The Comparing of Linear Damping Methods for Constant Power Loads and Stability Analysis

Abstract

Due to the limited reserves of fossil fuels and the devastating damage they cause to the environment, the interest in renewable energy sources is increasing all over the world. As a natural consequence of this trend, the traditional electricity grid has lost popularity, and DC microgrid, which employs many power converters and facilitates the grid integration of renewable energy sources, comes into prominence. The most of renewable energy sources produce DC voltage and they need DC microgrid. It could be possible that renewable energy sources are more increasingly located in traditional grid with using power electronic devices like converters. Despite the many advantages of DC microgrid, the most important shortcoming is the instability problem. In this study, the characteristic behavior of constant power load (CPL) encountered in cascade-connected DC converter system were firstly analyzed under the guidance of literature review. Then the instability effect on the feed-side converter caused by the CPL load was solved using the classical passive and active damping methods. The results obtained from the sample DC-DC cascade converter structure created in MATLAB software were compared with each other and their advantages over each other were emphasized. Thus, the comprehensive study on the instability problem and CPL load behavior on DC microgrids, which is a current research topic, has been performed.