A novel predictive rotor current control scheme for a doubly fed induction generator (DFIG) is implemented to perform the DFIG grid synchronization with a fast dynamic response. With this control strategy applied to an experimental setup, the rotor currents swiftly follow the necessary reference for grid synchronization in the range ±30% of the generator rated shaft speed. The DFIG and converter discrete models are used to predict the behavior of the rotor currents. By minimizing the error between the references and the predictive rotor currents for each of the valid states of the converter, the best-suited switching state is selected and applied at the next sampling time. To validate the feasibility of implementing this approach, simulations and experiments were carried out for various shaft speed profiles.

This study discusses how increased deployment of electric vehicles (EVs) acts as a catalyst for development of transformer and home energy management systems in order to reduce the impact of EV battery charging on distribution transformers. The analysis uses actual load consumption data from Austin, Texas, during a typical summer day. It also considers a case of high-density penetration of electric vehicle in line with plans announced as part of Austin's Pecan Street smart grid initiative. The presented discussion describes first that because of air conditioner use, both during day and at night, power consumption remains relatively constant throughout the day, which creates issues even when considering charging EVs at night. In particular, the analysis anticipates that in such areas with high density of EVs and where air conditioner load is also present at night, distribution transformer life may be reduced unless EV charging is managed adequately.

A simple and intuitive Doubly Fed Induction Generator (DFIG) predictive rotor current control scheme is presented. Predictive control of an Indirect Matrix Converter (IMC) is combined with predictive rotor current control of a DFIG to achieve a very good dynamic response as the rotor currents smoothly follow the applied reference in a ±30% range of the generator nominal rpm. Simulation results are presented for constant torque and rotational speed, as well as for variable rotational speed corresponding to a 10 kW generator dynamic response. Derivation and conjunction of each model equations are also presented along with a delay error compensation strategy to counter the practical implementation issue implicit in discrete time control computation.

This paper studies the benefits of the virtual ground (VG) connection for single-phase transformerless grid-tied inverters that is used to mitigate the leakage-ground currents (LGC) issue. This work also proposes common-mode and differential-mode models of single-phase inverters connected to the grid through an LCL output filter, that are used as a theoretical support. It is shown that LGC are simply common-mode currents (CMC) circulating through the ground path, which represents a contribution in the development of an approach to find solutions in general scenarios. In most of the cases, these currents are produced by the existence of common-mode voltages (CMV), which find a way through the ground-path established after the stray capacitances in the terminals of, for instance, photovoltaic (PV) panels. To prove the advantages of the proposed interconnection and for analysis, the single-phase full-bridge version of a two-level conventional inverter, as well as an NPC inverter are considered for model derivation and experimental validation.