Model-Based Intelligent Control of a Solar Energy Collector Field

Solar power plants should collect any available thermal energy in a usable form at the desired temperature range. Efficient operation requires a fast start-up and reliable operation in varying cloudy conditions without unnecessary shutdowns and start-ups. Fast and well damped linguistic equation (LE) controllers have been tested in Spain at a collector field, which uses parabolic-trough collectors to supply thermal energy in form of hot oil to an electricity generation system or a multi-effect desalination plant. Control is achieved by means of varying the flow pumped through the pipes in the field during the operation. Solar energy can be collected only when the irradiation is high enough. The nights and the heavy cloud periods need to come up with the storage. The LE controllers extend the operation to varying cloudy conditions by using predefined model-based techniques and activating special features to react well to operation requirements and disturbances. The latest test campaign focused on achieving a smooth operation in changing operating conditions. Fast start-up, smooth operation and efficient energy collection is achieved even in challenging situations: cloudy conditions and load disturbances are handled efficiently. A trade-off of the temperature and the flow is based on model-based optimisation to achieve a good level for the collected power. The working point is chosen in a way which improves the efficiency of the energy collection and problematic operating conditions are removed by limiting the acceptable range of the working point.