(40b) Control of a Heating, Ventilation and Air Conditioning (HVAC) System Using Decentralized Extremum Seeking

HVAC equipment are installed in residential, commercial and industrial buildings to meet the temperature requirements that provide maximum comfort for occupants and to maintain satisfactory indoor air quality. In meeting these requirements, a considerable amount of energy is utilized. It was reported that about 37% of the overall energy consumed in the province of Ontario, Canada in 2014 was from the building sector. Improvements in the design of buildings and the monitoring of human activities and behaviours have been suggested as ways to increase energy savings.

HVAC systems are nonlinear, complex and highly integrated. The malfunctioning of any of its components or units can affect its performance and result in energy wastage. The complexity of an HVAC system makes it very challenging to effectively describe it using a mathematical model. Also, with the technological advancement of HVAC equipment, there is a need to use highly effective and efficient control techniques to minimize energy consumption.

This paper looks at the application of decentralized extremum seeking control to heating, ventilation and air conditioning (HVAC) systems in residential, commercial and industrial buildings. The air conditioning system considered comprises two rooftop units that each provide cool air to two zones. The compressor, fan and expansion valve of each rooftop unit are controlled by three inner loop proportional-integral (PI) controllers to meet specified control requirements. The objective is to determine the optimal supply air temperature set-point for each rooftop unit that minimizes the overall power consumption of the units. In addition, each set-point must satisfy the control objectives of the three inner loop PI controllers. To tackle this problem, a decentralized proportional-integral extremum seeking control technique that avoids the need for communication between the units is employed. A simulation result is included to show the effectiveness of this technique.