New digital method of direct and indirect control applied to wind energy conversion systems using a Double Fed Induction Generator

Active and reactive energy are a very important factor that influences frequency and voltage setting on the electric grid. Many research projects have investigated how a wind turbine can contribute to frequency and voltage regulation, even though it is a decentralized production system. In this paper, we use a new control system to regulate active and reactive power generated by wind farms based on Double Fed Induction Generators (DFIG), which offer multiple advantages. We tested four control structures: direct and indirect control with and without a power loop, and developed a digital implementation of those controllers. Using MATLAB simulation, we found that indirect control using a digital Proportional-Integral-Derivative controller with a power loop results in an enhanced performance and a faster response, thus limiting the DFIG's rotor current, reducing the static error and improving the system's robustness.