PROJECT TITLE: Analysis of Stability Issues and Enhanced Stabilization Techniques of DC Microgrids
PhD period: 2018.07.01 – 2021.06.30.
Section: Esbjerg Energy Section
Research Programmes: Intelligent Energy Systems and Active Networks and Microgrids
Supervisor: Mohsen Soltani
Co-Supervisor: Amin Hajizadeh
Collaborator: SolarFlex, ELforsk.
DC microgrid have attracted more and more attention due to its prominent merits compared with AC microgrid: high efficiency, easy control and strong robustness. As a result, distributed DC generation systems with multiple power electronic converters are significantly used in applications such as aircrafts, spacecrafts, naval ships and electric vehicles. A typical DC microgrid is depicted in Fig.1. In the DC microgrid, the distributed generations (DGs) are usually connected to the DC bus through power electronic converters and loaded by various loads. DC microgrids consist of multiple power electronic converter units interconnected in a network with sources and loads. This project studies stability analysis and stabilization techniques of DC microgrids under different load conditions. One of conditions which will be investigated is Constant Power Loads (CPLs).It is well known that CPLs have negative impedance characteristics, which may yield instability in a DC microgrid. The main focus of this project is to study the stability issues and stabilization methods of power converters-based dc microgrids. Especially, in a DC microgrid system with multiple parallel connected converters, which that are exposed to different load conditions, the improper parameter settings of the converters may trigger oscillation and collapse. The dynamic behavior of the system in high frequency range is often not studied with the classical tools based on conventional averaging methods. In this project, the stability analysis of the system will be established based on a discrete-time model of the system, taking into account the switching frequency and intrinsic nonlinearities of the system model. The impacts of the filter parameters and interactions among the loads will be investigated with the proposed discrete-time technique. The simulation results based on MATLAB/Simulink platform verify the feasibility of the methods. Finally, Simulation results and theoretical observations will be validated on a laboratory hardware prototype.
Publications in journals and conference papers may be found at VBN.