Robust Control of a Central Heating System Using a Cascade Controller Based on Quantitative Feedback Theory

Abstract

A central heating system comprises of an arrangement of water pipes and boilers, sole purpose of which is to adjust and maintain the room temperature of a particular enclosure. The system stability and robust performance objectives can be achieved using a cascaded control system structure where the inner loop and equivalent loop controllers are meant to control the mixed water temperature and the room temperature respectively and are designed on the basis of the Quantitative Feedback Theory (QFT). The controllers designed using this framework ensure the robustness of the system. In this paper, designing the controllers and pre-filter is carried out using the QFT toolbox. Simulation is undertaken for 300 plants within the parametric uncertainty ranges and results obtained verify the performance of the system.