Assessing Wind Energy Uncertainty Impact on Joint Energy and Reserve Markets by using Stochastic Programming Evaluation Metrics

Wind energy is considered as a challenging problem for power systems because of its variable nature. As a result of accommodating wind resources with conventional thermal units in the system, performing of electricity markets will be more complicated. The results of the market clearing problem can be improved by proper wind uncertainty modeling. One of the best methods in order to handle wind uncertainty is to use stochastic programming. The expected value of the perfect information (EVPI) and value of the stochastic solution (VSS) are two well-known indices defined to analyse stochastic programming results compared to a case with having full information and a case disregarding uncertainty, respectively. In this paper, impact of the wind uncertainty on the EVPI and VSS indices is investigated in the joint energy and reserve market clearing problem. Wind uncertainty is characterized by two measures, namely wind penetration level and wind forecasting accuracy level. The wind penetration levels are modeled as a fraction of a basic wind power value while various forecasting accuracy levels are modeled by normal probability distribution function with different variances. The problem is investigated and results are analyzed under different levels of the wind penetration and forecasting accuracies. Based on obtained results, the value of the EVPI metric increases with increment of the wind penetration level or forecasting error variance. Also, because of the higher uncertainty level of the wind power arising from penetration level or variance increment, the value of the VSS metric increases.