Generation expansion planning under wide-scale RES energy penetration

Renewable energy penetration in electricity is expected to have a spectacular growth in the forthcoming years. Power systems and the codes of their operation will be modified to take into account the specific characteristics of variable renewable energy operation (wind energy, photovoltaics). A number of issues arise in the context of developing new generation expansion planning methodologies, under a large scale penetration of renewable energy. A probabilistic approach is necessary due to the strong stochastic nature of variable (non dispatchable) renewables incorporating the statistics of the customer load and the non dispatchable RES generation. The level of penetration of variable renewable energy has to be calculated according to restrictions implied by the energy curtailment which can occur when the customer load is low and RES generation is high. Hydro pumped storage plants decrease this curtailment and consequently increase the level of RES penetration. In addition, fast reserve capacity is required to deal with big variations of variable RES energy generation. In summary the necessary storage and reserve capacity has to be calculated and incorporated in the costs of different scenarios related to expansion planning or operation simulation. In addition, grid costs mainly related to the Transmission System Expansion have to be calculated since they are related to the penetration of areas with high RES potential. In the present paper an attempt is made to incorporate such costs in the TIMES model in order to have a more accurate approach of generation expansion scenarios, incorporating storage, reserve plants and Transmission System expansion in the cost of RES technologies. Using the results as an input, a more detailed probabilistic approach is used to calculate the relevant production costs under a wide-scale penetration of RES. Methodologies presented here are based on the so called residual load duration curves approach.