“On-line voltage and dynamic security assessments and control: Recent developments and some future directions”

Certain transmission corridors around the world are being forced to carry more power than they were originally designed to carry. These difficulties, coupled with a steady increase in load demands, have forced electric power systems into being operated with technical difficulties such as degraded reliability, degraded security, and degraded power quality. In addition, such factors as increasing numbers of bulk power interchange transactions and non-utility generators, and the trend toward installing higher-output generators with lower inertia constants and higher short-circuit ratios have all compounded the problem. To a large extent, these changes have contributed to the emergence of the new types of complex behaviors observed in many power systems. In this paper, a comprehensive package for on-line voltage stability assessments and control of large-scale power systems will be presented. The tool handles the full AC nonlinear modeling of the base-case power system under a contingency list. It takes the general characteristics of power system operating environments into account and includes the effects of control devices. Many practical aspects of power system operations and characteristics are modeled in the tool; such as limits of real power generation, generator capability curve, the sequence of generator pick-up, generation participation factor, userdefined priority of employing control devices and physical limitations of control devices. The major features of the tool are the speed, accuracy, and reliability of its simulation engine. The tool can handle power system models up to 80,000 buses and has several installations in the power industry. Another tool to be presented is TEPCO-BCU, an integrated package developed under joint multi-year efforts between Tokyo Electric Power Company, Tokyo, Japan and Bigwood systems, Inc., Ithaca, NY, USA, for fast and yet exact transient stability assessment and control of large-scale power systems for on-line mode or on-line study mode, or off-line planning mode. The algorithmic methods behind TEPCO-BCU include BCU method, Group-based BCU method, BCU classifiers, improved energy function construction, and BCU-guide time domain method. To meet the on-line dynamic security assessment for large power systems, a parallel version of TEPCO-BCU, termed Parallel TEPCO-BCU has been developed. Applications of TEPCOBCU, Parallel TEPCO-BCU to real-time stability monitoring system will be described. (1 page)