Dynamic performance of grid connected AC/DC Voltage Source Converter under voltage dips transient conditions

The intensive use of voltage source converters (VSCs) in grid-connected applications requires control strategies that should be robust against voltage transients, such as voltage dips. The voltage dips are mainly caused by short-circuit faults; many of them last only a few tens or hundreds of milliseconds and they are unbalanced in most cases. The grid connected VSC from back to back structures is usually employed to control the DC-link voltage and the grid currents, keeping them within their allowed values. The dynamic behavior of grid connected AC/DC VSC under voltage dip transients is investigated in this paper. Three different control strategies are compared, emphasizing the advantages and disadvantages of each solution. Experimental results are presented for all three control strategies, using a 20 kVA AC/DC PWM rectifier prototype.