A SINGLE PHASE ZERO STEADY STATE ERROR FOR SINGLE PHASE GRID-CONNECTED DC/AC INVERTER WITH HERIC CONVERTORS

Abstract

Feed forward control is reliable for rejecting fast and dynamic voltage disturbances in the grid. Mainly this
scheme is implemented based on phase voltages of the wyes connected configuration. Under unbalanced and distorted gridcondition, the online conversion of line-to-line values into the phase values is unworkable. In order to exploit full advantages
of feed forward controller, an appropriate modulator is needed. In this paper the feed forward of grid line-to-line voltages is
used in lieu of phase voltages. The introduced feed forward method is implemented with implicit zero-sequence discontinuous
pulse width modulation (IZDPWM) technique that is compatible for grid-connected inverters. Regardless the grid topology,
IZDPWM exactly copies the distorting harmonics of the grid voltage. Hence, a sinusoidal current is injected to the grid.
Moreover, for measuring the grid line-to-line voltages two sensors are required; hence overall system cost is reduced and
control system reliability is increased. The time-domain simulation in MATLAB/Simulink and experimental results from a
Hardware based laboratory prototypes are in good agreement, which verify the effectiveness of the proposed generalized
method.