The invention relates to a high-capacity unified
power quality conditioner based on a
chain structure and a control method of the high-capacity unified
power quality conditioner. A three-phase three-wire
system series-and-parallel structure is adopted in the high-capacity unified
power quality conditioner. The high-capacity unified power quality conditioner comprises a series type
voltage source converter and a parallel type
voltage source converter, wherein the series type
voltage source converter and the parallel type
voltage source converter are connected through a common direct-current
bus, single-phase H-bridge
cascade structures are adopted in the series type
voltage source converter, the H-bridge
cascade structure of each phase is connected to an alternating-current side
power grid through a series
capacitor, single-phase H-bridge
chain link structures are adopted in the parallel side converter, a back-to-
back structure is formed by the single-phase H-bridge
chain link structures and H-bridge chain links of the series type
voltage source converter, and each H-bridge
chain link of the parallel side converter is connected to a direct-current side
power grid through the
secondary side of a single-phase multi-winding
transformer. The invention further provides the control method of the high-capacity unified power quality conditioner. According to the high-capacity unified power quality conditioner, a series side
transformer is omitted, short-circuit impedance of a loop is reduced, voltage accuracy of open-
loop control is improved, performance of the high-capacity unified power quality conditioner is improved, and the problem that the instantaneous
inrush current phenomenon happens when
voltage drop of the series side happens is solved.