Study On Pumping Unit Variable Frequency Adaptive System Based On PLC

The oil resources in our country has get into the development of middle and late stages,the average load efficiency of oil pumping unit motor drive is low in the exploitation, it has brought the huge waste of energy. Development of adaptive frequency conversion technology makes the beam pumping unit has better performance of oil pumping. This technology can increase production, reduce production costs and improve economic efficiency, it is the mainstream and direction of development of the oil pumping. Therefore,this article study the a beam pumping unit variable frequency energy saving control system in the laboratory environment.In order to grasp the real-time oil pumping machine in the production process of load and the motor frequency, the key parameters of adaptive system-- load frequency must be changed and measured. It has important significance to improve the production rate and energy saving through determinating the load operation frequency accurate in the real time and changing linear according to the frequency changes.this paper is based on the characteristics that the motor frequency along with the change of load, a new method based on frequency conversion and energy saving is proposed, this method also provides a new way of energy saving pumping unit production. It reveals the response law of pumping unit motor frequency and load of pumping units through designing and optimizing the pumping oil machine frequency conversion system structure, multiple load frequency test and system of electric motor of pumping unit and the frequency of pumping unit load relationship. With the increasing of the load of pumping unit motor frequency and the measured data to verify, the corresponding frequency value has been got. One can provide theoretical guidance by being familiar with motor frequency change rules in order to fully understand the characteristics of pumping unit load, optimizing of mining scheme and improving energy efficiency, this theoretical guidance has laid a theoretical foundation for the application to the new energy saving system.according to the function and performance index which the system achieve the conversion, adaptive control system use the SIEMENS S7-300 processor as the core,the pumping unit model is object that is controlled, it controls inverter according to the load situation, adjust the speed of motor and acquisition of signal is done by the photoelectric encoder and the load sensor. The signal is feedbacked to the PLC, the closed-loop adaptive control system is constructed finally, the pumping unit motor frequency control of motor speed is realized, the trend with the load frequency value is reflected.From the results of laboratory test, pumping unit variable frequency adaptive system has been designed to achieve real-time feedback of the motor frequency measurement. The measurement results show that the frequency changes along with increasing of the load motor,combined with fuzzy PID control, the frequency is stability, the error in the process of measurement is 1%, the measurement system is stable and reliable, high precision, it can meet the pumping unit variable frequency adaptive measurement requirements.