Solar power system and control system

摘要

In a case in which a local solution to current-voltage characteristics is generated by way of a partial shade, it has been difficult to perform control for causing a solar cell to operate at a maximum power point efficiently in terms of power and at a low cost. During steady state operation, an MPPT control unit 1 for performing the normal hill climbing method is selected, and if the change amount of the output current of the solar cell is greater than or equal to a predetermined threshold, an MPPT control unit 2 for increasing the variation width of the output voltage of the solar cell to greater than the hill climbing method is selected. By way of such control, it is possible to achieve both efficient operation in a steady state and avoidance of a local solution to a partial shade at a low cost.

主权项

1. A solar power system, comprising:
solar cells; a voltage control unit for controlling an output voltage of the solar cells; a voltage detection unit for detecting the output voltage of the solar cells; a current detection unit for detecting an output current of the solar cells; a first control unit that makes the voltage control unit vary the output voltage of the solar cells within a first variation width and compares the output voltages of the solar cells before and after the variation; a second control unit that makes the voltage control unit vary the output voltage of the solar cells within a second variation width that is larger than the first variation width and compares the output voltages of the solar cells before and after the variation; and a comparison unit for comparing an absolute value of a change amount per unit time of the output current of the solar cells detected by the current detection unit and a predetermined threshold; wherein if the comparison unit determines that the absolute value of the change amount is smaller than the predetermined threshold, the first control unit will be selected, and if the comparison unit determines that the absolute value of the change amount is larger than the predetermined threshold, the second control unit will be selected; wherein the predetermined threshold is larger than the absolute value of the change amount per unit time of the output current of the solar cells as determined by equation |dI|=|I/V|*|dV|, where dI is the change amount per unit time of the output current of the solar cells, I is the output current of the solar cells, V is the output voltage of the solar cells, and dV is a change amount per unit time of the output voltage of the solar cells.