An Open-End Winding system is proposed able to manage the electric generator and the battery energy storage system in a wind power plant with integrated energy storage. The proposed system is formed by connecting a T-Type rectifier and a two-level inverter/rectifier equipped with fast GaN devices through the open stator winding of the AC generator. The T-Type rectifier feeds power to the dc bus of the grid inverter, while the energy storage system is managed by the inverter/rectifier, which acts also as an active power filter to sinusoidally shape the generator phase currents, and as a voltage equalizer to balance the voltage of the output capacitors. A three-port power conversion system with almost negligible switching power losses is obtained, because the T-Type rectifier is operated at very low switching frequency, while low inverter switching power losses are achieved thanks to the GaN devices. Purposely developed modulation and control techniques are exploited to cope with the specific features of the proposed Open-End Winding system. Simulation results confirm the consistence of the proposed system in managing with high efficiency a wind power plant with an integrated battery energy storage system.