Locational Marginal Pricing in Multi-Period Power Markets
The objective of this paper is to develop an analytical framework for interpretation of locational marginal prices (LMPs) in multi-period power markets with intertemporal ramping, limited energy, and energy storage constraints. Previous research dedicated to the techniques for decomposition of LMPs explicitly shows their formation as a spatial structure of components due to power flow, transmission and voltage constraints. In contrast to the traditional point of view, this study proposes formulae for discussing a temporal LMP structure, where LMPs are obtained as Lagrange multipliers for nodal real power balances in a multi-period AC optimal power flow (OPF) problem. In the beginning, marginal resources are discussed. It is shown that an energy resource with unbounded output at a specific time period may not be marginal. Then, the resources that actually form LMPs in the energy system are determined. The study shows that not all marginal resources directly affect LMPs. Finally, the dependence of LMPs on marginal resources from different time periods is considered. It is shown that binding ramping constraints lead to "cardiogram" curves of LMPs, while limited energy and energy storage constraints smooth them out and are used to form LMPs based on the overall price situation in specific time periods. The aim of the methodology is not to determine LMPs but to identify contribution of particular constraints that affect their formation. The methodology has been tested on the IEEE-30 energy system extended with a daily load profile for a day-ahead market with a full AC OPF model.
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