Design and analysis of a distributed control system for a multi-bowl solar power plant

Abstract

The Cnosbyton Solar Power Project has proposed a design for a solar-fossil hybrid electric power plant. The proposed plant will utilize ten hemispherical solar collections and a fossil boiler to produce 5 MWe on a steady basis. Before the final design for this plant can be made, detailed operational procedures must be defined. This study investigates the development of a control algorithm for the multi-bowl plant by the use of a computer simulation.

The first objective was to develop a one bowl simulation model. The one bowl model simulates the exit temperature given the solar insolation, the temperature setpoint, and the pressure setpoint. The one bowl simulation model was tested with data from July 5, 1980. The rms error between the simulated exit temperature and the actual exit temperature was 6.2% of the temperature setpoint.

The one bowl model was then incorporated into a multi-bowl model. For an N-bowl system there is one master controller and N-1 slave controllers. The master controller consists of the one bowl model, the economic model, and the master communication software. The economic model is used to determine the appropriate temperature and pressure setpoints for each bowl based on economic and environmental conditions. The slave controllers each consist of the one bowl model integrated with the appropriate slave communication software. A three bowl system was simulated, but the results can be extrapolated to a system with any number of bowls. Three computers were used, instead of one, so that the simulation could be executed in parallel. The multi-bowl simulation showed that a distributed control system would be ideal for the proposed power plant. Also, the simulation showed that this type of control strategy is flexible and can be easily expanded on modified.