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Showing papers by "Robert J. Thomas published in 2013"


Journal ArticleDOI
TL;DR: This paper details the proposed problem formulation and outlines potential approaches to solving it, and an implementation based on a DC power flow model solves systems of modest size and can be used to demonstrate the value of the proposed stochastic framework.
Abstract: This work presents a stochastic optimization framework for operations and planning of an electricity network as managed by an Independent System Operator. The objective is to maximize the total expected net benefits over the planning horizon, incorporating the costs and benefits of electricity consumption, generation, ancillary services, load-shedding, storage and load-shifting. The overall framework could be characterized as a secure, stochastic, combined unit commitment and AC optimal power flow problem, solving for an optimal state-dependent schedule over a pre-specified time horizon. Uncertainty is modeled to expose the scenarios that are critical for maintaining system security, while properly representing the stochastic cost. The optimal amount of locational reserves needed to cover a credible set of contingencies in each time period is determined, as well as load-following reserves required for ramping between time periods. The models for centrally-dispatched storage and time-flexible demands allow for optimal tradeoffs between arbitraging across time, mitigating uncertainty and covering contingencies. This paper details the proposed problem formulation and outlines potential approaches to solving it. An implementation based on a DC power flow model solves systems of modest size and can be used to demonstrate the value of the proposed stochastic framework.

168 citations


Journal ArticleDOI
01 Dec 2013
TL;DR: A problem formulation is developed to solve the day-ahead energy and reserve market allocation and pricing problem that explicitly considers the redispatch set required by the occurrence of contingencies and the corresponding optimal power flow, static and dynamic security constraints.
Abstract: It is widely agreed that optimal procurement of reserves, with explicit consideration of system contingencies, can improve reliability and economic efficiency in power systems. With increasing penetration of uncertain generation resources, this optimal allocation is becoming even more crucial. Herein, a problem formulation is developed to solve the day-ahead energy and reserve market allocation and pricing problem that explicitly considers the redispatch set required by the occurrence of contingencies and the corresponding optimal power flow, static and dynamic security constraints. Costs and benefits, including those arising from eventual demand deviation and contingency-originated redispatch and shedding, are weighted by the contingency probabilities, resulting in a scheme that contracts the optimal amount of resources in a stochastic day-ahead procurement setting. Furthermore, the usual assumption that the day-ahead contracted quantities correspond to some base case dispatch is removed, resulting in an optimal procurement as opposed to an optimal dispatch. Inherent in the formulation are mechanisms for rescheduling and pricing dispatch deviations arising from realized demand fluctuations and contingencies. Because the formulation involves a single, one stage, comprehensive mathematical program, the Lagrange multipliers obtained at the solution are consistent with shadow prices and can be used to clear the day-ahead and spot markets of the different commodities involved. Co-optimization of energy and reserves, including system contingency requirementsComplete AC power flow formulation with static and dynamic security constraintsLagrange multipliers determine various day-ahead and spot market commodity prices.Comparison with traditional method shows improvements in system security and costs.

37 citations


Proceedings ArticleDOI
07 Jan 2013
TL;DR: There exist consumer privacy risks associated with current concepts for V2G implementation and it is argued that consumer preferences and behaviors can be inferred from charging information if privacy is not a primary concern from the outset of V1G design.
Abstract: The vehicle-to-grid (V2G) framework proposes integration of battery-powered electric drive vehicles into the grid, enabling them to be recharged as necessary and to act as suppliers in the ancillary service electricity markets. This is expected to create incentives for the production and adoption of electric vehicles in the automotive industry. V2G frameworks require that the utility company or a third party aggregator has access to each vehicle's charging status via a two-way communication network for billing and planning purposes. We establish that there exist consumer privacy risks associated with current concepts for V2G implementation and argue that consumer preferences and behaviors can be inferred from charging information if privacy is not a primary concern from the outset of V2G design. Finally, we outline a privacy-aware architecture for V2G systems.

26 citations


Proceedings ArticleDOI
01 Nov 2013
TL;DR: A new probabilistic forecasting framework is developed based on a time in-homogeneous Markov chain representation of the realtime LMP calculation that generates the posterior probability distribution of future locational marginal prices with forecast horizons of 6-8 hours.
Abstract: The problem of forecasting the real-time locational marginal price (LMP) by a system operator is considered. A new probabilistic forecasting framework is developed based on a time in-homogeneous Markov chain representation of the realtime LMP calculation. By incorporating real-time measurements and forecasts, the proposed forecasting algorithm generates the posterior probability distribution of future locational marginal prices with forecast horizons of 6–8 hours. Such a short-term forecast provides actionable information for market participants and system operators. A Monte Carlo technique is used to estimate the posterior transition probabilities of the Markov chain, and the real-time LMP forecast is computed by the product of the estimated transition matrices. The proposed forecasting algorithm is tested on the PJM 5-bus system. Simulations show marked improvements over benchmark techniques.

20 citations


Proceedings ArticleDOI
01 Nov 2013
TL;DR: A data framing attack is presented to exploit the bad data detection and identification mechanisms at a typical ISO/RTO control center and is capable of perturbing the power system state estimate by an arbitrary degree using only half of the critical measurements.
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.

15 citations


Journal ArticleDOI
TL;DR: In this paper, a data framing attack is proposed to exploit the bad data detection and identification mechanisms currently in use at most control centers, where the attack frames meters that are providing correct data as sources of bad data such that the control center will remove useful measurements that would otherwise be used by the state estimator.
Abstract: A new mechanism aimed at misleading a power system control center about the source of a data attack is proposed. As a man-in-the-middle state attack, a data framing attack is proposed to exploit the bad data detection and identification mechanisms currently in use at most control centers. In particular, the proposed attack frames meters that are providing correct data as sources of bad data such that the control center will remove useful measurements that would otherwise be used by the state estimator. The optimal design of a data framing attack is formulated as a quadratically constrained quadratic program (QCQP). It is shown that the proposed attack is capable of perturbing the power system state estimate by an arbitrary degree controlling only half of a critical set of measurements that are needed to make a system unobservable. Implications of this attack on power system operations are discussed, and the attack performance is evaluated using benchmark systems.

12 citations


Journal ArticleDOI
01 Feb 2013
TL;DR: The purpose is to analyze price-dispatch sensitivity to determine whether there is a generator or a subset of generators that have the ability to increase its own price profitably.
Abstract: An ability to exercise market power by suppliers may significantly reduce market efficiency in restructured electricity markets. Many studies have been performed to develop an effective tool to identify market power based on indices. Most often it is rather difficult to use an index-based method for real-time analysis. This paper provides a method to identify market power that can be used in real time. The purpose is to analyze price-dispatch sensitivity to determine whether there is a generator or a subset of generators that have the ability to increase its own price profitably. Case studies performed on a modified IEEE 118-bus system are presented.

5 citations


Proceedings ArticleDOI
24 Oct 2013
TL;DR: In this paper, the authors discuss the state-of-the-art in storage technology development as well as the use of storage in a wide array of utility and customer applications.
Abstract: In this paper we discuss the state-of-the-art in storage technology development as well as the use of storage in a wide array of utility and customer applications. We also discuss the value and use of these various technologies, and how they might influence market design and structure should they become technically and economically viable for use in electric power systems.

2 citations