June 2012 article (Early View): “Short-Term Hydroscheduling with Discrepant Objectives Using Multi-Step Progressive Optimality Algorithm,” by Chuntian Cheng, Jianjian Shen, Xinyu Wu, and Kwok-wing Chau.
Short-term hydroscheduling (STHS) has received more attention in China with the rapid expansion of hydropower systems. This article presents a novel strategy for STHS with discrepant objectives in which all hydropower plants are classified into several types. The classification depends on the location and special operating characteristics of hydroplants, inflow, installed capacity, load demands, and other factors. In this way, the same type of plants take advantage of the same optimization objective for optimizing their generation scheduling, and the objectives used for different types are different. Each type of hydropower plant is expected to play its best role using the objective function chosen.
In this article, the authors present a multi-step progressive optimality algorithm (MSPOA) for the short-term hydroscheduling (STHS) problem to improve the quality of optimal solutions and enhance the convergence speed of progressive optimality algorithm (POA). In MSPOA, the original problem is first decomposed into a sequence of problems with the longer time steps. Next, the problem with the longest time step is solved, and the optimal solution is used as the initial solution for the problem with the second longest time step. This process proceeds until the original problem with the shortest time step is solved. The proposed discrepant-objective method and solution technique are tested for two types of hydroelectric systems. The results show that MSPOA can give better solutions and cost less time than POA due to enlarging feasible range of decision variables and reducing the number of computational stages. Discrepant objectives among hydropower plants can express the operation characteristics of complex hydropower systems more accurately than unique objective or multiple objectives.
[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own.]