Improvements for the short-term bidding process of a GENCO

This paper presents a new dispatch optimization model and different bidding strategies that an agent can adopt for the day-ahead electricity market, provided adequate forecasts of its Residual Demand Curves (RDC¡¯s) by means of ARIMA models. In the case study analyzed the resulting spot price and the total amount of energy delivered by the utility are related (in fact this relationship is measured through the slope of the RDC¡¯s), so the commonly used price-taker approach may not be always suitable. This dependence between the resulting spot price and the amount of power delivered by the agent makes the problem much more difficult to solve, as the objective function turns out to be non-linear. Also, the fact that there are groups not totally owned by a single utility, as is the case in the Spanish system, must be considered in the dispatch optimization model. Next, two different bidding strategies (profit-seeking and share-seeking) and the implications about considering or not a global share constraint in the dispatch model are shown. Finally, a case study is presented in order to clarify the previous ideas.