Security monitoring systems including fast transient stability studies

This paper relates to on-line security assessment and determination of optimal preventive measures of power system, which the authors have developed by using two methods, digital and digital-analog hybrid. The description includes the power system of the Tokyo Electric Power Co., Inc. (TEPCO) for the security assessment; the software configuration for the on-line security assessment; fast calculating methods for the assessment, with emphasis on the study of transient stability; methods for determinating optimal preventive measures to improve transient stability; performance test of the digital method for an actual bulk power system; and a model hybrid security monitoring system for a comparatively small power system and its performance test.