The pumping unit is the main equipment in the current oil production, the number of which is more than 100,000. The total installed capacity of the electric motor is 35 million KW, and the annual power consumption is more than 10 billion kWh. The electricity consumption of the pumping unit accounts for about 40% of the total electricity consumption of the oil field, and the operation efficiency is very low, the average operation efficiency is only 25%, the power factor is low, and the electric energy waste is large. Therefore, the energy-saving potential of pumping units is huge, and the petroleum industry is also a key industry for promoting "energy-saving of motor systems". By using the D71 frequency converter, the motion law of the pumping unit can be adapted to the changing working conditions of the oil well, so as to improve the system efficiency and achieve the purpose of energy saving and production increase.