负载力矩对旋转阀转速的影响分析及转速控制研究

旋转阀的转速控制关系到钻井液压力信号的产生。旋转阀负载力矩随旋转角的变化规律是影响转速控制的关键。根据旋转阀转子的受力情况分析了旋转阀负载力矩的组成及影响因素。通过理论分析结合计算流体力学(CFD)仿真分析建立了负载力矩的计算模型。研究表明,旋转阀负载力矩随旋转角呈严重的非线性变化,负载力矩与钻井液流量的平方有关,与钻井液密度呈线性关系,与钻井液黏度无关。负载力矩的非线性特性对旋转阀转速产生严重影响。基于负载力矩的计算模型,采用负载力矩的前馈补偿进行旋转阀转速控制系统的线性化校正,通过转速负反馈形成PID(比例-积分-微分)闭环实现旋转阀转速的快速随动控制。MATLAB/Simulink仿真结果表明,旋转阀转速闭环控制系统具有快速跟随调相脉冲变化的能力;同时对流量测量误差及负载力矩计算模型偏差产生的干扰影响具有较强的抑制作用,可以满足对32 Hz的压力载波进行相移键控(PSK)调制,实现16 bit/s的数据传输速率。

Analysis of influence of load torque on speed of rotary valve and research on speed control

The speed control of rotary valve is related to generation of the drilling fluid pressure signals. The changing rule of the load torque of the rotary valve with rotation angle is the key to the speed control. According to the force of the rotary valve rotor, the composition and influencing factors of the load torque are analyzed. The calculation model of the load torque is established by theoretical analysis and computational fluid dynamics (CFD) simulation. The calculation model reflects the influence of drilling fluid flow and density on the load torque. The results show that the load torque of the rotary valve varies non-linearly with the rotation angle, and the load torque is related to the square of the drilling fluid flow, which is linear with the drilling fluid density, which is independent of the viscosity of the drilling fluid. The nonlinear characteristic of the load torque seriously affects the rotation speed of the rotary valve. Based on the load torque calculation model, the linearization correction of the speed control system is carried out by the feedforward compensation of the load torque. The rapid follow-up control of the rotary valve speed is realized by forming the proportional-integral-differential (PID) closed-loop by the negative feedback of the speed. The simulation results of Matlab/Simulink show that the rotation speed closed-loop control system has the ability to follow the change of the phase-shifting voltage pulse quickly, and has a strong inhibitory effect on the interference caused by the flow measurement error and the load torque calculation model deviation, It can meet the 32Hz pressure carrier phase shift keying (PSK) modulation, to achieve 16bit/s data transfer rate.