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1997 Publications

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The dynamics of power system markets
Abstract - Market equilibrium conditions can be derived from more general dynamic equations describing the marketplace. Dynamic market equations provide additional insights into the behavior and stability of markets which are not available from static models. For example, markets with a single supplier with declining linear cost may or may not be stable, depending on specific cost charactertics. Markets with more than one supplier with declining linear cost are always unstable. Energy imbalance requires careful design: a combination of aggressive energy imbalance regulation and rapid response of the market can lead to unstable market conditions. Congestion has the potential of substantially altering the market equilibrium point. However, if properly handled, it does not affect market stability.

Final Report: March 12, 1997. Uploaded: July 27, 1998.  
Fernando L. Alvarado 07/27/98 217.59 KB PDF 97-01
Simulation of the Multi-Node Open Access Same-Time Information System
Abstract - This paper describes a Web-based simulator of the Federal Energy Regulatory Commission (FERC) mandated Open Access Same-Time Information System (OASIS) network. The purpose of the simulator is to provide a tool for study of the various aspects of an OASIS network and to gain a strong intuitive feel for its operations. For a specified simulation period, the OASISNET simulator reproduces an OASIS network of multiple nodes using the same communications medium as the actual system, the Internet, and with multiple players using the simulator simultaneously. Salient features of the simulator are its modular architecture, the ability to simulate multi-node OASIS network operations and to accept simultaneous access from remote users through use of client/server technology. The simulation focuses on the dissemination and use of the available transmission capability information. Sample applications of the new simulator are discussed.

Uploaded: July 27, 1998. 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 641-647, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Yong Tian, George Gross 07/27/98 144.72 KB PDF 97-02
A Simulation Tool for Analysis of Alternative Paradigms for the New Electricity Business
Abstract - Various proposals have been made for new paradigms for operating the restructuring electrical system. One of the key challenges associated with this restructuring is to effectively analyze and evaluate the effects these alternative paradigms may have on major aspects of power system operations, including the so called ancillary services. This paper provides preliminary results on the development of a simulation tool to perform analysis alternative paradigms. Since power systems are ultimately governed by the laws of physics, the heart of the tool is a power system simulation engine, valid over a simulated time frame of minutes to days. The modular structure of the tool then allows other packages to be superimposed on this structure to represent different proposed paradigms.

Uploaded: July 27, 1998. 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 634-640, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Thomas J. Overbye, Peter W. Sauer, George Gross, Mark J. Laufenberg, Jamie D. Weber 07/27/98 154.86 KB PDF 97-03
Technical Challenges of Computing Available Transfer Capability (ATC) in Electric Power Systems
This paper discusses the ATC definitions and determination guidelines approved by the North American Electric Reliability Council (NERC) and presents several concepts for dealing with the technical challenges of computation areas of the interconnected network and this required the consideration of a third limiting phenomena. The introduction of St. Clair curves were one of the first attempts to include thermal, voltage, and stability constraints into a single transmission line loading limitation [1]. These results were later verified and extended from a more theoretical basis in [2]. This "single rating" concept is extremely valuable from a computational point of view.
Abstract - A key concept in the restructuring of the electric power industry is the ability to accurately and rapidly quantify the capabilities of the transmission system. Transmission transfer capability is limited by a number of different mechanisms, including thermal, voltage, and stability constraints. This paper discusses the ATC definitions and determination guidelines approved by the North American Electric Reliability Council (NERC) and presents several concepts for dealing with the technical challenges of computation.

Uploaded: July 27, 1998. 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 589-593, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Peter W. Sauer 07/27/98 31.61 KB PDF 97-04
Unbundling Power Quality Services: Technical Issues
Abstract - The modern industrial facility depends on sensitive electronic equipment that can be shut down suddenly by severe power system disturbances. A large number of these disturbances on the power system are a result of line faults which can cause momentary voltage sags. This results in equipment malfunctioning and high cleanup cost. This papers describes some of the emerging oppor-tunities for new services to users of electrical power. In particular the focus is on the need for improved quality of power and methods for providing this new service.

Uploaded: July 27, 1998. 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 581-588, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Clark Hochgraf, and Robert H. Lasseter 07/27/98 128.15 KB PDF 97-05
MinISO: A Minimal Independent System Operator
Abstract - The Independent System Operator or ISO is the lead actor in the various proposals for a deregulated, competitive electric power industry. The ISO has three possible objectives: security maintenance, service quality assurance, and promotion of economic efficiency and equity. To achieve these objectives the ISO may be authorized to set the rules for transactions between suppliers and consumers, scheduling and dispatch of generators, loads and network services, and energy markets. Proposals differ in their specification of the ISO's objectives and authority. Two ISO structures are contrasted. MaxISO, based on the UK-Poolco model, has ambitious objectives and much regulatory authority. Its scientific merit derives from an Optimal Power Flow dispatch model. MinISO's objective is restricted to security, and its regulatory authority is correspondingly modest. MinISO seeks to provide direct consumer access. Its scientific merit is based on the Coordinated Multilateral Trades model.
By locating in the ISO both the transmission-security function and the generation-economic efficiency function, MaxISO ends up being a hindrance to structural reform. By separating those functions, MinISO maximizes consumer choice and technical and financial innovation. The California PUC decision of December 1995 is, understandably, a compromise between the two proposals. The unexpectedly rapid response nationwide of utility and non-utility entities to the potential opportunities of a deregulated industry, however, threatens to make irrelevant the MaxISO model and to shorten the life of California's compromise decision. MinISO remains an option that is exible enough to accommodate the choices that consumers and producers may want.

Uploaded: July 27, 1998. 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 602-607, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Pravin Varaiya and Felix Wu 07/27/98 168.82 KB PDF 97-06
Sensitivity of the loading margin to voltage collapse with respect to arbitrary parameters
Abstract - Loading margin is a fundamental measure of proximity to voltage collapse. Linear and quadratic estimates to the variation of the loading margin with respect to any system parameter or control are derived. Tests with a 118 bus system indicate that the estimates accurately predict the quantitative effect on the loading margin of altering the system loading, reactive power support, wheeling, load model parameters, line susceptance, and generator dispatch. The accuracy of the estimates over a useful range and the ease of obtaining the linear estimate suggest that this method will be of practical value in avoiding voltage collapse.

Uploaded: July 27, 1998. IEEE Transactions on Power Systems, vol. 12, no. 1, pp. 262-272, February 1997.  
Scott Greene, Ian Dobson, Fernando L. Alvarado 08/23/16 3.20 MB PDF 97-07
Contingency Ranking for Voltage Collapse via Sensitivities from a Single Nose Curve
The change in the loading margin to voltage collapse when line outages occur is estimated. First a nose curve is computed by continuation to obtain a nominal loading margin. Then linear and quadratic sensitivities of the loading margin to each contingency are computed and used to estimate the resulting change in the loading margin. The method is tested on a critical area of a 1390 bus system and all the line outages of the IEEE 118 bus system. The results show the effective ranking of contingencies and the very fast computation of the linear estimates.

Uploaded: July 27, 1998. 1997 IEEE Power Engineering Society Summer Meeting, Berlin, Germany, July 20-24, 1997.
IEEE Transactions on Power Systems, vol. 14, no. 1, pp. 232-240, February 1999.  
Scott Greene, Ian Dobson, Fernando L. Alvarado 08/23/16 2.77 MB PDF 97-08
Initial Concepts for Applying Sensitivity to Transfer Capability
The available transfer capability indicates how much interarea power transfers can be increased without compromising system security. The paper addresses transfer capabilities caused by voltage magnitude or voltage collapse limits. It suggests how the sensitivity of the transfer capability can be computed and used to estimate the effect on the transfer capability of variations in parameters such as those describing other transfers, operating conditions or data. A continuation method is used to find the transfer capability due to voltage magnitude or voltage collapse limits. The first order sensitivity of this transfer capability to a wide range of parameters can then be quickly computed. The objective is to use these sensitivities to quickly extract the maximum possible engineering information from each continuation. The sensitivity methods could contribute to the quick update of transfer capabilities when operating conditions or other transfers change and to the computation of a transfer reserve margin.

Uploaded: July 27, 1998. National Science Foundation Workshop on Available Transfer Capability, Urbana, Illinois, June 1997.  
Scott Greene, Ian Dobson, Fernando L. Alvarado, Peter W. Sauer 07/27/98 109.69 KB PDF 97-09
PowerWeb User's Manual
PowerWeb is an environment for testing various power exchange auction markets. It is interactive, distributed and web-based. It is designed to host simulations of a competitive "day-ahead" electric energy market in the context of a restructured electric power industry. See also the PowerWeb Home Page.

Uploaded: July 27, 1998. Copyright 1996-2001. Power Systems Engineering Research Center. PowerWeb's User Manual, Version 2.7, September 12, 2001.  
Robert J. Thomas, Ray D. Zimmerman, Robert Ethier 07/27/98 233.15 KB PDF 97-10
An Internet-Based Platform for Testing Generation Scheduling Auctions
Abstract - This paper describes the uses and architecture of a network-centered computing-rich software platform called PowerWeb. PowerWeb was designed and built as a simulation environment for experimentally testing various power exchange auction markets through tournaments. It is designed to host simulations of a competitive "day-ahead" electric energy market in the context of a restructured electric power industry. The PowerWeb environment is meant to be flexible so as to accommodate different "rules of the game". In this paper we describe its interactive, distributed and web-based character.

Uploaded: July 27, 1998. Published in the Proceedings of the 31st Hawaii International Conference on System Sciences (HICSS-31), vol. 3, pp. 138-146, Kohala Coast, Kona, Hawaii, January 6-9, 1998.  
Ray D. Zimmerman, Robert J. Thomas, Deqiang Gan, Carlos E. Murillo-Sanchez 07/27/98 454.80 KB PDF 97-11
Thermal Unit Commitment Including Optimal AC Power Flow Constraints
We propose a new algorithm for unit commitment that employs a Lagrange relaxation technique with a new augmentation of the Lagrangian. The new augmentation involves a duplication of variables that allows relaxation of the coupling between generator time-spanning constraints and system-wide instantaneous constraints. This framework allows the possibility of committing units that are required for the VArs that they can produce, as well as for their real power. Furthermore, although the algorithm is very CPU-intensive, the separation structure of the Lagrangian allows its implementation in parallel computers. Our work builds upon that of Batut & Renaud, as well as that of Baldick.

Uploaded: July 27, 1998. Published in the Proceedings of the 31st Hawaii International Conference on System Sciences (HICSS-31), vol. 3, pp. 81-88, Kohala Coast, Kona, Hawaii, January 6-9, 1998.  
Carlos E. Murillo-Sanchez, Robert J. Thomas 07/27/98 231.07 KB PDF 97-12
An Importance Sampling Application: 179 Bus WSCC System under Voltage Based Hidden Failures and Relay Misoperations
Abstract - Recent studies have shown that power systems protection mechanisms have played a major role in propagating disturbances. Out of the last five major Western Systems Coordinating Council (WSCC) events (the North Ridge earthquake, December 14, 1994, July 2-3, 1996, and August 10, 1996), the latter three involved false trips with line protection relays and generators. Using an importance sampling based algorithm on the 179 bus WSCC equivalent system, we modeled the sequence of rare events under generator trips and zone 3 relay misoperations. The resulting sequence of rare events and its corresponding probability are used to detect weak links in the system.

Uploaded: July 27, 1998. Published in the Proceedings of the 31st Hawaii International Conference on System Sciences (HICSS-31), vol. 3, pp. 39-46, Kohala Coast, Kona, Hawaii, January 6-9, 1998.  
Koeunyi Bae and James S. Thorp 07/27/98 146.61 KB PDF 97-13
A Transmission-Constrained Unit Commitment Method
Abstract - This paper presents a transmission-constrained unit commitment method. The transmission constraints are modeled as linear constraints based on a DC power flow model. The transmission constraints, as well as the demand and spinning reserves constraints, are relaxed by attaching Lagrange multipliers. In this paper we take a new approach in the algorithmic scheme. A three-phase algorithm is devised including dual optimization, a feasibility phase and unit decommitment. A test problem involving more than 2500 transmission lines and 2200 buses is tested along with other test problems.

Uploaded: July 27, 1998. 31st Hawaii International Conference on System Sciences (HICSS-31), vol. 3, pp. 71-80, Kohala Coast, Kona, Hawaii, January 6-9, 1998.  
Chung-Li Tseng, Shmuel S. Oren, Carol S. Cheng, Chao-an Li, Alva J. Svoboda, Raymond B. Johnson 07/27/98 207.95 KB PDF 97-14
The Efficiency of Multi-unit Electricity Auctions
Using a complete information, game-theoretic model, we analyze the performance of different electricity auction structures in attaining efficiency (i.e., least cost dispatch). We find that an auction structure where generators are allowed to bid for load "slices" outperforms an auction structure where generators submit bids for different hours in the day.

Uploaded: July 27, 1998. PSERC Report No. 97-15. September 12, 1997. An earlier abridged version of this paper appeared in the conference proceedings of the IAEE Fall 1997 meeting in San Francisco, California.
Journal: The Energy Journal, vol. 20, no. 4, pp. 89-116, 1999.
18th Annual North American Conference of the International Association for Energy Economic (IAEE), Fall 1997 Meeting, San Francisco, California, September 7-10, 1997.  
Wedad Elmaghraby and Shmuel S. Oren 08/25/17 4.35 MB PDF 97-15a
International Association for Energy Economic (IAEE) Fall 1997 Newsletter
International Association for Energy Economic (IAEE) Fall 1997 Newsletter  
IAEE 08/26/16 14.15 MB PDF 97-15b
A Simulation Based Approach to Pricing Reactive Power
In this paper we investigate the simulation of real and reactive power spot markets. While spot pricing of real power remains a viable option for the creation of a power system market, the future of a reactive power spot market remains cloudy. The large capital investment portion needed in pricing reactive power as well as the highly volatile nature of reactive power spot prices makes the creation of such a market difficult. In spite of this, a portion of the pricing scheme that is used for reactive power will likely be based on the spot pricing approach as this provides the most accurate signal for near real-time system operation. This paper will build on a simple modification to the standard optimal power flow (OPF) in order to simulate the spot markets for real and reactive power. To achieve this, price-dependent load models are introduced for both real and reactive power.

Uploaded: July 27, 1998. Published in the Proceedings of the 31st Hawaii International Conference on System Sciences (HICSS-31), vol. 3, pp. 96-103, Kohala Coast, Kona, Hawaii, January 6-9, 1998.  
James D. Weber, Thomas J. Overbye, Peter W. Sauer, Christopher L. DeMarco 07/27/98 98.00 KB PDF 97-16
Inclusion of Price Dependent Load Models in the Optimal Power Flow
Abstract - In this paper we investigate the inclusion of price- dependent loads into the traditional Optimal Power Flow algorithm. The development of the model will be based on the solution of the OPF using an objective function for maximization of social welfare. The paper will show that a traditional OPF algorithm that minimizes supplier costs can be modified to solve the social welfare maximization problem by including price- dependent load models. This modification to the standard OPF is intuitive and very simple. We will show this modified OPF formulation facilitates simulation of a spot market for electricity. While the development in this paper will account for both real and reactive power supply and consumption, the examples in the paper will concentrate on real power markets. The algorithm will be demonstrated on a range of practical examples, including several small systems, and on a system with over a hundred buses. The impact of such price dependent loads on congestion and bus marginal costs is highlighted.

Uploaded: July 27, 1998. Published in the Proceedings of the 31st Hawaii International Conference on System Sciences (HICSS-31), vol. 3, pp. 62-70, Kohala Coast, Kona, Hawaii, January 6-9, 1998.  
James D. Weber, Thomas J. Overbye, Christopher L. DeMarco 07/27/98 117.12 KB PDF 97-17
Underlying Technical Issues in Electricity Deregulation
This paper reports on the results of a recent attempt by the Power Systems Engineering Research Center (PSERC) and EPRI to determine the technical tools missing in currently unfolding electric power restructuring scenarios. The business and regulatory environment of the U.S. electricity enterprise is changing rapidly and these changes may prove to be radical. A workshop was organized to accomplish the urgent assessment of the potential extent of this change. The workshop was an internal joint effort of PSERC (The Power System Engineering Research Center) and EPRI (The Electric Power Research Institute) to anticipate the "end game" of the current trend towards electricity deregulation. The specific objective was to identify the engineering and economic tools that will be needed for the future environment. The vehicle for accomplishing this was through examining a range of alternative future scenarios and business structures. This paper reports on the outcome of the workshop and summarizes its findings.

Uploaded: July 27, 1998. Published in the Proceedings of the 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 561-570, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Robert J. Thomas and Thomas R. Schneider 07/27/98 58.60 KB PDF 97-18
Solving Unit Commitment by a Unit Decommitment Method
We present a new unit commitment algorithm which is initialized with a solution having all available generation units on-line. The solution is successively improved by decommiting units one at a time. The optimal decommitment strategy employed is based on a decommitment algorithm introduced by the first author in an earlier paper as a post processing algorithm for improving the results of a traditional Lagrangian Relaxation (LR) algorithm. We show that the proposed method may in fact be viewed as an approximate implementation of the LR approach. Furthermore, we show that the number of iterations required by the method is bounded by the number of units. Empirical tests suggest that the proposed method is more efficient and robust than the LR approach.

Uploaded: July 27, 1998. Final Report: October 14, 1997. Journal: Journal of Optimization Theory and Applications, vol. 105, no. 3, pp. 707-730, June 2000.  
Chung-Li Tseng, Chao-an Li, Shmuel S. Oren 08/26/16 212.72 KB PDF 97-19
The Impact of Generation Mix on Placement of Static Var Compensators
Abstract - This paper looks at the problem of placing Static Var Compensators to provide the maximum transfer capability for all possible generation mixes. The margin to low voltage limit is one of the quantities used to determine power system transfer capability. Fast methods for finding the location of SVC systems that will have the greatest impact on low voltage margin will be shown. The IEEE 24 bus system will be used to demonstrate this method over a wide range of generation patterns.

Uploaded: July 27, 1998. IEEE Transactions on Power Delivery, vol. 14, issue 3, pp. 1018-1023, July 1999.
1999 IEEE Power Engineering Society Winter Meeting, vol. 2, New York, New York, January 31 - February 4, 1999.  
Ronghai Wang, and Robert H. Lasseter 08/26/16 1.54 MB PDF 97-20
StatCom Controls for Operation with Unbalanced Voltages
Abstract - Voltage Sourced Static Var Compensators such as the StatCom need to be able to handle balanced voltages. Mild Imbalance can be caused by unbalanced loads while severe short-term imbalance can he caused by power system faults. A synchronous frame voltage regulator is presented that works even when three phase symmetry is lost. This regulator addresses voltage imbalance by using separate regulation loops for the positive and negative sequence components of the voltage. The regulator allows the StatCom to ride through severe transient imbalance without disconnecting from the power system and, further, to assist in rebalancing voltages. The regulator maintains sufficient bandwidth to perform flicker compensation. The controllers performance is simulated for a StatCom in a model distribution system where it is subjected to a severe single line to ground fault and a rapidly varying three phase load.

Uploaded: July 27, 1998. IEEE Transactions on Power Delivery, vol. 13, issue 2, pp. 538-544, April 1998.  
Clark Hochgraf, and Robert H. Lasseter 08/26/16 1.61 MB PDF 97-21a
STATCOM Controls for Operation with Unbalanced Voltages
Abstract - Voltage Sourced Static Var Compensators such as the StatCom need to be able to handle balanced voltages. Mild Imbalance can be caused by unbalanced loads while severe short-term imbalance can he caused by power system faults. A synchronous frame voltage regulator is presented that works even when three phase symmetry is lost. This regulator addresses voltage imbalance by using separate regulation loops for the positive and negative sequence components of the voltage. The regulator allows the StatCom to ride through severe transient imbalance without disconnecting from the power system and, further, to assist in rebalancing voltages. The regulator maintains sufficient bandwidth to perform flicker compensation. The controllers performance is simulated for a StatCom in a model distribution system where it is subjected to a severe single line to ground fault and a rapidly varying three phase load.

12th International Power Electronics and Motion Control Conference (EPE-PEMC 2006), pp. 1454-1459, Portoroz, Slovenia, Central Europe, August 30 - September 1, 2006.  
08/26/16 1.39 MB PDF 97-21b
Re-Dispatching Generation to Increase Power System Security Margin and Support Low Voltage Bus
Abstract - This article proposes a new method to increase a power system's security margin and/or support its low voltage buses by re- dispatching generator outputs, using a normal vector found at a voltage collapse boundary or a low voltage boundary (LVB). This method uses the normal vector as an indicator to change the generation direction so that more power can be transferred before reaching a boundary of a critical limit such as the voltage collapse boundary or the LVB, etc. The method has been tested in simulation on several systems and shown predicted results. It can be applied to many practical power systems to enhance the system's security and reliability, so as to increase the system's transfer capability. It also provides technical guidance for open access transmission in a deregulated environment, when bidding results are shown as generation directions (patterns).

Uploaded: July 27, 1998. IEEE TRANSACTIONS ON POWER SYSTEMS, VOL. 15, NO. 2, PP. 495-501, MAY 2000.  
Ronghai Wang, and Robert H. Lasseter 08/26/16 243.56 KB PDF 97-22
Power System Bidding Tournaments for a Deregulated Environment
Abstract - In this paper we describe certain tools for understanding and operating power systems in a deregulated environment. Many of the current models for this competitive market that employ an independent system operator (ISO) for controlling transmission, ensuring fair access and security and providing a spot market for power will be studied. This centrally- dispatched power pool also ensures that generation meets demand based on bids submitted daily from independent generators (and from customers offering interruptible loads). Currently, most ISO bidding models allow only a single bid per day. In this paper, we present an asynchronous bidding scheme as a possible alternative. In particular, we examine the effects of feedback mechanism such that upon receiving generation levels from the ISO, independent generators (IGs) be allowed to modify their bid if they so desire. This competitive or ‘sequential’ bidding process should be allowed to hopefully optimize their profit margins. This paper also discusses the development tools necessary for examining the effects of different bidding processes on the ISO model and evaluation their capability of driving the market to an efficient state of operation.

Uploaded: June 27, 2006. Proceedings of the 30th Hawaii International Conference on System Sciences (HICSS-30), vol. 5, pp. 681-686, Wailea-Makena, Maui, Hawaii, January 7-10, 1997.  
Eric Sakk, Robert J. Thomas, Ray D. Zimmerman 06/27/06 641.40 KB PDF 97-23