Method and device for optimizing motor rotation speed curve based on variable-speed driving

Abstract

The embodiment of the invention provides a method and a device for optimizing a motor rotation speed curve based on variable-speed driving. The method comprises the following steps: carrying out expansion of Fourier series on the motor rotation speed curve; calculating a suspension point movement rule of an oil pumping unit, a motor torque, rod string stress and a downhole pump indicator diagram under motor variable-speed driving; calculating liquid production capacity under the motor variable-speed driving according to the suspension point movement rule and the downhole pump indicator diagram; designing variable, taking the liquid production capacity, the motor torque and the rod string stress as functions of the variable, building constraint conditions of the liquid production capacity,the motor torque, the rod string stress and the motor rotation speed, taking motor energy consumption as a target function, and setting a convergence condition to generate the optimized motor rotationspeed curve. According to the method and the device for optimizing the motor rotation speed curve based on variable-speed driving, the real-time speed change of one stroke cycle is achieved by building a flexible control strategy; the inherent defects of the oil pumping unit four-rod structure can be overcome, so that the overall comprehensive performance of the system can be improved; the well yield of the oil pumping unit can be ensured; meanwhile, the motor energy consumption can be reduced, and the stress environment of the rod string can be improved.

Description

technical field [0001] The invention relates to the technical field of mechanical oil extraction and energy saving, in particular to a method and device for optimizing the speed curve of a motor based on variable speed drive. Background technique [0002] In the normal state of the pumping unit, the crank rotates at a constant speed, and the speed trajectory of the suspension point is quasi-sinusoidal, so that the motor and the gearbox are subjected to a periodic alternating load during the operation, and the peak torque and alternating load of the motor and the gearbox The amplitude is large, and the rod string bears unbalanced vibration load and inertial load, causing serious impact on the sucker rod string; the running speed of the pump plunger is unevenly distributed, and there is a large speed peak, which leads to problems such as low liquid production and pump efficiency. The variable speed drive of the pumping unit is just to solve this problem. [0003] However, the...

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Problems solved by technology

[0005] In order to solve the problem that the existing variable speed optimization strategy has a simple goal and can only simply realize the smooth operation of the pumping unit, and cannot guarantee the oil well fluid production, which is an important factor, the embodiment of the present invention provides a motor speed based on variable speed drive Curve optimization method and device

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