This paper presents a mathematical procedure for modeling rectangular (N rows with M modules each) and non-rectangular photovoltaic (PV) arrays in Total Cross-Tied (TCT) configuration operating in uniform and mismatching conditions. The proposed model uses the simple single diode representation for each PV module; then each row of the TCT array is represented as an equivalent non-linear PV circuit with a bypass diode, which allows to represent the TCT array as one string of equivalent PV circuits. The inflection voltages (array voltages that turn off the bypass diodes) of the string are calculated in order to solve only the non-linear equation system related to the active equivalent PV circuits for calculating the array current for a given voltage. Such a strategy reduces the computational burden and improves calculation speed. A TCT array of 4×2 with deep mismatching conditions was implemented in PSIM software to validate the proposed model, obtaining a correlation between model predicted data and the circuital simulation. The accuracy and improved calculation speed of the proposed model allow its use altogether with reconfiguration techniques as well as to reduce the time of energetic evaluations of TCT arrays for PV planning.Peer ReviewedPostprint (published version

No abstract

Devices connected to microgrids require safe conditions during their connection, disconnection and operation. The required safety is achieved through the design and control of the converters that interface elements with the microgrid. Therefore, the design of both power and control stages of a battery charger/discharger based on a flyback is proposed in this paper. First, the structure of a battery charger/discharger is proposed, including the battery, the flyback, the DC bus, and the control scheme. Then, three models to represent the battery charger/discharger are developed in this work; a switched model, an averaged model, and a steady-state model, which are used to obtain the static and dynamic behavior of the system, and also to obtain the design equations. Based on those models, a sliding-mode controller is designed, which includes the adaptive calculation of one parameter. Subsequently, a procedure to select the flyback HFT, the output capacitor, and the Kv parameter based on operation requirements of the battery charger/discharger is presented in detail. Five tests developed in PSIM demonstrate the global stability of the system, the correct design of the circuit and controller parameters, the satisfactory regulation of the bus voltage, and the correct operation of the system for charge, discharge and stand-by conditions. Furthermore, a contrast with a classical PI structure confirms the performance of the proposed sliding-mode controller.

No abstract

En este artículo se propone una metodología para diseñar microrredes en zonas no interconectadas de Colombia. El diseño de la microrred se realiza siguiendo la normativa eléctrica colombiana. Las etapas de la metodología son: recolección de información de campo, evaluación de recursos energéticos renovables y no renovables, estimación del perfil de carga, dimensionamiento de los generadores, diseño de la topología de la microrred y análisis eléctrico. Los calibres de los conductores se seleccionan según la NTC 2050. Se presenta un caso de estudio, para el cual se selecciona la región de Taroa, en el Departamento de la Guajira. Taroa está ubicada en una zona no interconectada de Colombia. A partir de información meteorológica de la zona y el análisis de carga, se seleccionan los equipos de generación usando el software HOMER. Las tensiones en la microrred son calculadas a partir de flujos de potencia utilizando el software Power System Analysis Toolbox. Los generadores son representados con modelos reducidos para agilizar el proceso de diseño. Las variaciones de tensión en los nodos de la microrred diseñada están dentro del 3% de la tensión nominal. Este rango de variación está definido en el Reglamento Técnico de Instalaciones Eléctricas (RETIE). Los resultados de las simulaciones, utilizando datos reales, evalúan la viabilidad de la metodología propuesta.