Proposed Terms and Definitions for Power System Stability Task Force on Terms & Definitions System Dynamic Performance Subcommittee Power System Engineering Committee

This paper presents proposed terms and definitions in pursuit of Electric Utility Industry uniformity and common understanding in the analysis of Power System Stability. Although most of the proposed terms are not new, an attempt has been made to define them precisely. In so doing, the historical usage of the terminology has been taken into account. However, it has been necessary, in certain cases, to deviate from some past practices to be able to resolve differences between the usage of a term in the power systems literature and the usage of that term in related fields. Power System Stability has been an area of study from the early days of power generation and transmission. This has become an area of concern as power systems over large geographic areas have been interconnected. As the problem has grown, sophisticated control equipment and protection schemes have been added to the power system to enhance stability. As a result the analysis of the problem has become more difficult, but fortunately, better mathematical models and their use in computer simulation have also brought increased understanding. As the interest in this subject has grown and the technical literature has increased, new terms have been introduced and old terms have been interpreted differently to keep up with the changes in the problem as well as the analytical tools. As a result, there has been some confusion about the precise meaning of certain terms.