A Multifunction Energy-Saving Device With a Novel Power-Off Control Strategy for Beam Pumping Motors

Based on the analysis of the load curves taken from more than 300 beam pumping motors (BPMs) in China, a novel power-off control method for BPMs is developed, which enables the oil pumps to work continuously relying solely on the potential energy released during the power-off interval. The main advantages of this are: (1) variation of load curves is monitored by micro-computer in real time, and the control parameters, such as power-off moment and duration, are adjusted automatically; and (2) rapid soft re-switching technology, which is realized by SCR controlled by micro-computer, is developed for re-switching when the power source is needed during the power-off interval, by which the inrushing current is less than the rated one. To further broaden the applications for various beam pumping units, the multifunctional energy-saving device (MESD) is also developed, which uniquely integrates power-off control, wye-delta automatic conversion and auto-reactive power compensation technologies. During the past five years, more than 600 sets of MESDs had been put into use in Daqing oil field and the power saving ratio is in the range of 10-25%.