Analysis of synchronous and stationary reference frame control strategies to fulfill LVRT requirements in Wind Energy Conversion Systems

In order to avoid stability problems, LVRT requirements (Low Voltage Ride Through) demand Wind Energy Conversion Systems (WECS) to remain connected to the grid in the presence of grid voltages dips. Because 88% of the grid failures are asymmetrical, positive and negative sequence components have to be controlled to fulfill LVRT requirements. This paper present a comparison between synchronous and stationary reference frame control strategies for an active front-end converter of a grid connected WECS working under grid fault conditions. The mathematical analysis and design procedure of both control system are presented in this work. Experimental results obtained from a 3kW prototype are fully discussed in this paper. The experimental implementation is realized using a novel implementation of a voltage sag generator which is based on a 3×4 Matrix Converter.