A comparison of two hydro scheduling algorithms, SDDP and LpSim

In this study we present the results of a comparison between the two methods implemented in two hydro scheduling algorithms, SDDP and LpSim. Both methods are carried out for a range of reservoir inflow series and variable load. The yardstick we use for the comparison of the methods is the amount of load each respective program can satisfy while fulfilling restrictions to maximum load shedding and minimum reservoir volumes. Iceland´s isolated power system was selected for this case study. Its electricity production is pre-dominantly hydro (74%), the rest being geothermal (26%) with intermittent thermal generation options (~0.02% in production, 2.4% in installed capacity). The system is not connected with other countries. In January 2013, wind power officially became the third renewable source for electricity in Iceland. In the near future the possibility of a submarine power cable connecting Iceland to mainland Europe may further increase the dynamics of Iceland´s currently isolated power system. If constructed, future power stations in the lower Thjórsá river basin will add more levels to the cascade of hydro plants there, decreasing the accuracy of hydro scheduling algorithms that rely on aggregate reservoir approximations. It is therefore imperative to investigate the performance of the currently used medium- and long-term hydro scheduling algorithm.