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Recently, the massive integration of renewable energy sources, especially wind and solar ones, has attracted researchers to new issues such as power quality. In this context, this article deals with an improved deadbeat predictive control for parallel grid-connected doubly fed induction generator-based wind systems under unbalanced grid conditions. The impact of an asymmetrical voltage sag has been treated for a doubly fed induction generator- wind system with emphasis on the occurrence of the negative current. In the case of a micro-grid based on wind systems, the effect of this current increases with the line impedance and thereby the system location. An improved predictive deadbeat control technique is proposed for the rotor side converter to enhance the behaviour of the wind system. A dynamic modelling of the doubly fed induction generator in both positive and negative reference frames has been proposed to focus on the behaviour of the system for these various operating conditions. Results of different simulation scenarios prove the effectiveness of the proposed improved predictive deadbeat control. [ABSTRACT FROM AUTHOR]

This paper deals with a hybrid fault-tolerant converter topology. It is performed through the connection of a classical three-phase three-level neutral-point-clamped (3L-NPC) converter with a fourth three-level flying capacitor (3L-FC) leg. The 3L-FC leg actively balances the 3L-NPC neutral-point voltage. For normal operation mode, this paper proposes a mathematical design of the filter needed to connect these two different topologies. Experimentally, and thanks to the already existing decoupling capacitors of the 3L-NPC converter, this filter requires the addition of only one low size inductance. When one fault of the power switch of the 3L-NPC occurs, this paper proposes a hardware reconfiguration technique based on only two fuses and one thyristor per leg allows a safe postfault operation recovery. This is achieved thanks to a simple fault-detection method and a new technique that combines fault leg isolation and corresponding phase postfault connection to the neutral point. Also, a dedicated field-programmable gate array (FPGA)-based control of the reconfigured converter is synthetized to ensure power system availability under fault operation mode. The converter fault-tolerant capabilities are addressed through simulation results and original overall experimental validations of the fault detection and isolation and the postfault operation steps, carried out on a 15-kW prototype converter. [ABSTRACT FROM AUTHOR]

The integration of a large number of photovoltaic systems into the electricity grid presents significant technical challenges. To address the issue of excess power injection into the grid, various standards recommend curtailment of PV systems, which results in penalizing renewable energy. This paper proposes a solution to the problem without resorting to curtailment. The key innovation is to optimize the energy injected into the grid, achieving a delicate balance between benefits for prosumers and the grid operator, while also avoiding PV curtailment. The results obtained underscore substantial advantages for prosumers when contrasted with commercial solutions that resort to curtailing PV power, while ensuring the alignment of interests with network providers. The proposed energy management system is based on a multi-objective linear programming algorithm and aims to increase energy injection into the grid during peak regional demand while simultaneously considering the electricity price profile. The study utilizes digital twin technology to establish a dependable framework for validating proposed algorithms and comparing simulated results with experimental ones. By doing so, this process guarantees the accuracy of simulation results and allows for informed decision-making regarding the system under investigation. [ABSTRACT FROM AUTHOR]