Showing papers by "Robert J. Thomas published in 2005"

A method for transmission system expansion planning considering probabilistic reliability criteria

Abstract: This paper proposes a method for choosing the best transmission system expansion plan considering a probabilistic reliability criterion (/sub R/LOLE). The method minimizes the investment budget for constructing new transmission lines subject to probabilistic reliability criteria, which consider the uncertainties of transmission system elements. Two probabilistic reliability criteria are used as constraints. One is a transmission system reliability criterion (/sub R/LOLE/sub TS/) constraint, and the other is a bus/nodal reliability criterion (/sub R/LOLE/sub Bus/) constraint. The proposed method models the transmission system expansion problem as an integer programming problem. It solves for the optimal strategy using a probabilistic branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Test results on an existing 21-bus system are included in the paper. They demonstrate the suitability of the proposed method for solving the transmission system expansion planning problem subject to practical future uncertainties.

Bidding strategies in oligopolistic dynamic electricity double-sided auctions

Abstract: In this paper, the problem of developing bidding strategies in oligopolistic dynamic electricity double-sided auctions is studied. We model electricity double-sided auctions as dynamic systems and use Nash-Cournot strategies for the market participants (generating firms and load serving entities). Through simulation studies, we compare the efficiency and competitiveness of electricity double-sided auctions to those of electricity supplier-only auctions (using the developed bidding strategies).

dcOvercoming Communications Challenges in Software for Monitoring and Controlling Power Systems

Abstract: The restructuring of the electric power grid has created new control and monitoring requirements for which classical technologies may be inadequate. The most obvious way of building such systems, using TCP connections to link monitoring systems with data sources, gives poor scalability and exhibits instability precisely when information is most urgently required. Astrolabe, Bimodal Multicast, and Gravitational Gossip, technologies of our own design, seek to overcome these problems using what are called "epidemic" communication protocols. This paper evaluates a hypothetical power monitoring scenario involving the New York State grid, and concludes that the technology is well matched to the need.

Location-based scheduling and pricing for energy and reserves: a responsive reserve market proposal

Abstract: It is well known that given a network that can become constrained on voltage or real power flows, reserves must also be spatially located in order to handle all credible contingencies. However, to date, there is no credible science-based method for assigning and pricing reserves in this way. Presented in this paper is a responsive-reserve scheduling algorithm incorporating constraints imposed by grid security considerations, which include one base case (intact system) and a list of credible contingencies (line out, unit lost, and load growth) of the system. By following a cost-minimizing co-optimization procedure, both power and reserves are allocated spatially for the combined energy and reserve markets. With the Lagrange multipliers obtained, the scheduling algorithm also reveals the locational shadow prices for the reserve and energy requirements. Unlike other pricing and scheduling methods in use, which are usually ad hoc and are based on engineering judgment and experience, this proposed formulation is likely to perform better in restructured markets when market power is a potential problem. An illustrative example of a modified IEEE 30-bus system is used to introduce concepts and present results.

Transmission System Planning-The Old World Meets The New

Abstract: Transmission systems in the United States and around the world have become more difficult to plan under deregulation. Uncertainties in generation type, location, and pricing coupled with market mechanisms that encourage transfers not designed for in the legacy transmission system have made the transmission planner's life difficult. This paper describes the planning process under regulation, some of the issues encountered during the present transition to a deregulated industry, and some of the open questions that need to be addressed in the United States.

Identification of load pockets and market power in electric power systems

Abstract: In this paper, we present a spectral method for the identification of load pockets and the application of practical techniques for the measurement of market power. Market power is a serious concern in electric energy markets, especially in the area of a load pocket. Common definitions for market power, which rely on a comparison between market prices and a so-called competitive price, are difficult to use in practice because the competitive price is not known when the market is not competitive. The competitive price cannot be computed from data naturally available to the market. Our technique focuses on the identification of participants with the ability to increase revenues by increasing prices, an ability not present in a competitive market. We then propose measures for quantifying the extent to which market power is being exercised. These measures can be computed from data available to the market; they are practical. We present results from a 30 bus, 6 generator system, which illustrates that generators in a load pocket have and can exploit joint market power.

Reliability, Electric Power, and Public Versus Private Goods: A New Look at the Role of Markets

Abstract: The economic theory that has been used to support restructuring of the electric power industry has ignored several important technological constraints and public goods that affect the way in which power is delivered Some of these public goods include voltage, frequency, and reliability of lines Similarly, engineers, by using security-constrained optimization to incorporate the demand for reliability, have failed to properly define the economic problem This research attempts to remedy this deficiency through a collaborative effort between economists and engineers to examine the theoretical and empirical properties of a networked power system that provides economically optimal reliability and draw conclusions regarding efficient market design

Determination of construction priority of transmission lines based on probabilistic reliability evaluation

Abstract: This paper proposes a method for determining the construction priority of transmission lines based on probabilistic reliability evaluation. This method suggests the priority for constructing lines from new transmission lines set of optimal solution obtained by the optimal transmission expansion planning. In this study, the optimality is solved by integer programming using branch and bound method, which utilizes a network flow approach and the maximum flow-minimum cut set theorem to minimize investment budget of transmission line construction and subject to deterministic criterion using a program Cmexp.For. The timing priority of new line construction is determined on the comparison of probabilistic reliability indices of each new system using TRELSS 6.2 program. The proposed method has been tested on IEEE-MRTS.

A study on probabilistic optimal reliability criterion determination in composite power system expansion planning

Abstract: The optimal design of composite power system expansion planning is an important part of the overall planning task of electric power system under competitive electricity market environments. One of main keys of the successful generators and grid expansion planning comes from optimal reliability level/criteria decision, which should be given for constraint in the optimal expansion problem. However, it's very difficult to decide logically the optimal reliability criteria of a transmission system as well as generation system expansion planning in a society. This paper approaches a methodology for deciding the optimal reliability criteria for an optimal composite power system expansion planning considering generation and transmission systems simultaneously. A probabilistic reliability criterion, LOLE/sub R/ (loss of load expectation), is used in this study. The optimal reliability criterion LOLE/sub R/* is decided at minimum cost point of total cost curve which is the sum of the utility cost associated with construction cost and the customer outage cost associated with supply interruptions for load considering forced outage rates of elements (generators and lines) in long term forecasting. The characteristics and effectiveness of this methodology are illustrated by the case study using MRBTS size system.

A basic method for composite power system expansion planning considering probabilistic reliability criteria

Abstract: This paper proposes a method for choosing the best composite power system expansion plan considering a probabilistic reliability criterion. The proposed method minimizes the investment budget (economics) for constructing new transmission lines subject to deterministic (demand constraint) and probabilistic reliability criteria (LOLER), while considering the uncertainties of system elements. It models the power system expansion problem as an integer programming one. The method solves for the optimal strategy using a probabilistic theory-based branch and bound method that utilizes a network flow approach and the maximum flow-minimum cut set theorem. Although the proposed method is applied to a simple sample study, the test results demonstrate that the proposed method is suitable for solving the power system expansion planning problem subject to practical future uncertainties

A method for classifying offer strategies observed in an electricity market

Abstract: The idea that large-scale generating units will operate at marginal cost when given the ability to offer their power for sale in a uniform price auction is at best wishful thinking. In fact, both real and experimental data show that the more uncertainty a supplier faces (e.g., load uncertainty, uncertainty of other suppliers, etc.), the more they will hedge their profits through higher than marginal cost offers and through withholding units if permitted. This makes predicting unit commitment and dispatch ahead of time difficult. This paper explores characteristics of software agents that were designed based on the outcome of human subject experiments on a uniform price auction with stochastic load. The agent behavior is compared to the behavior of the subjects. Both subject and agent behavior is classified based on the data. Differences and similarities are noted and explained. Based on the result of the simulation, a model was suggested to explain an offer submitted in deregulated markets based on double layer diffusion.

Electric power market agent design

Abstract: The electric power industry in many countries has been restructured in the hope of a more economically efficient system In the restructured system, traditional operating and planning tools based on true marginal cost do not perform well since information required is strictly confidential For developing a new tool, it is necessary to understand offer behavior The main objective of this study is to create a new tool for power system planning For the purpose, this dissertation develops models for a market and market participants A new model is developed in this work for explaining a supply-side offer curve, and several variables are introduced to characterize the curve Demand is estimated using a neural network, and a numerical optimization process is used to determine the values of the variables that maximize the profit of the agent The amount of data required for the optimization is chosen with the aid of nonlinear dynamics To suggest an optimal demand-side bidding function, two optimization problems are constructed and solved for maximizing consumer satisfaction based on the properties of two different types of demands: price-based demand and must-be-served demand Several different simulations are performed to test how an agent reacts in various situations The offer behavior depends on locational benefit as well as the offer strategies of competitors