Power Smoothing Control of PMSG Based Wind Generation Using Supercapacitor Energy Storage System

This paper proposes an efficient power smoothing control strategy for variable speed grid connected permanent magnet synchronous generator (PMSG) based wind turbine generator (WTG) with supercapacitor energy storage system (SCESS). As WTG installations are increasing, these systems generate a fluctuated output power as a result of varying wind speed and need to have a power smoothing capability to have a smooth output power profile. The optimal size of the SCESS is determined and a controller is proposed and implemented to continuously charge and discharge the SCESS to achieve its objectives. The SCESS is exploited to minimize the short term fluctuation to have a smooth power profile during normal operation. A bi-directional buck boost converter is used to integrate the SCESS with the system. Two back to back connected three level Neutral Point Clamped (NPC) converters are used for the power conversion. The control strategy and the system model have been developed for the NPCs, the buck boost converter and the variable speed WTG system. The Real Time Digital Simulator (RTDS) based results conducted on 2 MW/4 kV PMSG verify the effectiveness and superiority of the proposed controller.