Energy optimization of control loops for concentrated solar plants with the design of experiments

Heliostat fields for concentrated solar plants can be very large as the number of heliostats can reach several hundreds. All day long they follow the sun thanks to electric motors supplied by power electronics, generally through long underground cables across the field. This classical solution can lead to high costs due to trenches and long cables. An innovative solution has been proposed in the recent years with the concept of autonomous heliostats supplied by a photovoltaic panel and batteries. This paper describes a specific switching system that enables the use of a single chopper instead of two and a method for tuning the parameters of the position and speed controllers in order to minimize the global consumption of the heliostat. DoE (Design of Experiments) helps to tune the controllers through several factors and a specific attention is paid to way to fix the factor levels. The significance of the resulting factor effects are tested through the ANOVA (analysis of variance). The final objective is to reduce as much as possible the size of the battery and the solar panel.