Abstract
Abstract—Output current control is widely used as the inner?most
control loop of inverters, in particular virtual synchronous machines
(VSM). The realization of this controller is commonly based on a PI
controller working in a synchronous reference frame. The controller
should mitigate the grid currents distortion and the unsteady amplitudes
caused by A/D converter imperfec?tions, measurement errors and
processing delays. The elimination of any DC component in the output
currents is another relevant demand. The literature indicates that the
current controller parameters are usually chosen by experimental tuning.
In this paper, we propose a fast current controller design procedure
that provides compensation for the processing delays and eliminates the
DC components of the grid-side currents. We propose to control also the
zero component of the output currents (which helps in an unbalanced
grid). We present the performance of the novel features of our current
controller through a series of simulations, comparing it to the
performance of the same con?troller without the proposed additional
features. In addition, we compare our new current controller’s design
with one proposed in the literature. The results show that the new
current controller leads to a better performance of the VSM in terms of
output active power oscillations and stability.