Transmission planning and co-optimization with market-based generation and storage investment

Abstract

A tool for planning grid reinforcements while recognizing how supply and storage investments will respond to the changed network is presented here. The model is formulated as a mixed-integer linear program that co-optimizes transmission–generation–storage expansion; in an unbundled market context, use of such a model by transmission owners is termed “proactive” or “anticipative” transmission expansion planning (TEP). Using a case study of planning for the Western Electricity Coordinating Council (WECC) in the USA, we demonstrate how inclusion of battery storage co-optimization will change the TEP solution, and we quantify the economic benefit of such co-optimization. The results show that (1) optimizing while accounting for storage expansion will help TEP avoid overbuilding lines in some cases and underbuilding lines in others, while generation and storage are sited and sized more efficiently; and (2) explicitly recognizing that storage siting will react to network expansion will result in additional transmission benefits. This benefit increases as the cost of battery storage is reduced but changes nonmonotonically with respect to the assumed cost of carbon emissions.