Asymmetric Operation of AC Power Transmission Systems

ISBN9782553014031 EditorPresses internationales Polytechnique pages200 Published2006-01-23
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Today, simple and cost-effective strategies can be implemented to operate AC power transmission systems more reliably and economically. As will be seen in this book, asymmetric operation of three-phase transmission corridors brings new degrees of freedom to the planning and operation of point-to-point transmission, inter-area interconnections, singleand multiple-line corridors, and networks feeding large metropolitan areas, either for new build or retrofit. Asymmetric Operation of AC Power Transmission Systems is a comprehensive review of all aspects of asymmetric operation ranging from system implementation to costs, reliability and economics.

This book is an invaluable tool for professionals working in industry, government and research as well as students and professors in electrical engineering and applied science.


Richard J. Marceau, Eng., Ph.D., is professor of Electrical Engineering and Provost at the University of Ontario Institute of Technology.

Abdou-R. Sana, Eng., Ph.D., is an independent consultant in electric energy systems.

Donald T. McGillis, Eng., is an adjunct professor in the Department of Electrical and Computer Engineering at both McGill University and Concordia University.


Bulk power transmission systems are operated symmetrically. When a problem occurs on a three-phase line such as a short-circuit on an individual phase, all three phases are taken out of service even though two sound phases remain and are able to function normally. Such a strategy is fundamentally inefficient: considering that, on average, 95% of faults on EHV and UHV transmission systems are single-line-to-ground faults, such a strategy is fundamental incorrect 95% of the time and is therefore wasteful of installed transmission capacity.

Asymmetric operation involves operating power transmission corridors at full capacity from a few milliseconds to a few hours even though individual three-phase lines have been weakened due to fault conditions. This book describes how asymmetric operation is implemented, how much it costs and how it can improve the reliability, economics and flexibility of electric power transmission systems. Numerous examples of asymmetric operation are provided at all major HV, EHV and UHV voltages demonstrating the very real benefits of asymmetric operation.

First, the underlying concepts of symmetric three-phase transmission system planning and operation are introduced. Then, asymmetric operation is presented, and its impact on system security and reliability is considered. Different implementation strategies are examined, and numerous practical examples illustrate the ease and flexibility with which such strategies can be applied in the case of either multiple- or single-line AC power transmission corridors. Finally, economic analysis quantifies the benefits of asymmetric operation.
Chapter 1 - The Modern Power System
Introduction. Power System Engineering. Symmetric Versus Asymmetric Operation.

Chapter 2 - Introduction to Asymmetric Operation of PowerTransmission Systems
Concept of Asymmetric Operation. System Security. Strategies of Implementation. Reactive Power Management.

Chapter 3 - Probabilistic Aspects of Asymmetric Operation
Introduction. The Binomial Law. The Poisson Distribution. The Weibull Distribution. Application to Asymmetric Operation.

Chapter 4 - Asymmetric Operation of a Corridor with Multiple Lines
Introduction. Asymmetric Operation Using Conventional Compensating Devices: Lossless Line With Lumped Parameters. Asymmetric Operation Using Conventional Compensating Devices: Uncoupled Line With Distributed Parameters. Asymmetric Operation Using FACTS Controllers.

Chapter 5 - Asymmetric Operation of a Corridor With a Single Line
Introduction. Compensation With Conventional Devices. Compensation With FACTS Devices. Paired and Versatile Negative-sequence and Zero-sequence Currents Filtering.

Chapter 6 - Economic Analysis
Introduction. Estimating Costs. Investment Costs of Asymmetric Operation Using Conventional and Modern Compensating Devices. Investment Costs of Asymmetric Operation Compared to the Cost of the LOLE and the Cost of a New Line. Effect of the Number of Lines. Scenario Studies.

Chapter 7 - Enhancing the Flexibility of Power System Operation
Introduction. Review of the Three-phase N _ 1 Criterion. The Single-line Corridor. Distributed Generation. The Distribution System.

Chapter 8 - Conclusion

Appendix A - Underlying Concepts of Symmetrical Three-phase System Planning

Appendix B - Simulation Results