Accuracy assessment of the long-term hydro simulation model used in Brazil based on post-operation data

In the last two decades, the hydro-dominant Brazilian Power System (BPS) has been facing critical situations such as the rationing of 20% of the load during 2001/2002, and some spikes on spot market prices reaching the price cap as occurred in January 2008 and all over the years 2014 and 2015. Since the BPS is planned for a 5% risk of load shortage, the reason for these successive difficulties could be the lack of accuracy of the hydro simulation model in use for long-term operation planning studies. This paper presents a procedure for assessing the accuracy of the hydro simulation model used in the BPS based on post-operation data of the hydro plants. The procedure is based on the attempt to reproduce the verified operation over long periods of time using the water balance equations and the hydro power output functions adopted by the hydro simulation model. A case study with two hydro plants in cascade located in the São Francisco River, in the Northeast region of Brazil, has been performed. The results indicate that the simulation model in use in Brazil may be overestimating in more than 3% the hydro power output of the considered plants.