Decomposition and coordination of large-scale power systems

Summary form only given. In this presentation, we discuss coordination of the use of transmission between regions in a multi-region system and pose two basic questions: 1)What needs to be specified, or agreed to, in order to describe physically realizable trades between regions in a multi-region system? 2)How to characterize economically efficient trade in a multi-region system? In this context, "region" could mean either a traditional utility control area or a larger region defined by the purview of an ISO or RTO. We concentrate on real power dispatch in a multi-region system, although there are analogous issues for reactive power and there is some coupling between real and reactive power. However, real power issues are more pressing and reactive power is inherently more local. We also briefly consider state estimation in a multi-region system. We described a proposal for coordination of trade between regions, "decomposition by tie-lines," that provides a uniform interface between regions. We characterize efficient trading and describe an iterative process that provably converges to optimal dispatch for the multi-region system. We also present numerical results for the Electric Reliability Council of Texas System. Finally, we describe implementation issues and alternative decomposition schemes.