Application of a Self-tuning Regulator to a Solar Power Plant

Abstract

This paper presents an application of a self-tuning regulator to the distributed collector field of a solar power plant. The distributed collector field consists of a series of parabolic mirrors that reflect solar radiation on a pipe where oil gets heated while circulating. The purpose of the regulator is to maintain the oil outlet temperature as near as possible to a desired level. This is accomplished by varying the flow of the fluid through the field. The field exhibits a variable delay time that depends on the control variable (flow). The transfer function of the process varies with factors such as irradiance level, mirrors reflectance and oil inlet temperature. The self-tuning regulator uses an identifier with a variable forgetting factor and an adaptive PI controller. The paper also describes the heuristic used to make the regulator work an the experiences obtained at the SSPS solar plant of Almeria (Spain).