Karla Atkins

The structure of electrical networks: a graph theory-based analysis

We study the vulnerability of electrical networks through structural analysis from a graph theory point of view. We measure and compare several important structural properties of different electrical networks, including a real power grid and several synthetic grids, as well as other infrastructural networks. The properties we consider include the minimum dominating set size, the degree distribution and the shortest path distribution. We also study the network vulnerability under attacks in terms of maximum component size, number of components and flow vulnerability. Our results suggest that all grids are more vulnerable to targeted attacks than to random attacks. We also observe that the electrical networks have low treewidth, which explains some of the vulnerability. We prove that with a small treewidth, a few important structural properties can be computed more efficiently.

A web services based artificial market

We describe a web services based computational tool for studying large commodity markets. The software architecture is based on three important guiding principles: (i) efficiency and scalability, (ii) extensibility to incorporate several different clearing mechanisms and commodities, (iii) modularity for platform independent operations and use. The computational model has several distinguishing features. They include: (i) the ability to generate individualistic, demographics based, time-varying demand profiles, (ii) a highly configurable system that supports different market clearing mechanisms, strategies and matching algorithms for buyers and sellers (Atkins, Marathe, and Barrett 2007), (iii) ability to aggregate individuals into different hierarchy of classes and (iv) ability to physically clear flow based commodities. From the software standpoint, the architecture has several unique features, including use of web services for loosely coupling individual elements of the system, an easy to use web based graphical user interface for specifying input parameters as well as viewing the results, and a work flow language for modeling various markets and market mechanism (Atkins et al. 2004). The system provides users the unique ability to experiment with a variety of markets such as market for communication spectrum, Internet bandwidth, electricity, as well as traditional commodities like corn, cotton etc.

Physical clearing mechanisms in power industry

This paper studies the performance of several different physical clearing mechanisms in the electricity market. The study is done using the simulation tool, Marketecture, developed at the Los Alamos National Laboratory. Two cities, Portland and Chicago, are used for simulating the physical clearing algorithms. The algorithms were chosen according to their ability to serve as a proxy for some of the well known policies. Our results show that, based on the economic measures chosen, both cities perform very similarly under the different physical clearing mechanisms.