Solutions and practical experience for the calculation of LOLE and EDNS in the Spanish extrapeninsular isolated electric systems

This article presents the solutions adopted by Red Eleacutectrica de Espantildea (REE) in its software, LOLA, developed with the main purpose of calculating the probabilistic demand coverage indices LOLE-Loss Of Load Expectation- and EDNS-Expected Demand Not Supplied- for the 10 Spanish extrapeninsular electric systems, making it possible to assess system adequacy through a non deterministic approach. Several problems were encountered when calculating these indices using the methodologies found in the literature, dealing with computing time or with accuracy of simplified models. Three methodologies, presented in this article, developed by the authors allowed a successful analysis of large number of years, electric systems and scenarios. They are based in a Full Combinatorial Analysis, an innovative Limited Combinatorial Analysis, and a Monte Carlo analysis. Other solutions adopted in LOLA are presented.