Attenuation of Wind Power Fluctuations in Wind Turbine Generators using a DC Bus Capacitor Based Filtering Control Scheme

Wind energy is fluctuating. However, in wind turbine generators (WTGs), by allowing a certain amount of variations of the voltage on the bus, a dc bus capacitor is able to offer a power shaping ability, and can function as an energy storage system (ESS). This paper proposes a power fluctuation filtering algorithm, applied to the ESS to selectively and adequately attenuate the medium frequency wind power fluctuations. A medium-sized ESS produces a fairly smooth wind power output and ensures the WTG stability under severe wind fluctuations. The proposed algorithm is applied to a 2 MW permanent magnet synchronous machine (PMSM) WTG, simulated in an electromagnetic transients program. The fluctuations of both pre- and post-filtered wind powers are presented, and quantified in the different frequency regions. Simulation results confirm the effectiveness and robustness of the control algorithm