Robert J. Thomas

Bio: Robert J. Thomas is an academic researcher from Cornell University. The author has contributed to research in topics: Electric power system & Electricity market. The author has an hindex of 43, co-authored 178 publications receiving 11807 citations. Previous affiliations of Robert J. Thomas include University of California, Davis & National Renewable Energy Laboratory.

Direct load management of electric vehicles

Abstract: Electrical Vehicles are gaining increasing attention, due to the opportunities and challenges they present for the energy market. On the one hand, they will allow to drastically reduce the need for oil; on the other hand they may require a significant shift in the day to day management of the electricity generation. This paper is concerned with finding appropriate models for residential load in light of a widespread penetration of electric vehicles. The analysis is aimed at finding a SmartGrid solution that would enable us to optimize the generation dispatch in real time and allow to plug cars in any SmartGrid enabled plug. The key idea is to discriminate between regular load and the load due to the EVs, gathering in real time aggregate information about the sensed EV arrivals and their associated charging times in a demand matrix, that can be readily used to optimize the dispatch, while updating without real time constraints the billing record for the EV.

Identifying the potential for market power in electric power systems in real-time

Abstract: The analysis of recently restructured electric power systems has led to discussions concerning the ability of market participants to manipulate the market to their advantage. Indeed there are instances in which market manipulation has been convincingly established. In this paper we advocate a practical and objective approach to examine market power based on revenue sensitivities. Computing the sensitivities requires only currently available information together with the rules used to operate the electricity market and system. We specifically identify those suppliers with the ability to increase revenues by raising prices or withholding capacity. These suppliers may enjoy some measure of market power since such ability would not be possible in a competitive market in which their generation is easily substitutable. We present a visualization of relevant metrics that have the potential to allow those with the market monitoring function to observe opportunities for market power in real-time. Possible uses for the information are discussed.

The control of variable-speed wind turbine generators

Abstract: The problem of smooth control of electrical power from a large wind turbine generator to an electrical utility system grid is discussed. A control system is proposed which is applicable to either induction or synchronous machines asynchronously coupled to the grid through a controllable DC current link. A power limiting strategy is developed which spills powers at high wind velocities without recourse to blade pitch control mechanisms.

Data framing attack on state estimation with unknown network parameters

Abstract: A data framing attack is presented to exploit the bad data detection and identification mechanisms at a typical ISO/RTO control center. In particular, the proposed attack frames normal meters as sources of bad data and causes the control center to remove useful measurements from the framed meters. The proposed attack uses subspace information of power system measurements; neither the network topology nor the network parameters are required for constructing the attack. It is shown that the proposed attack is capable of perturbing the power system state estimate by an arbitrary degree using only half of the critical measurements. Implications of this attack on power system operations are discussed, and the attack performance is evaluated using benchmark systems.

Testing the effects of price responsive demand on uniform price and soft-cap electricity auctions

Abstract: Testing auction mechanisms experimentally in a controlled environment provides an inexpensive means for evaluating their relative merits. This paper describes a framework for testing the efficacy of a price-responsive load on a uniform-price last-accepted offer and a soft-cap market. Experimental evidence to date, based on uniform-price market testing has shown an ability of price-responsive load to mitigate high volatility and average price. The paper addresses a process to validate these results as well as our hypothesis that price-responsive load mitigates high soft-cap market price behavior, such as that observed in California.

Random graphs

Abstract: We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

MATPOWER: Steady-State Operations, Planning, and Analysis Tools for Power Systems Research and Education

Abstract: MATPOWER is an open-source Matlab-based power system simulation package that provides a high-level set of power flow, optimal power flow (OPF), and other tools targeted toward researchers, educators, and students. The OPF architecture is designed to be extensible, making it easy to add user-defined variables, costs, and constraints to the standard OPF problem. This paper presents the details of the network modeling and problem formulations used by MATPOWER, including its extensible OPF architecture. This structure is used internally to implement several extensions to the standard OPF problem, including piece-wise linear cost functions, dispatchable loads, generator capability curves, and branch angle difference limits. Simulation results are presented for a number of test cases comparing the performance of several available OPF solvers and demonstrating MATPOWER's ability to solve large-scale AC and DC OPF problems.

Smart Grid — The New and Improved Power Grid: A Survey

Abstract: The Smart Grid, regarded as the next generation power grid, uses two-way flows of electricity and information to create a widely distributed automated energy delivery network. In this article, we survey the literature till 2011 on the enabling technologies for the Smart Grid. We explore three major systems, namely the smart infrastructure system, the smart management system, and the smart protection system. We also propose possible future directions in each system. colorred{Specifically, for the smart infrastructure system, we explore the smart energy subsystem, the smart information subsystem, and the smart communication subsystem.} For the smart management system, we explore various management objectives, such as improving energy efficiency, profiling demand, maximizing utility, reducing cost, and controlling emission. We also explore various management methods to achieve these objectives. For the smart protection system, we explore various failure protection mechanisms which improve the reliability of the Smart Grid, and explore the security and privacy issues in the Smart Grid.

Trends in Microgrid Control

Abstract: The increasing interest in integrating intermittent renewable energy sources into microgrids presents major challenges from the viewpoints of reliable operation and control. In this paper, the major issues and challenges in microgrid control are discussed, and a review of state-of-the-art control strategies and trends is presented; a general overview of the main control principles (e.g., droop control, model predictive control, multi-agent systems) is also included. The paper classifies microgrid control strategies into three levels: primary, secondary, and tertiary, where primary and secondary levels are associated with the operation of the microgrid itself, and tertiary level pertains to the coordinated operation of the microgrid and the host grid. Each control level is discussed in detail in view of the relevant existing technical literature.