Fundamental conjectured supply function equilibrium: application to the Iberian system

Abstract

This paper presents a new two-step algorithm to compute a conjectured supply function electricity market equilibrium with DC transmission network constraints. This approach generalizes a previous authors’ model developed for the single-bus case. Unlike other approaches, its main contribution is that the parameters of the first order approximation of the conjectured supply functions (intercept and slope) are endogenously determined, coherently with the network lines status. Nodal prices are used to split the market into single prices areas. Each area is treated as a single-bus market from the transmission constraints point of view, and the authors’ singlebus algorithm is applied to compute the generators supply functions for each area. These new generators strategies are then cleared to determine new nodal prices and areas for the next iteration. Convergence is achieved when the network lines status and strategies of the generators do not change significantly in two consecutive iterations. The algorithm has been tested with some illustrative case examples, and with a simplified version of the MIBEL market (Spain-Portugal).