Applications Of Adaptive Control To Water Supply System

This paper deals with the problems in water supply system of constant pressure,where the accurate plant model is difficult to get and the power supplies of the pumpneed to switch. Those problems are resolved by adaptive inverse control, adaptivefuzzy control and synchronous transfer based on phase locking, respectively. The DSPhardware system of constant pressure control is tested on the analog of water supplysystem and the synchronous control of phase locking is simulated in Matlabenvironment. The findings prove the validity of the control strategies that improve theperformance of the water supply system. The model of the water supply system is intrinsic nonlinear and time variant, whichmakes it difficult to linearize the plant and tune the PID controller. Thus thetraditional PID controller cannot adapt to the changes. To tackle this problem, wehave designed an adaptive inverse controller and get high precise control, which canbe seen from the pressure waveforms of the experimental equipment. In this case, therun time states of the plant is achieved by the identification procedure and thisinformation is used to update the parameters of the controller by adaptive algorithmthat makes the controller can feed right control to the plant as the states changed.However, the nonlinear adaptive inverse control uses NARX filter as plant model andcontroller, which makes the computational complexity of the algorithm increase andthe cost of the hardware become high. So we also designed the adaptive fuzzycontroller that has no need to identify the model of the plant. It makes thecomputational complexity decrease, which helps the real time processing, reduce thecost and simplify the implementation. Another issue in water supply system is the parallel operation of multiple pumps.The main problem is, while the pump driven by the VFD is switched to the powerlines, large surge transient currents may be produced by the frequency and phasedifference between the power supply and the counter electromotive force of the motor,which will result in the failure of the automatic switches and the damage of the II摘 要electric equipments. Synchronous transfer based on phase locking is an advancedswitch mode that can reduce the surge transient currents. However, the generalphase-locked loop adopts PI control, which makes the response become slow and theswitch process long. To avoid this problem, this paper employs time optimal controland variable structure control by the reaching low method. The simulation of thecapture process, by Matlab, shows that the variable structure control is superior to PIcontrol both in capture time and steady state performance.