Gradient-free methods applied to optimisation of advanced ultra-supercritical power plant

Power Plant Optimisation—Effective Use of the Nelder-Mead Approach

“…The latter reason constitutes the primary motivation for the present study, which is, concomitantly, the continuation of the work already undertaken in [40]. The sensitivity of the NM algorithm to the choice of initial points may noticeably influence the computing time, particularly when a large number of decision variables is concerned.…”

“…Finally, the results can be used by NM to search for new values of decision variables, and afterwards, the whole processes repeats itself to the moment when the convergence criteria are satisfied, i.e., the difference of the value of the objective function is less than ε = 10 −6 from one iteration to the next one. A detailed discussion about the selection of this criterion can be found in the previous work [40]. Finally, the results can be used by NM to search for new values of decision variables, and afterwards, the whole processes repeats itself to the moment when the convergence criteria are satisfied, i.e., the difference of the value of the objective function is less than ε=10 -6 from one iteration to the next one.…”

“…In another work [39], the Nelder-Mead (NM) approach was used to optimise 900 MW PP working with A-UCS conditions. In one of the most recent papers [40], the usefulness of three different DS methods, i.e., NM, Rosenbrock and Hooke-Jeeves, in the optimisation of A-UCS PP was examined. The last work revealed a huge potential of these approaches in the optimisation of complex thermal cycles.…”

“…It is a widely used DS method for solving the unconstrained optimisation problem and it is very easy to implement in practice [23,41], • Its usefulness in the optimisation of A-USC PP has already been found, however, it was found that even when the position of the initial simplex is changed monotonously, the paths in the decision space can substantially change, leading to non-monotonous variations in computation time (CT) [40].…”

“…In order to introduce an additional novel element with respect to the work [40], the impact of different sets of decision variables-i.e., all of the bleed and outlet pressures from each turbine on the objective function (i.e., the PP efficiency)-was examined.…”