Reliability optimization of an electric power system by biomass fuelled gas engine

•A method to optimize the reliability of an electric power system.•Reliability index is determined as the failure probability of the system.•Shuffled Frog-Leaping Algorithm and probabilistic load flow.•Improvement of the reliability index due to distributed generation. This article presents a method to optimize the reliability of an electric power system by the introduction of distributed generation using biomass as fuel. The reliability index of the system is determined as the failure probability of the system. Probabilistic load flow is used to calculate the reliability index. This probabilistic load flow is solved by the method combined of cumulants and Gram–Charlier expansion. To determine the reliability index a number of contingencies should be simulated, the more the number of contingencies, the more accurate the index is. This probabilistic method uses the random variables as starting data, so both generators and loads are modelled as random variables. Generators considered for distributed generation are biomass fuelled gas engines, that are very abundant in Spain. This paper applies a new method utilizing Shuffled Frog-Leaping Algorithm and probabilistic load flow to solve this problem. Acceptable solutions are reached in a small number of iterations. Numerical applications are presented and considered regarding the power system IEEE 14-bus and including biomass fuelled gas engines at several nodes. The results obtained show the improvement of the reliability index due to the presence of distributed generation.