Modelling of an innovative and autonomous micro-grid based on a biomass - solar PV hybrid power system

¹ Istituto Motori, CNR, Viale Marconi, 4 – 80125 Naples, Italy
² University of Naples Federico II, Department of Industrial Engineering, Via Claudio, 21 – 80125 Naples, Italy

^* Corresponding author: m.costa@im.cnr.it

Abstract

Micro-Combined heat and power (m-CHP) systems fuelled by renewables, such as residual biomasses, are today of great interest to produce energy in an efficient and green way. The aim of the present work is to develop a numerical model of a hybrid energy system including a biomass powered m-CHP unit based on gasification and coupled with solar photovoltaic (PV) modules and to an electrical storage device, able to provide energy to remote areas. Main advantages of the considered configuration are its ultra-low environmental impact and just its autonomous operation by local resources. The developed unsteady multiphysical model accounts for the main plant components, namely the syngas powered engine, the PV panels and the battery, as well for a dynamic use of the produced energy. Main features of the adopted schematization of the actual system rely on the proper description of syngas combustion, that takes into account the extreme difficulty of working with a non-conventional gas, and on a PID control that is considered for energy flow management to meet the electrical demand curve. The PV panel current is calculated through an ad-hoc function that reads, at any given time, actual solar irradiance data in the city of Naples, Italy, the battery voltage and the main parameters of the PV module. The battery, with a voltage of 48V and a capacity of 100kWh, is modelled as an equivalent circuit with its proper State of Charge (SoC) versus Open Circuit Voltage (OCV) curve. The voltage response to a current at a particular SoC and temperature are calculated. This dynamic modelling permits the optimal control of the whole system to meet the electrical and thermal user’s demand and also to better design any possible change in the storage or PV size to meet specific real uses of the produced energy.