Probabilistic Capacity Value of a Hydroelectric Plant for Different Storage Capacity Levels

Abstract

This paper presents a sensitivity analysis on the reliability of a hydroelectric plant with reservoir with respect to its storage capacity level. The comparison is made in probabilistic terms, using the sequential Monte Carlo simulation, which takes into account equipment failures, hydrological inflow scenarios and a load curve. The reliability evaluation was carried out for a generation system composed of just one hydro power plant supplying its respective load, considering five hypotheses of its storage capacity. In addition to the traditional reliability indices, it was also computed a reliability indicator, denoted by P95, which can be used as the “capacity value” to be issued to the hydro plant for commercial purposes. The analysis of the resulting annual reliability indexes shows the impact of reducing the storage capacity not only on the plant's “firm energy” but also on its capacity value attribute. Moreover, for all storage levels considered, the monthly values of P95 presented significant seasonal variation, which further confirms the importance of storage capacity or “regulating capacity” to ensure system reliability all over the year.