Effective Tuning of Cascaded Control Loops for Nonlinear HVAC Systems
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© 2015 by ASME. Residential and commercial buildings are large consumers of energy in the United States with Heating, Ventilation, and Air- Conditioning (HVAC) systems representing a significant portion of total use. These systems control aspects such as humidity and room air temperature to ensure building occupant comfort. Control of HVAC units presents unique challenges due to large nonlinearities heavily dependent on operating conditions. Static linear controllers are unable to counteract such nonlinearities resulting in sustained oscillations known as hunting behavior. Previous research has shown the ability of cascaded architectures to compensate for HVAC nonlinearities and improve overall system performance without the need for detailed dynamic models. To aid the implementation of cascaded loops on real building systems, analysis of the effects of inner loop gain are presented and three outer loop tuning cases are identified. A simulation case study of an air handling unit demonstrates the simplicity of the procedure and compares it with optimally tuned gains.
author list (cited authors)
Price, C. R., & Rasmussen, B. P.