Control of a medium-voltage test generator

This paper describes the design of a digital control for a 3.3 kV, 1 MVA three-level PWM converter operating as test generator for disturbances in medium-voltage grids according to standards like IEC 61000, EN 50160, and IEEE 1547. The proposed control combines state-feedback with additional dynamic output feedback. It is designed fully in the stationary reference frame to avoid processing of complex transformations into different rotating reference frames. Resonant controllers provide zero steady-state error for up to ten harmonics. A DSP platform is used for implementing the control. It replaces the control unit of a commercial converter. Experimental results of a downscaled breadboard construction verify the functionality of the control.