Discreet-time distributed secondary control for DC microgrids via virtual voltage drop averaging

• Main Author: Tok, Zong Qing
• Other Authors: Wen Changyun
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering; Control-system
• Online Access: https://hdl.handle.net/10356/177040
• Institution: Nanyang Technological University

In today’s energy climate, there is an increasing demand for a Direct Current (DC) microgrid due to a multitude of environmental, technological, and economic factors. DC microgrids have had a rise in popularity in the context of renewable energy systems, urban development as well as the constant efforts to improve energy efficiency and reliability. In the ever-changing landscape of distributed energy resources (DERs), DC microgrids are known for their efficiency, reliability, and compatibility with renewable energy. Additionally, DC Microgrids have already been widely applied for industrial use and has been slowly going towards commercial use. For example, the recently announced AC/DC Hybrid Microgrid that is to be built at the National University of Singapore (NUS). In a DC Microgrid network, there is a need to ensure stable and equal load-sharing and precise voltage regulation among the power generation sources. This is to ensure that no single source is overstressed, and demand is met without any interruption, along with reducing wastage of renewable energy sources. Thus, to ensure stable and equal load sharing between all the sources, a discreet-time distributed secondary controller will be introduced alongside the droop controller. Using the idea of “Virtual voltage drop”, the proposed controller should help achieve the goal of flexible current sharing and accurate voltage regulation. The effectiveness of secondary controller will be modelled, simulated, and evaluated with a resistive load, constant power load (CPL) as well as a multi-bus system using the Simulink Application within the MATLAB Program. An augmented DC Microgrid model was modelled to perform various case studies under different simulation conditions. From the simulation results that was obtained using the three case studies mentioned above it can be concluded that the proposed secondary controller does indeed achieve flexible current sharing as well as accurate voltage regulation.