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 multiperiod
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.