New Control Method Including State Observer of Voltage Unbalance for Grid Voltage-Source Converters

New observer-based disturbance-estimation and control algorithms are introduced in this paper that compensate source voltage unbalances. The algorithms are also designed to compensate the detrimental impact of delay effects caused by the digital-signal processing. Consequently, these techniques are appropriate for higher power systems with reduced pulsewidth modulation switching frequency and limited current-controller bandwidth. Analytical, simulation, and experimental results are presented to illustrate the effectiveness of the new observer-based control techniques.