The problem of defining and classifying power system stability has been addressed by several previous CIGRE and IEEE Task Force reports. These earlier efforts, however, do not completely reflect current industry needs, experiences and understanding. In particular, the definitions are not precise and the classifications do not encompass all practical instability scenarios. This report developed by a Task Force, set up jointly by the CIGRE Study Committee 38 and the IEEE Power System Dynamic Performance Committee, addresses the issue of stability definition and classification in power systems from a fundamental viewpoint and closely examines the practical ramifications. The report aims to define power system stability more precisely, provide a systematic basis for its classification, and discuss linkages to related issues such as power system reliability and security.

Definition and classification of power system stability IEEE/CIGRE joint task force on stability terms and definitions

Preface to the Paperback Edition. Preface. About the Author. 1. Overview and Background. 2. Basic Concepts and Distributions for Product Life. 3. Probability Plotting of Complete and Singly Censored Data. 4. Graphical Analysis of Multiply Censored Data. 5. Series Systems and Competing Risks. 6. Analysis of Complete Data. 7. Linear Methods for Singly Censored Data. 8. Maximum Likelihood Analysis of Multiply Censored Data. 9. Analyses of Inspection Data (Qualtal--Response and Interval Data). 10. Comparisons (Hypothesis Tests) For Complete Data. 11. Comparisons with Linear Estimators (Singly Censored and Complete Data). 12. Maximum Likelihood Comparisons (Multiply Censored and Other Data). 13. Survey of Other Topics. Appendix A. Tables. References. Index.

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Applied life data analysis

This paper discusses conceptual frameworks for actively involving highly distributed loads in power system control actions. The context for load control is established by providing an overview of system control objectives, including economic dispatch, automatic generation control, and spinning reserve. The paper then reviews existing initiatives that seek to develop load control programs for the provision of power system services. We then discuss some of the challenges to achieving a load control scheme that balances device-level objectives with power system-level objectives. One of the central premises of the paper is that, in order to achieve full responsiveness, direct load control (as opposed to price response) is required to enable fast time scale, predictable control opportunities, especially for the provision of ancillary services such as regulation and contingency reserves. Centralized, hierarchical, and distributed control architectures are discussed along with benefits and disadvantages, especially in relation to integration with the legacy power system control architecture. Implications for the supporting communications infrastructure are also considered. Fully responsive load control is illustrated in the context of thermostatically controlled loads and plug-in electric vehicles.

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Achieving Controllability of Electric Loads

With the fast-paced changing technologies in the power industry, new power references addressing new technologies are coming to the market. So there is an urgent need to keep track of international experiences and activities taking place in the field of modern unit-commitment (UC) problem. This paper gives a bibliographical survey, mathematical formulations, and general backgrounds of research and developments in the field of UC problem for past 35 years based on more than 150 published articles. The collected literature has been divided into many sections, so that new researchers do not face any difficulty in carrying out research in the area of next-generation UC problem under both the regulated and deregulated power industry.

Unit commitment-a bibliographical survey

A method for determining the impact of wind generation on system reliability is developed. This method combines the effects of wind turbine forced outage rates and varying power output due to wind speed variations. Since individual wind turbines on a windfarm all have an output related to wind speed, each turbine's output cannot be assumed to be independent random variables. Because of this situation, special steps must be taken in der to arrive at the cumulative distribution function for the windfarm. This distribution function may be combined with the system distribution function using simple convolution and so the windfarm can be easily incorporated into a Loss of Load Expectation computer program. The method can then be used to determine the effective load carrying capability of a windfarm and also to supply better estimates of the benefits of wind generation to the overall system.

Development of a New Procedure for Reliability Modeling of Wind Turbine Generators

This paper proposes a neural network solution methodology for the problem of real power transfer capability calculations. Based on the optimal power flow formulation of the problem, the inputs, for the neural network are generator status, line status and load status and the output is the transfer capability. The Quickprop algorithm is used in the paper to train the neural network. A case study of the IEEE 30-bus system is presented demonstrating the feasibility of this approach. The new method will be useful for reliability assessment in the new utility environment.

Real power transfer capability calculations using multi-layer feed-forward neural networks

The paper describes a new method of scheduling thermal generating units to achieve minimum operating costs including both running and start-up costs while at the same time maintaining a desired level of system security.

Optimal Thermal Generating Unit Commitment

A reliability model of a system and its associated protection system is described. The protection system detects the presence of faults and isolates the faulted equipment so as to prevent damage and minimize the effect of the faulted equipment on the operation of the rest of the system. If the protection system does not respond and the faulted component is not disconnected, a backup protection system comes into operation. The backup operation isolates a larger segment and disturbs the system more than if the designated protection system had responded appropriately. An example is the protective relay systems for electric power transmission and distribution systems. A measure of system unreadiness is defined and suitable expressions are derived for this index and the mean duration of undetected faults. The unreadiness probability is sensitive not only to the failure rate of the protection system but also to the failure rate of the system, the pdf of interval between inspections and its mean value. The unreadiness probability estimated from a given system cannot be used for another system having a similar protection system. The protection system failure rate can, however, be used to obtain the unreadiness probability.

Protection System Reliability Modeling: Unreadiness Probability and Mean Duration of Undetected Faults

Power system reliability evaluation

The paper presents a new analytical approach to the calculation of generating system reliability indices. The new approach makes it possible to relax idealizing assumptions and to explicitly model the effects of operating considerations such as: (1) unit duty cycles reflecting load cycle shape, reliability performance of other units, unit commitment policy, and operating reserve policy; (2) start-up failures; (3) start-up times; and (4) outage postponability. The models presented can also be used to consider the effects of basic energy limitations and to give production cost estimates.

A.D. Patton

Papers

Real power transfer capability calculations using multi-layer feed-forward neural networks

Optimal Thermal Generating Unit Commitment

Protection System Reliability Modeling: Unreadiness Probability and Mean Duration of Undetected Faults

Power system reliability evaluation

Operating Considerations in Generation Reliability Modeling-An Analytical Approach