit 400, and the grid voltage (Vgrid) in the grid of the commercial power source 600 Each can be detected.

The combined power generation controller 800 controls the operation of the DC / DC converter 200 using the grid voltage Vgrid, the FC output voltage VFC, and the current IFC. And an inverter controller 820 for controlling the operation of the DC / AC inverter unit 400 based on the PV output voltage VPV and the current IPV from the voltage / current detector 700. .

3 is an output characteristic during grid-linked operation of the photovoltaic-fuel cell combined cycle power generation system according to the present invention.

2 and 3, in the grid-connected operation mode, the combined power generation control unit 800 is connected to the PV power (PPV) by the PV output voltage (VPV) and the current (IPV) of the solar cell 120. Determine the state of solar power according to the solar power generation, and perform one of the preset control modes of the first and second grid linkage-control modes according to the determination result of the solar power generation, and wherein the first grid linkage-control mode is grid-linked. In the operation mode, there is a control mode without solar power generation, and the second grid linkage-control mode is a control mode with solar power generation in the grid-linked operation mode.

More specifically, each of the converter controller 810 and the inverter controller 820, in the grid-connected operation mode, PV power (PPV) by the PV output voltage (VPV) and the current (IPV) of the solar cell 120. Determine the state of solar power generation, perform a control mode of one of the first and second grid connection-control modes preset according to the determination result of the presence or absence of solar power, and the first grid connection-control mode includes: The grid-connected operation mode is a control mode without solar power generation, and the second grid-connected control mode is a control mode with solar power generation in the grid-connected operation mode.

4 is an output characteristic diagram during independent operation of the solar-fuel cell combined cycle power generation system according to the present invention.

2, 3, and 4, the hybrid power generation controller 800 determines whether a grid-connected operation mode or an independent operation mode is determined according to the grid voltage Vgrid, and independent of the grid-connected operation mode. In each mode, the solar power generation state is determined according to the PV output voltage (VPV) of the solar cell 120 and the PV power (PPV) by the current (IPV), and the preset first and second grid connection-control modes. And perform a control mode of one of the first and second independent control modes, wherein the first grid linkage-control mode is a control mode without solar power in the grid linkage operation mode, and the second grid linkage-control The mode is a control mode with solar power in the grid-connected operation mode, and the first independent control mode is a control mode with solar power in the independent operation without grid linkage, and the second independent control mode is a grid linkage. It is a control mode without solar power when operating independently.

More specifically, each of the converter controller 810 and the inverter controller 820 determines whether to be grid-connected according to the grid voltage (Vgrid), and the PV output voltage (VPV) and current of the solar cell 120. The solar power generation state is determined according to the PV power (PPV) by the IPV, and the first and second grid connection-control modes and the first and second independent modes preset according to whether the grid is connected and whether the solar power is present. One control mode of the control mode is performed, wherein the first grid linkage-control mode is a control mode without solar power generation in a grid-linked operation mode, and the second grid linkage-control mode is a solar mode in a grid-linked operation mode. A control mode with generation of electricity, wherein the first independent control mode is a control mode with solar power generation during independent operation without grid linkage, and the second independent control mode with no solar power generation during independent operation without grid linkage Mode.

5 is a conceptual diagram illustrating a control of a first grid-control mode without solar power during grid-linked operation of the solar-fuel cell combined cycle power generation system according to the present invention.

Referring to FIG. 5, the converter controller 810 may calculate a first control error value for the constant power control of the DC / DC converter 200 in the first grid-control mode. A first control value compensator 812 for compensating the converter control value VC-con using the calculator 811, a first control error value from the first calculator 811, and the first control value The compensator 812 generates a PWM converter control signal PWM-con using the converter control value VC-con compensated for, and uses the PWM converter control signal to generate the PWM / DC converter 200. It may include a first PWM control unit 813 for controlling the operation.

In the first grid linkage-control mode, the first calculating unit 811 of the converter controller 810 divides a predetermined FC power command value P-FC by the FC output voltage VFC and an FC current command value I. And generate the first control error value corresponding to the difference between the FC current command value I * FC and the FC current IFC.

Referring to FIG. 5, the inverter controller 820 may control a second control error for DC link, grid linkage, and output current control with respect to the DC / AC inverter unit 400 in the first grid linkage-control mode. A second calculation unit 821 for calculating a value, a second control value compensation unit 822 for compensating the inverter control value VC-inv using a second control error value from the second calculation unit 821, and The PWM control signal PWM-inv is generated using the inverter control value VC-inv compensated by the second control value compensator 822, and the PWM inverter control signal PWM-inv is used. It may include a second PWM control unit 823 to control the operation of the DC / AC inverter 400.

In the first grid linkage-control mode, the second calculating unit 821 of the inverter controller 820 includes a current corresponding to a difference between a preset DC voltage command value V * DC and the DC voltage VDC. The DC link calculating unit 821-2 calculating the error value and compensating the current command value with the current error value, and dividing a predetermined FC power command value P * FC by the grid voltage Vgrid, to correct the current correction value Iout_ff. Error correction unit 821-4 for correcting the compensated current command value from the DC link calculating unit 821-2 with the current correction value Iout-ff, and the grid voltage Vgrid. A DC / AC converter 821-6 which detects a phase of the signal and converts the current command value of the error correction unit 821-4 into an AC output current command value I * out in synchronization with the detected phase. And a difference value between the output current command value I * out and the output current Iout from the DC / AC converter 821-6. It may include an error calculation unit (821-8) for generating the second control error value.

6 is a control conceptual diagram of a second grid linkage-control mode with solar power generation during grid linkage operation of the solar-fuel cell combined cycle power generation system according to the present invention.

Referring to FIG. 6, the converter controller 810 is configured to calculate a first control error value for the constant power control of the DC / DC converter 200 in the second grid connection-control mode. A first control value compensator 812 for compensating the converter control value VC-con using the calculator 811, a first control error value from the first calculator 811, and the first control value The PWM converter control signal PWM-con is generated using the converter control value VC-con compensated by the compensation unit 812, and the DC / DC converter 200 uses the PWM converter control signal. It may include a first PWM control unit 813 to control the operation of.

In the second grid linkage-control mode, the first calculating unit 811 of the converter controller 810 divides a predetermined FC power command value P * FC by the FC output voltage VFC and an FC current command value I. And generate the first control error value corresponding to the difference between the FC current command value I * FC and the FC current IFC.

Referring to FIG. 6, the inverter controller 820 may, in the second grid linkage-control mode, track maximum power point (MPPT), DC link, grid linkage, and output to the DC / AC inverter unit 400. A second calculating unit 821 calculating a second control error value for current control and a second compensating inverter control value VC-inv using the second control error value from the second calculating unit 821. The PWM inverter control signal PWM-inv is generated using the control value compensator 822 and the inverter control value VC-inv compensated by the second control value compensator 822, and the PWM inverter control is performed. The second PWM controller 823 may control the operation of the DC / AC inverter unit 400 using the signal PWM-inv.

In the second grid linkage-control mode, the second calculating unit 821 of the inverter controller 820 uses the PV output voltage VPV and the current IPV to track a preset maximum power point (MPPT). A maximum power point tracking unit 821-1 performing power point tracking to generate a PV output voltage command value V * PV, the PV output voltage VP and the PV output voltage command value V * PV. And a DC link calculating unit 821-2 calculating a voltage error value corresponding to a difference value from and compensating the output current command value with the voltage error value.

In addition, the second calculator 821 of the inverter controller 820 calculates a power command value by adding a preset FC power command value P * FC and a preset PV power command value P * PV, and the power command value. To calculate the current correction value Iout_ff by dividing by the grid voltage Vgrid, and correct the current error value of the DC link operation unit 821-2 by using the current compensation value Iout-ff. 821-4 and a DC / AC converter 821 which detects a phase of the grid voltage Vgrid and converts the current command value to an alternating current output current command value I * out in synchronization with the detected phase. -6) and an error calculator for generating the second control error value corresponding to a difference value between the output current command value I * out and the output current Iout from the DC / AC converter 821-6. (821-8).

7 is a conceptual diagram of the control of the first independent control mode with solar power during the independent power generation operation of the photovoltaic-fuel cell combined cycle power generation system according to the present invention.

Referring to FIG. 7, the converter controller 810 may include a first calculator configured to calculate a first control error value for current control of the DC / DC converter 200 in the first independent control mode. 811, a first control value compensator 812 for compensating the converter control value VC-con using the first control error value from the first calculator 811, and the first control value compensator A PWM converter control signal PWM- con is generated using the converter control value VC-con compensated at 812, and the operation of the DC / DC converter 200 is operated using the PWM converter control signal. It may include a first PWM control unit 813 to control.

At this time, the first operation unit 811 of the converter controller 810, in each of the first grid linkage-control mode, the second grid linkage-control mode and the first independent control mode, the predetermined FC power command value (P). * FC is divided by the FC output voltage VFC to generate an FC current command value I * FC, and the first corresponding to a difference value between the FC current command value I * FC and the FC current IFC. It can be made to calculate a control error value.

Here, the output power Pout is calculated using the AC voltage Vac and the output current Iout of the DC / AC inverter unit 400, and the PV output voltage VPV and the current of the solar cell 120 are calculated. The PV power PPV is calculated using IPV, and the FC power command value P * FC may correspond to a difference value between the output power Pout and the PV power PPV.

Referring to FIG. 7, the inverter controller 820 may control the maximum power point tracking (MPPT), the DC link, and the output constant voltage control for the DC / AC inverter unit 400 in the first independent control mode. A second control unit 821 for calculating a second control error value and a second control value compensator for compensating the inverter control value VC-inv using the second control error value from the second operation unit 821. 822 and a PWM inverter control signal PWM-inv using the inverter control value VC-inv compensated by the second control value compensator 822, and generates the PWM inverter control signal PWM-. It may include a second PWM control unit 823 to control the operation of the DC / AC inverter unit 400 by using inv).

In the first independent control mode, the second calculator 821 of the inverter controller 820 uses the PV output voltage VPV and the current IPV to track a preset maximum power point (MPPT). Difference between the maximum power point tracking unit 821-1 performing the point tracking and generating the PV output voltage command value V * PV, and the PV output voltage VPV and the PV output voltage command value V * PV. A DC link calculating unit 821-2 for calculating a voltage error value corresponding to the value and compensating an output voltage command value V * out with the voltage error value, and an output voltage from the DC link calculating unit 821-2. DC / AC converter 821-6 for converting the command value to the output voltage command value V * out of AC, and the output voltage command value V * out from the DC / AC converter 821-6 and the above-mentioned. An error calculator 821-8 generating the second control error value corresponding to a difference value from the output voltage Vout may be included.

8 is a conceptual diagram of a second independent control mode without solar power during the independent power generation operation of the solar-fuel cell combined cycle power generation system according to the present invention.

Referring to FIG. 8, the converter controller 810 is configured to calculate a first control error value for DC link control with respect to the DC / DC converter 200 in the second independent control mode. 811, a first control value compensator 812 for compensating the converter control value VC-con using the first control error value from the first calculator 811, and the first control value compensation A PWM converter control signal PWM-con is generated using the converter control value VC-con compensated by the unit 812, and the DC / DC converter 200 of the DC / DC converter 200 is generated using the PWM converter control signal. It may include a first PWM control unit 813 for controlling the operation.

At this time, the first operation unit 811 of the converter controller 810, the voltage corresponding to the difference between the predetermined DC voltage command value (V * DC) and the DC voltage (VDC) in the second independent control mode. The error value is calculated, and the voltage error value is used to compensate the predetermined FC current command value I * FC, and corresponds to a difference value between the compensated FC current command value I * FC and the FC current IFC. The first control error value may be calculated.

Referring to FIG. 8, the inverter controller 820 may calculate a second control error value for output constant voltage control of the DC / AC inverter unit 400 in the second independent control mode. 821, a second control value compensator 822 for compensating the inverter control value VC-inv using the second control error value from the second calculator 821, and the second control value compensation The PWM control signal PWM-inv is generated by using the inverter control value VC-inv compensated by the unit 822, and the DC / AC inverter unit is configured by using the PWM inverter control signal PWM-inv. It may include a second PWM control unit 823 for controlling the operation of (400).

In this case, in the second independent control mode, the second calculating unit 821 of the inverter controller 820 corresponds to the difference value between the AC voltage command value V * ac and the AC voltage Vac. Two control error values may be generated.

FIG. 9 is a flowchart illustrating a photovoltaic-fuel cell combined cycle power generation method using a single converter and a single inverter according to a third embodiment of the present invention.

2, 3 and 9, in the control method of the solar-fuel cell combined cycle power generation system according to the third embodiment of the present invention, the FC output voltage VFC from the fuel cell 110 is preset. DC / DC converter 200 for converting the voltage, PV output voltage (VPV) from the solar cell 120 and the converted FC output voltage (VFC) from the DC / DC converter 200 by linking It includes a DC link unit 300 for generating a DC voltage (VDC), DC / AC inverter unit 400 for converting the DC voltage (VDC) from the DC link unit 300 to a predetermined AC voltage (Vac) It can be applied to the solar-fuel cell composite power generation system.

The control method of the solar-fuel cell combined cycle power generation system according to a third embodiment of the present invention, the system start step (S50) for detecting the voltage and current required for grid connection determination and solar power generation determination, and the grid connection If possible, perform a grid-connected operation mode, and compare the PV power PPV calculated from the PV output voltage (VPV) and the output current (IPV) of the solar cell 120 with a predetermined minimum PV power (Pmin). In the grid-connected solar determination step (S200) and the grid-connected solar determination step (S200) to determine the state of solar power generation, if there is no solar power in the grid-connected operation mode to the DC / DC converter unit 200 The converter control step (S410) for controlling the constant power for the.

In addition, the control method of the photovoltaic-fuel cell combined cycle power generation system according to a third embodiment of the present invention, the inverter control step of controlling the DC link, grid connection and the output current to the DC / AC inverter 400 ( In a first grid linkage-control step of performing a first grid linkage-operation mode (S420) and the grid linkage-solar determination step (S200), when there is solar power generation in the grid linkage operation mode. Converter control step (S510) for controlling the constant power for the DC / DC converter unit 200, the maximum power point tracking (MPPT), DC link, grid connection and output current for the DC / AC inverter unit 400 It may include a second grid linkage-control step (S500) to perform a second grid linkage-operation mode having an inverter control step (S510) for controlling the.

FIG. 10 is a flowchart illustrating a photovoltaic-fuel cell combined cycle power generation method using a single converter and a single inverter according to a fourth embodiment of the present invention.

2, 3, 4, and 10, the control method of the solar-fuel cell combined cycle power generation system according to the fourth embodiment of the present invention, the FC output voltage (VFC) from the fuel cell 110 The DC / DC converter 200 converts the voltage into a predetermined voltage, the PV output voltage VPV from the solar cell 120 and the converted FC output voltage VFC from the DC / DC converter 200. A DC link unit 300 linking the DC link unit 300 to generate a DC voltage VDC, and a DC / AC inverter unit 400 converting the DC voltage VDC from the DC link unit 300 into a predetermined AC voltage Vac. It can be applied to a solar-fuel cell composite power generation system including).

The control method of the solar-fuel cell combined cycle power generation system according to a fourth embodiment of the present invention, the system start step (S50) for detecting the voltage and current required for grid linkage determination and solar power generation, and the grid voltage ( Operation mode determination step (S100) for determining whether the grid-connected operation mode or the independent operation mode according to (Vgrid), and when performing the grid-connected operation mode, the PV output voltage (VPV) and the output current (IPV) of the solar cell 120 And comparing the calculated PV power (PPV) and the predetermined minimum PV power (Pmin) with the grid-based solar determination step (S200) to determine the solar power generation state, the solar cell 120 when performing the independent operation mode Independent-solar determination step (S300) of comparing the PV power (PPV) and the predetermined minimum PV power (Pmin) of the solar power generation state (S300), and the grid-connected operation mode (S200), the grid-connected operation mode If there is no solar power at the DC / DC It includes a converter control step (S410) for controlling the electrostatic force for the converter unit 200.

In addition, the control method of the photovoltaic-fuel cell combined cycle power generation system according to a fourth embodiment of the present invention, the inverter control step for controlling the DC link, grid connection and the output current to the DC / AC inverter 400 ( In a first grid linkage-control step of performing a first grid linkage-operation mode (S420) and the grid linkage-solar determination step (S200), when there is solar power generation in the grid linkage operation mode. Converter control step (S510) for controlling the constant power for the DC / DC converter unit 200, the maximum power point tracking (MPPT), DC link, grid connection and output current for the DC / AC inverter unit 400 And a second grid linkage-control step (S500) for performing a second grid linkage-operation mode having an inverter control step (S510) to control the control.

In addition, the control method of the solar-fuel cell combined cycle power generation system according to a fourth embodiment of the present invention, in the independent-solar determination step (S300), when there is solar power in the independent operation mode, the DC / DC converter Converter control step (S610) for controlling the current to the unit 200, and inverter control step (S620) to control the maximum power point tracking (MPPT), DC link and output constant voltage for the DC / AC inverter 400 In the first independent control step (S600) and the independent-sun determination step (S300) for performing a first independent operation mode having a) when there is no solar power in the independent operation mode, the DC / DC converter ( Performing a second independent-operation mode having a converter control step (S710) of controlling the DC link with respect to 200 and an inverter control step (S720) of controlling the output constant voltage with respect to the DC / AC inverter unit 400. It may include a second independent control step (S700).

The system start step (S50), the operation mode determination step (S100). Grid-connected solar determination step (S200), independent-solar determination step (S300), the first grid linkage-control step (S400) and the second grid linkage-control step (S500), respectively, of the fuel cell 110 FC output voltage (VFC) and current (IFC), PV output voltage (VPV) and current (IPV) of the solar cell 120, AC voltage (Vac) and output current of the DC / AC inverter unit 400 ( Iout), and the grid voltage Vgrid may be detected in the grid of the commercial power supply 600, respectively.

Each of the first independent control step and the first independent control step may include an FC output voltage VFC and a current IFC of the fuel cell 110, a PV output voltage VPV of the solar cell 120, and The current IPV, the AC voltage Vac and the output current Iout of the DC / AC inverter unit 400 may be detected.

11 is a control flowchart of a first grid-control mode without solar power during grid-linked operation of the solar-fuel cell combined cycle power generation system according to the present invention.

9, 10, and 11, the converter control step S410 of the first grid linkage-control step S400 includes a first method for controlling electrostatic power with respect to the DC / DC converter unit 200. A first control value compensation step of compensating the converter control value VC-con using the first calculation step S411 for calculating a control error value and the first control error value from the first calculation step S411. And a PWM converter control signal PWM-con using the converter control value VC-con compensated in the first control value compensation step S412 and using the PWM converter control signal. It may include a first PWM control step (S413) for controlling the operation of the DC / DC converter 200.

In the first calculation step S411 of the first grid linkage-control step S400, a predetermined FC power command value P * FC is divided by the FC output voltage VFC to divide an FC current command value I * FC. And generate the first control error value corresponding to a difference value between the FC current command value I * FC and the FC current IFC.

9, 10 and 11, the inverter control step (S420) of the first grid connection-control step (S400), DC link, grid connection and output to the DC / AC inverter unit 400 Compensating the inverter control value VC-inv using the second operation step S421 for calculating a second control error value for current control and the second control error value from the second operation step S421. A PWM inverter control signal PWM-inv is generated using the second control value compensation step S422 and the inverter control value VC-inv compensated in the second control value compensation step S422, and the PWM is generated. A second PWM control step S423 of controlling the operation of the DC / AC inverter unit 400 using the inverter control signal PWM-inv may be included.

The second calculation step (S421) of the first grid connection-control step (S400) calculates a current error value corresponding to a difference value between a preset DC voltage command value V * DC and the DC voltage VDC. The current correction value Iout_ff is calculated by dividing the DC link operation step S421-2 for compensating the current command value with the current error value and the predetermined FC power command value P * FC by the grid voltage Vgrid. And an error correction step (S421-4) for correcting the compensated current command value from the DC link calculation step (S421-2) with the current correction value (Iout-ff), and the phase of the grid voltage (Vgrid). And a DC / AC conversion step (S421-6) for converting the current command value of the error correction step (S421-4) into an AC output current command value (I * out) in synchronization with the detected phase. The above corresponds to a difference value between the output current command value I * out and the output current Iout from the DC / AC conversion step S421-6. It may include an error operation step (S421-8) for generating a second control error value.

12 is a control flowchart of a second grid linkage-control mode with solar power generation during grid linkage operation of the solar-fuel cell combined cycle power generation system according to the present invention.

9, 10, and 12, the converter control step (S510) of the second grid linkage-control step (S500) may include a first method for controlling the constant power of the DC / DC converter unit 200. A first control value compensation step of compensating the converter control value VC-con using the first calculation step S511 for calculating a control error value and the first control error value from the first calculation step S511. In operation S512 and the converter control value VC-con compensated in the first control value compensation step S512, a PWM converter control signal PWM-con is generated and the PWM converter control signal is used. It may include a first PWM control step (S513) for controlling the operation of the DC / DC converter 200.

At this time, the first calculation step (S411) of the second grid connection-control step (S500), by dividing a predetermined FC power command value (P * FC) by the FC output voltage (VFC) FC current command value (I * FC). ) And calculate the first control error value corresponding to the difference between the FC current command value I * FC and the FC current IFC.

9, 10, and 12, the inverter control step (S520) of the second grid linkage-control step (S500) may include a maximum power point tracking (MPPT) for the DC / AC inverter unit 400. Inverter control value using a second operation step S521 for calculating a second control error value for DC link, grid linkage, and output current control, and a second control error value from the second operation step S521. PWM inverter control signal PWM- using the second control value compensation step S522 for compensating the VC-inv and the inverter control value VC-inv compensated for in the second control value compensation step S522. inv) and a second PWM control step S523 of controlling the operation of the DC / AC inverter unit 400 using the PWM inverter control signal PWM-inv.

In the second calculation step S421 of the second grid linkage-control step S500, a maximum power point tracking (MPPT) is preset using the PV output voltage VPV and the current IPV. Corresponds to a maximum power point tracking step (S421-1) for generating a PV output voltage command value (V * PV) and a difference between the PV output voltage (VPV) and the PV output voltage command value (V * PV). A DC link calculation step (S421-2) for calculating a voltage error value, and compensating an output current command value with the voltage error value, a predetermined FC power command value (P * FC) and a preset PV power command value (P * PV). ) To calculate a power command value, divide the power command value by the grid voltage Vgrid, calculate a current correction value Iout_ff, and calculate the DC link operation step using the current compensation value Iout-ff ( Error correction step (S421-4) for correcting the current error value of S421-2 and the phase of the grid voltage (Vgrid) And a DC / AC conversion step (S421-6) for converting the current command value to an AC output current command value (I * out) in synchronization with the detected phase, and the DC / AC conversion step (S421-6). It may include an error calculation step (S421-8) for generating the second control error value corresponding to the difference between the output current command value (I * out) and the output current (Iout) from the ().

13 is a control flowchart of the first independent control mode with solar power during the independent power generation operation of the photovoltaic-fuel cell combined cycle power generation system according to the present invention.

10 and 13, in the converter control step S610 of the first independent control step S600, a first control error value for current control is calculated for the DC / DC converter 200. A first control value compensation step S612 for compensating the converter control value VC-con using the first calculation step S611 and the first control error value from the first calculation step S611; The PWM control signal PWM-con is generated using the converter control value VC-con compensated in the first control value compensation step S612, and the DC / DC converter is generated using the PWM converter control signal. It may include a first PWM control step (S613) for controlling the operation of the unit 200.

At this time, the first operation step (S611) of the first independent control step (S600), by dividing the predetermined FC power command value (P * FC) by the FC output voltage (VFC) FC current command value (I * FC). And calculate the first control error value corresponding to the difference between the FC current command value I * FC and the FC current IFC.

Here, the output power Pout is calculated using the AC voltage Vac and the output current Iout of the DC / AC inverter unit 400, and the PV output voltage VPV and the current of the solar cell 120 are calculated. The PV power PPV is calculated using IPV, and the FC power command value P * FC may correspond to a difference value between the output power Pout and the PV power PPV.

10 and 13, the inverter control step (S620) of the first independent control step (S600) includes a maximum power point tracking (MPPT), a DC link, and the like for the DC / AC inverter unit 400. Compensating the inverter control value VC-inv by using a second calculation step S621 for calculating a second control error value for output constant voltage control and a second control error value from the second calculation step S621. By using the second control value compensation step (S622) and the inverter control value (VC-inv) compensated in the second control value compensation step (S622) to generate a PWM inverter control signal (PWM-inv), It may include a second PWM control step (S623) for controlling the operation of the DC / AC inverter unit 400 by using a PWM inverter control signal (PWM-inv).

10 and 13, the second calculation step S621 of the first independent control step S600 may be based on the preset maximum power point tracking using the PV output voltage VPV and the current IPV. A maximum power point tracking step (S621-1) of performing a maximum power point tracking (MPPT) to generate a PV output voltage command value (V * PV), the PV output voltage (VPV) and the PV output voltage command value (V). A DC link calculation step S621-2 calculating a voltage error value corresponding to a difference value of * PV), and compensating an output voltage command value V * out with the voltage error value, and the DC link calculation step S421. A DC / AC conversion step (S621-6) for converting the output voltage command value from -2) into an output voltage command value (V * out) of AC, and an output voltage command value from the DC / AC conversion step (S621-6). And an error calculation step S621-8 for generating the second control error value corresponding to the difference between V * out and the output voltage Vout.

14 is a control flowchart of a second independent control mode without solar power during the independent power generation operation of the solar-fuel cell combined cycle power generation system according to the present invention.

10 and 14, the converter control step (S710) of the second independent control step (S700) may include a first control error value for DC link control with respect to the DC / DC converter unit 200. A first control value compensation step S712 for compensating the converter control value VC-con using the first calculation step S711 for calculating and the first control error value from the first calculation step S711, and And generating a PWM converter control signal PWM-con using the converter control value VC-con compensated in the first control value compensating step S712 and using the PWM converter control signal. It may include a first PWM control step (S713) for controlling the operation of the converter unit 200.

The first calculation step S711 of the second independent control step S700 calculates a voltage error value corresponding to a difference value between a preset DC voltage command value V * DC and the DC voltage VDC, The voltage error value is used to compensate for a predetermined FC current command value I * FC, and the first control error corresponding to a difference value between the compensated FC current command value I * FC and the FC current IFC. It can be made to calculate a value.

10 and 14, the inverter control step S720 of the second independent control step S700 may include a second control error value for output constant voltage control with respect to the DC / AC inverter unit 400. And a second control value compensation step S722 for compensating the inverter control value VC-inv using the second calculation step S721 for calculating and the second control error value from the second calculation step S721; In addition, the PWM control signal PWM-inv is generated using the inverter control value VC-inv compensated in the second control value compensation step S722, and the PWM inverter control signal PWM-inv is used. The second PWM control step (S723) for controlling the operation of the DC / AC inverter unit 400 may be included.

The second operation step S721 of the second independent control step S700 generates the second control error value corresponding to a difference value between the AC voltage command value V * ac and the AC voltage Vac. It can be made to.

Hereinafter, the operation and effects of the present invention will be described in detail with reference to the accompanying drawings.

1 to 2, a solar-fuel cell combined cycle power generation system of the present invention will be described.

First, referring to FIGS. 1 and 2, in the solar-fuel cell combined cycle power generation system according to the first and second embodiments of the present invention, the DC / DC converter unit 200 of the present invention may convert chemical energy into electrical energy. The FC output voltage VFC from the fuel cell 110 to be converted to is converted into a predetermined voltage and output to the DC link unit 300.

In this case, the fuel cell 110 may output, for example, an FC output voltage of approximately 24V to 42V and an FC current IFC up to approximately 50A. The DC / DC converter 200 converts the FC output voltage VFC to about 350V to 380V required for DC / AC conversion.

The DC link unit 300 connects the output terminal of the solar cell 120 that converts sunlight into electrical energy and the output terminal of the DC / DC converter unit 200 in common, The PV output voltage VPV and the converted FC output voltage VFC from the DC / DC converter 200 are linked to generate a DC voltage VDC to be output to the DC / AC inverter 400.

In this case, the solar cell 120 may be implemented in such a manner that a plurality of solar cells are connected in series to generate a voltage of, for example, about 350V required for DC / AC conversion in the presence of the sun. In order to produce the maximum power using the solar cell 120, a maximum power point tracking (MPPT) that tracks the maximum power point for the power generated by the solar cell 120 should be performed.

The DC / AC inverter unit 400 converts the DC voltage VDC from the DC link unit 300 into a predetermined AC voltage Vac.

2, in the solar-fuel cell hybrid power generation system according to the second embodiment of the present invention, the voltage / current detector 700 of the present invention includes the fuel cell 110, the solar cell 120, and the like. The voltage and current generated by each of the DC / AC inverter units 400 are detected and provided to the combined power generation controller 800.

The combined power generation control unit 800 is based on the plurality of voltages and currents detected by the voltage / current detection unit 700, and controls the DC / DC converter unit 200 and the DC / AC inverter unit 400. You can control the operation.

1 and 2, in the first and second embodiments of the present disclosure, the DC link unit 300 may include a capacitor Cdc, and in this case, the capacitor Cdc Since noise or an AC ripple component that may be included in the DC voltage VDC may be removed, the DC link unit 300 may provide a more stable DC voltage VDC.

In addition, when the DC / AC inverter unit 400 includes a DC / AC inverter 410 and a filter 420, the DC / AC inverter 410 may be a DC voltage from the DC link unit 300. (VDC) is converted into a pulse-shaped voltage and output to the filter 420. The filter 420 may convert the voltage of the pulse type of the DC / AC inverter 410 into the AC voltage Vac.

When the DC / AC inverter unit 400 further includes a grid transmission unit 430, the grid transmission unit 430 may transfer an AC voltage Vac from the filter 420 to a grid. have.

Referring to FIG. 2, in the second embodiment of the present disclosure, the voltage / current detector 700 may include the FC output voltage VFC and the current IFC of the fuel cell 110, and the solar cell 120. PV output voltage (VPV) and current (IPV) of the, AC voltage (Vac) and output current (Iout) of the DC / AC inverter unit 400, and the grid voltage (Vgrid) in the grid of the commercial power source 600 Each can be detected.

When the combined power generation control unit 800 includes the converter controller 810 and the inverter controller 820, the converter controller 810 may include the grid voltage Vgrid, the FC output voltage VFC, and the current IFC. ) May control the operation of the DC / DC converter 200. The inverter controller 820 may control the operation of the DC / AC inverter unit 400 based on the PV output voltage VPV and the current IPV from the voltage / current detector 700.

Photovoltaic-fuel cell combined cycle power generation system of the present invention, the grid-driven operation can be operated by connecting to the commercial power source 600, or independent operation that is operated independently because it is not connected to the commercial power source, such as islands, mountainous region, etc. This is possible.

2 and 3, the combined power generation controller 800, or the converter controller 810 and the inverter controller 820, respectively, in the grid-connected operation mode, the PV output voltage of the solar cell 120 ( The solar power generation state is determined according to the PV power (PPV) by the VPV) and the current (IPV). Can be done. Here, the first grid linkage-control mode is a control mode without solar power generation in the grid linkage operation mode, and the second grid linkage-control mode is a control mode with solar power generation in the grid linkage operation mode.

2 and 4, each of the combined power generation controller 800, the converter controller 810, and the inverter controller 820 may be pre-determined according to a determination result of the solar power generation in the independent operation mode. One control mode of the set first and second independent control modes may be performed. Here, the first independent control mode is a control mode in which solar power is generated during independent operation without grid linkage, and the second independent control mode is a control mode without solar power during independent operation without grid linkage.

Hereinafter, in the solar-fuel cell combined cycle power generation system according to the present invention with reference to FIGS. 5 and 6, the first grid linkage-control mode without solar power and the second grid linkage-control with solar power generation during grid linkage operation. The mode will be described.

5 and 6, the converter controller 810 may include a first calculator 811, a first control value compensator 812, and a first PWM controller 813. The 820 may include a second calculator 821, a second control value compensator 822, and a second PWM controller 823.

First, referring to FIG. 5, a first grid linkage-control mode of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 5, the first calculator 811 of the converter controller 810 calculates a first control error value for the constant power control with respect to the DC / DC converter 200 to generate the first control value. Output to the compensator 812. The first control value compensator 812 compensates the converter control value VC-con by using the first control error value from the first calculator 811 and outputs the compensating converter control value VC-con to the first PWM controller 813. . The first PWM controller 813 generates a PWM converter control signal PWM-con by using the converter control value VC-con compensated by the first control value compensator 812. An operation of the DC / DC converter 200 may be controlled by using a PWM converter control signal.

At this time, the first calculating unit 811 of the converter controller 810 divides a predetermined FC power command value P * FC by the FC output voltage VFC in the first grid linkage-control mode, and thus, the FC current command value. (I * FC) may be generated and the first control error value corresponding to a difference value between the FC current command value I * FC and the FC current IFC may be calculated. For example, the first control error value may correspond to a difference value obtained by subtracting the FC current IFC from the FC current command value I * FC.

Here, the first control value compensator 812 removes an error component of the converter control value VC-con by using a first control error value from the first calculator 811. Proportional Integrate) controller.

The first PWM controller 813 compares the converter control value VC-con compensated by the first control value compensator 812 with a reference signal having a predetermined triangular waveform. If the converter control value VC-con is higher than the reference signal, a high level is output. On the contrary, if the converter control value VC-con is not higher than the reference signal, a low level is output. That is, the first PWM controller 813 generates a PWM converter control signal PWM-con whose pulse width is variable according to the magnitude level of the converter control value VC-con.

In addition, referring to FIG. 5, the second calculating unit 821 of the inverter controller 820 includes a second control error value for controlling the DC link, grid linkage, and output current with respect to the DC / AC inverter unit 400. Is calculated and output to the second control value compensator 822. The second control value compensator 822 compensates the inverter control value VC-inv using the second control error value from the second calculator 821 and outputs the compensating inverter control value VC-inv to the second PWM controller 823. . The second PWM controller 823 may generate a PWM inverter control signal PWM-inv using the inverter control value VC-inv compensated by the second control value compensator 822. An operation of the DC / AC inverter unit 400 may be controlled by using a PWM inverter control signal PWM-inv.

Here, the inverter controller 820 controls the output current of the DC / AC inverter unit 400, so that the DC link voltage of the DC link unit 300 located in front of the DC / AC inverter unit 400 The output power of the DC / AC inverter unit 400 may be controlled accordingly.

In addition, the grid connection is synchronized with the phase of the AC voltage (Vac) from the filter 420 and the phase of the grid (Grid), so that the grid transmission unit of the DC / AC inverter unit 400 ( Through 430, the AC voltage Vac from the filter 420 is transferred to the grid.

In this case, the second operation unit 821 of the inverter controller 820 includes a DC link operation unit 821-2, an error correction unit 821-4, a DC / AC converter 821-6, and an error operation unit 821. -8), the DC link calculating unit 821-2 calculates a current error value corresponding to a difference value between a preset DC voltage command value V * DC and the DC voltage VDC, The current command value is compensated by the current error value and provided to the error correction unit 821-4.

Thus, the error correction unit 821-4 divides the predetermined FC power command value P * FC by the grid voltage Vgrid to calculate the current correction value Iout_ff, and the current correction value Iout−. ff) corrects the compensated current command value from the DC link calculating unit 821-2 and provides it to the DC / AC converter 821-6. The DC / AC converter 821-6 detects the phase of the grid voltage Vgrid, and synchronizes the detected phase with the current command value of the error correction part 821-4 to output an AC output current command value. It converts to (I * out) and provides it to the error calculating part 821-8. The error calculating unit 821-8 may further include the second control error corresponding to a difference value between the output current command value I * out and the output current Iout from the DC / AC converter 821-6. Create a value.

Here, for example, the current error value in the DC link calculating unit 821-2 may correspond to a difference value obtained by subtracting the DC voltage VDC from a preset DC voltage command value V * DC. The current command value compensation in the DC link operation unit 821-2 may be implemented by a proportional integral controller which removes a current error of the current command value by using a phase current error value.

First, referring to FIG. 6, a second grid linkage-control mode of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 6, the first calculator 811 of the converter controller 810 calculates a first control error value for the constant power control of the DC / DC converter 200 to compensate for the first control value. To the unit 812. The first control value compensator 812 compensates the converter control value VC-con using the first control error value from the first calculator 811 and provides it to the first PWM controller 813. The first PWM controller 813 generates a PWM converter control signal PWM-con by using the converter control value VC-con compensated by the first control value compensator 812. An operation of the DC / DC converter 200 may be controlled by using a PWM converter control signal.

At this time, the first calculating unit 811 of the converter controller 810 divides a predetermined FC power command value P * FC by the FC output voltage VFC in the second grid linkage-control mode, and thus, the FC current command value. (I * FC) may be generated and the first control error value corresponding to a difference value between the FC current command value I * FC and the FC current IFC may be calculated.

In addition, referring to FIG. 6, the second calculating unit 821 of the inverter controller 820 may perform a maximum power point tracking (MPPT), a DC link, a grid connection, and an output current with respect to the DC / AC inverter unit 400. The second control error value for the control is calculated and provided to the second control value compensator 822. The second control value compensator 822 compensates the inverter control value VC-inv by using the second control error value from the second calculator 821 and provides it to the second PWM controller 823. The second PWM controller 823 may generate a PWM inverter control signal PWM-inv using the inverter control value VC-inv compensated by the second control value compensator 822. An operation of the DC / AC inverter unit 400 may be controlled by using a PWM inverter control signal PWM-inv.

In the meantime, the maximum power point tracking (MPPT) will be briefly described. When the PV power is higher than a predetermined reference power, the solar cell has a maximum power point due to its characteristics, so that the maximum power point tracking is performed in order to produce the maximum power. It refers to the control to find the maximum power point while varying one of the resistance, voltage and current related to.

At this time, the second operation unit 821 of the inverter controller 820 includes a maximum power point tracking unit 821-1, a DC link operation unit 821-2, an error correction unit 821-4, and DC / AC conversion. In the case of including the unit 821-6 and the error calculating unit 821-8, the maximum power point tracking unit 821-1 uses a maximum of the PV output voltage VPV and the current IPV. Maximum power point tracking (MPPT) is performed to generate a PV output voltage command value (V * PV) and provide it to the DC link operation unit 821-2. The DC link calculating unit 821-2 calculates a voltage error value corresponding to a difference value between the PV output voltage VPV and the PV output voltage command value V * PV, and outputs an output current command value as the voltage error value. To compensate for the error correction unit 821-4.

Subsequently, the error correction unit 821-4 calculates a power command value by adding a preset FC power command value P * FC and a preset PV power command value P * PV, and calculates the power command value from the grid voltage. Divide by (Vgrid) to calculate the current correction value Iout_ff, and correct the current error value of the DC link operation unit 821-2 by using the current compensation value Iout-ff to convert the DC / AC converter 821. -6). The DC / AC converter 821-6 detects a phase of the grid voltage Vgrid, converts the current command value into an AC output current command value I * out in synchronization with the detected phase, and an error. It provides to the calculating part 821-8. The error calculator 821-8 controls the second control corresponding to a difference value between the output current command value I * out and the output current Iout from the DC / AC converter 821-6. Error value can be generated.

Hereinafter, in the solar-fuel cell combined cycle power generation system according to the present invention with reference to Figures 7 and 8, for the first independent control mode with solar power and the second independent control mode without solar power in independent operation Explain.

7 and 8, the converter controller 810 may include a first calculator 811, a first control value compensator 812, and a first PWM controller 813. The 820 may include a second calculator 821, a second control value compensator 822, and a second PWM controller 823.

First, referring to FIG. 7, a first independent control mode of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 7, the first calculator 811 of the converter controller 810 calculates a first control error value for current control with respect to the DC / DC converter 200, and thus, a first control value compensator. Provided at 812. The first control value compensator 812 compensates the converter control value VC-con using the first control error value from the first calculator 811 and provides it to the first PWM controller 813. . The first PWM controller 813 generates a PWM converter control signal PWM-con by using the converter control value VC-con compensated by the first control value compensator 812. An operation of the DC / DC converter 200 may be controlled by using a PWM converter control signal.

At this time, the first operation unit 811 of the converter controller 810, in each of the first grid linkage-control mode, the second grid linkage-control mode and the first independent control mode, the predetermined FC power command value (P). * FC is divided by the FC output voltage VFC to generate an FC current command value I * FC, and the first corresponding to a difference value between the FC current command value I * FC and the FC current IFC. The control error value can be calculated.

Here, the output power Pout is calculated using the AC voltage Vac and the output current Iout of the DC / AC inverter unit 400, and the PV output voltage VPV and the current of the solar cell 120 are calculated. The PV power PPV is calculated using IPV, and the FC power command value P * FC may correspond to a difference value between the output power Pout and the PV power PPV.

In addition, referring to FIG. 7, the second calculating unit 821 of the inverter controller 820 may control the maximum power point tracking (MPPT), the DC link, and the output constant voltage control with respect to the DC / AC inverter unit 400. The second control error value is calculated and provided to the second control value compensator 822. The second control value compensator 822 compensates the inverter control value VC-inv by using the second control error value from the second calculator 821 and provides it to the second PWM controller 823. . The second PWM controller 823 generates the PWM inverter control signal PWM-inv using the inverter control value VC-inv compensated by the second control value compensator 822, and generates the PWM inverter. An operation of the DC / AC inverter unit 400 may be controlled by using a control signal PWM-inv.

In this case, the second calculating unit 821 of the inverter controller 820 includes a maximum power point tracking unit 821-1, a DC link calculating unit 821-2, a DC / AC converter 821-6, and an error calculating unit. In the case of including 821-8, the maximum power point tracking unit 821-1 tracks a predetermined maximum power point tracking (MPPT) using the PV output voltage (VPV) and the current (IPV). Tracking) to generate the PV output voltage command value (V * PV) and provide it to the DC link operation unit 821-2.

Thus, the DC link calculating unit 821-2 calculates a voltage error value corresponding to a difference value between the PV output voltage VPV and the PV output voltage command value V * PV, and calculates the voltage error value as the voltage error value. The output voltage command value V * out is compensated for and provided to the DC / AC converter 821-6. The DC / AC converter 821-6 converts the output voltage command value from the DC link operation unit 821-2 to an output voltage command value V * out of AC and converts the output voltage command value into an error calculation unit 821-8. to provide. The error calculating unit 821-8 corresponds to the second value corresponding to a difference value between the output voltage command value V * out and the output voltage Vout from the DC / AC converter 821-6. A control error value can be generated.

Next, referring to FIG. 8, a second independent control mode of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 8, the first calculator 811 of the converter controller 810 calculates a first control error value for DC link control with respect to the DC / DC converter 200 to compensate for the first control value. To the unit 812. The first control value compensator 812 compensates the converter control value VC-con using the first control error value from the first calculator 811 and provides it to the first PWM controller 813. . The first PWM controller 813 generates a PWM converter control signal PWM-con by using the converter control value VC-con compensated by the first control value compensator 812. An operation of the DC / DC converter 200 may be controlled by using a PWM converter control signal.

At this time, the first operation unit 811 of the converter controller 810, the voltage corresponding to the difference between the predetermined DC voltage command value (V * DC) and the DC voltage (VDC) in the second independent control mode. The error value is calculated, and the voltage error value is used to compensate the predetermined FC current command value I * FC, and corresponds to a difference value between the compensated FC current command value I * FC and the FC current IFC. The first control error value may be calculated.

In addition, referring to FIG. 8, the second calculating unit 821 of the inverter controller 820 calculates a second control error value for output constant voltage control with respect to the DC / AC inverter unit 400 to control the second control unit. The value compensation unit 822 is provided. The second control value compensator 822 compensates the inverter control value VC-inv by using the second control error value from the second calculator 821 and provides it to the second PWM controller 823. . The second PWM controller 823 may generate a PWM inverter control signal PWM-inv using the inverter control value VC-inv compensated by the second control value compensator 822. An operation of the DC / AC inverter unit 400 may be controlled by using a PWM inverter control signal PWM-inv.

In this case, in the second independent control mode, the second calculating unit 821 of the inverter controller 820 may be configured to correspond to a difference value between the AC voltage command value V * ac and the AC voltage Vac. Two control error values can be generated.

Hereinafter, a control method of the solar-fuel cell hybrid power generation system of the present invention will be described with reference to FIGS. 2, 3, 4, and 9 to 14.

2, 3, and 9 to 14, the combined photovoltaic-fuel cell power generation method according to the third and fourth embodiments of the present invention, the FC output voltage from the fuel cell 110 ( DC / DC converter 200 converting VFC into a predetermined voltage, PV output voltage PVV from the solar cell 120 and FC output voltage converted from the DC / DC converter 200 DC link unit 300 for linking the VFC to generate a DC voltage (VDC), DC / AC inverter unit for converting the DC voltage (VDC) from the DC link unit 300 into a predetermined AC voltage (Vac) It can be applied to a solar-fuel cell composite power generation system including (400).

First, referring to FIG. 9, in the method for controlling a photovoltaic-fuel cell combined cycle power generation system according to a third embodiment of the present invention, first, the system start step (S50) includes a voltage required for grid linkage determination and solar power generation determination. And current.

Next, the grid-connected solar determination step (S200), if the grid-linked state is possible, performs a grid-connected operation mode, calculated from the PV output voltage (VPV) and the output current (IPV) of the solar cell 120. The solar power generation state is determined by comparing the PV power PPV and the preset minimum PV power Pmin. For example, if the PV power PPV is higher than the minimum PV power Pmin, it is determined that there is an effective solar power generation. On the contrary, if the PV power PPV is not higher than the minimum PV power Pmin, there is no effective solar power generation. It can be judged that.

Next, the first grid linkage-operation mode of the first grid linkage-control step (S400), in the grid linkage-solar determination step (S200), when there is no solar power in the grid linkage operation mode, the converter control step ( S410 and the inverter control step S420 are performed.

At this time, in the converter control step (S410), the constant power is controlled for the DC / DC converter 200. In the inverter control step (S420), the DC link, grid linkage, and output current are controlled with respect to the DC / AC inverter unit 400.

Then, the second grid linkage-operation mode of the second grid linkage-control step (S500), in the converter control step (S510), when there is solar power in the grid linkage operation mode, the converter control step (S510) And inverter control step (S510) is performed.

At this time, in the converter control step (S510), it is possible to control the electrostatic power for the DC / DC converter 200. In the inverter control step (S510), the maximum power point tracking (MPPT), DC link, grid connection, and output current may be controlled with respect to the DC / AC inverter unit 400.

Next, referring to FIG. 10, in the method for controlling a photovoltaic-fuel cell combined cycle power generation system according to a fourth embodiment of the present invention, first, in a system start step (S50), voltage required for grid linkage determination and solar power generation determination. And current.

Next, in the operation mode determination step (S100), it is determined whether the grid-connected operation mode or the independent operation mode according to the grid voltage (Vgrid).

Next, in the grid-connected solar determination step (S200), when the grid-connected operation mode is performed, the PV power (PPV) calculated from the PV output voltage (VPV) and the output current (IPV) of the solar cell 120 is preset. Solar power generation is determined by comparing the minimum PV power (Pmin).

Next, in the independent-solar determination step (S300), when the independent operation mode is performed, the solar power generation state is determined by comparing the PV power (PPV) of the solar cell 120 with a predetermined minimum PV power (Pmin).

Next, the first grid linkage-operation mode of the first grid linkage-control step (S400), in the grid linkage-solar determination step (S200), when there is no solar power in the grid linkage operation mode, the converter control step ( S410 and the inverter control step S420 are performed. That is, in the converter control step (S410), the constant power is controlled for the DC / DC converter 200. In the inverter control step (S420), the DC link, grid linkage, and output current are controlled with respect to the DC / AC inverter unit 400.

Next, the second grid linkage-operation mode of the second grid linkage-control step (S500), in the converter control step (S510), when there is solar power in the grid linkage operation mode, the converter control step (S510) and Inverter control step S510 is performed. That is, in the converter control step (S510), it is possible to control the constant power for the DC / DC converter unit 200, and in the inverter control step (S510) to the maximum for the DC / AC inverter unit 400 Power point tracking (MPPT), direct current link, grid linkage and output current can be controlled.

Next, the first independent operation mode of the first independent control step (S600), the converter control step (S610) and the inverter control step when there is solar power in the independent operation mode in the independent-sun determination step (S300) (S620) is performed. That is, the converter control step (S610) can control the current for the DC / DC converter unit 200, and in the inverter control step (S620) the maximum power point for the DC / AC inverter unit 400. Tracking (MPPT), direct current link and output constant voltage can be controlled.

Next, the second independent operation mode of the second independent control step (S700), in the independent-sun determination step (S300), when there is no solar power in the independent operation mode, the converter control step (S710) and the inverter control Step S720 is performed. That is, the converter control step (S710) can control the DC link for the DC / DC converter unit 200, and in the inverter control step (S720) output constant voltage for the DC / AC inverter unit 400 Can be controlled.

In the third and fourth embodiments of the present invention, the system start step (S50), the operation mode determination step (S100). Grid-connected solar determination step (S200), independent-solar determination step (S300), the first grid linkage-control step (S400) and the second grid linkage-control step (S500), respectively, of the fuel cell 110 FC output voltage (VFC) and current (IFC), PV output voltage (VPV) and current (IPV) of the solar cell 120, AC voltage (Vac) and output current of the DC / AC inverter unit 400 ( Iout) and the grid voltage Vgrid may be detected in the grid of the commercial power supply 600, respectively.

In addition, each of the first independent control step and the first independent control step may include an FC output voltage VFC and a current IFC of the fuel cell 110 and a PV output voltage of the solar cell 120. VPV) and current (IPV), AC voltage (Vac) and output current (Iout) of the DC / AC inverter unit 400 can be detected.

11 and 12, a control method of a solar-fuel cell combined cycle power generation system according to the present invention includes a first grid linkage that performs a first grid linkage-control mode without solar power during grid linkage operation. A second grid linkage-control step (S500) of performing the control step (S400) and the second grid linkage-control mode with solar power generation is performed.

First, referring to FIG. 11, in the control method of the solar-fuel cell combined cycle power generation system of the present invention, a first grid linkage-control step (S400) performing a first grid linkage-control mode will be described.

Referring to FIG. 11, in the first calculation step S411 of the converter control step S410 of the first grid linkage-control step S400, the DC / DC converter 200 may be configured to control the constant power. The first control error value is calculated and provided to the first control value compensation step (S412). In the first control value compensation step (S412), the converter control value (VC-con) is compensated by using the first control error value from the first calculation step (S411) to the first PWM control step (S413). to provide. In the first PWM control step S413, a PWM converter control signal PWM-con is generated using the converter control value VC-con compensated in the first control value compensation step S412, and the An operation of the DC / DC converter 200 may be controlled by using a PWM converter control signal.

At this time, the first calculation step (S411) of the first grid linkage-control step (S400), the predetermined FC power command value (P * FC) divided by the FC output voltage (VFC) FC current command value (I * FC). ) And calculate the first control error value corresponding to the difference between the FC current command value I * FC and the FC current IFC.

In addition, referring to Figure 11, in the second calculation step (S421) of the inverter control step (S420) of the first grid linkage-control step (S400), the DC link, for the DC / AC inverter unit 400, A second control error value for grid linkage and output current control is calculated and provided to the second control value compensation step (S422). In the second control value compensation step (S422), the inverter control value (VC-inv) is compensated by using the second control error value from the second calculation step (S421) to the second PWM control step (S423). to provide. In the second PWM control step S423, a PWM inverter control signal PWM-inv is generated using the inverter control value VC-inv compensated in the second control value compensation step S422. The operation of the DC / AC inverter unit 400 may be controlled using the PWM inverter control signal PWM-inv.

At this time, in the DC link calculation step (S421-2) of the second calculation step (S421) of the first grid linkage-control step (S400), a preset DC voltage command value (V * DC) and the DC voltage (VDC). The current error value corresponding to the difference between and is calculated, and the current command value is compensated by the current error value and provided to the error correction step (S421-4). In the error correction step (S421-4), the predetermined FC power command value (P * FC) is divided by the grid voltage (Vgrid) to calculate a current correction value (Iout_ff), and to the current correction value (Iout-ff). The compensated current command value from the DC link operation step S421-2 is corrected and provided to the DC / AC conversion step S421-6.

Subsequently, in the DC / AC conversion step S421-6, the phase of the grid voltage Vgrid is detected, and the current command value of the error correction step S421-4 is outputted in synchronization with the detected phase. The current command value I * out is converted to the error calculation step S421-8. In the error calculation step S421-8, the second corresponding to the difference value between the output current command value I * out and the output current Iout from the DC / AC conversion step S421-6. A control error value can be generated.

Next, referring to FIG. 12, a second grid linkage-control step S500 of performing a second grid linkage-control mode in the control method of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 12, in the first calculation step S511 of the converter control step S510 of the second grid linkage-control step S500, the DC / DC converter 200 may be configured to control the constant power. The first control error value is calculated and provided to the first control value compensation step S512. In the first control value compensation step S512, the converter control value VC-con is compensated using the first control error value from the first calculation step S511 to the first PWM control step S513. to provide. In the first PWM control step S513, a PWM converter control signal PWM-con is generated using the converter control value VC-con compensated in the first control value compensation step S512. The operation of the DC / DC converter 200 may be controlled using the PWM converter control signal.

At this time, the first calculation step (S511) of the second grid linkage-control step (S500), by dividing a predetermined FC power command value (P * FC) by the FC output voltage (VFC) FC current command value (I * FC). ) And calculate the first control error value corresponding to the difference between the FC current command value I * FC and the FC current IFC.

12, in the second calculation step S521 of the inverter control step S520 of the second grid linkage-control step S500, the maximum power point with respect to the DC / AC inverter unit 400 is obtained. A second control error value for tracking (MPPT), DC link, grid connection, and output current control is calculated and provided to the second control value compensation step (S522). In the second control value compensation step (S522), the inverter control value (VC-inv) is compensated by using the second control error value from the second calculation step (S521) to the second PWM control step (S523). to provide. In the second PWM control step S523, a PWM inverter control signal PWM-inv is generated using the inverter control value VC-inv compensated in the second control value compensation step S522. The operation of the DC / AC inverter unit 400 may be controlled using the PWM inverter control signal PWM-inv.

At this time, in the maximum power point tracking step (S421-1) of the second calculation step (S421) of the second grid linkage-control step (S500), the PV output voltage (VPV) and the current (IPV) are used. By performing the set maximum power point tracking (MPPT), a PV output voltage command value (V * PV) is generated and provided to the DC link operation step S421-2. In the DC link operation step S421-2, a voltage error value corresponding to a difference value between the PV output voltage VPV and the PV output voltage command value V * PV is calculated and an output current is used as the voltage error value. The command value is compensated for and provided to the error correction step S421-4.

Thus, in the error correction step (S421-4), the power command value is calculated by adding the preset FC power command value P * FC and the preset PV power command value P * PV, and calculating the power command value in the system. The current correction value Iout_ff is calculated by dividing by the voltage Vgrid, and the current error value of the DC link operation step S421-2 is corrected using the current compensation value Iout-ff to convert the DC / AC. To (S421-6). In the DC / AC conversion step (S421-6), the phase of the grid voltage Vgrid is detected, and the current command value is converted into an AC output current command value I * out in synchronization with the detected phase to thereby obtain an error. It is provided to the calculation step (S421-8). In the error calculation step S421-8, the second corresponding to the difference value between the output current command value I * out and the output current Iout from the DC / AC conversion step S421-6. A control error value can be generated.

Next, referring to FIG. 13, the first independent control step S600 of performing the first independent control mode in the control method of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 13, in the first calculation step S611 of the converter control step S610 of the first independent control step S600, the first DC / DC converter 200 performs a current control for the current. The control error value is calculated and provided to the first control value compensation step (S612). In the first control value compensation step S612, the converter control value VC-con is compensated for using the first control error value from the first calculation step S611 and provided to the first PWM control step S613. do. In the first PWM control step S613, a PWM converter control signal PWM-con is generated using the converter control value VC-con compensated in the first control value compensation step S612. The operation of the DC / DC converter 200 may be controlled using the PWM converter control signal.

At this time, the first operation step (S611) of the first independent control step (S600), by dividing the predetermined FC power command value (P * FC) by the FC output voltage (VFC) FC current command value (I * FC). May be generated and the first control error value corresponding to a difference value between the FC current command value I * FC and the FC current IFC may be calculated.

Here, the output power Pout is calculated using the AC voltage Vac and the output current Iout of the DC / AC inverter unit 400, and the PV output voltage VPV and the current of the solar cell 120 are calculated. The PV power PPV is calculated using IPV, and the FC power command value P * FC may correspond to a difference value between the output power Pout and the PV power PPV.

In addition, referring to FIG. 13, in the second calculation step S621 of the inverter control step S620 of the first independent control step S600, the maximum power point tracking is performed for the DC / AC inverter unit 400. A second control error value for controlling the MPPT, the DC link, and the output constant voltage is calculated and provided to the second control value compensation step S622. In the second control value compensation step S622, the inverter control value VC-inv is compensated using the second control error value from the second calculation step S621 to the second PWM control step S623. to provide.

In the second PWM control step S623, a PWM inverter control signal PWM-inv is generated using the inverter control value VC-inv compensated in the second control value compensation step S622. The operation of the DC / AC inverter unit 400 may be controlled using the PWM inverter control signal PWM-inv.

At this time, in the maximum power point tracking step S421-1 of the second calculation step S621 of the first independent control step S600, the PV output voltage VPV and the current IPV are preset. Maximum power point tracking (MPPT) is performed to generate a PV output voltage command value (V * PV) and provide the DC link operation step (S421-2). In the DC link operation step S421-2, a voltage error value corresponding to a difference value between the PV output voltage VPV and the PV output voltage command value V * PV is calculated, and an output voltage is used as the voltage error value. The command value V * out is compensated for and provided to the DC / AC conversion step S421-6.

In the DC / AC conversion step (S421-6), the output voltage command value from the DC link calculation step (S421-2) is converted into an output voltage command value (V * out) of AC to calculate an error (S421-8). To provide. In the error calculating step S421-8, the first voltage corresponding to the difference value between the output voltage command value V * out and the output voltage Vout from the DC / AC converting step S421-6. Two control error values can be generated.

In addition, referring to FIG. 14, the second independent control step S700 of performing the second independent control mode in the control method of the solar-fuel cell combined cycle power generation system of the present invention will be described.

Referring to FIG. 14, in the first calculation step S711 of the converter control step S710 of the second independent control step S700, the DC / DC converter unit 200 may be configured to control the DC link. The first control error value is calculated and provided to the first control value compensation step (S712). In the first control value compensation step S712, the converter control value VC-con is compensated using the first control error value from the first calculation step S711 to the first PWM control step S713. to provide. In the first PWM control step S713, the PWM converter control signal PWM-con is generated using the converter control value VC-con compensated in the first control value compensation step S712. An operation of the DC / DC converter 200 may be controlled by using a PWM converter control signal.

At this time, the first operation step (S711) of the second independent control step (S700), calculates a voltage error value corresponding to the difference between the preset DC voltage command value (V * DC) and the DC voltage (VDC). The voltage error value is used to compensate the predetermined FC current command value I * FC, and corresponds to a difference value between the compensated FC current command value I * FC and the FC current IFC. 1 The control error value can be calculated.

In addition, referring to FIG. 14, in the second operation step S721 of the inverter control step S720 of the second independent control step S700, output constant voltage control is performed on the DC / AC inverter unit 400. The second control error value for the calculation is calculated and provided to the second control value compensation step (S722). In the second control value compensation step S722, the inverter control value VC-inv is compensated using the second control error value from the second calculation step S721 to the second PWM control step S723. to provide. In the second PWM control step S723, a PWM inverter control signal PWM-inv is generated using the inverter control value VC-inv compensated in the second control value compensation step S722. The operation of the DC / AC inverter unit 400 may be controlled using the PWM inverter control signal PWM-inv.

In this case, the second operation step S721 of the second independent control step S700 may include the second control error value corresponding to a difference value between the AC voltage command value V * ac and the AC voltage Vac. Can be generated.

In the combined power generation system of the present invention as described above, in terms of power control, the fuel cell generates power at a rated capacity at all times and the solar cell outputs maximum power at a power generation time by applying an algorithm to assist the fuel cell. Output power can be controlled independently. In addition, in order to supply a constant output to the load, PV can generate a maximum power, and FC can be controlled to generate a difference between the set power and the PV generated power.

In addition, the output voltage of the DC / DC converter can be operated by a voltage command value plus the voltage change due to the output voltage change of the solar cell and the MPPT control of the DC / AC inverter, the DC / AC inverter is the maximum power output of the solar cell MPPT and Inverting, grid linkage and protection coordination algorithms can be applied.

When the output of the solar cell falls below the minimum power value due to sunset or environmental factors, the MPPT mode is terminated, and after sunset, the DC / DC converter is controlled to follow the command power continuously by the power command. In addition, DC / AC inverter can perform DC link voltage control, output current control and grid connection operation.

In addition, in the hybrid power generation system and control method thereof of the present invention, a system and a control method for operating two energy sources of a solar cell and a fuel cell in combination, and driven by a single DC / DC converter unit and a single DC / AC inverter unit The single power generation controller can control the voltage, current, and power for the combined power generation, thereby reducing the material cost, system loss, and volume.

In addition, the output voltage of the solar cell is designed to be above the DC link minimum voltage for DC / AC conversion.

Accordingly, according to the complex power generation system of the present invention, first, the system efficiency is reduced by 50% compared to conventional system hardware using two DC / DC converter units and two DC / AC inverters. Second, the size of the system is reduced by about 40%, and the material cost burden is reduced by more than 30%, enabling low-cost implementation and securing price competitiveness. Third, it is possible to preoccupy the market because it is possible to realize power generation using the ultimate solar energy (PV) -fuel cell (FC) hybrid power generation system and ultimately use the pollution-free energy source.

1 is a circuit block diagram showing a solar-fuel cell combined cycle power generation system using a single converter and a single inverter according to a first embodiment of the present invention.

2 is a circuit block diagram showing a solar-fuel cell combined cycle power generation system using a single converter and a single inverter according to a second embodiment of the present invention.

Figure 3 is an output characteristic of the grid-linked operation of the solar-fuel cell combined cycle power generation system according to the present invention.

Figure 4 is an output characteristic of the independent operation of the photovoltaic-fuel cell combined cycle power generation system according to the present invention.

5 is a control conceptual diagram of a first grid-controlled mode without solar power during grid-connected operation of a solar-fuel cell combined cycle power generation system according to the present invention.

6 is a control conceptual diagram of a second grid linkage-control mode with solar power during grid linkage operation of a solar-fuel cell combined cycle power generation system according to the present invention;

7 is a control conceptual diagram of a first independent control mode with solar power during independent power generation operation of a solar-fuel cell combined cycle power generation system according to the present invention.

8 is a control conceptual diagram of a second independent control mode without solar power during the independent power generation operation of the solar-fuel cell combined cycle power generation system according to the present invention.

FIG. 9 is a flowchart illustrating a photovoltaic-fuel cell combined cycle power generation method using a single converter and a single inverter according to a third embodiment of the present invention. FIG.

FIG. 10 is a flowchart illustrating a solar-fuel cell combined cycle power generation method using a single converter and a single inverter according to a fourth embodiment of the present invention. FIG.

11 is a control flowchart of a first grid-control mode without solar power during grid-linked operation of the solar-fuel cell combined cycle power generation system according to the present invention.

12 is a control flowchart of a second grid linkage-control mode with solar power generation during grid linkage operation of the solar-fuel cell combined cycle power generation system according to the present invention.

13 is a control flowchart of a first independent control mode with solar power during the independent power generation operation of the photovoltaic-fuel cell combined cycle power generation system according to the present invention.

14 is a control flowchart of a second independent control mode without solar power during the independent power generation operation of the solar-fuel cell combined cycle power generation system according to the present invention.

Explanation of symbols on the main parts of the drawings

110: fuel cell 120: solar cell

200: DC / DC converter unit 300: DC link unit

400: DC / AC inverter unit 410: DC / AC inverter

420: filter to be converted 430: grid transmission unit

600: commercial power supply 700: voltage / current detection unit

800: combined power control unit 810: converter controller

811: first calculating unit 812: first control value compensating unit

813: First PWM controller 821: Second calculator

822: Second control value compensation unit 823: Second PWM control unit

820; Inverter controller

Claims (66)

A DC / DC converter unit converting the FC output voltage from the fuel cell into a predetermined voltage; A direct current link which connects the output terminal of the solar cell and the output terminal of the DC / DC converter unit in common and links the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter unit to generate a DC voltage. part; And DC / AC inverter unit for converting the DC voltage from the DC link unit to a predetermined AC voltage Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 1, wherein the DC link unit, A capacitor connected between a common connection node and ground connected to the output terminal of the solar cell and the output terminal of the DC / DC converter unit in common with each other Photovoltaic-fuel cell composite power generation system comprising a. The DC / AC inverter unit of claim 2, A DC / AC inverter for converting a DC voltage from the DC link unit into a DC voltage in a pulse form; A filter for converting a voltage of a pulse form of the DC / AC inverter into the AC voltage; And System transmission unit for transmitting the AC voltage from the filter to the system Photovoltaic-fuel cell composite power generation system comprising a. A DC / DC converter unit converting the FC output voltage from the fuel cell into a predetermined voltage; DC link which connects the output terminal of the solar cell and the output terminal of the DC / DC converter unit in common, and links the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter unit to generate a DC voltage. part; A DC / AC inverter unit converting a DC voltage from the DC link unit into a predetermined AC voltage; A voltage / current detector for detecting a voltage and a current generated by each of the fuel cell, the solar cell, and the DC / AC inverter unit; And A hybrid power generation control unit for controlling operations of the DC / DC converter unit and the DC / AC inverter unit based on a plurality of voltages and currents detected by the voltage / current detection unit. Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 4, wherein the DC link unit, A capacitor connected between a common connection node and a ground of which the output terminal of the solar cell and the output terminal of the DC / DC converter part are connected to each other in common Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 5, wherein the DC / AC inverter unit, A DC / AC inverter for converting the DC voltage from the DC link unit into a pulse voltage; And A filter for converting a voltage of a pulse form of the DC / AC inverter into the AC voltage; And System transmission unit for transmitting the AC voltage from the filter to the system Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 4, wherein the voltage / current detection unit, Detecting the FC output voltage and current of the fuel cell, the PV output voltage and current of the solar cell, the AC voltage and output current of the DC / AC inverter unit, and the grid voltage in a system of commercial power supply, respectively. Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 7, wherein the combined power control unit, A converter controller controlling the operation of the DC / DC converter unit using the grid voltage, the FC output voltage, and the current; And An inverter controller that controls the operation of the DC / AC inverter section based on the PV output voltage and current from the voltage / current detector; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 8, wherein each of the converter controller and inverter controller, In the grid-connected operation mode, the solar power generation state is determined according to the PV power by the PV output voltage and the current of the solar cell, and among the first and second grid-linked-control modes preset according to the determination result of the solar power generation. One control mode is performed, wherein the first grid linkage-control mode is a control mode without solar power generation in a grid-linked operation mode, and the second grid linkage-control mode includes solar power generation in a grid-linked operation mode. In control mode Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 7, wherein the combined power control unit, In the grid-connected operation mode, the solar power generation state is determined according to the PV power by the PV output voltage and the current of the solar cell, and among the first and second grid-linked-control modes preset according to the determination result of the solar power generation. One control mode is performed, wherein the first grid linkage-control mode is a control mode without solar power generation in a grid-linked operation mode, and the second grid linkage-control mode includes solar power generation in a grid-linked operation mode. In control mode Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 9, wherein the converter controller, A first calculator configured to calculate a first control error value for constant power control of the DC / DC converter in the first grid-control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And A first PWM controller which generates a PWM converter control signal using the converter control value compensated by the first control value compensator and controls the operation of the DC / DC converter unit by using the PWM converter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 11, wherein the inverter controller, A second calculator configured to calculate a second control error value for DC link, grid linkage, and output current control in the first grid linkage-control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And A second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and to control the operation of the DC / AC inverter using the PWM inverter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 12, wherein the first operation unit of the converter controller, In each of the first grid-control mode, the second grid-control mode, and the first independent-control mode, a predetermined FC power command value is divided by the FC output voltage to generate an FC current command value, and the FC current command value Calculating the first control error value corresponding to a difference value from the FC current Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 13, wherein the second operation unit of the inverter controller, In the first system linkage-control mode, a DC link calculating unit for calculating a current error value corresponding to a difference value between a predetermined DC voltage command value and the DC voltage, and compensates the current command value by the current error value; An error correction unit for dividing a predetermined FC power command value by the grid voltage to calculate a current correction value, and correcting the compensated current command value from the DC link calculating unit with the current correction value; A DC / AC converter for detecting a phase of the system voltage and converting a current command value of the error correcting unit into an AC output current command value in synchronization with the detected phase; And An error calculator configured to generate the second control error value corresponding to a difference value between the output current command value from the DC / AC converter and the output current; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 9, wherein the converter controller, A first calculator configured to calculate a first control error value for constant power control of the DC / DC converter in the second grid linkage-control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And A first PWM controller which generates a PWM converter control signal using the converter control value compensated by the first control value compensator and controls the operation of the DC / DC converter unit by using the PWM converter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 15, wherein the inverter controller, A second calculator configured to calculate a second control error value for the maximum power point tracking, the DC link, the grid linkage, and the output current control in the second grid linkage-control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And A second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and to control the operation of the DC / AC inverter using the PWM inverter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 16, wherein the first operation unit of the converter controller, In the second grid linkage-control mode, a predetermined FC power command value is divided by the FC output voltage to generate an FC current command value, and the first control error value corresponding to a difference value between the FC current command value and the FC current. Yielding Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 17, wherein the second operation unit of the inverter controller, A maximum power point tracking unit configured to generate a PV output voltage command value by performing a preset maximum power point tracking using the PV output voltage and current in the second grid linkage-control mode; A DC link calculating unit calculating a voltage error value corresponding to a difference value between the PV output voltage and the PV output voltage command value and compensating an output current command value with the voltage error value; A power command value is calculated by adding a predetermined FC power command value and a predetermined PV power command value, dividing the power command value by the grid voltage to calculate a current correction value, and using the current compensation value, the current error value of the DC link operation unit. Error correction to correct the error; A DC / AC converter for detecting a phase of the system voltage and converting the current command value to an AC output current command value in synchronization with the detected phase; And An error calculator configured to generate the second control error value corresponding to a difference value between the output current command value from the DC / AC converter and the output current; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 8, wherein each of the converter controller and inverter controller, Determine whether or not grid connection according to the grid voltage, and determine the state of solar power according to the PV power by the PV output voltage and current of the solar cell, and the first and the first predetermined and pre-set according to whether or not the grid connection Perform a control mode of two grid linkage-control modes and one of the first and second independent-control modes; The first grid linkage-control mode is a control mode without solar power generation in the grid linkage operation mode, and the second grid linkage-control mode is a control mode with solar power generation in the grid linkage operation mode, wherein the first independent The control mode is a control mode in which solar power is generated during independent operation without grid linkage, and the second independent control mode is a control mode in which solar power is generated during independent operation without grid linkage. Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 7, wherein the combined power control unit, It is determined whether it is a grid-connected operation mode or an independent operation mode according to the grid voltage, and in each of the grid-connected operation mode and the independent operation mode, the solar power generation state is determined according to the PV power by the PV output voltage and the current of the solar cell. To perform one of the preset first and second grid connection-control modes and one of the first and second independent control modes. The first grid linkage-control mode is a control mode without solar power generation in the grid linkage operation mode, and the second grid linkage-control mode is a control mode with solar power generation in the grid linkage operation mode, wherein the first independent The control mode is a control mode in which solar power is generated during independent operation without grid linkage, and the second independent control mode is a control mode in which solar power is generated during independent operation without grid linkage. Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 19, wherein the converter controller, A first calculator configured to calculate a first control error value for constant power control of the DC / DC converter in the first grid-control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And A first PWM controller which generates a PWM converter control signal using the converter control value compensated by the first control value compensator and controls the operation of the DC / DC converter unit by using the PWM converter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 21, wherein the inverter controller, A second calculator configured to calculate a second control error value for DC link, grid linkage, and output current control with respect to the DC / AC inverter in the first grid linkage-control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And A second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and to control the operation of the DC / AC inverter using the PWM inverter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 22, wherein the first operation unit of the converter controller, In the first system linkage-control mode, a predetermined FC power command value is divided by the FC output voltage to generate an FC current command value, and the first control error value corresponding to a difference value between the FC current command value and the FC current. Yielding Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 23, wherein the second operation unit of the inverter controller, In the first system linkage-control mode, a DC link calculating unit for calculating a current error value corresponding to a difference value between a predetermined DC voltage command value and the DC voltage, and compensates the current command value by the current error value; An error correction unit for dividing a predetermined FC power command value by the grid voltage to calculate a current correction value, and correcting the compensated current command value from the DC link calculating unit with the current correction value; A DC / AC converter for detecting a phase of the system voltage and converting a current command value of the error correcting unit into an AC output current command value in synchronization with the detected phase; And An error calculator configured to generate the second control error value corresponding to a difference value between the output current command value from the DC / AC converter and the output current; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 19, wherein the converter controller, A first calculator configured to calculate a first control error value for constant power control of the DC / DC converter in the second grid linkage-control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And A first PWM controller which generates a PWM converter control signal using the converter control value compensated by the first control value compensator and controls the operation of the DC / DC converter unit by using the PWM converter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 25, wherein the inverter controller, A second calculator configured to calculate a second control error value for the maximum power point tracking, the DC link, the grid linkage, and the output current control in the second grid linkage-control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And A second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and to control the operation of the DC / AC inverter using the PWM inverter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 26, wherein the first calculator of the converter controller, In the second grid linkage-control mode, a predetermined FC power command value is divided by the FC output voltage to generate an FC current command value, and the first control error value corresponding to a difference value between the FC current command value and the FC current. Yielding Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 27, wherein the second operation unit of the inverter controller, A maximum power point tracking unit configured to generate a PV output voltage command value by performing a preset maximum power point tracking using the PV output voltage and current in the second grid linkage-control mode; A DC link calculating unit calculating a voltage error value corresponding to a difference value between the PV output voltage and the PV output voltage command value and compensating an output current command value with the voltage error value; A power command value is calculated by adding a predetermined FC power command value and a predetermined PV power command value, dividing the power command value by the grid voltage to calculate a current correction value, and using the current compensation value, the current error value of the DC link operation unit. Error correction to correct the error; A DC / AC converter for detecting a phase of the system voltage and converting the current command value to an AC output current command value in synchronization with the detected phase; And An error calculator configured to generate the second control error value corresponding to a difference value between the output current command value from the DC / AC converter and the output current; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 19, wherein the converter controller, A first calculator for calculating a first control error value for current control for the DC / DC converter in the first independent control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And A first PWM controller which generates a PWM converter control signal using the converter control value compensated by the first control value compensator and controls the operation of the DC / DC converter unit by using the PWM converter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 29, wherein the inverter controller, A second calculator configured to calculate a second control error value for the maximum power point tracking, the DC link, and the output constant voltage control for the DC / AC inverter in the first independent control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And A second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and to control the operation of the DC / AC inverter using the PWM inverter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 30, wherein the first operation unit of the converter controller, In each of the first grid-control mode, the second grid-control mode, and the first independent-control mode, a predetermined FC power command value is divided by the FC output voltage to generate an FC current command value, and the FC current command value Calculating the first control error value corresponding to a difference value from the FC current Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 31, wherein the first operation unit of the converter controller, In the first independent control mode, the output power is calculated using the AC voltage and the output current of the DC / AC inverter unit, the PV power is calculated using the PV output voltage and the current of the solar cell, and the output Obtaining the FC power command value corresponding to a difference between power and PV power Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 32, wherein the second operation unit of the inverter controller, In the first independent control mode, the maximum power point tracking unit for generating a PV output voltage command value by performing a predetermined maximum power point tracking using the PV output voltage and current; A DC link calculating unit calculating a voltage error value corresponding to a difference between the PV output voltage and the PV output voltage command value and compensating an output voltage command value with the voltage error value; A DC / AC converter for converting an output voltage command value from the DC link calculator into an AC output voltage command value; And An error calculator configured to generate the second control error value corresponding to a difference value between the output voltage command value from the DC / AC converter and the output voltage; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 19, wherein the converter controller, A first calculator for calculating a first control error value for DC link control in the second independent control mode; A first control value compensator for compensating a converter control value using a first control error value from the first calculator; And A first PWM controller which generates a PWM converter control signal using the converter control value compensated by the first control value compensator and controls the operation of the DC / DC converter unit by using the PWM converter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 34, wherein the inverter controller, A second calculator configured to calculate a second control error value for output constant voltage control with respect to the DC / AC inverter in the second independent control mode; A second control value compensator for compensating an inverter control value using a second control error value from the second calculator; And A second PWM controller configured to generate a PWM inverter control signal using the inverter control value compensated by the second control value compensator and to control the operation of the DC / AC inverter using the PWM inverter control signal; Photovoltaic-fuel cell composite power generation system comprising a. The method of claim 35, wherein the first operation unit of the converter controller, In the second independent control mode, a voltage error value corresponding to a difference between a predetermined DC voltage command value and the DC voltage is calculated, and the voltage error value is used to compensate the predetermined FC current command value, and the compensated Calculating the first control error value corresponding to a difference value between an FC current command value and the FC current; Photovoltaic-fuel cell composite power generation system, characterized in that. The method of claim 36, wherein the second operation unit of the inverter controller, In the second independent control mode, generating the second control error value corresponding to a difference value between the AC voltage command value and the AC voltage. Photovoltaic-fuel cell composite power generation system characterized in that. delete delete delete delete delete DC / DC converter for converting the FC output voltage from the fuel cell to a predetermined voltage, DC for linking the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter to generate a DC voltage In the control method of the photovoltaic-fuel cell combined cycle power generation system comprising a link unit, a DC / AC inverter unit for converting the DC voltage from the DC link unit to a predetermined AC voltage, A system start step of detecting voltage and current required for grid linkage determination and solar power generation determination; When the grid connection is possible, the grid connection operation mode is performed by comparing the PV power calculated from the PV output voltage and the output current of the solar cell with a predetermined minimum PV power to determine the solar power generation status. step; In the grid-connected solar determination step, when there is no solar power generation in the grid-connected operation mode, a converter control step of controlling the electrostatic power for the DC / DC converter unit, DC link, grid-linked for the DC / AC inverter And a first grid linkage-control step of performing a first grid linkage-operation mode having an inverter control step of controlling the output current. And In the grid-connected solar determination step, if there is solar power in grid-connected operation mode, the converter control step of controlling the electrostatic power for the DC / DC converter unit, tracking the maximum power point for the DC / AC inverter, A second grid linkage-control step of performing a second grid linkage-operation mode having an inverter control step of controlling the DC link, the grid linkage and the output current, The system start step, operation mode determination step, grid connection-sun determination step, independent-sun determination step, the first grid connection-control step and the second grid connection-control step, respectively, The FC output voltage and current of the fuel cell, the PV output voltage and current of the solar cell, the AC voltage and output current of the DC / AC inverter unit, and the grid voltage in the system of commercial power, respectively,       The converter control step of the first grid-control step is, A first calculating step of calculating a first control error value for constant power control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And A first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step, and controlling the operation of the DC / DC converter unit using the PWM converter control signal; , The inverter control step of the first grid linkage-control step, A second calculation step of calculating a second control error value for DC link, grid linkage, and output current control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And A second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal; ,       The first calculation step of the first grid linkage-control step may include: Generating a FC current command value by dividing a predetermined FC power command value by the FC output voltage, and calculating the first control error value corresponding to a difference between the FC current command value and the FC current,       The second calculation step of the first grid linkage-control step may include: A DC link calculation step of calculating a current error value corresponding to a difference value between a preset DC voltage command value and the DC voltage, and compensating the current command value with the current error value; An error correction step of dividing a predetermined FC power command value by the grid voltage to calculate a current correction value, and correcting the compensated current command value from the DC link calculating step with the current correction value; A DC / AC conversion step of detecting a phase of the grid voltage and converting a current command value of the error correction step into an output current command value of AC in synchronization with the detected phase; And An error calculation step of generating the second control error value corresponding to a difference value between the output current command value and the output current from the DC / AC conversion step; Control method of a photovoltaic-fuel cell composite power generation system comprising a. delete delete delete DC / DC converter for converting the FC output voltage from the fuel cell to a predetermined voltage, DC for linking the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter to generate a DC voltage In the control method of the photovoltaic-fuel cell combined cycle power generation system comprising a link unit, a DC / AC inverter unit for converting the DC voltage from the DC link unit to a predetermined AC voltage, A system start step of detecting voltage and current required for grid linkage determination and solar power generation determination; When the grid connection is possible, the grid connection operation mode is performed by comparing the PV power calculated from the PV output voltage and the output current of the solar cell with a predetermined minimum PV power to determine the solar power generation status. step; In the grid-connected solar determination step, when there is no solar power generation in the grid-connected operation mode, a converter control step of controlling the electrostatic power for the DC / DC converter unit, DC link, grid-linked for the DC / AC inverter And a first grid linkage-control step of performing a first grid linkage-operation mode having an inverter control step of controlling the output current. And In the grid-connected solar determination step, if there is solar power in grid-connected operation mode, the converter control step of controlling the electrostatic power for the DC / DC converter unit, tracking the maximum power point for the DC / AC inverter, A second grid linkage-control step of performing a second grid linkage-operation mode having an inverter control step of controlling the DC link, the grid linkage and the output current, The system start step, operation mode determination step, grid connection-sun determination step, independent-sun determination step, the first grid connection-control step and the second grid connection-control step, respectively, The FC output voltage and current of the fuel cell, the PV output voltage and current of the solar cell, the AC voltage and output current of the DC / AC inverter unit, and the grid voltage in the system of commercial power, respectively,       The converter control step of the second grid linkage-control step may include: A first calculating step of calculating a first control error value for constant power control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And A first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step, and controlling the operation of the DC / DC converter unit using the PWM converter control signal; ,       The inverter control step of the second grid linkage-control step, Calculating a second control error value for the maximum power point tracking, the DC link, the grid connection, and the output current control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And A second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal; ,       The first calculation step of the second grid linkage-control step may include: Generating a FC current command value by dividing a predetermined FC power command value by the FC output voltage, and calculating the first control error value corresponding to a difference between the FC current command value and the FC current,       The second calculation step of the second grid linkage-control step may include: A maximum power point tracking step of generating a PV output voltage command value by performing a preset maximum power point tracking using the PV output voltage and current; Calculating a voltage error value corresponding to a difference value between the PV output voltage and the PV output voltage command value and compensating an output current command value with the voltage error value; A power setpoint is calculated by adding a predetermined FC power setpoint and a predetermined PV power setpoint, dividing the power setpoint by the grid voltage to calculate a current correction value, and using the current compensation value, the current error of the DC link operation step. An error correction step of correcting a value; A DC / AC conversion step of detecting a phase of the grid voltage and converting the current command value to an AC output current command value in synchronization with the detected phase; And An error calculation step of generating the second control error value corresponding to a difference value between the output current command value and the output current from the DC / AC conversion step; Control method of a photovoltaic-fuel cell composite power generation system comprising a. DC / DC converter for converting the FC output voltage from the fuel cell to a predetermined voltage, DC for linking the PV output voltage from the solar cell and the converted FC output voltage from the DC / DC converter to generate a DC voltage In the control method of the photovoltaic-fuel cell combined cycle power generation system comprising a link unit, a DC / AC inverter unit for converting the DC voltage from the DC link unit to a predetermined AC voltage, A system start step of detecting voltage and current required for grid linkage determination and solar power generation determination; An operation mode determination step of determining whether the system-linked operation mode or the independent operation mode is based on the system voltage; A grid connection-sun determination step of determining a solar power generation state by comparing the PV power calculated from the PV output voltage and the output current of the solar cell with a predetermined minimum PV power when the grid connection operation mode is performed; An independent-sun determination step of determining a solar power generation state by comparing the PV power of the solar cell with a preset minimum PV power when the independent operation mode is performed; In the grid-connected solar determination step, when there is no solar power generation in the grid-connected operation mode, a converter control step of controlling the electrostatic power for the DC / DC converter unit, DC link, grid-linked for the DC / AC inverter And a first grid linkage-control step of performing a first grid linkage-operation mode having an inverter control step of controlling the output current. In the grid-connected solar determination step, if there is solar power in grid-connected operation mode, the converter control step of controlling the electrostatic power for the DC / DC converter unit, tracking the maximum power point for the DC / AC inverter, A second grid linkage-control step of performing a second grid linkage-operation mode having an inverter control step of controlling the DC link, the grid linkage and the output current; In the independent-sun determination step, when there is solar power in the independent operation mode, the converter control step of controlling the current for the DC / DC converter unit, the maximum power point tracking, DC link and A first independent control step of performing a first independent operation mode having an inverter control step of controlling an output current; And In the independent-sun determination step, when there is no solar power in the independent operation mode, the converter control step of controlling the DC link for the DC / DC converter unit, and the inverter control for controlling the output constant voltage for the DC / AC inverter Second independent-control step of performing a second independent-operation mode having the step Control method of a photovoltaic-fuel cell composite power generation system comprising a. 49. The method of claim 48, wherein each of the system start step, the operation mode determination step, the grid connection-sun determination step, the independent-sun determination step, the first grid connection-control step and the second grid connection-control step, respectively, The FC output voltage and current of the fuel cell, the PV output voltage and current of the solar cell, the AC voltage and output current of the DC / AC inverter unit, and the grid voltage in the grid of commercial power, respectively, Each of the first independent-control step and the first independent-control step, Detecting FC output voltage and current of the fuel cell, PV output voltage and current of the solar cell, AC voltage and output current of the DC / AC inverter unit Control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that. 50. The method of claim 49, wherein the converter control step of the first on-grid control step comprises: A first calculating step of calculating a first control error value for constant power control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And A first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step and controlling the operation of the DC / DC converter unit using the PWM converter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 51. The method of claim 50, wherein the inverter control step of the first on-grid control step, A second calculation step of calculating a second control error value for DC link, grid linkage, and output current control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And A second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 52. The method of claim 51, wherein the first calculating step of the first system linkage-control step comprises: Dividing a predetermined FC power command value by the FC output voltage to generate an FC current command value, and calculating the first control error value corresponding to a difference value between the FC current command value and the FC current. Control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that. 53. The method of claim 52, wherein the second calculating step of the first grid linkage-control step comprises: A DC link calculation step of calculating a current error value corresponding to a difference value between a preset DC voltage command value and the DC voltage, and compensating the current command value with the current error value; An error correction step of dividing a predetermined FC power command value by the grid voltage to calculate a current correction value, and correcting the compensated current command value from the DC link calculating step with the current correction value; A DC / AC conversion step of detecting a phase of the grid voltage and converting a current command value of the error correction step into an output current command value of AC in synchronization with the detected phase; And An error calculation step of generating the second control error value corresponding to a difference value between the output current command value and the output current from the DC / AC conversion step; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 50. The method of claim 49, wherein the converter control step of the second grid linkage-control step comprises: A first calculating step of calculating a first control error value for constant power control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And A first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step and controlling the operation of the DC / DC converter unit using the PWM converter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 55. The method of claim 54, wherein the inverter control step of the second grid linkage-control step, Calculating a second control error value for the maximum power point tracking, the DC link, the grid connection, and the output current control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And A second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 56. The method of claim 55, wherein the first calculating step of the second grid linkage-control step comprises: Dividing a predetermined FC power command value by the FC output voltage to generate an FC current command value, and calculating the first control error value corresponding to a difference value between the FC current command value and the FC current. Control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that. 59. The method of claim 56, wherein the second calculating step of the second grid-controlling step comprises: A maximum power point tracking step of generating a PV output voltage command value by performing a preset maximum power point tracking using the PV output voltage and current; Calculating a voltage error value corresponding to a difference value between the PV output voltage and the PV output voltage command value and compensating an output current command value with the voltage error value; A power setpoint is calculated by adding a predetermined FC power setpoint and a predetermined PV power setpoint, dividing the power setpoint by the grid voltage to calculate a current correction value, and using the current compensation value, the current error of the DC link operation step. An error correction step of correcting a value; A DC / AC conversion step of detecting a phase of the grid voltage and converting the current command value to an AC output current command value in synchronization with the detected phase; And An error calculation step of generating the second control error value corresponding to a difference value between the output current command value and the output current from the DC / AC conversion step; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 50. The converter control of claim 49 wherein the converter control step of the first independent control step comprises: A first calculation step of calculating a first control error value for current control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And A first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step and controlling the operation of the DC / DC converter unit using the PWM converter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 59. The method of claim 58, wherein the inverter control step of the first independent control step comprises: Calculating a second control error value for the maximum power point tracking, the DC link, and the output constant voltage control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And A second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 60. The method of claim 59, wherein the first calculating step of the first independent control step comprises: Dividing a predetermined FC power command value by the FC output voltage to generate an FC current command value, and calculating the first control error value corresponding to a difference value between the FC current command value and the FC current. Control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that. 61. The method of claim 60, wherein the first computing step of the first independent control step comprises: The output power is calculated using the AC voltage and the output current of the DC / AC inverter unit, the PV power is calculated using the PV output voltage and the current of the solar cell, and the difference between the output power and the PV power is calculated. Obtaining the corresponding FC power setpoint Control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that. 61. The method of claim 60, wherein the second calculating step of the first independent control step comprises: A maximum power point tracking step of generating a PV output voltage command value by performing a preset maximum power point tracking using the PV output voltage and current; Calculating a voltage error value corresponding to a difference value between the PV output voltage and the PV output voltage command value and compensating an output voltage command value with the voltage error value; A DC / AC conversion step of converting the voltage command value from the DC link calculating step into an output voltage command value of AC; And An error calculation step of generating the second control error value corresponding to a difference value between the output voltage command value from the DC / AC conversion step and the output voltage; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 50. The converter control of claim 49 wherein the converter control step of the second independent control step comprises: A first calculating step of calculating a first control error value for DC link control with respect to the DC / DC converter; A first control value compensation step of compensating a converter control value using the first control error value from the first calculation step; And A first PWM control step of generating a PWM converter control signal using the converter control value compensated in the first control value compensation step and controlling the operation of the DC / DC converter unit using the PWM converter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 66. The method of claim 63 wherein the inverter control step of the second independent control step comprises: Calculating a second control error value for output constant voltage control with respect to the DC / AC inverter; A second control value compensation step of compensating the inverter control value using the second control error value from the second calculation step; And A second PWM control step of generating a PWM inverter control signal using the inverter control value compensated in the second control value compensation step and controlling the operation of the DC / AC inverter using the PWM inverter control signal; Control method of a photovoltaic-fuel cell composite power generation system comprising a. 65. The method of claim 64, wherein the first calculating step of the second independent control step comprises: A voltage error value corresponding to a difference between a preset DC voltage command value and the DC voltage is calculated, and the FC error command value is compensated using the voltage error value, and the compensated FC current command value and the FC current are calculated. Calculating the first control error value corresponding to the difference value Control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that. 66. The method of claim 65 wherein the second calculating step of the second independent control step comprises: Generating the second control error value corresponding to a difference value between the AC voltage command value and the AC voltage; A control method of a photovoltaic-fuel cell combined cycle power generation system, characterized in that.

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