A Comparative Study of Signal Analysis Methods Applied in the Detection of Instantaneous Frequency

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

Comparación computacional de motores AC y DC ante cambios hidrodinámicos en embarcaciones marítimas pesqueras

The objective of this article is to make a comparison in a computational environment between an alternating current motor and a direct current motor is made for dynamic variations in the propulsion of an artisanal fishing boat. Initially, the boat was simulated in the Maxsurf software to obtain the dynamic behaviors for pitching, rolling, yawing, and heave motions with wind and wave perturbations for a Pierson Moskowitz spectrum. Subsequently, the motors are selected and in Matlab/Simulink software and a torque behavior required by the vessel to act on the resistance presented in each dynamic motion is proposed. This allows for analyzing the required mechanical and electrical conditions, using the curves obtained in the simulation. Finally, it is concluded that taking into account the criteria of torque, power, speed, and current, the results obtained show that the DC motor is more efficient than the three-phase AC motor for artisanal fishing vessel applications. In addition, the two motors require greater effort to overcome the disturbance related to the rolling motion in the steady-state, while in the transient state the DC motor requires a higher starting torque and the AC motor presents oscillations, which are undesirable disturbances because they produce instability in the electrical system. Additionally, it is important to take into account the energy source that feeds the motors, which can be alternating current or direct current.El objetivo de este artículo fue realizar la comparación en un ambiente computacional entre un motor de corriente alterna y un motor de corriente continua ante variaciones dinámicas en la propulsión de una embarcación marítima de pesca artesanal. Inicialmente, se simuló la embarcación en el software Maxsurf con el objetivo de obtener los comportamientos dinámicos para los movimientos de cabeceo, balanceo, guiñada y oleaje con perturbaciones de viento y ola para un espectro de Pierson-Moskowitz. Posteriormente, se seleccionaron los motores en el software Matlab/Simulink, donde se propone un comportamiento de torque requerido por la embarcación para actuar ante la resistencia presentada en cada movimiento dinámico. Esto permitió analizar las condiciones mecánicas y eléctricas requeridas mediante las curvas obtenidas en la simulación. Finalmente, teniendo en cuenta los criterios de torque, potencia, velocidad, y corriente, los resultados obtenidos mostraron que el motor DC presenta mayor eficiencia que el motor AC trifásico para aplicaciones de buques de pesca artesanal. Además, se evidenció que los dos motores requieren mayor esfuerzo para vencer la perturbación relacionada al movimiento de balanceo en estado estable, mientras que, en el estado transitorio, el motor DC requiere un par de arranque mayor y el motor AC presenta oscilaciones, las cuales son perturbaciones indeseables debido a que producen inestabilidad en el sistema eléctrico. Es importante tener en cuenta la fuente energética que alimenta los motores que pueden ser de corriente alterna o corriente continua

Interval-based Resource Usage Verification by Translation into Horn Clauses and an Application to Energy Consumption

Many applications require conformance with specifications that constrain the use of resources, such as execution time, energy, bandwidth, etc. We have presented a configurable framework for static resource usage verification where specifications can include lower and upper bound, data size-dependent resource usage functions. To statically check such specifications, our framework infers the same type of resource usage functions, which safely approximate the actual resource usage of the program, and compares them against the specification. We review how this framework supports several languages and compilation output formats by translating them to an intermediate representation based on Horn clauses and using the configurability of the framework to describe the resource semantics of the input language. We provide a more detailed formalization and extend the framework so that both resource usage specification and analysis/verification output can include preconditions expressing intervals for the input data sizes for which assertions are applicable, proved, or disproved. Most importantly, we also extend the classes of functions that can be checked. We provide results from an implementation within the Ciao/CiaoPP framework, and report on a tool built by instantiating this framework for the verification of energy consumption specifications for imperative/embedded programs. This paper is under consideration for publication in Theory and Practice of Logic Programming (TPLP).Comment: Under consideration for publication in Theory and Practice of Logic Programming (TPLP

Análisis de expansión de una microrred en una zona no interconectada

Context: The use of microgrids in non-interconnected areas has become the only alternative that people living in these regions have to access the electricity service. Because of this it is necessary to optimize the use of these systems and if it is possible to expand existing ones to increase coverage and, in that way, support the implementation of the sustainable development goal 7 set by United Nations:  Ensure access to affordable, reliable, sustainable and modern energy for all. Methodology: In this paper, we present two cases of expansion for a microgrid based on a photovoltaic generation system that is located in a non-interconnected area of Colombia. The analysis of the electrical generation of the system is carried out using Matlab/Simulink and the small signal analysis to evaluate the stability is executed in Neplan. Based on the above, it is possible to establish a methodology that allows to define the expandability of a microgrid. Results: From the small signal stability analysis performed in Neplan, the system's own values are obtained, both from the current microgrid and from the two cases of expansion, this in order to guarantee the property of stability in the micro grid in three different scenarios; non-linear loads, increased power demanded and generated. Conclusions: In photovoltaic systems located in non-interconnected areas and operating in island mode the inverters influence frequency stability considerably, because the reduced inertia in these systems leads to a faster frequency variation. This is why the analysis of small signal stability is the method indicated to study the behavior of microgrids before variations in demand and generated power, particularly in systems that operate in areas not interconnected, because with small disturbances it is possible to identify the changes in the dynamics of the system.Contexto: La utilizacion de microrredes en zonas no interconectadas se ha convertido en la unica alternativa que tiene las personas que habitan estas regiones para acceder al servicio de energía eléctrica. Debido a esto se hace necesariooptimizar la utilización de estos sistemas y en caso que sea posible expandir las ya existentes para aumentar la cobertura y de esta manera apoyar el cumplimiento del objetivo de desarrollo sostenible numero 7 planteado por las naciones unidas: Energía asequible y no contaminante. Metodología: En este artículo se presenta dos casos de expansión para una microrred basada en un sistema de generación fotovoltaica que se encuentra en una zona no interconectada de Colombia. Se realiza el análisis de generación eléctrica del sistema mediante Matlab/Simulink y el análisis de pequeña señal para verificar la estabilidad es ejecutado a través de Neplan. Con base en lo anterior se logra establecer una metodología que permite definir la capacidad de expansión de una microrred.   Resultados: A partir del análisis de estabilidad de pequeña señal realizado en Neplan se obtiene los valores propios del sistema, tanto de la microrred actual como de los dos casos de expansión, esto con el fin de garantizar la estabilidad en la microrred ante tres escenarios diferentes; cargas no lineales, aumento de potencia demandada y generada. Conclusiones: En los sistemas de generación solar fotovoltaica ubicados en zonas no interconectadas y operando en modo isla los inversores influyen en la estabilidad de frecuencia considerablemente, debido a que la reducida inercia en estos sistemas conduce a una variación más rápida de este parámetro. Es por esto por lo que el análisis de estabilidad de pequeña señal es el método indicado para estudiar el comportamiento de microrredes ante variaciones de potencia demanda y generada, particularmente en los sistemas que operan en las zonas no interconectadas, porque ante pequeñas perturbaciones es posible identificar los cambios en la dinámica del sistema

Control Methods for Single-phase Voltage Supply with VSCs to Feed Nonlinear Loads in Rural Areas

This paper addresses the problem of sinusoidal voltage generation in linear loads using a voltage source inverter (VSI). The port-Hamiltonian structure in open-loop is used to design a passivity-based controller with proportional-integral gains (PI-PBC) in order to develop the control strategy. The main advantage of using passivity-based controllers corresponds to the possibility of guaranteeing asymptotic stability by transforming the trajectory tracking problem into a regulation control one. In addition to the PI-PBC, a linear load estimator is employed based on an integral formulation to determine the value of the equivalent conductance in the load, which reduces the number of current sensors. Numerical validations demonstrate that the sinusoidal voltage provided by the VSI to the load has a tracking error lower than $1~\%$, with harmonic distortions lower than $2.6~\%$, both for voltage and currents in the load. All the simulations were conducted in MATLAB/Simulink using the SimPowerSystems library version 2017a

Contraction Analysis for a MMC Converter

One of the present barriers to the widespread use of Modular Multilevel Converters (MMC) is the complexity of its control. We use a suitable degree of simplifications of the MMC converters, under given conditions, to allow system level studies over potentially large networks. The analysis is based on a recently proposed simplified model of the MMC. Based on this model, we propose an analysis using the theory of Contraction to define some stability conditions. Some simulation results allow to see the advantages of the proposed method.acceptedVersio

Analysis of the power coefficient for a wind generation system

This paper presents an analysis of the conditions and problems that occur when Wind Generation Systems operates in different mode of tracking maximum power. The analysis focuses on the effect of the power coefficient of the wind turbine in the condition of balance of power between the wind generation systems and the electrical network. In the specialized literature there are not enough papers that address this problem. Therefore, in the present paper this problem is solved, showing that there are two desired mechanical speeds for the one particular operating condition of the wind generation systems when this is interacting with the electrical network for each wind speed value

Sustainable model for rural electrification projects in Non-Interconnected Areas in Colombia

Rural electrification projects (REP) in Colombia lack a strong institutional framework. About 5% of the population in Colombia does not have access to electricity service and that hinders their social and economic development. In this paper, we review the recent developments in the topic of rural electrification in Colombia and propose some strategies to ensure the sustainability of the projects implemented in the rural area. The great challenge for Colombia is to have universal access to electricity and in that process are several actions that have been developed and could serve as a model for other countries. The Sustainability strategies presented are validated through a case study