Since the shock of the 1965 North American blackout, other multi-million-dollar blackouts have continued to occur throughout the world. Though each event is analyzed carefully, and targeted corrective actions are identified, additional comprehensive system-wide measures are still needed to protect against severe unforeseen fast-developing cascading events. The CIGRE Technical Brochure C2.02.24 provides a roadmap for the development of defense plans to mitigate extreme contingencies with the intent to lead power system professionals to improve electric system reliability and security of the grid. The basic premise for protection against extreme contingencies is that a failure in one area of the grid should not result in blackouts elsewhere, and that such situations could be minimized by well designed, maintained, operated and coordinated power grids.
Many considerations and elements from concept to application of defense plans—including engineering, design, implementation, documentation, operational training and maintenance—are covered in-depth in the report. It offers best industry practices to make use of such schemes. The industry has implemented this concept in several parts of the world. However, the advantages of these schemes have not been fully recognized due to perceived drawbacks such as impact on operation and maintenance, unintended Special Integrity Protection Schemes (SIPS) action, complex technical training for operators and technicians, perceived high costs, etc. New technologies enable cost-effective coordinated wide-area monitoring, protection, and control systems, while offering user-friendly operational tools to system controllers.
The initial chapters of the report describe the evolution of the power system with its increasing dependence on the interconnected transmission grid, and explain how this dependence has introduced many challenges. The most pressing concern is improving power system operational security. In this context, the Defense Plan concept is introduced to provide effective measures that will reduce the likelihood of blackouts. Several of these schemes are then described, showing the wide application of Defense Plans on transmission systems throughout the world.
The continuing advances in development of analytical tools and study procedures for various types of disturbances are discussed. The values of sound system design, improved substation layout, operational readiness and training are highlighted as basic measures to mitigate extreme contingencies.
The report then presents all possible means of action that could be used in a defense plan. Practical techniques using available technologies with implementation examples are presented. Finally, advanced technology will play an important role providing enhanced security that recognizes the unique attributes of electricity infrastructure.
The report also includes a wealth of references in each chapter and can be viewed as a complete bibliography on any of the subjects.
The contributors to this report believe that recent blackouts, in a number of countries, have reinforced the need for the implementation of defense plans. The basic philosophy is that large-scale cascading outages could be reasonably avoided, or when they occur, the systems should be quickly restored.
The CIGRE C2.02.24 Report Defense Plans Against Extreme Contingencies consists of:
