Power control device and control method employed therein

1. A power control device that controls power generated by a solar power generation device,

wherein the solar power generation device includes:

a solar cell, and

a power conditioner that performs maximum power point tracking control on the solar cell and converts a direct current generated by the solar cell into an alternating current, and

wherein the power control device includes

a storage battery connected between the solar cell and the power conditioner,

a converter that is disposed between the storage battery and the solar cell and charges the storage battery with output power of the solar cell, and

a control unit that controls the converter such that the converter charges the storage battery with differential power between the output power of the solar cell and the output power of the power conditioner when the control unit determines an output of the solar cell is greater than outputtable power of the power conditioner,

wherein the control unit controls the charging of the storage battery using the converter with a time constant larger than a time constant of the maximum power point tracking control of the power conditioner.

2. The power control device according to claim 1 , wherein when an output suppression signal for suppressing an output of the power conditioner is received, the control unit sets a suppression output indicated in the output suppression signal by the outputtable power of the power conditioner.

3. The power control device according to claim 1 , further comprising:

a power meter that measures power of the power conditioner,

wherein the control unit determines that an output of the solar cell is greater than the outputtable power of the power conditioner when the power measured by the power meter reaches the outputtable power of the power conditioner.

4. The power control device according to claim 3 , further comprising:

an illumination meter,

wherein the control unit retains current/voltage feature data of the solar cell in accordance with an incident amount obtained from the illumination meter,

wherein the control unit calculates power of the solar cell corresponding to incidence data obtained from the illumination meter with reference to the current/voltage feature data,

wherein the control unit subtracts the outputtable power of the power conditioner from the calculated power to calculate charging power when the calculated power is greater than the outputtable power of the power conditioner, and

wherein the control unit controls the converter such that the storage battery is charged with the charging power.

5. The power control device according to claim 4 ,

wherein the control unit calculates a maximum power point of the solar cell corresponding to the incidence data obtained from the illumination meter,

wherein the control unit calculates a charging power obtained by subtracting the outputtable power of the power conditioner from power of the solar cell at the maximum power point, and

wherein the control unit controls the converter such that a bus line connecting the solar cell to the power conditioner is maintained at a voltage at the maximum power point and the storage battery is charged with the calculated charging power.

6. The power control device according to claim 4 ,

wherein the control unit calculates a maximum power point of the solar cell corresponding to the incidence data obtained from the illumination meter with reference to the current/voltage feature data, and

wherein when the control unit determines that the power measured by the power meter is less than the calculated power, the control unit controls the converter such that a bus line connecting the solar cell to the power conditioner maintains a voltage at the calculated maximum power point of the solar cell and power is discharged from the storage battery.

7. The power control device according to claim 1 , wherein the control unit controls the charging of the storage battery using the converter not to deviate from a maximum power point in the maximum power point tracking control.

8. The power control device according to claim 1 , wherein a speed of the charging is slowed when the output power of the power conditioner is determined to be less than the outputtable power.

9. The power control device according to claim 1 , wherein when the control unit determines that the power of the solar cell is less than the outputtable power of the power conditioner, the control unit controls the converter such that power is discharged from the storage battery.

10. A control method of a power control device that controls power generated by a solar power generation device,

wherein the solar power generation device includes

a solar cell, and

a power conditioner that performs maximum power point tracking control on the solar cell and converts a direct current generated by the solar cell into an alternating current,

wherein the power control device includes

a storage battery connected between the solar cell and the power conditioner,

a converter that is disposed between the storage battery and the solar cell and charges the storage battery with output power of the solar cell, and

a control unit, and

wherein the control unit controls the converter such that the converter charges the storage battery with differential power between the output power of the solar cell and the output power of the power conditioner when the control unit determines an output of the solar cell is greater than outputtable power of the power conditioner, wherein the control unit controls the charging of the storage battery using the converter with a time constant larger than a time constant of the maximum power point tracking control of the power conditioner.

11. The control method according to claim 10 , wherein when an output suppression signal for suppressing an output of the power conditioner is received, the control unit sets a suppression output indicated in the output suppression signal by the outputtable power of the power conditioner.

12. The control method according to claim 10 ,

wherein the power control device further includes a power meter that measures power of the power conditioner, and

wherein the control unit determines that an output of the solar cell is greater than the outputtable power of the power conditioner when the power measured by the power meter reaches the outputtable power of the power conditioner.

13. The control method according to claim 12 ,

wherein the power control device further includes an illumination meter,

wherein the control unit retains current/voltage feature data of the solar cell in accordance with an incident amount obtained from the illumination meter,

wherein the control unit calculates power of the solar cell corresponding to incidence data obtained from the illumination meter with reference to the current/voltage feature data,

wherein the control unit subtracts the outputtable power of the power conditioner from the calculated power to calculate charging power when the calculated power is greater than the outputtable power of the power conditioner, and

wherein the control unit controls the converter such that the storage battery is charged with the charging power.

14. The control method according to claim 13 ,

wherein the control unit calculates a maximum power point of the solar cell corresponding to the incidence data obtained from the illumination meter,

wherein the control unit calculates a charging power obtained by subtracting the outputtable power of the power conditioner from power of the solar cell at the maximum power point, and

wherein the control unit controls the converter such that a bus line connecting the solar cell to the power conditioner is maintained at a voltage at the maximum power point and the storage battery is charged with the calculated charging power.

15. The control method according to claim 13 ,

wherein the control unit calculates a maximum power point of the solar cell corresponding to the incidence data obtained from the illumination meter with reference to the current/voltage feature data, and

wherein when the control unit determines that the power measured by the power meter is less than the calculated power, the control unit controls the converter such that a bus line connecting the solar cell to the power conditioner maintains a voltage at the calculated maximum power point of the solar cell and power is discharged from the storage battery.

16. The control method according to claim 10 , wherein the control unit controls the charging of the storage battery using the converter not to deviate from a maximum power point in the maximum power point tracking control.

17. The control method according to claim 10 , wherein a speed of the charging is slowed when the output power of the power conditioner is determined to be less than the outputtable power.

18. The control method according to claim 10 , wherein when the control unit determines that the power is less than the outputtable power of the power conditioner, the control unit controls the converter such that power is discharged from the storage battery.