Optimization of SO2 and NO x Emissions in Thermal Plants

This paper presents an environmental dispatch algorithm in a hydrothermal system and addresses the problem of minimization of emissions of SO₂ and NO _x caused by the operation of thermal plants. Several models have been used to represent the emissions function. In this paper, we first construct a quadratic model for both emissions: E(P)=α+β P+γ P ², where P is the power generated and the parameters were computed via the least-square criteria from several tests at thermal plants. We shall see that the problem consists in the minimization of a functional F(z) within the set of piecewise C ¹ functions that satisfy boundary conditions and non-holonomic inequality constraints. An optimal control technique is applied and Pontryagin’s theorem is employed. The algorithm proposed is easily implemented using the Mathematica Package and is applied to a sample system to illustrate the results obtained.