A Cost-Effective Single Architecture to Operate DC Microgrid Interfaced DFIG Wind System During Grid-Connected, Fault, and Isolated Conditions

An increase in the utilization of renewable energy has called for a cost-effective and reliable solutions to overcome their intermittency. With this regard, this paper offers a unique way of interfacing dc microgrid (DCMG) to the doubly fed induction generator (DFIG) wind system during grid-connected, fault, and isolated working conditions making it economical. The control flow strategy proposed here uses the grid-side converter (GSC) of the DFIG system to serve multiple purposes; first, the GSC is used to regulate the DCMG voltage during the grid-connected mode and avoids the need for an additional converter for the DCMG to connect it to the grid. Second, the GSC is allowed to function as a simple diode bridge rectifier thereby allowing the DFIG machine to feed DCMG during isolated conditions hence avoiding the need for replacing the converter. This paper also improves the fault ride through performance of the DFIG wind system without any additional investment. This is possible due to the usage of already available ultracapacitor in the DCMG. Hence, the DFIG wind system need not have to finance separately to protect its dc link during the fault. Furthermore, a small-signal-based stability analysis performed also indicates the robustness of the proposed control strategy. A 2.2-kW hardware prototype has been developed and the results obtained from the elaborate experimentation justify that this paper is economical, efficient, reliable, and offers better power quality compared to the existing work.