Steam generation control in Solar Invictus 53S - A parabolic dish solar collector for direct steam generation

This paper presents a control methodology for steam generation at desired steam outlet conditions for the Solar Invictus 53S System. The system consists of a parabolic solar dish with an effective projected area of 51.6 m2 and a cavity type receiver which works as Once Through direct Solar Steam Generator (OTSSG). The challenge is to control the feedwater mass flow rate precisely in order to maintain the steam generation at desired steam conditions at the outlet of OTSSG. The controller must be robust to incorporate the varying external conditions like Direct Normal Irradiance (DNI), ambient temperature, soiling and wind speed. This paper formulates the control problem and presents a solution using two cascaded loops. In the first loop, feed forward mass flow rate to achieve the desired steam conditions is calculated. Feed forward control is implemented to give better disturbance rejection. For the mass flow rate calculated, a feedback loop is applied. The methodology is verified and tested in a simulated environment.