In this paper, a photovoltaic (PV) microinverter capable of operating in both island mode and grid-connected mode by means of a reconfigurable control scheme is proposed. The main advantage of control reconfiguration is that in grid-connected mode, the microinverter works as a current source in phase with the grid voltage, injecting power to the grid. This is the operation mode of most commercial grid-connected PV microinverters. The idea is to provide those microinverters with the additional functionality of working in island mode without changing their control algorithms for grid-connected mode, which were developed and refined over time. It is proposed that in island mode, the microinverter control is reconfigured to work as a voltage source using droop schemes. These schemes consist in implementing P/Q strategies in the inverters, in order to properly share the power delivered to the loads. The aim of the paper is to show that the proposed control reconfiguration is possible without dangerous transients for the microinverter or the loads. Simulation and experimental results on an 180-W PV microinverter are provided to show the feasibility of the proposed control strategy.

An alternative way to control a nonlinear system, such as a two Degree Of Freedom helicopter, is the linearization of the model around an equilibrium point, in this case, an equilibrium point around the Pitch angle. Subsequently, the design a Robust Controller for this system is done, using a the DK iteration method. However, when a variation of an angle such as its uncertainty is modeled, the performance of the controller is affected and it might turn itself into an unstable system even when minimal perturbations are presented. In this paper, a nonlinear mathematical model of a two Degree of Freedom helicopter is used. This model is linearized around one specific equilibrium point. Consequently, the uncertainties of the systems are modeled, and finally, the Robust controller by the DK iteration is designed and simulated.

Este artículo presenta una revisión de las principales tecnologías para almacenamiento de energía y su utilización en micro redes eléctricas. La utilización de fuentes de energía renovable en sistemas de distribución de energía eléctrica aumenta los requerimientos de instrumentación, gestión y control, debido al grado de intermitencia y variabilidad de dichas fuentes. Los sistemas de almacenamiento brindan la confiabilidad, disponibilidad y calidad del servicio que se requiere. Sin embargo, la selección del sistema de almacenamiento debe ser parte del diseño de la microred, teniendo en cuenta los objetivos y las características requeridas. El análisis muestra que la implementación de sistemas de almacenamiento de energía en una micro red mejora los transitorios, la capacidad, aumenta la potencia instantánea y permite la introducción de sistemas renovables de energía.

The peregrine falcon, known as the fastest bird in the world, has been studied for its ability to stabilize during high-speed dives, a capability attributed to the configuration of its dorsal feathers. These feathers have inspired the design of vortex generators devices that promote controlled turbulence to delay boundary layer separation on aircraft wings and turbine blades. This study presents an experimental wind tunnel investigation of a bio-inspired peregrine falcon prototype, equipped with movable artificial feathers, a hot-wire anemometer, and a 3D accelerometer. Wake velocity profiles measured behind the prototype revealed fluctuations associated with feather motion. Spectral analysis of the velocity signals, recorded with oscillating feathers at a wind tunnel speed of 10 m/s, showed attenuation of specific frequency components, suggesting that feather dynamics may help mitigate wake fluctuations induced by structural vibrations. Three-dimensional acceleration measurements indicated that prototype vibrations remained below 1 g, with peak differences along the X and Z axes ranging from −0.06 g to 0.06 g, demonstrating the sensitivity of the vibration sensing system. Root Mean Square (RMS) values of velocity signals increased with wind tunnel speed but decreased as the feather inclination angle rose. When the mean value was subtracted from the signal, higher RMS variability was observed, reflecting increased flow disturbance from feather movement. Fast Fourier Transform (FFT) analysis revealed that, for fixed feather angles, spectral magnitudes increased uniformly with wind speed. In contrast, dynamic feather oscillation produced distinctive frequency peaks, highlighting the feather’s influence on the wake structure in the frequency domain. To complement the experimental findings, 3D CFD simulations were conducted on two HAWT-type wind turbines—one with bio-inspired vortex generators and one without. The simulations showed a significant reduction in turbulent kinetic energy contours in the wake of the modified turbine, particularly in the Y-Z plane, compared to the baseline configuration.

En este estudio se realiza un análisis numérico de torque en turbinas con modificaciones denominadas generadores de vórtice (VGs) mediante el uso de simulación computacional de la dinámica de fluidos (CFD) en 3D. Los torques simulados se obtienen para variaciones de inclinación angular de los generadores de vórtice ubicados en los extra-dorsos de las aspas y dos diferentes temperaturas de aire. Los resultados muestran que el máximo torque se presenta con una temperatura de 10°C y ángulo de inclinación de generadores de vórtice de 30° con valor de 8.5 Nm. El mínimo torque se observa con temperatura de 25°C y ángulo de inclinación de 45° con valor de 4.2 Nm. En conclusión, la simulación CFD muestra que a una mayor temperatura del aire se reduce el torque en la turbina, reduciendo la potencia mecánica rotacional, y que los generadores de vórtice reducen la energía cinética de turbulencia (TKE) en la estela de viento generada.