A Security-Constrained Hydrothermal Unit Commitment Model in the Day-Ahead Electricity Market

In 2015, the Ministry of Energy created a wholesale electricity market in Mexico. As a result, the country shifted from a vertically integrated regulation to a competitive market framework. In this context, the day-ahead market is essential to plan better the generation and sales of energy. This paper evaluates a hydro-thermal security-constrained unit commitment model and its solution method. The objective function determines the maximum economic surplus of the participants in the market. The problem is modeled as a mixed-integer non-linear programming incorporating real-world constraints from the particular problem and a hydropower generator function non-linear features. A decomposition approach that solves a master problem and a series of subproblems is developed. Furthermore, a new component has been added to deal with the non-linear features of the hydropower generator function using a first-order Taylor's approximation. Simulation results are presented starting by solving a representative case of the electricity market in Mexico, demonstrating its use. Moreover, to evaluate the performance, multiple instances are created from publicly available information on the day-ahead market in Mexico. The model can be helpful in markets with sizable hydropower sources to obtain a more accurate and timely system operation scheduling.