The invention relates to a grid-side current balancing control method of a unified
power quality conditioner. The method comprises: a three-phase
grid voltage, a load
voltage, a load current are converted from a three-phase ABC alternating-current coordinate
system to a two-phase dq rotation coordinate
system and phase information needed by coordinate conversion is obtained by
phase locking of a
grid voltage; after coordinate conversion, alternating-current components and direct-current components of the
grid voltage, the load
voltage, and the load current are obtained, and after
processing by a low-pass filter, alternating-current components in variables are filtered; according to the filtered direct-current components, a grid-side current fundamental
current amplitude is calculated; and the grid-side current fundamental
current amplitude and a direct-current
bus voltage adjustment result are superposed to obtain a three-phase grid-side
reference current amplitude. With the method provided by the invention, the grid-side three-phase current balancing degree can be reduced; the direct-current
bus voltage fluctuation can be reduced; the dynamic response speed of the
system can be increased; and defects of poor steady-
state control effect and slow dynamic response speed of the direct-current
bus voltage loop can be overcome.