Minimization of DC Bus Side Current Ripple in DFIG Supported DC Micro Grid

Integration of solar PV power plants, battery storage systems and DC loads through DC microgrid (DCMG) has become very popular. Due to absence of additional DC to AC power conversion stage, DCMG based systems have been proven to be efficient and reliable compared to AC grid-based systems. Type IV wind turbines can also be connected to DC microgrid due to the topological flexibility. In this paper, a type IV wind turbine consisting of, dual voltage-source inverter (VSI) fed doubly fed induction generator (DI-DFIG), is used for supporting DCMG having solar PV, battery storage and EV charging station. DC bus of both VSIs are connected to DCMG directly and DFIG is operated in super-synchronous generating mode. Synchronous sine-triangle (SST) pulse width modulation (PWM) technique is used for operating both VSIs. A carrier interleaving based technique is proposed in this paper for minimization of current ripple on the DC bus. Optimized interleaving angles are determined over complete range of turbine speed. Current ripple on DC-bus is found to be reduced significantly. The same is validated through simulations on a 250kW DFIG.