Evaluating the performance of the BTB converter under unbalanced voltage sags

In this work, a control structure to maintain the power flow transference in renewable energy systems based on wind turbines operating under unbalanced voltage conditions is presented. In the proposed scheme, the Back-to-Back (BTB) converter preserves the electrical cogeneration under the occurrence of voltage sags type B, C and D in three-phase systems. The control modeling is developed in the dq reference frame and two control schemes are proposed to control the BTB converter. A per-phase analysis at the interconnected grid side is considered; on the other hand, for the load side, a three-phase analysis is established. The effectiveness of the BTB converter to compensate voltage sags is shown through simulation and experimental results.