M odern power systems have grown both in size and complexity. Various constraints, such as security, economy, and environmental regulations, are forcing power systems to operate closer to their design capabilities and security margins. Utilities are required to operate as optimally as is feasible. Energy control centers play a vital role in optimal and secure operation of a power system. Applications in an energy control center require monitoring and control of the large interconnected power

more »

... tem. Energy management system (EMS) decision-support tools, such as optimal power flow (OPF), base their decisions on the real-time model of the power system network along with the realtime data. Usually, real-time modeling of a power system follows a four-step procedure that involves the following: I Network configuration analysis I Observability analysis I State estimation and bad data processing I Network application functions. A network topology processor (NTP) processes real-time circuitbreaker (CB) status to obtain current electrical network topology. This article builds on information presented by the authors in the October 2000 issue of IEEE Computer Applications in Power and focuses on an object-oriented design for an NTP. The design and application is expected to be part of an overall object-oriented EMS. Network Topology Network topology processors perform a time-critical EMS operation but also add to the complexity of the EMS software system, which can be handled elegantly in the object-oriented paradigm. Object-oriented systems stress reuse of software components. Typically, with changes in technology, applications evolve ( Figure 1) ; however, physical laws governing them remain the same. Thus, an object-oriented approach can be used to develop a toolkit for power system applications. Figure 2 shows a typical power system network (PSN) in which substations are connected through circuits (lines, transformers, cables, etc.). In each of the substations, buses are interconnected through CBs (Figure 3 ). Various substation configurations exist, such as ring main, breaker and a half; with varying costs, flexibility of operation, and reliability. In real-time, breakers may operate at any time, changing the system configuration dynamically. The substation status must be analyzed to update connectivity; as with the operation of a CB, any of S. Pandit, S.A. Soman, and S.A. Khaparde are with IIT Bombay, Mumbai, India.