Research On Venturi Tube Frequency Conversion And Voltage Regulation Control System Based On PLC

Venturi tube is widely used in petrochemical,electric power and nuclear industries because of its simple device,durability and good performance of steady cavitation flow.Domestic Venturi tubes are difficult to meet the requirements for accuracy because of high cost and limited manufacturing technology.Moreover,there is a lack of mature theoretical and experimental verification in the design and application of nuclear-power-grade Venturi tubes.The steady flow performance of Venturi tube is generally measured by fitting the data obtained by controlling its inlet pressure into the flow characteristic curve.However,the inlet pressure of Venturi tube for nuclear power is as high as 22 MPa.It is difficult to adjust the pressure under high pressure,and it is difficult to obtain accurate venturi tube flow characteristic curve.In view of the above problems,this paper designs the Venturi tube frequency conversion and voltage regulation control system based on PLC.In this paper,by controlling the inlet pressure of the test pipeline to rise uniformly at the set speed,the approximate linear boost is achieved.To achieve the goal of uniform pressure regulation,it is necessary to analyze the relationship between pressure change rate and pipe resistance and frequency because there is a non-linear relationship between pump and pipe network.This paper studies the structure,linear boost principle and fuzzy PID control algorithm of variable frequency and voltage regulation control system based on the theory of constant voltage and frequency conversion,compiles the program of frequency conversion and voltage regulation control by TIA portal with the programmable logic controller(PLC)as the core controller,and establishes the system monitoring interface based on the study of the hardware and software of the control system.A fuzzy PID control algorithm is composed of fuzzy control and conventional PID in the system,and the tracking effect of the system on pressure change rate is verified by the established mathematical model and simulation model.The flow characteristic curve of the Venturi tube is fitted by the collected data,which can detect the cavitation flow stability of Venturi tube better.A fuzzy PID combining the advantages of both the fuzzy algorithm and the PID algorithm is applied in frequency and voltage regulating control system by simulation,the output frequency of the frequency converter can be dynamically adjusted,which can well adapt to the non-linear,time-varying and inertial pressure control system,enhance the robustness and reduce the steady-state error of the system,and finally realize the tracking of different pressure change rates.The research results provide a theoretical basis for the application and design of Venturi tubes in related fields,and have a big theoretical reference value and practical engineering significance.