Design and Analysis of Non-Linear Sliding Mode Control Variants with Hierarchical Energy Management System for a Multi-Level Multi-Source DC Microgrid /

Abstract

The recent transition in power generation and consumption depends upon the integration of clean energy sources using DC microgrids. DC microgrids are known to be versatile networks that can deal with the uncertainties caused by the interconnection of green energy resources and storage devices. To facilitate this integration, a multisource DC microgrid structure including wind, photovoltaics, fuel cell, battery and supercapacitor is presented in this research work. Unidirectional and bidirectional converters link these sources to the DC-bus. For the analysis of the system, mathematical models of power converters is derived. Following that, hierarchical control for energy sources coordination is explained. This control system consists of a high and low-level of control. For the low-level control, a variable structure based sliding mode control ensures global asymptotic stability and regulation of the DC bus voltage. Whereas high-level control compensates for the supply and demand mismatches by using a rule-based fuzzy system. To verify the effectiveness of the proposed scheme by variants of sliding mode control, real-time weather data and load data is used. The variants are simulated and compared in the MATLAB/Simulink environment. The simulated results showed that amongst all the controllers, adaptive terminal and super twisting sliding mode control are the most efficient ones. They had negligible chattering as well as better convergence in contrast to conventional, integral, and double integral sliding mode controllers. However, the adaptive technique overtakes supertwisting control as it deals with the system's parametric variations. Furthermore, hardware in loop experiments validate the system's efficiency in realtime.