A Parameter Optimization Simulation Method for Crank Torque of Double Horse Head Pumping Unit Dynamics Model with Cable

Abstract

Background: Patents revealed that Double Horse Head (DHH) pumping unit is one of the improved models developed from the conventional units, and some unbalanced crank torque may cause high cycle alternating stress which can lead to cracking failure in some key components. This makes the research on simulation of crank torque in beam pumping units a more interesting topic in its maintenance operation. Objective: This paper aims to improve the accuracy of crank torque simulation model for the DHH pumping unit by a parameter optimization method for cable joints. Methods: By using a series of cylinders to model the steel cable, a pumping unit multibody dynamics model was constructed to simulate the crank torque. Then the stiffness and damping coefficient in bushing joint and contact force of cable were treated as the key factors, and a Genetic Algorithms based the method was proposed to optimize them for improving the simulation accuracy of the model. Results: This method was applied to simulate the crank torque of a DHH pumping unit, and the experimental torque was also tested from real unit. Results show that the crank torque simulated from improved model is much closer to the experimental tested torque compared with the original model. Conclusion: The parameter optimization method proposed in this paper greatly improved the accuracy of simulated crank torque in DHH pumping unit multibody dynamics model. Keywords: Double horse head pumping unit, crank torque, genetic algorithms, stiffness and damping coefficient, bushing joint, contact force.