Building a Topology Estimator for Large Inter-Regional Networks

The Common Information Model (CIM) [1] defines a utility industry standard object-model for the development and integration of applications used for electric power systems engineering, planning, management, operation and commerce. This paper describes the scope and technical basis for a project to develop a real-time Common Information Model (CIM) for the entire Eastern Interconnection. The project, which also features an automatic real-time network topology estimator, could have farreaching implications for on-line security assessment in North America. The project will be implemented using the ICCP, CIM and Common Data Access (CDA) Application Program Interface (API) standards sponsored by the Electric Power Research Institute. Wide Area Models Needed In the area of power grid operation, the energy industry in North America faces a variety of challenges. Foremost among these is the difficulty of continuing to ensure secure grid operation in an open access environment. Electric load continues to grow at a steady rate, yet North American transmission system additions have slowed to a crawl. These facts, Building a Topology Estimator for Large Inter-regional Networ 0-7695-0493-0/00 combined with mandated open access to transmission systems, are forcing the industry to operate the power grid closer to its operating limits. Pushing the system to its limits for maximum economic benefit while maintaining adequate security margins requires on-line security assessment. This, in turn, requires real-time models for the entire interconnected system network. Currently, at the interconnection level, this responsibility is assigned to regional Security Coordinators as shown in Figure 1. Each Security Coordinator is responsible for monitoring the overall security of the system for their region. The Security Coordinator Computer Systems are based on Energy Management Systems from a variety of suppliers. These systems include Topology Processor, State Estimator, Contingency Analysis and Dispatcher Powerflow applications. The Security Coordinator Systems are connected using the Interregional Security Network (ISN) Nodes with the ICCP protocol. The nodes all connect to the NERC ISN Frame Relay Network. Control Area Computer Systems are those systems that perform data acquisition, supervisory control, automatic generation control and possibly network analysis functions. The Control Area Computer Systems have the