Ali Reza Rajabi - Master’s Degree in Mechanical engineering
Morteza Mohammadi Ardehali - PhD, PE Power and Energy Management Department, Amirkabir University of Technology, Tehran, Iran

In this considered solar heating system (SHS), the Performance index, which should be minimized, includes Cost of comfort index and Cost of auxiliary energy index. On the other hand, the state vector of the system is affected by some disturbances such as absorbed solar energy and temperature of environment. In this state, optimal control theory seems appropriate for controlling SHS under given performance index.The objectives of this study include: ۱- Study of dynamic modeling of the SHS, ۲-Design the controllers, On-Off, PID and LQR (Linear quadratic regulator) in order to find the optimized parameters for each System-Controller combination using MATLAB-Simulink ۳- Comparison between their performances.The results indicate, the saving of auxiliary energy using the PID and LQR are ۸% and ۹.۱%, respectively compared with On-Off. Since On-Off controllers are very popular in SHS, so in case of using LQR, there is a reasonable potential not only for reducing consumption of auxiliary energy but also to manage the SHS to desire path.

Solar heating system, Performance index, Linear quadratic optimal control