Effective performance and power transfer operation of a current controlled WRIG based WES in a hybrid grid

This paper deals with the performance and possible power transfer modes of Wound Rotor Induction Generator (WRIG) based Wind Energy System (WES) in a hybrid grid (AC and DC Micro grid (DCM)) delivering power in islanded and utility tied conditions. The current controlled Rotor Side Converter (RSC) with its DC end connected to DCM facilitates bidirectional slip power flow. In islanded mode, a decoupled voltage vector control with cascaded PI loops is used for regulating stator voltage and stator frequency. In utility tied mode, reference current generation technique based on Instantaneous Power Theory (IPT) is adopted for slip power transfer by PWM rectification/inversion of RSC. The excitation is supplied via rotor and stator during islanded and utility tied conditions respectively. All possible operational modes are formulated aiming incessant power transfer by WRIG. Maximum power extraction during occasional situations like short circuit faults/low wind/overload and no load claims the merit of the system. The dynamic power transfer operation to maintain the power balance during hybrid mode is analyzed through laboratory experimentation on a 500 W induction machine. Experimental findings confirm the efficacious working of WRIG based WES.