| Name | Author | Date | Size | Type | ID |
Visualization of Power Systems and Components
The need for enhanced power system visualizations has been increasingly acute over the last decade as the size of power system models has grown. And with the development of competitive, optimal power flow (OPF) based electricity markets, new study variables (such as locational marginal prices) have increased as well. Finally, large-scale blackouts around the world recent have dramatically demonstrated how a lack of operational ?situational awareness? can put millions in the dark.
This report, along with the related publications, present results from the PSERC ?Visualization of Power Systems and Components? project. The specific results from the project can be grouped into four areas. First, the project developed enhanced two-dimensional (2D) power system visualizations. Second, the project demonstrated how three-dimensional (3D) visualizations could be used to display contingency analysis bus voltage magnitude information and transmission line/transformer flow information. Third, the project demonstrated how system wide overview visualizations could be supplemented with visualizations of the detailed status and operating conditions of important power system devices. Last, the project focused on the performance of formal human factor experiments to evaluate the effectiveness of power system visualizations.
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Tom Overbye
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02/22/06
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2.18 MB
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PDF
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06-01
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Generation Adequacy via Call Options Obligations: Safe Passage to the Promised Land
In contrast to the controversial LICAP and other capacity mechanisms based on capacity products or capacity payments, the call option approach relies on standard hedging instruments that a mature energy-only market can support without regulatory intervention. Unlike payments for an artificial capacity product, for which there is no natural demand, energy call options provide intrinsic value to customers, since the generators who are paid for such options must pay back any windfall profits. This amounts to a risk trading arrangement where the consumers assume some of the investment risk, in exchange for reducing their price risk. This talk will describe the rationale and mechanics of the proposed approach along with some variants and recent implementation experience.
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Shmuel Oren
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03/16/06
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191.56 KB
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PDF
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06-02
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Effects of Voltage Sags on Household Loads
Voltage sags pose a serious power quality issue for the electric power industry. Much work has been done assessing the effects of voltage sags on power system operation, and on industrial and commercial loads. However, more research has been needed on the effects of voltage sags on residential loads, particularly sensitive equipment such as computers.
This project helps fill that information gap by providing new detailed information on the effects of voltage sags of varying depths and durations on selected residential equipment. In addition, to better understand how voltage sags affect the residential customer class, surveys were conducted to determine the type of equipment present in residential apartment complexes in Tempe, Arizona. With testing and survey data, it was possible to develop predictions of the overall effect of voltage sags of various depths and durations on selected apartment complexes. Finally, the testing enabled assessment of the accuracy of standard ?CBEMA? curves that allow prediction of the effect of voltage sags on equipment performance.
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George Karady
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02/22/06
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545.37 KB
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PDF
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06-03
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Adaptive Islanding to Prevent Cascading Failure Events
Power systems are under increasing stress as market policies introduce new economic objectives for operation. To achieve those economic objectives, power systems are being operated closer to their limits. As a result, any one of a large number of factors (such as weak connections, unexpected events, hidden failures in protection system, and human errors) may cause a system to lose stability, possibly leading to catastrophic failure. Therefore, there is a need for a systematic study and design of a comprehensive system control strategy to mitigate the possibility of such catastrophic failures.
Among the control strategies, controlled system islanding is the final resort to save a system from a blackout. In the literature, many approaches have been proposed to undertake controlled islanding. Some approaches only take static power flow into consideration; others require a great deal of computational effort. Following large disturbances, groups of generators tend to swing together. Research has focused on control strategies to maintain stability of inter-area oscillations between groups of machines. The slow coherency-based generator grouping is one potential method for capturing the movement of generators between groups under disturbance. The research issue is how to take advantage of the information from the slow coherency generator grouping method to island the system in a controlled way by tripping an identified set of transmission lines.
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Vijay Vittal
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03/20/06
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442.49 KB
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PDF
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06-04
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Real-Time Monitoring of Cascading Events
This tele-seminar presents research results on new technologies for monitoring and control at the system and local levels. To achieve more reliable operation, power system operators could benefit from new tools that provide an interactive scheme to detect and prevent possible cascading events. The tools are research grade, but have the potential for further development.
For system monitoring and control, the technologies include routine and event-based security analysis, along with security control schemes. Routine security analysis includes vulnerability analysis, and static and dynamic contingency analysis. The security control scheme includes emergency control for expected and unexpected events. The tools incorporate a fast network contribution factor method that addresses single and multiple network parameters variance for steady state analysis and control. For transient stability analysis and control, the new tools use the potential energy boundary surface method and analytical sensitivity of the energy margin. In addition, two indices, the Vulnerability Index and Margin Index, are developed to represent the vulnerability and security margin information for an individual power system element and for the operating condition of the entire system.
The local monitoring and control consists of an advanced real time fault analysis tool and a relay operation monitoring tool. The main technologies used in the local monitoring tool are a neural network based fault detection and classification algorithm, a synchronized sampling based fault location algorithm, and event tree analysis.
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Mladen Kezunovic
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03/28/06
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1.16 MB
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PDF
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06-05
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Wide-Area Small-Signal Stability Controller (06-06)
Recent blackout events (such as the 1996 Western U.S. events, the 2004 Northeastern disturbance, and the 2004 Italian blackout) have demonstrated the need for new automatic controllers that respond to unforeseen operating conditions to keep power system problems from cascading into large-scale blackouts. One way to prevent, slow or mitigate large-scale outages is to monitor and control the effects of instability events in large electric power systems. This research produced a real-time centralized controller that addresses small-signal stability events that could initiate a cascade leading to a large-scale outage. The controller is central to a proposed real-time, wide-area control strategy that detects and mitigates small-signal stability phenomena as they emerge. In essence, the strategy uses the controller to provide a safety net for the power system. Simulations showed that the controller could have stabilized oscillations before they became critically large in the Western U.S. blackout on August 10, 1996.
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Mani Venkatasubramanian
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04/04/06
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273.70 KB
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PDF
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06-06
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Security Enhancement through Direct Non-Disruptive Load Control
Dynamic security enhancement is generally associated with improvements in the response of generation and transmission systems, with network controls provided by FACTS devices and special protection schemes gaining acceptance. Load control, on the other hand, has (rightly) been viewed as disruptive to customers and, therefore, as the response of last resort. However, significant enhancements in communications, metering and computer technologies have meant that coordinated control of massive numbers of diverse loads is becoming feasible. Issues arising from such a control strategy have been explored. Our research has focused on the viability of load control for alleviating voltage collapse, and hence, for mitigating the possibility of cascading system failures.
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Ian Hiskens and Vijay Vittal
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04/18/06
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587.19 KB
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PDF
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06-07
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Detecting Circuit Breaker Status Errors in Substations
Detecting and identifying breaker status errors can be accomplished by a two stage procedure. The first stage involves regular state estimation whose results will be used to designate a set of suspect substations. The second stage involves a modified state estimation which uses expanded subtation models for the suspected substations. These models include explicit representation of breakers and switches. Flows through the breakers are estimated and the status of breakers are predicted based on the significance of these estimated flows. One of the shortcomings of this approach is the uncertainty involved in the way the suspect substations are identified.
Recently a new method, which can address this shortcoming, was proposed for topology error analysis. In this method, the size of a detailed substation model is reduced by applying Kirchhoff?s law and by implicitly considering topological constraints. This model reduction is achieved without losing any capability to detect and identify topology errors. Hence, the method does not have to specify the suspect substation ahead of time because all substations can be modeled by using a small number of extra state variables.
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Ali Abur
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05/01/06
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398.84 KB
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PDF
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06-08
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Trying to Maintain Generation Adequacy in ?Deregulated? Markets
The initial efforts to deregulate the electric utility industry in the USA occurred in states that had relatively high rates (the northeast and California). The main promise of deregulation was that market forces would lead to more efficient and innovative decisions, and hopefully, to lower rates for customers. Unfortunately, the promise of deregulation has not been fully realized, and in California, there was a major market ?meltdown? in 2000/01 with persistent high prices in the spot market. Regulators in the northeast have been successful in ensuring that a similar crisis did not occur in their region. These efforts have resulted in less volatility of spot prices by suppressing price spikes, but they have also reduced the financial incentives for investing in peaking capacity. Under current market conditions, investors are reluctant to build new peaking units, and this, in turn, poses a threat to the future reliability of supply. The objective of this seminar is to discuss how this predicament over generation adequacy in ?deregulated? markets is being and should be addressed.
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Tim Mount
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05/15/06
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472.19 KB
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PDF
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06-09
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Risk-Based Resource Allocation for Distribution System Maintenance
The effectiveness of expending maintenance resources can vary dramatically, depending on the target of the maintenance activities. The existing state-of-the-art power system maintenance program offers three approaches for making decisions associated with identifying maintenance activities: condition-based maintenance (CBM), which initiates a maintenance activity when the equipment?s monitoring data indicates a need; reliability-centered maintenance (RCM), which prioritizes maintenance activities based on quantification of likelihood and consequence of equipment failures; and optimization techniques, which offer methods of maximizing effectiveness of maintenance activities subject to constraints on economic resources and available maintenance crews.
The objective of the work described in this tele-seminar was to develop a comprehensive and cost-effective maintenance allocation and scheduling system based on the integration of these three approaches. A comprehensive and systematic method was developed for allocating and prioritizing maintenance resources that will optimize the effect of maintenance on the reliability levels of the system by maximizing risk-reduction achieved from selected maintenance tasks. This framework reduces maintenance costs while increasing equipment reliability to meet challenges from the increasingly competitive marketplace. It also helps to extend equipment life and helps utilities avoid or defer costly capital investments resulting from poor equipment performance.
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Ward Jewell and Jim McCalley
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01/16/07
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492.30 KB
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PDF
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06-10
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Toward Optimal Operations
By ?Operations? we mean the decisions made in real-time by human operators and computer-based controllers. Necessary conditions for optimal operations are:
? A view that extends over a time-horizon (rather than being limited to a snapshot of the system), so that anticipated changes and dynamics are included while short-sighted reactions to disturbances are avoided.
? Allowing for the full decision-space (all possible reconfigurations and all possible adjustments of the continuously controllable variables), so the best possible decisions are not excluded.
? Coordinating the decision-makers (both human and computer-based), so they cover the full decision space and do not work at cross-purposes.
The talk will cover:
? MPC (Model Predictive Control) as the framework for formulating operating problems so they include both time-horizons and the full decision space.
? The MPC formulation is too big to solve directly. Instead, a decomposition is developed to break it into sub-problems that can be solved in parallel by autonomous agents (human operators and computer-based controllers).
? Techniques by which the agents can cooperate (exchange suggestions and other useful information), each at its own speed (so fast computers can cooperate with slower computers and much slower humans).
? Preliminary results?a demonstration of the scheme for the control of cascading failures in a small system (about 300 buses).
This talk summarizes the work done by Paul Hines for his Ph.D. and for PSERC project S-26, ?The Risk of Cascading Failures.?
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Paul Hines
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06/23/08
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768.66 KB
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PDF
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06-11
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Optimizing Power System Restoration Resources
Restoration of a large and interconnected grid from a complete shutdown is a highly complex operation involving many technical and non-technical constraints. Practical and generic computer tools to support system dispatchers in their decision-making are desirable. Topics related to a restoration strategy will include optimization techniques to maximize available generation capability subject to time-varying constraints during restoration, use of tie lines, and time to restoration. The presentation will draw on research using information from a case study.
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Chen-Ching Liu
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11/06/06
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413.56 KB
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PDF
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06-12
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Carbon and Climate Issues for the Electric Power Sector
Increasing levels of greenhouse gases (GHG) - and the climate change they are causing - are real and they are a major problem. To stabilize concentrations, the world is going to have to reduce its emissions of CO2 and other GHGs by at least 90%. Over the coming decades, there will be pressure for changes in the nature and operation of the global energy systems, with pressure on the generation of electric power, which produces one third of US GHG emissions. Technology for carbon capture and sequestration (CCS) in the electric power sector can probably be made economically and environmentally viable. The current regulatory system is inadequate and will need to be improved. Public perception could be a major obstacle. Public education about CCS and about alternative ways to reduce CO2 emissions needs to start now.
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Jay Apt
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11/16/06
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3.05 MB
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PDF
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06-13
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Markets for Reactive Power and Reliability
The FERC report on reactive power clearly and succinctly lays out the issues and raises important questions about market power, contingent-claim versus real-time markets, the need for an optimal power flow that incorporates reactive power, etc. Unfortunately, the economic/engineering models so far available in the literature fail to represent the true economic optimum. This optimum involves maximization of the expected net benefits of electricity production, transportation, and use under the constraint of a full alternating-current (AC) power flow where the expected net benefit is defined as the sum of the probability-weighted economic outcomes for all contingencies, including line and generator failures. This is the correct way, in terms of economics, to determine optimal reliability, levels of investment, and operation parameters under alternative contingencies, as well as efficient and optimal production and prices for real and reactive power. The purpose of this paper is to take a broad look at how markets should be organized, not only for reactive power but for real power and reliability, since these markets are fundamentally interdependent and essential for efficient and reliable delivery of electric power. To accomplish this end, the paper opens with specification of an economic/engineering model of optimal investment and operation that is then simulated so that principles and goals for optimal market design can be established. The paper then examines issues of market power through both simulation and experimental economics. Finally, a variety of possible market designs are presented and evaluated in light of the conclusions drawn from the conceptual model, simulations, and experiments. The paper concludes with specific recommendations.
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William Schulze
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12/05/06
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85.23 KB
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PDF
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06-14
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