The invention discloses a grid-
connection control method for solar
photovoltaic power generation and belongs to the field of solar
photovoltaic power generation. The method is characterized in that:
constant voltage control of a direct-current
bus is taken as a basic starting point and the output
voltage and current of a photovoltaic
cell are adjusted by adjusting the pulse-width modulation (PWM) duty ratio of a DC /
DC converter so as to realize the tracking control of the maximum output power point of the photovoltaic
cell; and in addition, stable and grid-connection running of a photovoltaic generating
system is realized and the
constant voltage of the direct-current
bus is maintained by adjusting the output current of a DC / AC grid-connected
inverter. The tracking control of the maximum power point of the photovoltaic
cell is characterized in that: the variation track of a power-
voltage vector is obtained by sampling the output
voltage and current of the photovoltaic cell at three or more points and is matched with a preset variation mode so as to determine the adjusting direction of the output current. During grid-connection running, the PWM duty ratio of the
inverter is adjusted by using the measured
voltage amplitude, phase position and frequency information of a
power grid so as to synchronize the voltage generated by the
system and the
power grid. Moreover, the voltage of the direct-current
bus is kept constant by using high-speed feedback of the output current of the
inverter, so that the power of the
system fed in the
power grid is close to the power generated by a
solar cell to the maximum.