Limiting power control strategy combining spring system and speed control feasible to small WECS

This paper presents a grid-connected Wind Energy Conversion System (WECS) using a permanent magnet synchronous generator (PMSG) operating with variable speed. A maximum power point tracking (MPPT) algorithm is used to determinate the power to be extracted from the generator for each rotational speed while wind power remains lower than the PSMG rated power. Otherwise, the MPPT algorithm is disabled and the proposed external mechanical power control loop maintains the rated power condition. Both control techniques determine the proper current ratings through the PMSG, which is driven by a three-phase bridgeless boost rectifier using digitally-implemented self-control strategy. The rectifier supplies a three-phase full-bridge inverter that provides an ac output with the desired requirements. Simulations results on a 6-kW WECS are shown in order to validate the proposal.