Estimation of marginal system costs and emissions of changes in generating unit characteristics

A method is presented for estimating the marginal system costs and emissions caused by the changes in the fixed costs, variable cost, emissions or capacity of generating units. Changes in dispatch order are accounted for. The method is based on a second-order Taylor series expansion of unit output as calculated by probabilistic production simulation. An approach is developed to compute the first and second derivatives of expected generation with respect to the capacity of a unit, which are essential components of the Taylor series approximation. An illustrative application is presented