  This paper presents a time decomposition strategy to reduce the computational
complexity of power system multi-interval operation problems. We focus on the
economic dispatch problem. The considered scheduling horizon is decomposed into
multiple smaller sub-horizons. The first time interval of each sub-horizon is
modeled as the coupling interval between two consecutive sub-horizons. The
interdependencies between the sub-horizons are mathematically modeled using
ramp rates of generating units. A distributed coordination strategy, which is
based on auxiliary problem principle, is developed to coordinate the economic
dispatch solutions of the sub-horizons to find an optimal solution for the
whole operation horizon. We also propose an initializing technique to start the
iterative coordination algorithm from a good-enough point. This technique
enhances the convergence rate significantly. The proposed algorithm is deployed
to solve a week-ahead economic dispatch problem on the IEEE 118-bus system, and
promising results are obtained.
