Optimal Planning to Include Storage Devices in Power Systems

Abstract—It is difficult to forecast renewable energy resources due to their variability. High uncertainty of the resources in-creases the concern about the reliable operation of the electric power system. Storage devices have been considered a candidate to control variable energy resources, and most studies on storage de-vices are performed in the economic dispatch. Therefore, electric power adequacy may be an issue. In this paper, a new approach in the optimal power flow framework is proposed for deploying storage devices, and the feasibility and economic impact analyses are discussed. Index Terms—DC power flow, optimal power flow (OPF), power transfer distribution factor (PTDF), storage devices, variable en-ergy resources. NOMENCLATURE Branch impedance matrix. Bus impedance matrix. C Grand offer/operation cost of generators. GA Group of generators with high ramp rate so that such generators have the capability to change their output after realizing the renewable outputs. GB Group of generators that do not have the capability to change their generation according to the renewable outputs. H PTDF matrix with cardinality of-by-. Identity matrix with cardinality of-by-. L Generator location matrix with cardinality of-by-. LL Storage device location matrix with cardinality of-by-Number of states of the output from the variable generators at time. Pg Power injection vector. Probability that variable generators ’ output is in th state at time