vol. 1 núm. 1 (2020): transactions on energy systems and engineering applications

Este artículo aborda el problema de la generación de voltaje sinusoidal en cargas lineales utilizando un inversor de fuente de voltaje (VSI). La estructura port-Hamiltoniana en lazo abierto se utiliza para diseñar un controlador basado en pasividad con ganancias proporcionales-integrales (PI-PBC) con el fin de desarrollar la estrategia de control. La principal ventaja de utilizar controladores basados en pasividad corresponde a la posibilidad de garantizar la estabilidad asintótica transformando el problema de seguimiento de trayectoria en uno de control de regulación. Además del PI-PBC, se emplea un estimador de carga lineal basado en una formulación integral para determinar el valor de la conductancia equivalente en la carga, lo que reduce el número de sensores de corriente. Las validaciones numéricas demuestran que el voltaje sinusoidal proporcionado por el VSI a la carga tiene un error de seguimiento menor a $ 1~\% $, con distorsiones armónicas menores a $2.6~\% $, tanto para voltaje como para corrientes en la carga. Todas las simulaciones se realizaron en MATLAB/Simulink utilizando la biblioteca SimPowerSystems versión 2017a.

This paper presents a non-linear method based on sum-of-squares (SOS), to determine the stability of equilibrium points for the Buck, Boost, Buck-Boost and non-inverter Buck-Boost converters. These converters share a similar structure with a PI controller to regulate the output voltage. A quadratic Lyapunov function is proposed in all cases, and the conditions for stability are evaluated using convex optimization based on SOS models. The methodology is useful for academic purposes but also in practical applications like DC microgrids. Simulation results shows the advantages of the proposed method.

The smart grid concept is being applied more and more frequently and this is due to the need to integrate all the components that are part of power systems today, starting from generation units, storage systems, communications and connected loads. Non-linear and non-stationary signals have been obtained in this type of systems, which have high penetration of non-conventional energy sources (NCSRE) and non-linear loads. The power quality criterion has had to be adapted to the new conditions of the electrical systems and this has led to the need to search for new analysis methodologies for the acquired signals. In this article we present a review on non-linear and non-stationary signal analysis methods in electrical systems with high NCSRE penetration. To this end we explore the application of the Hilbert-Huang Transform (HHT), Wavelet Transform (WT) and Wigner-Ville Distribution (WVD), exposing each of the advantages and disadvantages of these methods. To validate the methodology, we have selected some synthetic signals that adequately describe the typical behaviors in these systems.

In this paper is addressed the optimal power flow problem in direct current grids, by using solution methods based on metaheuristics techniques and numerical methods. For which was proposed a mixed integer nonlinear programming problem, that describes the optimal power flow problem in direct current grids. As solution methodology was proposed a master–slave strategy, which used in master stage three continuous solution methods for solving the optimal power flow problem: a particle swarm optimization algorithm, a continuous version of the genetic algorithm and the black hole optimization method. In the slave stages was used a methods based on successive approximations for solving the power flow problem, entrusted for calculates the objective function associated to each solution proposed by the master stage. As objective function was used the reduction of power loss on the electrical grid, associated to the energy transport. To validate the solution methodologies proposed were used the test systems of 21 and 69 buses, by implementing three levels of maximum distributed power penetration: 20%, 40% and 60% of the power supplied by the slack bus, without considering distributed generators installed on the electrical grid. The simulations were carried out in the software Matlab, by demonstrating that the methods with the best performance was the BH/SA, due to that show the best trade-off between the reduction of the power loss and processing time, for solving the optimal power flow problem in direct current networks.