The invention brings forward a
power balancing control method of cascaded photovoltaic grid-connected
inverter on the partial shadow condition. The method comprises the following steps: (1), carrying out independent
maximum power point tracking (MPPT) controlling on H bridges of all
cascade units to obtain all-stage direct-
current voltage instruction values and then carrying out PI controlling on a general direct-
current voltage to obtain a grid-connected current instruction value; (2), carrying out quasi-proportional resonant (PR) control of the grid-connected current and
grid voltage feedforward control so as to obtain initial duty ratio values of the H bridges; (3) carrying out per-unit
processing on actual values of the direct-current side voltages of the
cascade units according to the respective direct-current side
voltage instruction values of all the
cascade units, carrying out comparison with 1 and carrying out PI controlling so as to obtain active correction values of the duty ratios of the H bridges, and realizing
power balancing control based on the duty ratio correction. According to the control method, floating control of the grid-connected current can be realized; and
power balancing of all power units of the cascade
inverter can be maintained. The provided control method has advantages of clear conception, simple control structure, and easy
engineering realization and the like.