Instantaneous direct voltage and frequency control in DC grid tied DFIG based wind energy system

The paper presents a new configuration of DFIG based wind energy system which belongs to the connection with the DC grid/bus. The presented configuration of DFIG based wind energy systems is kind of stand-alone DC-DFIG based system where: (i) The load replaces the utility grid; (ii) the rotor is connected to the DC grid/bus/micro-grid via rotor side converter. Being a stand-alone DC-DFIG based system, only voltage and frequency regulation is considered here in this research. The rotor side converter provides the controlled amplitude & frequency of the rotor current for regulating the stator side voltage magnitude and frequency. Also, a simple and easy to implement in hardware as well as in software control technique for the rotor side converter, based on root mean square detection of stator/load voltage, is proposed in this study. The proposed configuration is found suitable in the areas having low-to-medium wind speed. The MATLAB Simulink model of 2 MVA DFIG has been considered to evaluate the performance of the system. Also, hardware set-ups comprise with (i) 3.2 kW DFIG (ii) DC shunt motor, and (iii) FPGA Altium NanoBoard3000 controller, are considered to reveal the effectiveness of the proposed configuration and controller in real time environment.