JP5882845B2 - Power storage type solar power generation system - Google Patents

Description

This invention relates to a power storage type solar power generation system, in particular, to a power storage type photovoltaic power generation system provided with a DC converter for storing the excess power of the DC power generated by the solar cell to power storage device.

  For example, in Patent Document 1, at night, AC power from an electric power system is converted into DC power and stored in a storage battery, and in the daytime, DC power from a solar battery and a storage battery is converted into AC power and supplied to a load. A storage solar power generation system is disclosed. In this system, surplus power flows backward to the power system.

JP 2002-171694 A

  By the way, a power storage type solar power generation system that is not connected to the power system, stores only surplus power of the solar battery in the storage battery, converts the DC power from the solar battery and the storage battery into AC power, and supplies the power to the load is also conceivable. .

  However, in such a system, when the surplus power of the solar battery becomes excessive, the voltage applied to the load and the voltage between the terminals of the storage battery become excessive, and the load and the storage battery are damaged.

Another object of the present invention is to provide a power storage type solar power generation system capable of preventing a DC load and the power storage device may be damaged.

A power storage solar power generation system according to the present invention supplies a solar cell that converts solar energy into DC power, a power storage device that stores DC power, and DC power generated by the solar cell to a DC load. And a DC converter for storing surplus power in the power storage device. The DC converter includes an output terminal connected to the DC load, a capacitor connected between the output terminal and the reference voltage line, and a current corresponding to the first current command value from the solar cell to the output terminal. A first DC / DC converter that flows through the second DC / DC converter, a second DC / DC converter that passes a current corresponding to the second current command value between the output terminal and the power storage device, and the output voltage and output of the solar cell The first control unit that performs the maximum power point tracking control based on the current and generates the first current command value so that the output voltage of the solar cell becomes the optimum operating voltage, and the voltage of the output terminal becomes the reference voltage The second control unit that generates the second current command value and the first control unit that decreases the first current command value when the voltage at the output terminal exceeds the first upper limit voltage that is higher than the reference voltage. Power during charging of voltage limiter and power storage device And a second voltage limiting unit to reduce the second current command value when the inter-terminal voltage of the built device exceeds the lower second upper limit voltage than the reference voltage. This power storage solar power generation system is further connected to an output terminal as a DC load, receives DC power from a DC converter and receives commercial AC power from a commercial AC power supply, and the voltage at the output terminal is lower than the reference voltage If the voltage is higher than the lower limit voltage, the DC power received from the output terminal is converted to AC power and supplied to the AC load. If the voltage at the output terminal is lower than the lower limit voltage, the DC power received from the output terminal is converted to AC. An AC power supply device that stops the conversion into electric power and supplies the AC load with the commercial AC power received from the commercial AC power supply is provided.

  Preferably, the second DC / DC converter includes a diode that causes a current to flow from the power storage device to the output terminal when the voltage between the terminals of the power storage device is higher than the voltage of the output terminal.

The engagement Ru electricity storage photovoltaic system to the present invention, the decrease of the first current command value when the voltage of the output terminal of the DC converter exceeds the higher first upper limit voltage than the reference voltage 1 And a second voltage limiter for reducing the second current command value when the voltage between the terminals of the power storage device exceeds a second upper limit voltage lower than the reference voltage during charging of the power storage device. Are provided. Therefore, even when the surplus power of the solar cell becomes excessive, it is possible to prevent the voltage at the output terminal of the DC converter and the voltage between the terminals of the power storage device from becoming excessive, and the DC load and the power storage device It can be prevented from being damaged.

1 is a circuit block diagram showing a configuration of a power storage solar power generation system according to an embodiment of the present invention. It is a circuit block diagram which shows the structure of the chopper shown in FIG. It is a circuit block diagram which shows the structure of the control part 6 shown in FIG. It is a figure for demonstrating operation | movement of the MPPT controller shown in FIG. It is a circuit block diagram which shows the structure of the control part 9 shown in FIG. It is a circuit block diagram which shows operation | movement of the power storage type solar power generation system in mode 1. FIG. It is a circuit block diagram which shows operation | movement of the power storage type solar power generation system in mode 2. FIG. It is a circuit block diagram which shows operation | movement of the power storage type solar energy power generation system in mode 3. FIG. FIG. 6 is a circuit block diagram showing the operation of the power storage solar power generation system in mode 4. FIG. 6 is a circuit block diagram showing the operation of the power storage solar power generation system in mode 5. FIG. 10 is a circuit block diagram showing the operation of the power storage solar power generation system in mode 6.

  As shown in FIG. 1, a power storage solar power generation system according to an embodiment of the present invention includes a solar cell 1, a storage battery 2, a DC (Direct Current) converter 3, and a DC load 11. The solar cell 1 converts sunlight energy into DC power. The power generation amount of the solar cell 1 increases according to the solar radiation intensity. The storage battery 2 is a battery capable of charging and discharging DC power. The DC load 11 is an electric device or the like driven by direct current power.

  The DC converter 3 performs maximum power point tracking control based on the output voltage VPV and the output current IPV of the solar cell 1, and the DC load 11 from the solar cell 1 so that the output voltage VPV of the solar cell 1 becomes the optimum operating voltage. Current is passed through. DC converter 3 supplies direct-current power from solar cell 1 to storage battery 2 when output voltage VDC is higher than a predetermined reference voltage VDCR (for example, 400 V), and output voltage VDC is equal to predetermined reference voltage VDCR. If it is lower, the DC power from the storage battery 2 is supplied to the DC load 11.

  DC converter 3 limits output voltage VDC to upper limit voltage VDCH (for example, 500 V) or lower, and limits terminal voltage VB of storage battery 2 to upper limit voltage VBH (for example, 300 V) or lower. Further, the DC converter 3 causes a current to flow from the storage battery 2 to the DC load 11 when the output voltage VDC is lower than the inter-terminal voltage VB of the storage battery VB.

  More specifically, the DC converter 3 includes terminals T1 to T3, current sensors 4 and 7, choppers 5 and 8, control units 6 and 9, and a smoothing capacitor 10. Terminals T <b> 1 to T <b> 3 are connected to solar cell 1, storage battery 2, and DC load 11, respectively. Smoothing capacitor 10 is connected between terminal T3 and a reference voltage (for example, ground voltage) line.

  The chopper 5 is connected between the terminals T <b> 1 and T <b> 3 and controlled by the control unit 6, and supplies the direct-current power generated by the solar cell 1 to the smoothing capacitor 10. The current sensor 4 detects the direct current IPV flowing from the solar cell 1 to the chopper 5 and gives a signal indicating the detected value to the control unit 6.

  The control unit 6 detects the inter-terminal voltage VPV of the solar cell 1 and the inter-terminal voltage VDC of the smoothing capacitor 10, and controls the chopper 5 based on those detection values and the detection value of the current sensor 4. The control unit 6 controls the chopper 5 so that the inter-terminal voltage VPV of the solar cell 1 becomes the optimum operating voltage VPVR, and controls the chopper 5 so that the inter-terminal voltage VDC of the smoothing capacitor 10 becomes equal to or lower than the upper limit voltage VDCH. To do.

  The chopper 8 is connected between the terminals T1 and T3 and controlled by the control unit 9, and supplies DC power from the smoothing capacitor 10 to the storage battery 2, or conversely supplies DC power of the storage battery 2 to the smoothing capacitor 10. . The current sensor 7 detects a current IB flowing between the chopper 8 and the storage battery 2 and gives a signal indicating the detected value to the control unit 9.

  The control unit 9 detects the inter-terminal voltage VB of the storage battery 2 and the inter-terminal voltage VDC of the smoothing capacitor 10, and controls the chopper 8 based on those detection values and the detection value of the current sensor 7. The control unit 9 controls the chopper 8 so that the inter-terminal voltage VDC of the smoothing capacitor 10 becomes the reference voltage VDCR (<VDCH), and the inter-terminal voltage VB of the storage battery 2 becomes less than the upper limit voltage VBH. To control.

  FIG. 2 is a circuit block diagram showing the configuration of the choppers 5 and 8. In FIG. 2, the chopper 5 includes a capacitor 21, an inductor 22, an IGBT (Insulated Gate Bipolar Transistor) 23, and diodes 24 and 25. The capacitor 21 is connected between the terminal T1 and the reference voltage line. The inductor 22 and the IGBT 23 are connected in series between the terminal T1 and a reference voltage line. The diode 24 is connected to the IGBT 23 in antiparallel. The anode of the diode 25 is connected to the collector of the IGBT 23, and its cathode is connected to the terminal T3.

  The IGBT 23 is PWM (pulse width modulation) controlled by the control unit 6 and turned on and off at a predetermined cycle. When the IGBT 23 is turned on, a current flows from the solar cell 1 to the reference voltage line via the inductor 22 and the IGBT 23, and electromagnetic energy is stored in the inductor 22. When the IGBT 23 is turned off, the electromagnetic energy stored in the inductor 22 is released, and a current flows from the inductor 22 through the diode 25 to the smoothing capacitor 10. At this time, the anode voltage of the diode 25 is a voltage obtained by adding the inter-terminal voltage of the inductor 22 to the inter-terminal voltage VPV of the solar cell 1.

  That is, the chopper 5 boosts the inter-terminal voltage VPV of the solar cell 1 and supplies it to the smoothing capacitor 10. Increasing the ON time of the IGBT 23 increases the rising speed of the inter-terminal voltage VDC of the smoothing capacitor 10, and decreasing the ON time of the IGBT 23 decreases the increasing speed of the inter-terminal voltage VDC of the smoothing capacitor 10.

  The chopper 8 includes a capacitor 31, an inductor 32, an IGBT 33, and diodes 34 and 35. The capacitor 31 is connected between the terminal T2 and the reference voltage line. The IGBT 33 and the inductor 32 are connected in series between the terminals T3 and T2. The diode 34 is connected in antiparallel to the IGBT 33. The anode of the diode 35 is connected to the reference voltage line, and its cathode is connected to the emitter of the IGBT 33.

  The IGBT 33 is PWM-controlled by the control unit 9. The IGBT 33 is turned on and off at a predetermined cycle when VDC> VB. When the IGBT 33 is turned on, a current flows from the smoothing capacitor 10 to the storage battery 2 via the IGBT 33 and the inductor 32, and electromagnetic energy is stored in the inductor 32. When the IGBT 33 is turned off, the electromagnetic energy stored in the inductor 32 is released, and a current flows through the path of the inductor 32, the storage battery 2, and the diode 35. At this time, the inter-terminal voltage VB of the storage battery 2 is a voltage obtained by subtracting the inter-terminal voltage of the inductor 32 from the inter-terminal voltage VDC of the smoothing capacitor 10.

  That is, the chopper 8 steps down the voltage VDC between the terminals of the smoothing capacitor 10 and supplies it to the storage battery 2. Increasing the ON time of the IGBT 33 increases the rate of increase of the inter-terminal voltage VB of the storage battery 2, and decreasing the ON time of the IGBT 33 decreases the increase rate of the inter-terminal voltage VB of the storage battery 2. Further, when VDC <VB, the IGBT 33 is fixed in the off state, and a direct current flows from the storage battery 2 to the smoothing capacitor 10 via the inductor 32 and the diode 34.

  FIG. 3 is a circuit block diagram showing the configuration of the control unit 6. In FIG. 3, the control unit 6 includes an MPPT (Maximum Power Point Tracking) controller 50, subtractors 51, 53, 58, voltage controllers 52, 54, a limiter 55, an adder 57, and a current controller. 59, and a PWM controller 60.

  The MPPT controller 50 performs maximum power point tracking control of the solar cell 1, obtains an optimum operating voltage at which the output of the solar cell 1 is maximized based on the output voltage VPV and the output current IPV of the solar cell 1, and generates a reference voltage Set VPVR to its optimum operating voltage. FIG. 4 is a diagram for explaining the maximum power point tracking control of the solar cell 1. In FIG. 4, the solar cell 1 has a characteristic that when the output current IPV increases, the inter-terminal voltage VPV decreases, and the output of the solar cell 1 follows a gentle mountain-shaped curve according to the inter-terminal voltage VPV. Change. The point at which the output of the solar cell 1 is maximum is called the maximum power point, and the terminal voltage VPV of the solar cell 1 at that time is called the optimum operating voltage.

  In other words, the maximum power can be extracted from the solar cell 1 by extracting the current IPV so that the inter-terminal voltage VPV of the solar cell 1 matches the optimum operating voltage. When the solar radiation intensity changes, the maximum power point and the optimum operating voltage also change. For this reason, the MPPT controller 50 adjusts the reference voltage VPVR so as to match the optimum operating voltage based on the output voltage VPV and the output current IPV of the solar cell 1.

  Specifically, the MPPT controller 50 increases and decreases the reference voltage VPVR by a minute voltage ΔV in a predetermined cycle, and changes the reference voltage VPVR by ΔV in the direction in which the output of the solar cell 1 increases. When the output of the solar cell 1 increases when it is increased by ΔV, and when the output of the solar cell 1 decreases when it is decreased by ΔV, VPV is located on the left slope of the curve of FIG. Increase the reference voltage VPVR by ΔV. Further, when the output of the solar cell 1 is decreased when increased by ΔV, and when the output of the solar cell 1 is increased when decreased by ΔV, VPV is located on the right slope of the curve of FIG. Therefore, the reference voltage VPVR is decreased by ΔV.

  Returning to FIG. 3, the subtractor 51 subtracts the reference voltage VPVR generated by the MPPT controller 50 from the detected value of the output voltage VPV of the solar cell 1, and outputs a signal indicating the subtraction result VPV−VPVR to the voltage controller 52. To give. The voltage controller 52 generates a current command value for setting VPV-VPVR to 0, and gives the current command value to the adder 57.

  Subtractor 53 subtracts voltage VDC between terminals of smoothing capacitor 10 from upper limit voltage VDCH (for example, 500 V), and provides signal indicating voltage subtraction result VDCH-VDC to voltage controller 54. The voltage controller 54 generates a current command value for setting VDCH-VDC to 0, and gives the current command value to the limiter 55. The limiter 55 passes the current command value when the current command value from the voltage controller 54 is negative, and sets the current command value to 0 when the current command value from the voltage controller 54 is positive. The subtractor 53, the voltage controller 54, and the limiter 55 constitute a voltage limiting unit 56 that limits the inter-terminal voltage VDC of the smoothing capacitor 10 to a voltage equal to or lower than the upper limit voltage VDCH.

  When VDC <VDCH, the value of the current command value output from the voltage limiting unit 56 is zero. When VDC> VDCH, the current command value output from the voltage limiting unit 56 is a value corresponding to VDC-VDCH.

  The adder 57 adds the current command value from the voltage controller 52 and the current command value from the voltage limiter 56 to generate a reference current value IPVR. The subtractor 58 subtracts the detected value of the output current IPV of the solar cell 1 from the reference current value IPVR, and gives a signal indicating the subtraction result IPVR−IPV to the current controller 59. The current controller 59 generates a current command value for causing the current IPVR-IPV obtained by the subtractor 58 to flow. The PWM controller 60 controls the chopper 5 so that a current having a value corresponding to the current command value from the current controller 59 flows from the solar cell 1 to the DC load 11. The chopper 5 and the PWM controller 60 constitute a first DC / DC converter. Thereby, the output voltage VDC of the DC converter 3 is limited to the upper limit voltage VDCH or less.

  FIG. 5 is a circuit block diagram showing the configuration of the control unit 9. In FIG. 5, the control unit 9 includes subtractors 61, 66 and 70, voltage controllers 62 and 67, limiters 63 and 68, an adder 65, a current controller 71, and a PWM controller 72.

  The subtractor 61 subtracts a reference voltage VDCR (for example, 400 V) from the inter-terminal voltage VDC of the smoothing capacitor 10, and gives a signal indicating the subtraction result VDC-VDCR to the voltage controller 62. Reference voltage VDCR is set to a voltage lower than upper limit voltage VDCH. The voltage controller 62 generates a current command value for setting VDCR-VDC to 0, and gives the current command value to the limiter 63.

  When the current command value from the voltage controller 62 is a value between the positive upper limit value and the negative lower limit value, the limiter 63 passes the current command value. Further, when the current command value from the voltage controller 62 is on the positive side with respect to the positive upper limit value, the limiter 63 sets the current command value to the positive upper limit value. Further, when the current command value from the voltage controller 62 is on the negative side of the negative lower limit value, the limiter 63 sets the current command value to the negative lower limit value. The subtractor 61, the voltage controller 62, and the limiter 63 constitute a voltage control unit 64 that controls the inter-terminal voltage VDC of the smoothing capacitor 10 to a constant voltage VDCR.

  Subtractor 66 subtracts inter-terminal voltage VB of storage battery 2 from upper limit voltage VBH (for example, 300 V), and provides a signal indicating the subtraction result VBH−VB to voltage controller 67. Voltage controller 67 generates a current command value for setting VBH−VB to 0, and provides the current command value to limiter 68. The limiter 68 passes the current command value when the current command value from the voltage controller 67 is negative, and sets the current command value to 0 when the current command value from the voltage controller 54 is positive. The subtractor 53, the voltage controller 67, and the limiter 68 constitute a voltage limiting unit 69 that limits the inter-terminal voltage VB of the storage battery 2 to a voltage equal to or lower than the upper limit voltage VBH.

  When VB <VBH, the value of the current command value output from the voltage limiting unit 69 is zero. When VB> VBH, the current command value output from the voltage limiting unit 69 is a value corresponding to VB−VBH.

  The adder 65 adds the current command value from the voltage control unit 64 and the current command value from the voltage limiting unit 69 to generate a reference current value IBR. The subtractor 70 subtracts the detected value of the charging current IB of the storage battery 2 from the reference current value IBR, and gives a signal indicating the subtraction result IBR-IB to the current controller 71. The current controller 71 generates a current command value for causing the current IBR-IB obtained by the subtractor 70 to flow. The PWM controller 72 controls the chopper 8 so that a current having a value corresponding to the current command value from the current controller 71 flows between the smoothing capacitor 10 and the storage battery 2. The chopper 8 and the PWM controller 71 constitute a second DC / DC converter.

  FIG. 6 is a circuit block diagram showing an operation of the power storage type solar power generation system shown in FIGS. In FIG. 6, the breaker B1 is connected between the solar cell 1 and the terminal T1, and the breaker B2 is connected between the storage battery 2 and the terminal T2. Breaker B1 is turned off when the solar cell 1 is replaced, and is normally turned on. Breaker B2 is turned off when the storage battery 2 is replaced, and is normally turned on.

  Further, the switch S1 is connected between the terminal T1 and the input terminal of the chopper 5, and the switch S2 is connected between the terminal T2 and the input terminal of the chopper 8. The switches S1 and S2 are turned off when the DC converter 3 is stopped, and are turned on when the DC converter 3 is in operation.

  As the DC load 11, a UPS (Uninterruptible Power Supply) 81 is used. The breaker B3 is connected between the terminal T3 and the DC terminal 81a of the UPS 81. The breaker B3 is turned off when the UPS 81 is replaced, and is normally turned on. The AC terminal 81 b of the UPS 81 is connected to a commercial AC power supply 80, and the output terminal 81 c is connected to an AC (alternating current: AC) load 82.

  The UPS 81 is based on, for example, an inverter that converts AC power into DC power, a switch connected between the terminals 81b and 81c, a voltage detector that detects the voltage of the DC terminal 81a, and a detection result of the voltage detector. And a control unit for controlling the inverter and the switch.

  When the output voltage VDC of the DC converter 3 is higher than the lower limit voltage VDCL (for example, 200 V), the UPS 81 converts the DC power from the DC converter 3 into AC power having a commercial frequency and supplies it to the AC load 82. . Lower limit voltage VDCL is set to a voltage lower than reference voltage VDCR. In addition, when the output voltage VDC of the DC converter 3 is lower than the lower limit voltage VDCL, the USP 81 stops converting the DC power from the DC converter 3 into AC power having a commercial frequency, and from the commercial AC power supply 80. AC power is supplied to the AC load 82.

  This power storage solar power generation system operates in one of six modes depending on the amount of power generated by the solar cell 1 and the like. When the power generation amount of the solar cell 1 is larger than the power amount required by the UPS 81, the power generation system operates in mode 1 as shown in FIG. In mode 1, DC power generated by the solar cell 1 is supplied to the UPS 81 by the chopper 5, and surplus power is supplied to the storage battery 2 by the chopper 8. The UPS 81 converts the DC power from the DC converter 3 into AC power and supplies it to the AC load 82. Surplus power is stored in the storage battery 2.

  At this time, the output voltage VPV of the solar cell 1 is set to the optimum operating voltage, and a current flows from the solar cell 1 to the UPS 81 via the chopper 5. Further, a current is passed from the output terminal T3 to the storage battery 2 via the chopper 8 so that the output voltage VDC of the DC converter 3 becomes the reference voltage VDCR. For example, when sunny weather continues and the inter-terminal voltage VB of the storage battery 2 reaches the upper limit voltage VBH, the operation of the chopper 8 is stopped and charging of the storage battery 2 is stopped. Further, for example, when the power consumption in the AC load 82 decreases and surplus power increases, and the output voltage VDC of the DC converter 3 reaches the upper limit voltage VDCH, the current flowing through the chopper 5 is reduced.

  When the power generation amount of the solar cell 1 is smaller than the power amount required by the UPS 81, the power generation system operates in mode 2 as shown in FIG. In mode 2, the DC power generated by the solar cell 1 is supplied to the UPS 81 by the chopper 5, and the DC power of the storage battery 2 is supplied to the UPS 81 by the chopper 8. The UPS 81 converts the DC power from the DC converter 3 into AC power and supplies it to the AC load 82.

  At this time, the output voltage VPV of the solar cell 1 is set to the optimum operating voltage, and a current flows from the solar cell 1 to the UPS 81 via the chopper 5. In addition, a current flows from the storage battery 2 to the output terminal T3 via the chopper 8 so that the output voltage VDC of the DC converter 3 becomes the reference voltage VDCR.

  For example, when the amount of power generated by the solar cell 1 becomes 0 at night, the power generation system operates in mode 3 as shown in FIG. In mode 3, the operation of the chopper 5 is stopped and the DC power of the storage battery 2 is supplied to the UPS 81 by the chopper 8. The UPS 81 converts the DC power from the DC converter 3 into AC power and supplies it to the AC load 82.

  At this time, a current flows from the storage battery 2 to the output terminal T3 via the chopper 8 so that the output voltage VDC of the DC converter 3 becomes the reference voltage VDCR. When the output voltage VDC of the DC converter 3 decreases and falls below the lower limit voltage VDCL, the UPS 81 stops converting the DC power from the DC converter 3 into AC power, and the AC from the commercial AC power supply 80 Electric power is supplied to the AC load 82. In addition, when the inter-terminal voltage VB of the storage battery 2 becomes the lower limit voltage VBL, the discharge of the storage battery 2 is stopped in order to prevent the overdischarge of the storage battery 2.

  Further, when the power generation amount of the solar battery 1 is larger than the power amount required by the UPS 81, for example, when the storage battery 2 is disconnected from the terminal T2 in order to perform maintenance of the storage battery 2, as shown in FIG. The system operates in mode 4. In mode 4, the operation of the chopper 8 is stopped, and DC power generated by the solar cell 1 is supplied to the UPS 81 by the chopper 5. The UPS 81 converts the DC power from the DC converter 3 into AC power and supplies it to the AC load 82.

  At this time, the output voltage VPV of the solar cell 1 is set to the optimum operating voltage, and a current flows from the solar cell 1 to the UPS 81 via the chopper 5. Further, for example, when the power consumption in the AC load 82 decreases and surplus power increases, and the output voltage VDC of the DC converter 3 reaches the upper limit voltage VDCH, the chopper 5 is set so that the VDC becomes a constant voltage VDCH. Be controlled.

  Further, the amount of power generated by the solar cell 1 is smaller than the amount of power required by the UPS 81, the output voltage VDC of the DC converter 3 falls below the lower limit voltage VDCL, and the power supply from the DC converter 3 to the UPS 81 is stopped. In this case, the power generation system operates in mode 5 as shown in FIG. In mode 5, DC power generated by the solar cell 1 is supplied to the storage battery 8 by the choppers 5 and 8.

  At this time, the output voltage VPV of the solar cell 1 is set to the optimum operating voltage, and a current flows from the solar cell 1 to the chopper 8 via the chopper 5. Further, a current is passed from the output terminal T3 to the storage battery 2 via the chopper 8 so that the output voltage VDC of the DC converter 3 becomes the reference voltage VDCR.

  Further, when the power generation amount of the solar battery 1 is 0 and the storage battery 2 cannot be discharged, the power generation system is set to mode 6 as shown in FIG. In mode 6, the operation of the choppers 5 and 8 is stopped.

  When the chopper 5 fails, the power generation system is set to mode 3 or mode 6. When the chopper 8 fails, the power generation system is set to mode 4 or mode 6. Further, when the DC converter 3 is stopped due to a serious failure before starting, the power generation system is set to mode 6.

  In this embodiment, when the output voltage VDC of the DC converter 3 rises and exceeds the upper limit voltage VDCH, the current flowing from the solar cell 1 through the chopper 5 to the output terminal T3 is reduced. When the inter-terminal voltage VB of the storage battery 2 exceeds the upper limit voltage VBH, the current flowing from the output terminal T3 to the storage battery 2 via the chopper 8 is reduced. Therefore, even when the surplus power of the solar cell 1 becomes excessive, it is possible to prevent the voltage VDC of the output terminal T3 and the voltage VB between the terminals of the storage battery 2 from becoming excessive, and the DC load 11 and the storage battery 2 are damaged. Can be prevented.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Solar cell, 2 Storage battery, 3 DC converter, T1-T3 terminal, 4,7 Current sensor, 5,8 Chopper, 6,9 Control part, 10 Smoothing capacitor, 11 DC load, 21,31 Capacitor, 22,32 Inductor, 23, 33 IGBT, 24, 25, 34, 35 Diode, 50 MPPT controller, 51, 53, 58, 61, 66, 70 Subtractor, 52, 54, 62, 67 Voltage controller, 55, 63, 68 Limiter, 56, 69 Voltage limiter, 57, 65 Adder, 59, 71 Current controller, 60, 72 PWM controller, 64 Voltage controller, 80 Commercial AC power supply, 81 UPS, 82 AC load.

Claims (2)

A solar cell that converts solar energy into DC power;
A power storage device for storing DC power;
A DC converter for supplying DC power generated by the solar cell to a DC load and storing surplus power in the power storage device;
The DC converter is
An output terminal connected to said DC load,
A capacitor connected between the output terminal and a reference voltage line;
A first DC / DC converter supplying a current of a value corresponding to the first current command value to said output terminal from said solar cell,
A second DC / DC converter to flow between said output terminal and said power storage device current of a value corresponding to the second current command value,
A first controller that performs maximum power point tracking control based on the output voltage and output current of the solar cell, and generates the first current command value so that the output voltage of the solar cell becomes an optimum operating voltage; ,
A second control unit that generates the second current command value so that the voltage of the output terminal becomes a reference voltage;
A first voltage limiter that decreases the first current command value when the voltage at the output terminal exceeds a first upper limit voltage that is higher than the reference voltage;
A second voltage limiter configured to decrease the second current command value when a voltage between terminals of the power storage device exceeds a second upper limit voltage lower than the reference voltage during charging of the power storage device; Including
Further, the DC load is connected to the output terminal, receives DC power from the DC converter and receives commercial AC power from a commercial AC power supply, and the voltage at the output terminal is higher than a lower limit voltage lower than the reference voltage. In the case, the DC power received from the output terminal is converted into AC power and supplied to an AC load. When the voltage at the output terminal is lower than the lower limit voltage, the DC power received from the output terminal A power storage solar power generation system including an AC power supply device that stops the conversion into the AC and supplies the AC load with the commercial AC power received from the commercial AC power source . The said 2nd DC / DC converter contains the diode which flows an electric current from the said electric power storage apparatus to the said output terminal when the voltage between the terminals of the said electric power storage apparatus is higher than the voltage of the said output terminal. The power storage solar power generation system described.

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