Development and application of a fuzzy control system for a lead-acid battery bank connected to a DC microgrid

Abstract

This study presents the development and application of a fuzzy control system (FCS) for the control of the charge and discharge process for a bank of batteries connected to a DC microgrid (DC-MG). The DC-MG runs on a maximum power of 1kW with a 190V DC bus using two photovoltaic systems of 0.6kW each, a 1kW bidirectional DC-AC converter to interconnect the DC-MG with the grid, a bank of 115 Ah to 120V lead-acid batteries, and a general management system used to define the operating status of the FCS. This FCS uses a multiplexed fuzzy controller, normalizing the controller's inputs and outputs in each operating status. The design of the fuzzy controller is based on a Mamdani inference system with AND-type fuzzy rules. The input and output variables have two trapezoidal membership functions and three triangular membership functions. LabVIEW and the NI myRIO-1900 embedded design device were used to implement the FCS. Results show the stability of the DC bus of the microgrid when the bank of batteries is in the charging and discharging process, with the bus stabilized in a range of 190 V± 5%, thus demonstrating short response times to perturbations considering the microgrid's response dynamics.