Utilizing Distributed Resources in Smart Grids - A Coordination Approach

The Danish electricity grid is expected to face numerous challenges in the future. These are the combined effect of several factors, such as an increased use of renewable resources for power production; an increased use of electricity for previously fossil-fueled consumption; and an increase in local power generation at household level. These factors pose challenges relating to how supply and demand should be balanced when supply relies on volatile resources; how to avoid grid congestion when demand increases; how to deal with increasing costs of transport losses; and how to maintain quality of power
if the flow reverses on account of residential production. The focus of this thesis is to show that proper utilization and coordination of distributed resources in the grid can be an important tool to alleviate these challenges.
We initially elaborate on the expected challenges, where we focus specifically on
grid balancing, congestion management, minimization of transport losses, and control of power quality. Subsequently, we discuss various classes of resources in the grid and introduce the concept of a smart grid, within which we derive optimization strategies to demonstrate the resources applicability for alleviating the presented challenges.
Our strategies relies on coordination of power producers and consumers by utilizing the flexibility provided by the ability of shifting either production or consumption, from one time instance to another. We present models describing this flexibility as well as its limitations. Enforcing coordination through temporal shifts of consumption and production requires the problems we consider to be solved across some predefined time-horizon.
Utilizing flexibility of consumers through coordination, is known as demand management, and considers how consumers may be motivated to mobilize their flexibility to obtain a trade-off between private desires, and social expenses. We discuss two conceptually different approaches for demand management, outlining their benefits and disadvantages.
For this we formally present several problems concerning the central challenges,
and demonstrate how demand management may solve these. We solve the problems using several methods based on distributed optimization, catering to the distributed nature of the resources in the grid.
Our work adds to the current insight in the field of smart grids, by demonstrating
how the presented issues, concerns and challenges may be solved within a smart grid framework, by identifying, coordinating and utilizing the available flexibility of various distributed resources through optimization based techniques.