JP6592590B2 - Photovoltaic power converter and solar power generation system - Google Patents

Description

  The present invention relates to a power converter for photovoltaic power generation and a photovoltaic power generation system.

  The solar power generation power conversion device is a power conversion device that converts DC power generated by a solar panel into AC power and supplies power to the power system.

  One example of a photovoltaic power converter is a chopper and an inverter. In this method, the DC power output from the solar panel is boosted by a chopper, the inverter converts the DC power output from the chopper into AC power having a commercial frequency, and transmits the AC power to the power system. Another example is an inverter. In this case, the inverter converts the DC power output from the solar panel into AC power having a commercial frequency and transmits it to the power system.

  In such a power conversion device for photovoltaic power generation, generally, maximum power tracking (MPPT) control is performed so that the output power of the solar panel is maximized. The maximum power follow-up control is control that adjusts the panel voltage of the solar panel so that the output power of the solar panel becomes maximum by following the output characteristics of the solar panel that change depending on the surrounding environment. Such maximum power tracking control is performed by the chopper or inverter adjusting the panel voltage of the solar panel.

  On the other hand, electric power must always balance supply and demand. When there is too much supply for the demand for electric power, there is a risk that a stable supply of electric power may be hindered, such as a power outage. In order to avoid such a situation, the photovoltaic power conversion device is required to control the output of the solar panel in accordance with an output command from an electric power company. Patent Document 1 describes a photovoltaic power conversion apparatus that stops maximum power tracking control and suppresses output power according to an output power suppression command when output power suppression is required.

JP2013-183578

  However, when the maximum power tracking control is stopped and the output power is suppressed according to the output power suppression command, the output power suppression may not be achieved depending on the output characteristics of the solar panel. For example, when the solar panel is shaded by the influence of clouds or the like, the output characteristics of the solar panel may change greatly. Specifically, in a photovoltaic power conversion device having an output characteristic having a plurality of convex shapes without taking a convex output characteristic having a maximum value at one point, the maximum power When the follow-up control is stopped and the control for reducing the output power is performed, a situation occurs in which the output tends to increase despite the output power suppression command being issued.

  An object of the present invention is to provide a control device or the like that can appropriately suppress the output of a photovoltaic power conversion device in accordance with an output power suppression command.

In order to solve the above problems, for example, a plurality of the solar panels, a plurality of solar panels to output DC power multiple you output to the system is converted into AC power by the inverter solar power for the power converter And a control unit that outputs gate pulse signals to a plurality of inverters, and the control unit outputs the output of the power converter for photovoltaic power generation when performing an output suppression operation in order to balance power supply and demand. In response to an output upper limit command that is a signal for suppression, an output distribution control unit that outputs a panel voltage command for output suppression that is a voltage command for a plurality of solar panels when performing output suppression operation, and an output suppression operation When performing, output the gate pulse signal based on the output suppression panel voltage command, and when not performing the output suppression operation, the maximum power so that the output power of multiple solar panels is maximized And a plurality of inverter control unit for outputting a gate pulse signal based on the maximum power follow-up operation panel voltage command which is a voltage command for performing slave control, the output distribution control unit, when performing output suppression operation, when increasing the output of the photovoltaic power conversion apparatus to the system, when varying the panel voltage of the solar panel when the output of the inverter is the first inverter in the downward trend, the solar panels varying the panel voltage extra increase the output of a different second inverter from the first inverter output of the inverter tends to increase, so as to monotonously increase the output of the photovoltaic power converter or, in the case of lowering the output of the photovoltaic power conversion apparatus to the system, when varying the panel voltage of the solar panel, the output of the inverter is rising trend That when the third is of the inverter is extra reducing the output of a different fourth inverter Varying the panel voltage solar panel and a third inverter output of the inverter tends to decrease, the sun An output suppression panel voltage command is obtained and output so that the output of the photovoltaic power converter is monotonously lowered .

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the control apparatus etc. which the power converter device for photovoltaic power generation can suppress output appropriately according to an output electric power suppression instruction | command.

The structure of the 1st Example of a solar power generation system is shown. The configuration of the control unit 8 is shown. The structure of the inverter control part 9a is shown. The configuration of the inverter control units 9b to 9n is the same. The configuration of the output distribution control unit 10 is shown. When the solar panels 1a to 1n are respectively performing maximum power follow-up control, an operation example is shown when receiving an output upper limit command from the outside and suppressing the output respectively. FIG. 6 shows an example of operation shown in FIG. 5 as a time waveform. When the solar panels 1a to 1n are respectively performing maximum power tracking control, another operation example is shown when receiving an output upper limit command from the outside and suppressing the output respectively. The operation example shown in FIG. 7 is shown as a time waveform. When the solar panels 1a to 1n are respectively performing maximum power tracking control, another operation example is shown when receiving an output upper limit command from the outside and suppressing the output respectively. The operation example shown to a figure is shown as a time waveform. The structure of the 2nd Example of a solar energy power generation system is shown. When the solar panels 1a to 1n are each performing maximum power tracking control, an operation example in the case of receiving an output upper limit command from the outside and increasing the respective outputs will be shown. The operation example shown in FIG. 12 is shown as a time waveform.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a photovoltaic power converter according to the present invention and embodiments thereof will be described with reference to the drawings.

  FIG. 1 shows a configuration of a first embodiment of a photovoltaic power generation system.

  The solar power generation system of the present embodiment includes solar panels 1a to 1n, inverters 2a to 2n, and a control unit 8. The solar panels 1a to 1n are connected to the DC parts of the inverters 2a to 2n, respectively, and the AC parts of the inverters 2a to 2n are connected to the three-phase power system 3. The inverters 2a to 2n convert the DC power supplied from the solar panels 1a to 1n into AC power and supply it to the power system 3. The voltage detectors 4a to 4n are provided on the output side of the solar panels 1a to 1n, and detect the output voltages of the solar panels 1a to 1n, respectively. Since the output voltages of the solar panels 1a to 1n are the same as the DC voltages of the inverters 2a to 2n, respectively, it can be said that the voltage detectors 4a to 4n detect the DC voltages of the inverters 2a to 2n. The current detectors 5a to 5n are provided on the output side of the solar panels 1a to 1n, and detect the output currents of the solar panels 1a to 1n, respectively. The output currents of the solar panels 1a to 1n are the same as the input currents to the DC parts of the inverters 2a to 2n, respectively, and it can be said that the input currents to the DC parts of the inverters 2a to 2n are detected. The voltage detectors 6a to 6n are provided on the output side of the inverters 2a to 2n, and detect the system voltage of the system to which the inverters 2a to 2n are connected. Current detectors 7a to 7n detect output currents output to the systems connected to inverters 2a to 2n, respectively. The voltage detection values and current detection values detected by the voltage detectors 4a to 4n, the current detectors 5a to 5n, the voltage detectors 6a to 6n, and the current detectors 7a to 7n are input to the control unit 8. In addition, an output upper limit command that is a signal for suppressing the output of the photovoltaic power converter is input to the control unit 8 from the outside. The control unit 8 performs a predetermined calculation based on the input voltage detection value, current detection value, and output upper limit command, and outputs a gate pulse signal for driving the inverters 2a to 2n.

  FIG. 2 shows the configuration of the control unit 8.

  The inverter control units 9a to 9n receive the output voltage and output current of the solar panels 1a to 1n, the system voltage, and the output current of the inverters 2a to 2n, respectively, and output gate pulse signals for driving the inverters 2a to 2n. To do. Further, each of the inverters 2a to 2n calculates and outputs power output to the power system 3. The output distribution control unit 10 inputs the output power of the inverters 2a to 2n output from the inverter control units 9a to 9n, the output voltage of the panels 1a to 1n, and the output upper limit command input from the outside. When the solar power generation system performs the output suppression operation, the output distribution control unit 10 outputs voltage commands to the panels 1a to 1n when performing the output suppression operation to the inverter control units 9a to 9n. Hereinafter, these commands will be referred to as an output suppression operation panel 1a voltage command, an output suppression operation panel 1b voltage command,..., An output suppression operation panel 1n voltage command. On the other hand, when the photovoltaic power generation system does not perform the output suppression operation, the output distribution control unit 10 notifies the inverter control units 9a to 9n that the output suppression operation is not performed, instead of the panel voltage command for the output suppression operation. Is output.

  FIG. 3 shows the configuration of the inverter control unit 9a. The configuration of the inverter control units 9b to 9n is the same.

  The inverter control unit 9a includes an MPPT control unit 11, an output control unit 12, a DC voltage control unit 13, a current control unit 14, a PWM control unit 15, and an output calculation unit 16. The MPPT control unit 11 receives the output voltage and output current of the solar panel 1a as input, and performs maximum power tracking control so that the output power of the solar panel 1a is maximized. That is, a voltage command for the panel 1a when the maximum power follow-up operation is performed is output. Hereinafter, this command is referred to as a maximum power follow-up operation panel 1a voltage command. The output control unit 12 inputs the maximum power follow-up operation panel 1a voltage command and the output suppression operation panel 1a voltage command output from the MPPT control unit 11, and outputs the voltage command of the panel 1a. When the solar power generation system performs the output suppression operation, the output control unit 12 outputs the output suppression operation panel 1a voltage command as the voltage command of the panel 1a. On the other hand, when the output suppression operation is not performed, the panel 1a voltage command for maximum power follow-up operation is output as the voltage command for the panel 1a. The DC voltage control unit 13 uses the panel 1a voltage command output from the output control unit 12 and the output voltage of the solar panel 1a as inputs, and creates a command for the current output from the inverter 2a. The current control unit 14 receives the current command output from the DC voltage control unit 13, the system voltage of the power system 3, and the inverter 2a output current flowing from the inverter 2a to the power system 3, and the current command and the output current match. Thus, current control is performed to output an output voltage command of the inverter 2a. The PWM controller 15 receives the voltage command output from the current controller 14 and performs PWM (Pulse Width Modulation) control, and outputs a gate pulse signal for driving the inverter 2a. The output computation unit 16 computes and outputs the power output from the inverter 2a to the power system 3 with the system voltage of the power system 3 and the inverter 2a output current flowing from the inverter 2a to the power system 3 as inputs.

  FIG. 4 shows the configuration of the output distribution control unit 10.

  The output distribution control unit 10 includes panel state determination units 17a to 17n and an output suppression operation panel voltage command calculation unit 18. Panel state determination units 17a to 17n receive the output power of inverters 2a to 2n and the output voltage of panels 1a to 1n as input, determine the panel states of panels 1a to 1n, and output the results. Here, the panel state refers to a state of whether or not the panel can reduce output. The panel voltage command calculation unit 18 for output suppression operation determines which panel is to be greatly reduced by inputting the panel state of the panels 1a to 1n output from the panel state determination units 17a to 17n and the output upper limit command from the outside, The panel voltage command of the panel is obtained, and the output suppression operation panel 1a voltage command, the output suppression operation panel 1b voltage command,..., The output suppression operation panel 1n voltage command are output. Note that which panel is greatly reduced is not limited to one panel, but may be a plurality of panels.

  FIG. 5 shows an operation example when each of the solar panels 1a to 1n is performing maximum power tracking control, receiving an output upper limit command from the outside, and suppressing the output. Here, the relationship of the panel output with respect to the panel voltage in the panel 1a, the panel 1b, and the panel 1n is described.

  When maximum power follow-up control is performed, the operating point is at points Sa, Sb,. When an output upper limit command with an upper limit value P is received from the outside, the respective operation points are output suppression operation panel 1a voltage command output by the output distribution control unit 10, output suppression operation panel 1b voltage command, ... Operates according to the output 1n voltage command. That is, for panel 1a, the operating point is from point Sa to point P1a, for panel 1b, the operating point is from point Sb to point P1b, and for panel 1n, the operating point is from point Sn to point P1n. The output of each panel is suppressed by moving in the direction. At this time, the output distribution control unit 10 determines whether or not each panel can suppress output based on the panel state determined by the panel state determination units 17a to 17n. For example, in FIG. 5, since the output characteristics of the panel 1a have a plurality of convex shapes, the output of the panel 1a is less likely to decrease as the operating point approaches the point P1a from the point Sa. It can be seen that 1a is in a state where the output cannot be suppressed. On the other hand, the panel 1b does not become difficult to decrease the output of the panel 1b even when the operating point approaches the point P1b from the point Sb, so that it can be seen that the panel 1b can suppress the output. Similarly, the panel 1n does not become difficult to decrease the output of the panel 1n even when the operating point approaches the point P1n from the point Sn, so that it can be seen that the panel 1n can also suppress the output. In this case, if the panel that can suppress other outputs instead of the panel 1a that cannot suppress the output suppresses the output excessively, the total output can be suppressed. Therefore, the panel voltage command calculation unit 18 for output suppression operation uses the panel state of the panels 1a to 1n determined by the panel state determination units 17a to 17n, for example, the output of the panel 1b instead of the panel 1a that cannot suppress the output. Output a voltage command to reduce excessively. That is, when the operating point of panel 1a moves from point P1a to point P2a, the operating point of panel 1b moves from point P1b to point P2b. The operating point of panel 1n is moved from point P1n to point P2n. Thereafter, when the operating point of panel 1a moves from point P2a to point Ga, the operating point of panel 1b moves from point P2b to point Gb. The operating point of panel 1n is moved from point P2n to point Gn. By doing in this way, it becomes possible to suppress the total output of the whole.

  FIG. 6 shows the operation example shown in FIG. 5 as a time waveform.

  As shown in FIG. 6, the output of the panels 1a to 1n monotonously decreases from time 0 to T1, but the output of the panel 1a increases at times T1 to T2, so that the panel 1b reduces the output instead. Thus, the total output of the panels 1a to 1n is reduced. At time T2 to T3, the output of the panel 1a is lowered. Instead, the output of the panel 1b is raised to prevent the output of the panel 1b from being reduced more than necessary. At time T3, the output target value of each panel is reached.

  FIG. 7 shows another example of operation when the solar panels 1a to 1n are each performing maximum power tracking control, receiving an output upper limit command from the outside, and suppressing the output.

  The difference from FIG. 5 is that instead of the panel 1a that cannot suppress the output at the point P1a, a plurality of panels such as the panel 1b and the panel 1n reduce the output excessively, thereby suppressing the total output. It is a point. Thus, the total output may be suppressed by reducing the output excessively by the plurality of panels. FIG. 8 shows the operation example shown in FIG. 7 as a time waveform as in FIG.

  FIG. 9 shows another example of operation when the solar panels 1a to 1n are each performing maximum power tracking control, receiving an output upper limit command from the outside, and suppressing the output.

  The difference from FIG. 5 is that, for example, there are states in which output cannot be suppressed by a plurality of panels, such as panel 1a and panel 1b, in which output cannot be suppressed at points P1a and P1b. In this way, even if the output cannot be suppressed by a plurality of panels, the total output may be suppressed by reducing the output of other panels excessively. FIG. 10 shows the operation example shown in FIG. 9 as a time waveform as in FIG.

  The operation of each panel output is not limited to the example shown in FIGS. 5 to 10, and the operation point of each panel may be freely selected as long as the total output of each panel is suppressed according to the output upper limit command. There is no need to align each panel output later.

  As mentioned above, when suppressing the output of the power converter for photovoltaic power generation, if there is a panel whose output temporarily rises, the other panel will reduce the output excessively, so that the total output of the panel can be reduced. It can suppress and the output of the power converter device for photovoltaic power generation can be suppressed.

  The present embodiment shows a configuration in the case where a chopper is further provided in the photovoltaic power generation system in the first embodiment.

  FIG. 11 shows a configuration of a second embodiment of the photovoltaic power generation system.

  The solar panels 1a to 1n are connected to the input parts of the choppers 19a to 19n, the output parts of the choppers 19a to 19n are connected to the direct current parts of the inverters 2a to 2n, respectively, and the alternating current parts of the inverters 2a to 2n are respectively three Connected to phase power system 3. The choppers 19a to 19n boost the DC power generated by the solar panels 1a to 1n, respectively, and supply the DC power to the DC units of the inverters 2a to 2n. The inverters 2a to 2n convert the DC power supplied from the choppers 19a to 19n into AC power and supply the AC power to the power system 3, respectively. The voltage detectors 4a to 4n detect the output voltages of the solar panels 1a to 1n, respectively. Since the output voltages of the solar panels 1a to 1n are the same as the input voltages of the choppers 19a to 19n, the voltage detectors 4a to 4n can detect the input voltages of the choppers 19a to 19n, respectively. Current detectors 5a to 5n detect output currents of solar panels 1a to 1n, respectively. Since the output currents of the solar panels 1a to 1n are the same as the input currents of the choppers 19a to 19n, the current detectors 5a to 5n can detect the input currents of the choppers 19a to 19n, respectively. Voltage detectors 20a to 20n detect the DC voltages of inverters 2a to 2n, respectively. Voltage detectors 6a to 6n detect the system voltage of the system to which inverters 2a to 2n are connected. Current detectors 7a to 7n detect output currents output to the systems connected to inverters 2a to 2n, respectively. Voltage detection values and current detection values detected by the voltage detectors 4a to 4n, current detectors 5a to 5n, voltage detectors 6a to 6n, current detectors 7a to 7n, and voltage detectors 20a to 20n are input to the control circuit 21. Is done. Further, an output upper limit command that is a signal for suppressing the output of the photovoltaic power conversion device is input to the control unit 21 from the outside. The control circuit 21 performs a predetermined calculation based on the input voltage detection value, current detection value, and output upper limit command, and outputs a gate pulse signal for driving the inverters 2a to 2n and the choppers 19a to 19n.

  Similarly, in such a configuration, when suppressing the output of the power conversion device for photovoltaic power generation, if there is a panel whose output temporarily rises, other panels will reduce the output excessively, The total output can be suppressed and the output of the photovoltaic power conversion device can be suppressed.

  FIG. 12 shows an operation example when the output upper limit command increases from P to P ′ to increase the respective outputs when the solar panels 1a to 1n receive the output upper limit command from the outside and perform output suppression. Show. Similarly to FIGS. 5 and 7, the relationship of the panel output with respect to the panel voltage in the panel 1a, the panel 1b, and the panel 1n is described.

  When an output increase command is received from the outside, the respective operating points are output suppression operation panel 1a voltage command output by output distribution control unit 10, output suppression operation panel 1b voltage command, ..., output suppression operation panel 1n Operates according to the voltage command. That is, for panel 1a, the operating point is from point Ga to point P1a, for panel 1b, the operating point is from point Gb to point P1b, and for panel 1n, the operating point is from point Gn to point P1n. The output of each panel is raised by moving in the direction. At this time, the output distribution control unit 10 determines whether or not each panel can increase the output based on the panel state determined by the panel state determination units 17a to 17n. The panel voltage command calculation unit 18 for output suppression operation uses the panel state of the panels 1a to 1n determined by the panel state determination units 17a to 17n, and, for example, outputs the output of the panel 1b redundantly instead of the panel 1a whose output cannot be increased. Output voltage command to increase. That is, when the operating point of panel 1a moves from point P1a to point P2a, the panel state output tends to decrease, so the operating point of panel 1b is moved from point P1b to point P2b. The operating point of panel 1n is moved from point P1n to point P2n. By doing in this way, it becomes possible to raise the total output of the whole.

  FIG. 13 shows the operation example shown in FIG. 12 as a time waveform.

  As shown in FIG. 13, the output of the panels 1a to 1n monotonously increases from time 0 to T1, but the output of the panel 1a decreases from time T1 to T2, so that the panel 1b increases the output instead. Thus, the total output of the panels 1a to 1n is monotonously increased. From time T2 to T3, since all the panels are in an upward trend, the total output can be shifted in an increasing trend. At time T3, the output target value of each panel is reached.

  As described above, according to the present embodiment, it is possible to control the output of each panel so as to satisfy the output increase command for the system even when the increase / decrease tendency of the panel output of the plurality of panels is different. is there.

1a-1n: Solar panel, 2a-2n: Inverter, 3: Power system, 4a-4n: Voltage detector, 5a-5n: Current detector, 6a-6n: Voltage detector, 7a-7n: Current detector , 8: Control circuit, 9a to 9n: Inverter control unit, 10: Output distribution control unit, 11: MPPT control unit, 12: Output control unit, 13: DC voltage control unit, 14: Current control unit, 15: PWM control , 16: Output calculation unit, 17a to 17n: Panel state determination unit, 18: Panel voltage command calculation unit for output suppression operation, 19a to 19n: Chopper, 20a to 20n: Voltage detector

Claims (4)

Multiple solar panels,
Wherein a plurality of the DC power solar panel output is converted into AC power by a plurality of inverters you output to the grid solar power for the power converter,
A controller that outputs gate pulse signals to the plurality of inverters;
With
The controller is
When performing an output suppression operation in order to balance power supply and demand, the output suppression operation is performed according to an output upper limit command that is a signal for suppressing the output of the photovoltaic power conversion device. An output distribution control unit that outputs a panel voltage command for output suppression that is a voltage command for a plurality of solar panels;
When performing the output suppression operation, the gate pulse signal is output based on the output suppression panel voltage command, and when the output suppression operation is not performed, the output power of the plurality of solar panels is maximized. A plurality of inverter control units that output the gate pulse signal based on a panel voltage command for maximum power following operation, which is a voltage command for performing maximum power following control;
With
When the output distribution control unit performs the output suppression operation,
When increasing the output of the photovoltaic power converter to the grid, when the output of the inverter and to vary the panel voltage of the solar panel is the first inverter in the downward trend, said extra increase the output of a different second inverter with varying panel voltage solar panel and the first inverter output of the inverter tends to increase, the solar photovoltaic power converter To increase the output monotonically,
Or
When there is a third inverter in which the output of the inverter tends to increase when the panel voltage of the solar panel is varied when the output of the photovoltaic power conversion device to the system is decreased the varying the panel voltage of the solar panel excess reduces the output of the different fourth inverter and the third inverter output of the inverter tends to decrease, the solar photovoltaic power converter As the output decreases monotonously,
A photovoltaic power generation system characterized by obtaining and outputting the panel voltage command for output suppression . In the photovoltaic power generation system according to claim 1,
Wherein the control unit includes a wherein said plurality of comprises determining panel state determination unit panels state of solar panels, on the basis of the result of the determination, determines the second inverter and said fourth inverter Solar power generation system. The photovoltaic power generation system according to claim 2,
The said panel state determination part determines the state of the said solar panel based on the output electric power of the said inverter or the panel voltage of the said solar panel, and the change of the output voltage of the said solar panel, The sunlight characterized by the above-mentioned Power generation system. A plurality of power conversion devices for photovoltaic power generation that convert DC power output by a plurality of solar panels into AC power by a plurality of inverters and output them to the system,
A controller that outputs gate pulse signals to the plurality of inverters;
The controller is
When performing an output suppression operation in order to balance power supply and demand, the output suppression operation is performed according to an output upper limit command that is a signal for suppressing the output of the photovoltaic power conversion device. An output distribution control unit that outputs a panel voltage command for output suppression that is a voltage command for a plurality of solar panels;
When performing the output suppression operation, the gate pulse signal is output based on the output suppression panel voltage command, and when the output suppression operation is not performed, the output power of the plurality of solar panels is maximized. A plurality of inverter control units that output the gate pulse signal based on a panel voltage command for maximum power following operation, which is a voltage command for performing maximum power following control;
With
When the output distribution control unit performs the output suppression operation,
When increasing the output of the photovoltaic power converter to the grid, when the output of the inverter and to vary the panel voltage of the solar panel is the first inverter in the downward trend, said extra increase the output of a different second inverter with varying panel voltage solar panel and the first inverter output of the inverter tends to increase, the solar photovoltaic power converter To increase the output monotonically,
Or
When lowering the output to the system, when varying the panel voltage of the solar panels, when the output of the inverter there is a third inverter in the upward trend, the panel voltage of the solar panel and extra reducing the output of a different fourth inverter and varying with said third inverter output of the inverter tends to decrease, so as to monotonously lowered output of the photovoltaic power converter ,
A photovoltaic power generation power conversion device characterized by obtaining and outputting the panel voltage command for output suppression .

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