Investigating the Effect of a Relay and PID controller on the Performance of a Residential Hydronic Heating System Using a Real-Time Simulation Platform

The need for reductions in cost and in carbon emissions through the use of efficient heating systems is the motivation of this work. Heating systems that use energy efficiently, while maintaining user comfort are important for energy conservation.;The objective of this work is twofold. First, we developed a model-based platform through which advanced thermal system controls could be designed and tested for wide-ranging home heating applications. Secondly, we applied our model-based platform to model and compare the performance of a typical relay controller, to that of an advanced controller. In this work, the advanced controller tested was a Proportional-Integral-Derivative (PID) controller. The model-based platform allowed us to test the hypothesis that the PID controller will outperform the Relay controller. Our results show that in the aspects considered in this work, the PID controller outperforms the relay controller.;The hydronic heating system is the focus of this analysis. In this work, the heating system only provides space-heating to a home, which is idealized as a box with thermal properties that match those of a single-family residential building. A coupled system of ordinary differential equations (ODE's) was developed based on the energy balance principle to model the heating system and space. The resulting plant model based on the coupled ODE's are solved using LabView, a computer software package. On a separate personal computer (PC), the controller for the plant was developed using the Simulink software platform interfaced to the dSPACE hardware. A physical link between the PC housing the plant model and the PC housing the controller is established so that the controller can turn the simulated heating system on and off such as to maintain the home at a desired temperature. This system of separating the plant and the controller facilitates real-time controller design. The real-time system allows for prediction of transient parameters like boiler efficiency and heating system performance. Therefore, this real-time controller model can be a better indicator of controller performance in widely varying situations.;The results of this work show that, in general, the PID controller outperforms the Relay controller in terms of user-comfort and effectiveness at delivering heat to space, and in terms of operating the boiler more efficiently than the relay controller. The specific performance metrics compared are the boiler daily cumulative efficiency and the overall performance of the heating system. The results of the simulation will show a slight improvement in the efficiency of the system. The real-time controller development approach presented in this work may be applied to improve the efficiency of hydronic heating systems powered by microgrids. Real-time platforms such as the one formulated in this work may be useful in developing systems that provide user comfort while maximizing efficiency.