Global Solution of Economic Dispatch with Valve Point Effects and Transmission Constraints.

• Impact of the valve point effect in the economic dispatch. • Implementation of heuristics and tests on modified benchmark problems. • Optimality gap analysis of the global solution of the non-convex problem. Gas units are becoming an increasingly important component of modern power system operations, due to the flexibility that they offer in a regime of large-scale renewable energy integration. The valve point effect refers to the loss of efficiency when operating a turbine off a valve point, that is just after the previous valve opens. The valve point effect for gas power plants is a primary attribute of their operation, however its representation raises computational challenges, due to the non-convex and non-smooth model that is required for representing the fuel cost. In this work, a new heuristic based on successive piecewise approximations of the cost function is described. This heuristic consists in two steps: first, the optimization is run over the whole feasible set and a lower bound for the optimal objective is obtained, then the feasible solutions collected in the previous step are enhanced through local searches. The approach is tested on several IEEE bus systems that have been extended with generators obeying a valve point effect. [ABSTRACT FROM AUTHOR]