Optimization of Isolated Hybrid Microgrids with Renewable Energy Based on Different Battery Models and Technologies

Abstract

Energy supply in remote areas (mainly in developing countries such as Colombia) has become a challenge. Hybrid microgrids are local and reliable sources of energy for these areas where access to the power grid is generally limited or unavailable. These systems generally include a diesel generator, solar modules, wind turbines, and storage devices such as batteries. Battery life estimation is an essential factor in the optimization of a hybrid microgrid since it determines the system’s final costs, including future battery replacements. This article presents a comparison of different technologies and battery models in a hybrid microgrid. The optimization is achieved using the iHOGA software, based on data from a real microgrid in Colombia. The simulation results allowed the comparison of prediction models for lifespan calculation for both lead–acid and lithium batteries in a hybrid microgrid, showing that the most accurate models are more realistic in predicting battery life by closely estimating real lifespans that are shorter, unlike other simplified methods that obtain much longer and unrealistic lifetimes.

Estimating Degradation Costs for Non-Cyclic Usage of Lithium-Ion Batteries

“…Using Equations (17), (18), and (28), the values of the calendar aging life loss function ( ) and cyclical aging life loss function ( ) can be expressed by Equations (33) and (34): From this, the calculation of cyclic degradation cost due to a single charge or discharge can be realized in one only step. Nevertheless, estimation of calendar degradation cost, if cell parameters change, needs subdivision of time in small increments, considering the parameters as constant over time.…”

“…Using Equations (17), (18), and (28), the values of the calendar aging life loss function ( LFP cal ) and cyclical aging life loss function ( LFP cyc ) can be expressed by Equations (33) and (34):…”

“…Several degradation models have been applied to optimization problems. Dufo-López et al [2] applied several battery aging models developed for the optimization of lead-acid batteries, and García Vera et al [18] also applied various battery life models to the optimization of off-grid systems, considering both lead-acid and lithium-ion batteries. Due to their increasing use, a detailed study of lithium-ion battery life models is necessary in order to be able to apply them to this type of problem.…”

Special Issue on Standalone Renewable Energy System: Modeling and Controlling

“…Usually the main source of energy in the optimal hybrid off-grid system is a photovoltaic generator [8], and also includes in many cases a diesel or gasoline backup generator and battery storage. In windy places, the optimal hybrid off-grid system may also include wind turbines [9].…”

“…Nowadays, most off-grid systems installed in the world include storage using lead acid batteries. However, with the recent reduction of the price of lithium batteries, these kind of batteries may be economically feasible in some cases [8,11].…”