Energy Storage Siting and Sizing in the WECC Area and the CAISO System

Spatio-temporal arbitrage using energy storage systems reduces the cost of operating a power system. However, since the cost of deploying storage is significant, it is essential to determine the optimal locations and ratings of these systems. This paper proposes a stochastic storage siting and sizing method that determines the optimal locations and ratings. This is first done from a centralized perspective where the objective is to minimize the sum of the operating and investment costs. The method is then modified to combine this cost minimization with the perspective of an investor who wants to find the storage locations and ratings that will maximize its profits. The effectiveness of the centralized method is demonstrated on a 240-bus, 448-line model of the WECC system. The combined perspective is analysed using a 4754-bus and 6377transmission line model of the CAISO system. The effect of adding constraints on the maximum number of locations where storage can be installed and on the size of energy storage systems is discussed. Sensitivity analyses are also performed to assess the impact of the investment cost and of the value attached to avoiding spillage of renewable energy. We also consider how a significant increase in the marginal costs of conventional generators and in the renewable generation capacity would affect these results. ∗The authors are with the Department of Electrical Engineering, University of Washington, Seattle, WA, 98195 USA (e-mail: [email protected]; [email protected]; [email protected]; [email protected]; and [email protected]).