Precise Determination of Power-Off Time of Intermittent Supply Technology Based on Fuzzy Control for Energy Saving of Beam Pumping Motor Systems

Abstract

Beam pumping motors undergo heavy and light loads as well as motor and generator modes during a running cycle. The intermittent supply control technology can achieve significant energy saving in such a motor system. However, due to the vibration of the mechanical transmission link and the dynamic liquid level in oil wells, it is difficult to determine the power-off time precisely. This paper proposes a power-off time determination method based on fuzzy control strategy. The method first determines the operation parameters, such as the load changing rates and the durations of motor and generator modes. Then the optimal scheme of intermittent supply control is selected according to the identified parameters. Finally, the fuzzy controller is established with the speed variation after the power-off set as the input, and the cumulative power value set as the output. The power-off time is corrected by comparing the output variable with the cumulative power value obtained by real-time identification. In addition, the controller can automatically track the dynamic load by correcting the identification results of input power curve. The energy saving device is developed and applied to oilfields. The tests show that the energy saving ratio reaches 15% without reducing oil yields.