Study On Optimal Control Of The Underground Water Source Heat Pump Air-conditioning System

The Underground water source heat pump air-conditioning system is an advanced,highly efficient, energy-saving, environmental air-conditioning system. It is a way touse the renewable geothermal resource. Facing an increasingly serious environmentalproblems and energy shortage crisis currently, reasonable and efficient utilization ofgeothermal resources is an effective way to solve the environmental and energy issues.However,because the ground water source heat pump air-conditioning system has thecharacter of time-varying, nonlinear, and delay, etc, in practical application，the controleffect of conventional control strategy is not so good and the energy saving effect is notobvious.The paper is based on a underground water source heat pump air-conditioningsystem in Yangling, Shaanxi Province, and has a research on the optimal control of thesystem. Firstly, it introduces the basic principles, structure,characteristics, control modeand variable flow control technology of the ground water source heat pumpair-conditioning system.Then, And then collect some related data of the ground watersource heat pump air-conditioning system, use System Identification Toolbox ofMATLAB and least-square method to establish a mathematic model between frequencyconversion status of the water pump in deep well and supply and return cooling watertemperature difference, providing the basis for the system simulation.Secondly, aiming to the current situation that conventional PID is powerless to thetime-varying, nonlinear, and delay object, combine with the characteristics of fuzzycontrol and neural network, and then use the adaptive fuzzy PID which is thecombination of Conventional PID and fuzzy control and the Neural Network PID whichis the combination of Conventional PID and BP neural network. So, it can exert the superiority of fuzzy control and neural network, and achieve to the parametersself-adjustment.Finally, it designs a conventional PID controller, an adaptive fuzzy PIDcontroller and a PID controller based on BP neural network, and simulates the systemwith those three controllers.The simulation results show that adaptive fuzzy PID and neural network PID havea great advantage in improving the dynamic characteristic and steady-state performance.So it can be used as a good strategy of optimal control of the underground water sourceheat pump air-conditioning system.