Unified Control based Adaptable Converters with a Fractional Harmonic Inter Converter Signalling channel for Dynamic tracking of PCC and Managing Multiple Converters Connected in Parallel in a Microgid

Abstract

The increasing demand of energy over the past few years as well as the growing environmental concerns have forced the mankind to look out for non conventional sources of energy such as solar, wind etc. Consequently a large number of these energy resources are integrated to the existing power grid in a distributive manner. These resources known as distributed energy resources (DERs) are interfaced to the grid through power electronic converters. More and more DERs are being integrated to the grid. The increased penetration of DERs interfaced through power electronic converters have led to the concept of microgrids. The installation of microgrids have become a common scenario across the globe. However, the microgrid is also not devoid of technical issues like any other system. In this thesis, the author looks at some of the persistent issues in the microgrid and proposes some relevant practical solutions. The thesis is broadly divided into four parts. The first part deals with the concept of a Utility Interactive Uninterruptible Power Converter (UIUPC) and its role in a microgrid. In the first part, a new UIUPC, making use of a concept known as unified control is proposed. The proposed unified control is based on controlling the perturbations in the magnitude and speed of the point of common coupling (PCC) space vector with respect to a reference space vector applied continuously along the direction of the PCC space vector. The proposed unified control based UIUPC inherently transfers from a grid follower to a grid former and vice -versa according to the modes without the help of any islanding detection algorithms or external synchronising mechanisms. The second part of the thesis looks at the issue of communication between power converters connected in a microgrid. The thesis proposes a novel method of inter converter communication through the existing power line. The proposed method is based on the concept of using a fractional harmonic space vector to carry the data. The data is modulated and demodulated in t...