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No FOLDERS found.   Sort by:   Number   Name Author Date Size Type 02-01 Quantifying Transmission Reliability Margin In bulk electric power transfer capability computations, the transmission reliability margin accounts for uncertainties related to the transmission system conditions, contingencies, and parameter values. We propose a formula which quantifies transmission reliability margin based on transfer capability sensitivities and a probabilistic characterization of the various uncertainties. The formula is verified by comparison with results from two systems small enough to permit accurate Monte-Carlo simulations. The formula contributes to more accurate and defensible transfer capability calculations. Jianfeng Zhang, Ian Dobson, Fernando Alvarado 2/20/2002 120.9k PDF 02-02 Two-Settlement Systems for Electricity Markets: Zonal Aggregation under Network uncertainty and Market Power We analyze welfare properties of two-settlement systems for electricity in the presence of network uncertainty and market power. We formulate and analyze several models which simulate the different market designs adopted or proposed for many electricity markets around the world. In particular, we examine the extent to which a two-settlement system with zonal aggregation in the forward market facilitates forward trading, as well as the welfare and distributional implications of having such zonal aggregation in the presence of network uncertainty. Using a duopoly model over simple two- and three-node networks, we show that for even small probabilities of congestion, forward trading may be substantially reduced, and the market power mitigating effect of forward markets (as shown in Allaz and Vila, 1993) may be nullified to a great extent. We find that the imposition of a delivery requirement on the forward contract in the form of a spot transmission charge alleviates some of the incentive problems associated with zonal aggregation. Even with the imposition of the spot transmission charge, we find that some reduction in forward trading persists due to the segregation of the markets in the constrained state, and the absence of natural incentives for generators to commit to more aggressive behavior in the spot market. In our analysis, we find that the standard assumption of 'no-arbitrage' across forward and spot markets leads to very little contract coverage even in the no congestion case. We provide an alternative view of the market where we assume that all of the demand shows up in the forward market, and is aggregated to determine the forward price using a 'market clearing' condition. Rajnish Kamat and Shmuel S. Oren 2/20/2002 366.1k PDF 02-03 Human Factors Aspects of Power System Voltage Contour Visualizations This paper presents experimental results associated with human factors aspects of utilizing color contours to visualize electric power system bus voltage magnitude information. Participants were divided into three groups: the first group saw only one-line numeric data, the second only one-line contour data, while the third saw both. The purpose of the experiment was to determine how quickly participants could both acknowledge low voltage violations and perform corrective control actions. Results indicated the contour only visualization resulted in the quickest voltage violation acknowledgements, while the numeric data only visualization resulted in the quickest solution times. Testing was done using a modified version of the IEEE 118 bus system. Thomas J. Overbye, Douglas A. Wiegmann, Aaron M. Rich, Yan Sun 3/7/2002 752.3k PDF 02-04 Symbolic Dynamic Models for Highly Varying Power System Loads Representation and modeling of loads in a power system are very important, as a system may have different types of complex loads. The work reported here is aimed at loads which are highly varying in nature, such as electric arc furnaces and steel rolling mills. These loads do not have fully accepted physical models because of the unpredictable nature of load current, but they often have a rich set of operating data over a wide range of operation. In this masters thesis, time series data on voltages and currents are used to formulate the models. Diwakar Tewari 3/7/2002 637.5k PDF 02-05 An Advanced Visualization Platform for Real-Time Power System Operations The size and complexity of the interconnected power grid pose significant challenges to system operators. The requirement of rapid response under diverse conditions in a highly complex environment underscores the need for tools that can help operators detect potential problems and identify solutions quickly and accurately. This paper discusses the design, development, and deployment of a software application that attempts to address this need. The software illustrates system conditions on a geographic map of the interconnection using a variety of innovative visualization techniques that help the application convey the current state of the system in a clear, unambiguous, and engaging way. This paper dis-cusses the architecture of the application, the benefits, design, and implementation of each of its visualization tools, guidelines for designing displays that take maxi-mum advantage of the platform’s strengths, and planned future enhancements. It also emphasizes a key ingredient to the success of the application: seeking and responding to the ideas and needs of the operators who depend on the platform for the information they require to operate the power system. Several figures are included that demonstrate the types of displays currently being shown in the control room. Ray Klump, David Schooley, Thomas Overbye 3/25/2002 1.2M PDF 02-06 (Dis)Proving Market Power The purpose of this paper is to establish an accurate, systematic and rigorous methodology and framework for proving or disproving the exercise of market power in specific instances, and to do so taking full consideration of all the realities of power markets. Original posted 3/25/02 Revised version posted 11/6/03 Rajesh Rajaraman and Fernando Alvarado 11/6/2003 276.3k PDF 02-07 An Individual Welfare Maximization Algorithm for Electricity Markets An algorithm that allows a market participant to maximize its individual welfare in electricity spot markets is presented. The use of the algorithm in determining market equilibrium points, called Nash equilibria, is demonstrated. The start of the algorithm is a spot market model that uses the optimal power flow (OPF), with a full representation of the transmission system and inclusion of consumer bidding. The algorithm utilizes price and dispatch sensitivities, available from the Hessian matrix and gradient of the OPF, to help determine an optimal change in an individual’s bid. The algorithm is shown to be successful in determining local welfare maxima, and the prospects for scaling the algorithm up to realistically sized systems are very good. Nash equilibria are investigated assuming all participants attempt to maximize their individual welfare. This is done by iteratively solving the individual welfare maximization algorithm until all individuals stop modifying their bids. James D. Weber, Thomas J. Overbye 4/1/2002 239.4k PDF 02-08 A Concurrent Non-Recursive Textured Algorithm for Distributed Multi-Utility State Estimation During power deregulation, power companies are releasing their transmission grids to form ISOs/RTOs while maintaining their own state estimators over their own areas. A recent trend for these ISOs/RTOs is to further combine and enlarge to become a bigger Mega-RTO grid for a better market efficiency. The determination of state over the whole system becomes challenging due to its size. Instead of a totally new estimator over the whole grid, we propose a distributed textured algorithm to determine the whole state; in our algorithm, the existing state estimators in local companies/ISOs/RTOs are fully utilized and the new estimator is no longer required. We need only some extra communication for some instrumentation or estimated data exchange. In addition, such an algorithm has the following advantages: 1) The distributed textured algorithm is non-recursive, asynchronous and avoids central controlling node. Therefore, it is fast and practical. 2) Based on exchanging data with neighboring companies/ISOs/RTOs, textured overlapped areas become part of the process. With the developed textured decomposition method, bad data detection and identification ability is better than existing distributed state estimation algorithm, especially when bad data occur around the boundary of individual estimators. 3) Discrepancy on the boundary buses of different estimators decreases and the result over whole grid become more consistent. Moreover, when updating local estimation through estimated data exchanges, matrix modification techniques that utilize sparse techniques are developed to accelerate the computation speed. Detailed numerical tests are given to verify the efficiency and validity of the new approach. Garng. M. Huang, Jiansheng Lei 4/2/2002 275.5k PDF 02-09 A Knowledge Based Data Exchange Design for Distributed Mega-RTO Operations During power deregulation, companies and ISOs are releasing their transmission grids to form RTOs/Mega-RTOs. The question then arises: should we design a totally new state estimator for the whole system? To avoid a huge cost of a new estimator for mega RTOs, we propose a cost effective distributed textured state estimator that maintains old state estimators with instrumentation or estimated data exchanges among neighboring entities. The distributed textured state estimator will be more reliable since one computer failure will not jeopardize the whole system estimation result. At the same time, our estimator will achieve high bad data detection capability and high precision as the one estimator for the whole system. The approach also reduced the problem complexity dramatically. In this paper a knowledge-based system is proposed to search for beneficial data exchange scheme. The knowledge base includes the information of Bus Credibility Index, which considers the probability of good measurements. The reasoning machine consists of several principles, where economic factor is also taken into account. Numerical tests on IEEE-14 bus system verify that selected data exchange improves the estimator quality of individual entities for both bad data analysis and estimation accuracy. Accordingly, data exchange has a major impact on traditional measurement design. It is also shown that the benefit of different data exchange schemes can be quite different; some data exchanges are even harmful if our principles are not carefully followed. Garng. M. Huang, Jiansheng Lei 4/2/2002 349.6k PDF 02-10 A New Bifurcation Analysis for Power System Dynamic Voltage Stability Studies The dynamic of a large class of power systems can be represented by parameter dependent differential-algebraic models of the form dx/dt = f(x,y,p) and 0 = g(x,y,p). When the parameter p of the system (such as load of the system) changes, the stable equilibrium points may lose its dynamic stability at local bifurcation points. The systems will lose its stability at the feasibility boundary, which is caused by one of three different local bifurcations: the singularity induced bifurcation, saddle-node and Hopf bifurcation. In this paper the dynamic voltage stability of power system will be introduced and analyzed. Both the reduced and unreduced Jacobian matrix of the system are studied and compared. It is shown that the unreduced Jacobian matrix, whose eigen-structure matches well with the reduced one; and thus can be used for bifurcation analysis. In addition, the analysis avoids the singularity induced infinity problem, which may happen at reduced Jacobian matrix analysis, and is more computationally attractive. generator (such as d w, ), as well as the variables of the exciter, speed governor and so on; sometimes the dynamics of the load behavior will also be considered. The instantaneous variables are the power flow variables such as magnitudes and the angles of bus voltages. The parameter space p is composed of the system parameter (which describe the system topography, i.e., which lines, buses are energized, and equipment constants such as inductance, capacitor, transformer ratio, etc.) and operating parameters (such as load, generations and voltage set-point etc.). The dynamics of the generator, exciter, load dynamic and some other control devices together form the differential equations (1), and the power flow balance form the equations (2). For different objectives, some part of the differential or algebraic equations can be ignored. For example, when the dynamics Garng M. Huang, Liang Zhao 4/2/2002 55.5k PDF 02-11 Contribution Allocation for Voltage Stability In Deregulated Power Systems With deregulation of power systems, it is of great importance to know who contributes to avoid a voltage collapse, which could be due to different parts of the power system¡ª generator, control system and transmission part, etc. This paper focused on how to allocate the responsibility and contribution by bifurcation analysis. We investigate how parameters of the system influence the bifurcation points. Three bifurcations (the singularity induced bifurcation, saddle-node and Hopf bifurcation [1] , and their relationship to several commonly used controllers are analyzed. Their parameters¡¯ impact on the bifurcation points is investigated in this paper, from which we found a way to allocate the contribution by analyzing the relative positions of the bifurcations. We also analyzed the influence of other parameters (parameters of transmission and generators) on the bifurcation points. A simple two-bus system is used in this paper to demonstrate our approach. Our result shows that bifurcation analysis is a credible way to allocate the contribution, and the analysis will help us design the controller and optimize the system to avoid the voltage collapse. Garng. M. Huang, Kun Men 4/2/2002 324.3k PDF 02-12 Detection of Dynamic Voltage Collapse This paper investigates how to detect a dynamic voltage collapse situation. The generator and governor dynamics are considered in the simulation process. An index proposed earlier has been investigated for its applicability to indicate the collapse situation. Time domain simulations, using a commercial software EUROSTAG, has been carried out in this work. The test result reflects the applicability of the index during the line loss, slow increasing loading and step loading situations. The paper also brings out the details of the simulation setup used, which would help others in carrying out further simulations and investigation. Garng. M. Huang, Nirmal-Kumar C Nair 4/2/2002 273.6k PDF 02-13 Measurement Design of Data Exchange for Distributed Multi-Utility Operation With power market deregulation, member companies cooperate to share one whole grid system and try to achieve their own economic goals. This paper focuses on how to improve the state estimation result of member companies or ISO by exchanging raw or estimated data with neighboring member companies/ISO. The concept of Bus Redundancy Descriptor (BRD) is developed based on critical measurement set. BRD and leverage points are used as criteria to evaluate the quality of measurement systems. Accordingly, based on BRD a heuristic algorithm for measurement design under distributed multi-utility operation is presented to search for possible beneficial data exchange schemes. Numerical results verify that every member companies including ISO benefit from mutual data exchange when some principles of design are carefully applied. Garng. M. Huang, Jiansheng Lei 4/2/2002 191.7k PDF 02-14 Voltage Stability Constrained Load Curtailment Procedure to Evaluate Power System Reliability Measures This paper reports a method to evaluate composite power system reliability indices incorporating the voltage stability margin criteria. To compute the load curtailment evaluation, an optimal power flow (OPF) computation algorithm, considering the steady state voltage stability margin constraint is developed. A steady state voltage stability indicator is first discussed for its applicability as a suitable indicator for representing stability margin from the collapse point. The load curtailment formulation is then evolved and described into the OPF¡¯s objective function. A criterion based on the voltage stability indicator is then incorporated as an additional constraint into the OPF. A numerical example has been used to illustrate the effect of the algorithm on the composite system reliability evaluation. The Expected Energy Not Served (EENS) and down time is computed, both analytically and by the Monte Carlo Simulation. Garng. M. Huang, Nirmal-Kumar C Nair 4/2/2002 172.3k PDF 02-15 Incorporating TCSC into the Voltage Stability Constrained OPF Formulation This paper investigates the effect of Thyristor Controlled Series Capacitor (TCSC) on the voltage stability constrained Optimal Power Flow (OPF) formulation where the objective function is to minimize power system load curtailment. Incorporating TCSC affects the topology and hence the power flow distribution. Some numerical cases are presented to discuss the effects of TCSC that is expected when it is incorporated into the load curtailment formulation. The test result reflects the impacts TCSC has in reducing load curtailment during a line congestion situation. The paper also discusses the applicability of the approach in security based reliability studies for systems having control components like TCSC. Garng. M. Huang, Nirmal-Kumar C Nair 4/2/2002 92.9k PDF 02-16 Supergames in Electricity Markets: Beyond the Nash Equilibrium Concept The periodical repetition in electricity markets of market conditions over time leads to the repeated playing of similar games (or supergames) by the participants. This repetition of games tempts participants to walk away from the best-response equilibrium strategies provided by the Nash solutions. Although Nash solutions make theoretical sense in non-repeated games, their applicability in repeated games is weakened by the fact that these solutions are not, in general, Pareto optimal. This fact paves the way to more complex games where participants are driven by profit maximization in the long run and are, therefore, enticed to explore different solutions in the short term. Knowing that they will meet in similar games in the near future, makes the players adopt implicit cooperative behavior. The willingness to work to a common end may be modeled in automata or agents, which substitute for the players, that incorporate collaborative profiles in their stochastical responses to the other automata strategic moves. Pedro Correia, Thomas J. Overbye, Ian Hiskens 4/3/2002 1.5M PDF 02-17 Assessing Deterioration of ADSS Fiber Optic Cables Due to Corona Discharge This is the final project report for the project "Corona Discharge Caused Deterioration of All Dielectric Self-Supporting (ADSS) Fiber-Optic Cables." Utilities have reported failures of ADSS fiber optic cables installed on high voltage lines. The high electric field on those lines generates continuous corona discharge at the end of supporting armor rods. This discharge leads to cable deterioration. In a polluted environment, dry-band arcing causes cable deterioration when fog or dew occasionally wet the cable. This report presents a novel experimental technique to assess cable deterioration due to dry-band arcing. George G. Karady and Johnny Madrid 4/1/2003 5.7M PDF 02-18 Identification and Tracking of Parameters for a Large Synchronous Generator This document is the draft final report from the PSERC project with the same title. The main project objective was to describe a method to identify synchronous machine parame-ters from on-line measurements and to develop a Graphical User Interface (GUI) application that is user friendly and self guiding to enable rapid estimation of desired parameters. Last Edited: 11/27/02 G. T. Heydt and Elias Kyriakides 4/5/2003 206.4k PDF 02-19 Computation Of Critical Values Of Parameters In Power Systems Using Trajectory Sensitivities It has been known in the literature that system sensitivity increases sharply as the trajectory approaches the boundary of the region of attraction (ROA) while the trajectory does not exhibit such a sharp behavior. The relationship between sensitivity and stability of a nonlinear dynamic system such as the power system is investigated in this paper. In this context the role of the principal singular surface (PSS) also becomes significant. The principal singular surface is defined as a set of points enclosing the origin and where the Jacobian of the system evaluated at these points is singular. As the trajectory evolves, the Jacobian of the flow becomes singular at a point on the PSS and a sharp increase in trajectory sensitivity is observed. The mode of instability (MOI) can thus be defined very early during a faulted trajectory in most cases. A technique is also proposed using the norm of trajectory sensitivity vector at two points and then extrapolating it to estimate the critical parameter of interest which may be clearing time, mechanical power, etc. Tony B. Nguyen, M. A. Pai, and I. A. Hiskens 4/16/2002 97.2k PDF 02-20 Agent-Oriented Approach to Work Order Management for Circuit Breaker Maintenance Abstract—Compared with Object-Oriented Programming, Agent-Oriented Programming provides higher level abstraction and encapsulation. The software agents are autonomous entities with abilities to adapt the changing environments. An example of carrying out a circuit breaker maintenance work order has been used to illustrate the flexibility and advantages of Agent-Oriented Programming. X. Xu, M.Kezunovic, and D. Wong 4/22/2002 78.5k PDF 02-21 Advanced Substation Data Collecting and Processing for State Estimation Enhancement Many functions within a substation can be performed more efficiently if all the substation data is collected from and shared among Intelligent Electronic Devices (IEDs). Substation data integration is facilitated by existence and appropriate connection of IEDs. The paper presents an approach to implementation of substation data integration and information exchange. The emphasis is on the utilization of local data redundancy to enhance power system state estimation, especially topology error detection. Sasa Jakovljevic and Mladen Kezunovic 4/22/2002 148.6k PDF 02-22 A Novel Method for Transmission Network Fault Location Using Genetic Algorithms and Sparse Field Recordings The paper presents an approach to locate a fault in a transmission network based on waveform matching. Matching during-fault recorded phasor with the during-fault simulated phasor is used to determine the fault location. The search process to find the best waveform match is actually an optimization problem. The genetic algorithm (GA) is introduced to find the optimal solution. The proposed approach is suitable for the situations where only the data recorded sparsely is available. Mladen Kezunovic, Shanshan Luo, and Donald R. Sevcik 4/22/2002 59.9k PDF 02-23 Congestion Management in Restructured Power Systems Using an Optimal Power Flow Framework The work described in this masters thesis and project report is one of the research products from the PSERC project “New System Control Methodologies.” In this report we look at a modified OPF whose objective is to minimize the absolute MW of rescheduling. In this framework, we also consider dispatching bilateral contracts in case of serious congestion, with the knowledge that any change in a bilateral contract is equivalent to modifying the power injections at both the buyer and the seller buses. We also seek to develop an OPF solution incorporating FACTS devices in a given market mode (pool or bilateral dispatch). Last Edited: 11/27/02 A.S. Nayak and M.A. Pai 4/5/2003 180.8k PDF 02-24 Development of a Graphic User Interface for an Overhead Conductor Sag Instrument This document is the draft final report from the project "Differential GPS Measurement of Overhead Conductor Sag." This project developed a graphic user interface (GUI) and estimation software package for the depiction of transmission line sag data and the calculation of real time conductor rating. Last Edited: 11/27/02 G. T. Heydt 4/5/2003 171.0k PDF 02-25 Condition Monitoring of In-Service Nonceramic Insulators and Underground Cables This is the final report for the project with the same title. The report is in two parts. Part 1: Quantification of Corona Discharges on Polymer Insulators. Corona discharges present a serious threat to the long term performance of nonceramic (also known as composite or polymeric) insulators. The results from this project indicate that there is a correlation between the visible pattern of corona, measured discharge energy and the pixel intensity and area. An UV camera capable of capturing the corona discharge even during daytime has been employed. Part 2: Prediction of Future Performance of In Service XLPE Cables. This study examines the performance of 15kV XLPE new and aged cable (taken out from the service after 10 + years) in context with electrical tree and electrical failure of cable. The breakdown tests are preformed using needle-plane geometry at room temperature as well as elevated temperature of 100 degrees C. A statistical technique like regression analysis is utilized to analyze the test results as well as to predict the future performance and life expectancy of cables. The analytical techniques like Fourier Transform Infra-Red (FTIR) spectroscopy is used to study the permanent changes in the XLPE material. This project proves the fact that there are permanent changes occurring in the material that lead to progressive degradation and/or failure in the long run. Last Edited: 11/27/02 R. S. Gorur 4/5/2003 603.7k PDF 02-26 Investigation of Fuel Cell System Performance and Operation: A Fuel Cell as a Practical Distributed Generator This is the initial report in a multi-year project entitled “Investigation of Fuel Cell System Performance and Operation.” The project is to study the system performance and operation of a fuel cell distributed generator and to provide an assessment of the electrical, thermal, and economic issues associated with the fuel cell system. This report provides an introduction to technical and thermal performance of fuel cells in general, and to the Phosphoric Acid Fuel Cell installed in the City of Mesa, Arizona in particular. It also describes an economic analysis of a fuel investment decision from the end-user’s perspective. Future project work will look more broadly at issues associated with integrating fuel cells as a form of distributed generation in the distribution network. Last Edited: 11/27/02 George Karady, Priyantha Sirisooriya and Richard G. Farmer 4/5/2003 180.3k PDF 02-27 Equilibrium Analysis of Forward Markets for Electricity and Reserves In this dissertation, we examine the issues of price volatility, equilibrium forward pricing, and price-elastic demand. We begin by investigating the extreme price volatility in the reserves markets of a deregulated electricity industry. In the first year of operation of the California electricity markets, the prices of reserves were more volatile than those for electricity. Furthermore, there was little correlation between electricity and reserves prices although the two products use the same underlying technology. Motivated by such distortions in markets for reserves, we next develop a protocol for pricing forwards for electricity and reserves. We use a market-equilibrium approach to model a perfectly competitive electricity industry with generators, retailers, and an independent system operator (ISO) that procures enough reserves to maintain system reliability. Our analysis suggests that electricity reserves are essentially call options that can be used as derivatives to manage risk. In order to assess the impact of price-elastic demand, we allow end-users in our model to perceive real-time variations in the electricity spot price. This price responsiveness both decreases the electricity spot price and increases the risk exposure of retailers. Afzal Saeed Siddiqui 5/15/2002 845.1k PDF 02-28 Coordination of Transmission Line Transfer Capabilities In the present power system operation, the transfer capacity studies of transmission lines are carried out separately by their owners with little coordination. The objective of this project has been to propose a global framework for coordinating the capabilities of several transmission paths, while also meeting the regulatory requirements on voltage security and dynamic security. As an example, we focus on maximizing the transmission capacity of the California-Oregon AC Inter-tie (COI), by coordinating other path-flows that have an impact on the COI capacity. We show that substantial improvements in the COI MW transfer can be achieved with reasonable rescheduling of neighboring tie-line flows using the optimization algorithms presented. Last Edited: 11/27/02 Mani V. Venkatasubramanian 4/5/2003 185.8k PDF 02-29 An Initial Complex Systems Analysis of the Risks of Blackouts in Power Transmission Systems Recent analyses of blackout data from NERC have suggested that the frequency distribution of blackout sizes has a power tail. This power tail is consistent with the North American electric power transmission system operating as a complex system near criticality. The presence of power tails has a profound effect on risk analysis for larger blackouts and the main purpose of this paper is to outline some of these effects and suggest ideas towards quantifying and mitigating the risks of larger blackouts from a complex systems perspective. Ian Dobson, David Newman, Ben Carreras, Vickie Lynch 7/9/2002 247.4k PDF 02-30 Incorporating Operational Characteristics and Startup Costs in Option-Based Valuation of Power Generation Capacity We describe a stochastic dynamic programming approach for “real option” based valuation of electricity generation capacity incorporating operational constraints and startup costs. Stochastic prices of electricity and fuel are represented by recombining multinomial trees. Generators are modeled as a strip of cross commodity call options with a delay and a cost imposed on each option exercise. We illustrate implications of operational characteristics on valuation of generation assets under different modeling assumptions about the energy commodity prices. We find that the impacts of operational constraints on real asset valuation are dependent upon both the model specification and the nature of operating characteristics. Shi-Jie Deng and Shmuel Oren 8/20/2002 289.8k PDF 02-32 Blackout Mitigation Assessment in Power Transmission Systems Electric power transmission systems are a key infrastructure and blackouts of these systems have major direct and indirect consequences on the economy and national security. Analysis of North American Electrical Reliability Council blackout data suggests the existence of blackout size distributions with power tails. This is an indication that blackout dynamics behave as a complex dynamical system. Here, we investigate how these complex system dynamics impact the assessment and mitigation of blackout risk. The mitigation of failures in complex systems needs to be approached with care. The mitigation efforts can move the system to a new dynamic equilibrium while remaining near criticality and preserving the power tails. Thus, while the absolute frequency of disruptions of all sizes may be reduced, the underlying forces can still cause the relative frequency of large disruptions to small disruptions to remain the same. Moreover, in some cases, efforts to mitigate small disruptions can even increase the frequency of large disruptions. This occurs because the large and small disruptions are not independent but are strongly coupled by the dynamics. Ben Carreras, Vicki Lynch, David Newman, Ian Dobson 10/4/2002 423.3k PDF 02-33 A probabilistic loading-dependent model of cascading failure and possible implications for blackouts Catastrophic disruptions of large, interconnected infrastructure systems are often due to cascading failure. For example, large blackouts of electric power systems are typically caused by cascading failure of heavily loaded system components. We introduce the CASCADE model of cascading failure of a system with many identical components randomly loaded. An initial disturbance causes some components to fail by exceeding their loading limit. Failure of a component causes a fixed load increase for other components. As components fail, the system becomes more loaded and cascading failure of further components becomes likely. The probability distribution of the number of failed components is an extended quasibinomial distribution. Explicit formulas for the extended quasibinomial distribution are derived using a recursion. The CASCADE model in a restricted parameter range gives a new model yielding the quasibinomial distribution. Some qualitative behaviors of the extended quasibinomial distribution are illustrated, including regimes with power tails, exponential tails, and significant probabilities of total system failure. Ian Dobson, Ben Carreras, David Newman 10/4/2002 225.2k PDF 02-34 Markets for Reliability and Financial Options in Electricity: Theory to Support the Practice The underlying structure of why and how consumers value reliability of electric service is explored, together with the technological options and cost characteristics for the provision of reliability and the conditions under which market mechanisms can be used to match these values and costs efficiently. This analysis shows that the level of reliability of electricity provided through a network is a public good within a neighborhood, and unless planned demand reductions by customers have the identical negative value as an unexpected service interruption, market mechanisms will not reveal the true value of reliability. A public agency must determine that value and enforce the reliability criteria. Furthermore, in order to get an efficient level of demand response by customers in periods of system stress, they must see real time energy prices plus they must be paid an amount equal to the suppliers’ cost of adding reliability to the system, if that amount is not included in real time prices. Tim Mount, William Schulze and Richard E. Schuler 10/17/2002 238.7k PDF 02-35 Personnel Grounding and Safety Issues/Solutions Related to Servicing Optical Fiber Telecommunication Circuits in Optical Ground Wire (OPGW) In this project, a study has been made of the voltages and currents to which workers are exposed while performing OPGW maintenance on or near energized transmission lines during fault conditions. The technique used for modeling this problem was first validated by comparing simulations with measurements performed during a bolted fault test by the U.S. Bureau of Reclamation (USBoR) and the Western Area Power Administration (WAPA). Once validated, the model was used to simulate typical situations that might be encountered during maintenance of OPGW while either the line being maintained or a nearby line is energized. It has been found that unless special measures are taken to protect workers, they may be exposed to dangerous levels of voltage and current during a fault. This conclusion is true even if the work is being performed on a de-energized line that is parallel to an energized line on which a fault occurs. Although not specifically evaluated as part of this project, one solution to the problem is the installation of a temporary ground mat underneath the work area. Last Edited: 11/27/02 Richard G. Olsen, Sakis Meliopoulos and George Karady 4/5/2003 386.4k PDF 02-36 Visualization of Power Systems Effective power system operation requires power system engineers and operators to analyze vast amounts of information. In systems containing thousands of buses, a key challenge is to present this data in a form such that the user can assess the state of the system in an intuitive and quick manner. This is particularly true when trying to analyze relationships between actual network power flows, the scheduled power flows, and the capacity of the transmission system. With restructuring and the move towards having a single entity, such as an independent system operator or pool, operate a much larger system, this need has become more acute. This report describes the results of the research performed to address this need. This the draft final report for the PSERC Project "Visualization of Power Systems." User Note: The report contains about 50 color figures illustrating the results. As a result, the document is quite large and will take time to display. Last Edited: 11/27/02 Thomas J. Overbye, Douglas A. Wiegmann and Robert J. Thomas 4/5/2003 7.8M PDF 02-37 Designs for Ramp-Constrained Day-Ahead Auctions Some electric power markets allow bidders to specify constraints on ramp rates for increasing or decreasing power production. We show in a small example that a bidder could use an overly restrictive constraint to increase profits, and explore the cause by visualizing the feasible region from the linear program corresponding to the power auction. We propose two penalty approaches to discourage bidders from such a tactic: one based on duality theory of Linear Programming, the other based on social cost differences caused by ramp constraints. We evaluate the two approaches using a simplified scaled model of the California power system, with actual 2001 California demand data. Shmuel S. Oren and Andrew A. Ross 11/13/2002 226.2k PDF 02-38 Two-Settlement Systems for Electricity Markets We analyze welfare and distributional properties of a two-settlement system consisting of a spot market over a two-node network and a single forward contract. We formulate and analyze several models which simulate joint dispatch of energy and transmission resources coordinated by a system operator. The spot market is subject to network uncertainty, which we model as a random capacity derating of an important transmission line. Using a duopoly model, we show that even for small probabilities of congestion (derating), forward trading may be substantially reduced, and the market power mitigating effect of forward markets (as shown in Allaz and Vila, 1993) may be nullified to a great extent. There is a spot transmission charge reflecting transportation costs from location of generation to a designated hub whose price is the underlying for the forward contract. This alleviates some of the incentive problems associated with the forward market in which spot-market trading is residual. We find that the reduction in forward trading is due to the segregation of the markets in the constrained state, and the absence of natural incentives for generators to commit to more aggressive behavior in the spot market (the ‘strategic substitutes’ effect). In our analysis, we find that the standard assumption of ‘no-arbitrage’ across forward and spot markets leads to very little contract coverage, even for the case with no congestion. We present an alternative view of the market where limited intertemporal arbitrage enables temporal price discrimination by competing duopolists. In this framework we assume that all of the demand shows up in the forward market (or that the market is cleared against an accurate forecast of the demand), and the forward price is determined using a ‘market clearing’ condition. Rajnish Kamat and Shmuel S. Oren 11/13/2002 359.5k DOC 02-39 Displaying Aggregate Data, Interrelated Quantities, and Data Trends in Electric Power Systems This paper describes a number of effective techniques for visualizing some of the more complex data relationships that characterize an electric power system in real time. Power systems are large, dynamic physical entities that are constantly changing. While SCADA systems capture the quantitative aspects of these changes, visualizing their magnitudes, pinpointing their locations, and interpreting their collective significance for the current and future security of the interconnection pose tremendous challenges for system operators. This paper describes how advanced visualization techniques such as area tie diagrams, calculated data analogs, historical trend animations, and three-dimensional views clarify the complex relationships, aggregate subsystem characteristics, and emerging trends that describe the current state of the interconnection and help predict its future evolution. The paper provides a number of illustrations that demonstrate the effectiveness of the proposed techniques. Ray Klump, Warren Wu, and Greg Dooley 11/13/2002 652.2k PDF 02-40 Estimating the Actual Cost of Transmission System Congestion This paper describes a methodology that could be used by a utility to estimate the actual cost of congestion on its transmission system using limited, non-state estimator data. The assumed problem inputs are a power flow model of an entire interconnected grid (i.e., the Eastern Interconnect), costs for the utility's generators, and then hourly values of the utility's generation, load and tie-line flows over the study time period. Due to the common lack by most utilities of external measurements, the system is first equivalenced to retain only the utility's own internal buses and a small subset of the external buses. Then, for each hour, the utility's load and generation is set to match their historical values, while the external generation is adjusted to match the tie-line flows. Next, an economic dispatch is performed to determine the unconstrained cost. Finally, a security constrained OPF (SCOPF) is solved to take into account base case and contingent constraints. The methodology uses a complete ac power flow formulation to accurately estimate the impact of voltage constraints and the incremental impact of system losses. The inclusion of hydro generation is also considered. For illustrative purposes only, the methodology demonstrated on the TVA system using publicly available data transmission system data. Thomas J. Overbye 11/13/2002 872.3k PDF 02-50 Visualization for Shipboard Power Systems Shipboard Power Systems (SPS) are geographically spread all along the ship. It consists of various components such as generators, cables, switchboards, circuit-breakers, bus transfer switches and loads, all interconnected with each other and located at various places (decks) on the ship. Geographical information on these components is required to assess the impact of faults caused due to battle damage or material casualties. Information regarding faulted components is required for the Automation methods such as failure assessment, restoration and reconfiguration. Good Visualization and information retrieval tools are required to assess the effect of battle damage on the shipboard power systems so that failure assessment and restoration can be quickly done to as many loads as possible. This paper presents the details of visualization for SPS. Karen L. Butler-Purry and N.D.R. Sarma 3/6/2003 535.7k PDF 02-51 Animation and Visualization of Spot Prices via Quadratized Power Flow Analysis This paper presents a new model for efficient calculation of spot prices and animation and visualization of spot price evolution as the system operating point is changing. The computational method is based on the quadratized power flow approach that cast the power flow problem as a set of quadratic equations. The load model consists of constant power, constant impedance and induction motor loads. The electric load time variation is modeled via a small set of independent random variables resulting in a nonconforming electric load model. Constraints of voltage limits as well as circuit loading are imposed. For a specific load point, the operation of the system is determined by the appropriate formulation of the power flow problem and subsequent solution. At this operating point, the spot prices are computed from a linear program defined at the operating point. The results are visualized in a three-dimensional OpenGL display. As the system load evolves, the spot prices are recomputed and the visualization display is updated thus generating an animated evolution of the system spot prices. The paper describes the proposed computational method and discusses the efficiency of the proposed method. The method is also demonstrated on the IEEE RTS system which has been modified to include a model of a spot price market. The presentation of the paper will include a demonstration of the visualization and animation of the spot prices for the IEEE RTS system. A. P. Sakis Meliopoulos, Sun Wook Kang, G. J. Cokkinides, and Roger Dougal 3/11/2003 373.2k PDF 02-52 Data Integration and Information Exchange for Enhanced Control and Protection of Power Systems One issue that did not get adequate attention regarding control and protection of power systems in the past is the data integration and information exchange. The traditional approaches assume that each function such as protection, control, monitoring, and maintenance are supported by a separate infrastructure of recording instruments and/or controllers for obtaining and processing data. With introduction of the new computer-based equipment for control and protection in the mid eighties, the integration of data and information exchange were possible, but not explored. This paper indicates what are the improvements and benefits that can be obtained by integrating the data and exchanging information among control and protection as well as system-wide monitoring and control functions. Mladen Kezunovic, 3/11/2003 255.6k PDF 02-53 Bluenet II - A Detailed Realization of the Algorithm and Performance Analysis The recent interest in ad hoc networks, in general, and in the Bluetooth technology, in particular, has stimulated much research in algorithms for topology control of such networks. In particular, the issue of scatternet formation has been addressed by a number of papers in the technical literature. In [1], we have proposed one such algorithm called the Bluenet algorithm. In this paper, we further investigate the realization and properties of the Bluenets algorithm. The performance of the resulting scatternets, such as, piconet density, usage of potential links, deviation of node degrees, average shortest path length, and maximum traffic flows are also studied. From the analysis, it is showed that the choice of p0, the initial probability for each node to enter the page state, is very important. Since each performance index only reflects one side of the scatternet performance, we need to make trade offs when selecting p0 to build Bluenets. Zhifang Wang, Zygmunt J. Haas, Robert J. Thomas 3/11/2003 223.3k PDF 02-54 Identifying Transformer Incipient Events for Maintaining Distribution System Reliability This paper presents the time domain and time-frequency domain analysis results of incipient events in single-phase distribution transformers. This analysis will aid in the development of an automatic detection method for internal incipient faults in the transformers. The detection method can provide information to predict failures ahead of time so that the necessary corrective actions are taken to prevent outages and reduce down times. The analyzed data was obtained from simulations and experiments. Time-frequency analysis was performed using Discrete Wavelet Transform (DWT). The obtained results are discussed. Karen L. Butler-Purry, Mustafa Bagriyanik 3/12/2003 945.2k PDF 02-55 Locational Pricing and Scheduling for an Integrated Energy-Reserve Market 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 new scheduling algorithm incorporating constraints imposed by grid security considerations, which include one base case (intact system) and a list of possible contingencies (line-out, unit-lost, and load-growth) of the system. By following a cost-minimizing co-optimization procedure, both power and reserve are allocated spatially for the combined energy and reserve markets. With the Lagrange multipliers (dual variables) 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. Jie Chen, James S. Thorp, Robert J. Thomas, Timothy D. Mount 3/11/2003 267.3k PDF 02-56 A MultiPhase Power Flow Model for µGrid Analysis This paper presents a new advanced model of an electric power system with distributed energy sources forming a microgrid ( µGrid). The µGrid is a radial or networked low voltage distribution system with distributed sources. Each source is interfaced to the system via converters. The DC bus of the converter may have energy storage capability via large capacitors or batteries. The µGrid load consists of both single and three phase loads resulting in unbalanced operating conditions. The µGrid circuits may be three-wire, four-wire or five-wire. The grounding of the system may be single point or multipoint. The analysis of this system requires a new approach. This paper presents a new method for modeling and analysis of this system. The approach consists of two steps: (a) modeling each component of the system via a set of quadratic equations no matter how complex the nonlinearities of the model are and (b) a Newton’s method for the solution of the overall network equations. The method is extremely efficient and robust. The proposed method can accommodate various control modes of micro-sources. Examples of these controls are given in the paper. A. P. Sakis Meliopoulos, George J. Cokkinides, Robert Lasseter 3/11/2003 268.2k PDF 02-57 Is System Control Entirely by Price Feasible? This paper revisits the possibility of controlling the power system entirely by means of price signals. It expands on notions introduced in an earlier paper and addresses several unresolved issues: problems with linear cost structures, response delays, varying costs, market power, and stability problems caused by market/system interactions. The results suggest that control by price can, in fact, be made to work with some caveats. Fernando L. Alvarado 3/11/2003 238.7k PDF 02-58 Feasibility Evaluation of Distributed Energy Generation and Storage for Cost and Reliability Using the ‘Worth-Factor’ Criterion The unprecedented growth in the electronic and semiconductor industries, process controlled industries like automobile, textile and paper, in addition to the growing domestic load over the past three decades has imposed severe operational, economic and maintenance constraints on the power utility companies. Service reliability and power quality are the key contributing factors imposing these constraints. Distributed technologies are a potential solution for the current problem but may not be the optimum solution when specific characteristics like the nature of load, desired level of performance, geographical location and the available energy resources at the time instance of operation are considered. This paper describes the feasibility of distributed resources in terms of the ‘worth-factor,’ a criterion that incorporates intangible benefits and translates them in terms of cost. Phanikrishna Gomatom and Ward Jewell 3/13/2003 350.6k PDF 02-59 Single Phase Harmonic Limits The International Electrotechnical Commission (IEC) sets limits for harmonics in the current of small single-phase or three-phase loads, less than 16 A per phase, in Electromagnetic compatibility (EMC) - Part 3-2: Limits - Limits for harmonic current emissions (IEC 61000-3-2). The IEEE Single Phase Harmonics Task Force (P1495) is developing a similar standard for single phase loads of less than 40 A. There is, however, still no agreement on what such limits should be, or whether limits are even needed. Electric utilities are concerned about the effects of harmonics on their systems: telephone noise, excessive heating of transformers and other equipment, capacitor damage, and others, and would like to limit the levels of harmonics produced by loads on their systems. Manufacturers, however, are concerned about the cost of changes to their equipment to reduce harmonic production. This paper summarizes the IEC limits and the proposed IEEE limits, discusses the need for single phase harmonic limits, and presents what those limits might be. Last Edited: 03/14/03 Ward Jewell and Daniel J. Ward 4/5/2003 153.1k PDF 02-60 Harmonic Limits for Single-Phase Equipment "Perhaps now is the time for manufacturers, utilities, and end users to agree on acceptable harmonic limits." This article in EC&M magazine followed our paper in the 2002 PSERC Power Quality and EMI Conference. The article discusses existing and proposed harmonic standards for single phase loads. Last Edited: 03/14/03 Ward Jewell and Dan Ward 4/5/2003 Link URL 02-61 Risk-based Maintenance Allocation and Scheduling for Bulk Electric Power Transmission System Equipment This paper describes a new maintenance selection and scheduling approach for bulk transmission equipment that is based on the cumulative long-term risk caused by each piece of equipment. This approach not only accounts for equipment failure probability and equipment damage, as do most state of the art reliability centered maintenance (RCM) approaches, but it also accounts for the outage consequence in term of overload and voltage security in a rigorous and systematic way. The method is illustrated on the IEEE reliability test system (RTS). Yong Jiang, Ming Ni, James D. McCalley and Tim Van Voorhis 5/15/2003 254.4k PDF 02-62 Consequence and Impact of Electric Utility Industry Restructuring on Transient Stability and Small Signal Stability Analysis The electric utility industry is undergoing unprecedented changes in its structure world wide. With the advent of an open market environment and competition in the industry, and restructuring of the industry into separate generation, transmission, and distribution entities, new issues in power system operation and planning are inevitable. One of the major consequences of this new electric utility environment is the greater emphasis on reliability and secure operation of the power system. This paper examines the impact of restructuring on power system dynamic analysis. It specifically addresses issues related to transient stability analysis and small signal stability analysis. Four major topics to examine the effect on the nature of studies conducted are considered. These topics are system adequacy and security, system modeling data requirements, system protection and control, and system restoration. The consequences and impact of each of these topics on the nature of the studies conducted are examined and discussed. The emphasis on greater reliability has led to a clearer enunciation of standards, measurements, and guides in some countries. These requirements will result in a) more measurements on existing systems, b) rigorous analysis of transient stability and small signal stability to determine operating limits and plan systems, c) greater emphasis on studies to verify coordination and proper performance of protection and controls, and d) development of a detailed plan for system restoration in the case of wide-spread outages. Vijay Vittal 8/15/2003 292.7k PDF 02-63 Lp State Estimators for Power Systems The widely used method of least squares for state estimation is revisited. The commonly used least squares philosophy is based on the L2 Hölder norm. The L1 and L∞ norms are considered for applications in power engineering. The effects of outliers in measurements and multicollinearity on state estimation are studied. An application in parameter estimation for synchronous generators is given as an example. N. Logic, E. Kyriakides and G. T. Heydt 8/24/2003 69.2k PDF 02-64 Economic Congestion Relief Across Multiple Regions Requires Tradable Physical Flow-Gate Rights This paper is concerned with market-based protocols for relieving congestion caused by transactions outside the control area in which the congestion occurred. One approach, proposed by Cadwalader et al. is based on dual decomposition in which out of area congestion is “priced-out” and added to the optimal power flow(OPF) objective function of the control area operator while the prices are determined iteratively via nodal energy adjustment bids. The paper demonstrates through a simple three node example that even with “correct prices” on out-of-area congested interfaces, the augmented AC-OPF objective function of a control area operator might not be locally convex at the optimal solution and hence the control area’s optimal dispatch may violate the thermal constraints on out-of-area interfaces. That conclusion supports the alternative “flow-based” approach that enforces thermal limits more directly, which is consistent with North American Electric Reliability Council’s (NERC’s) FLOWBAT proposal for interzonal transmission load relief (TLR). IEEE TRANSACTIONS ON POWER SYSTEMS, VOL. 17, NO. 1, FEBRUARY 2002. Uploaded: Sep. 20, 2005. Shmuel S. Oren and Andrew M. Ross 9/20/2005 278.9k PDF 02-65 Comments on the FERC SMD NOPR The SMD NOPR is on the right track in terms of its overall objective and attempt to institute a sound science based approach to electricity market design. However, details matter and the objective of this note is to highlight three specific details in the SMD NOPR that require attention. The comment identifies potential problems associated with the specific design features and recommends remedies that will improve the design while keeping with the stated objectives of the NOPR. Comments in Docket RM01 12 000. November 15, 2002. Uploaded: Sep. 20, 2005. Shmuel Oren 9/20/2005 313.0k PDF 02-66 Effectiveness of the Distribution Factor Approximations Used in Congestion Modeling Congestion has widespread impacts on the availability and utilization of the existing transmission systems and consequently on the operation of competitive markets in electricity. The distribution factors play a key role in the modeling of congestion in various market applications. These factors are linear approximations of sensitivities of variables with respect to various inputs and are computed for a specified network topology and parameter values. In practice, the factors are used over a wide range of system conditions. This paper investigates the analytical characteristics, the robustness and the quality of the approximations provided by key distribution factors such as injection shift factors (ISFs) and power transfer distribution factors (PTDFs). We examine the range of conditions over which these factors can provide a reliable approximation for large power system networks. The numerical simulation results indicate that the errors of the approximations stay in an acceptable range under a broad spectrum of conditions including contingencies used to establish n-1 security. Proceedings of the 14th Power Systems Computation Conference. Sevilla, Spain. June 24-29, 2002. Uploaded: Sep. 26, 2005. Minghai Liu and George Gross 9/26/2005 1.1M PDF 02-67 California Electricity Market Crisis: Causes, Remedies, and Prevention Summary of a panel organized by the authors at the IEEE PES 2001 meeting. IEEE Power Engineering Review, Vol. 22, No. 8 (August 2002) pp. 4-5. Uploaded Sep. 26, 2005. C. Mensah-Bonsu, and S. Oren 9/26/2005 358.9k PDF 02-68 Experimental Evidence about the Persistence of High Prices in a Soft-Cap Auction for Electricity The high prices for electricity in California during the summer of 2000 led to a substantial amount of regulatory and political intervention. Price caps were lowered and the Federal Energy Regulatory Commission (FERC) proposed that a new type of “soft-cap” auction be adopted to replace the uniform price auction. This auction combines a standard uniform price auction with a discriminative auction for offers higher than a specified soft-cap ($150/MWh). All offers to sell generating capacity below the soft-cap are submitted in a uniform price auction and paid a clearing price set to the last (highest) accepted offer. Any capacity offered above the soft-cap needed to meet the load is paid the actual offer in a discriminative price auction. With this structure, high offers above the soft-cap can not set the clearing price for all capacity sold. Nevertheless, high prices persisted during the winter of 2001. As a result, FERC abandoned the soft-cap auction in May, 2001. This paper presents results from four experiments using uniform and soft-cap auctions, with and without price-responsive load. The objective of this paper is to show that it is hard to mitigate high prices in a soft-cap auction when prices are driven above the soft-cap and to demonstrate how price-responsive load is a more effective strategy in uniform price auctions. Both industry professionals and students are used as participants who represent generators in a “smart” market, POWERWEB, which replicates the physical constraints of meeting loads on an electrical grid. Proceedings of the 25th Annual International Conference, Internaational Association of Energy Economics, Aberdeen, Scotland, June 26-29, 2002. Uploaded: June 27, 2006. T. Mount, R. Thomas, C. Vossler, R. Zimmerman 6/27/2006 575.9k PDF 02-69 Innovative Developments in Load as a Reliability Resource This paper reports on work the Consortium for Electric Reliability Technology Solutions (CERTS) has been pursuing to hasten the arrival of meaningful load participation in competitive electricity markets. The activities include: experimental economic analysis of the effect of price responsive load in reducing market prices and price volatility; assessments of emerging demand response programs and technologies for enabling customer participation in electricity markets, and demonstrations of load in providing ancillary services (notably, spinning reserve). IEEE Power Engineering Society Winter Meeting 2002. Vol. 2, pp.1002-1004. Uploaded: June 27, 2006. J. Eto, C. Goldman, G. Heffner, B. Kirby, J. Kueck, M. Kintner-Meyer, J. Dagle, T. Mount, W. Schulze, R. Thomas, R. Zimmerman 6/27/2006 128.6k PDF

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