Resumen de Long-term optimal hydropower reservoir operation with minimum flows and maximum ramping rates
This thesis studies the long-term operation of price-taker peak hydropower plants associated to reservoirs and subject to minimum flows and maximum ramping rates that sell energy in day-ahead electricity markets. The thesis is organised in five chapters and two appendixes. The first chapter is an introduction of the above-mentioned issue. It aims to provide both an overview as well as a mathematical description of the addressed problem and define the scope and objectives of the thesis. The second chapter shows a review of the literature related to the main topics tackled in the thesis, such as the principal approaches of reservoir decision support tools, the optimisation techniques most used in hydro scheduling, the main procedures for the characterisation of the involved random inputs and the methods most employed to estimate the generation characteristic of a peak hydropower plant. Furthermore, the chapter also presents a brief description of the hydro scheduling models that have considered minimum flows and maximum ramping rates jointly. The third and the fourth chapters are devoted to the achievement of the thesis objectives and are divided in several studies. Among the main contributions cointaned in these studies can be found different long-term optimisation models for hydropeaking subject to minimum flows and maximum ramping rates, several sensitivity analyses of the long-term effects of these constraints on certain economical and operational aspects of a peak hydropower plant, a set of formulae for the approximate assessment of the long-term economic impact caused by these constraints on this type of plants, and the introduction of a new concept in hydro scheduling: flow value. The fith chapter sets out the conclusions of the thesis which can be summarised as follows. On the one hand, the presence of minimum flows in hydropeaking increases the spillage volume and the water value, whereas decreases the generated energy, the number of start-ups and shut-downs of the hydro units, the plant capability for price tracking and the revenue. On the other hand, the presence of maximum ramping rates, in turn, increases the number of plant operating hours, the spillage volume, and, in the driest weeks, the flow value, whereas decreases the number of start-ups and shut-downs of the hydro units, the plant capability for price tracking, the revenue, the water value, and, in the wettest weeks, the flow value. The appendix A contains the equations involved in the developed optimisation models and the appendix B provides a summary of the main data of the case studies considered in the third and fourth chapters. Finally, both the cited references and the applied nomenclature can be found at the end of the thesis.
