Research On Long-term Drive Control Technology Of Synchronous Reluctance Submersible Motor

The development of the petroleum industry is inseparable from the advancement of the control technology of downhole submersible motors.In recent years,in order to enable downhole submersible motors to work in the best condition at any time,to achieve energy conservation and consumption reduction,and to extend the life of the motor,frequency conversion speed regulation technology has begun to be extensive It is used in the field of driving control of submersible oil motors.As a new type of motor,synchronous reluctance motor has the advantages of simple and reliable structure,low cost and high efficiency,and it has gradually become a popular choice for submersible motors.Therefore,it is of great significance to study the long-term drive control system of downhole synchronous reluctance submersible motor.This paper proposes and studies a long-term drive control system for synchronous reluctance submersible motors based on a low-topology(low-voltage inverter + step-up transformer)structure.The system is mainly composed of a low-voltage inverter,a sine wave filter,a step-up transformer,and a long-line cable.It is composed of a synchronous reluctance submersible motor located downhole,and the research work focuses on the design of key equipment and the selection control,position sensorless control strategy and low-speed switching control between different control strategies.First,the structural characteristics and operating principles of the synchronous reluctance motor are analyzed,and a mathematical model is established.According to the actual situation of the subject,the influence of the system equipment on the motor control is analyzed,the long-line cable is simplified into an equivalent circuit,and the system is designed by engineering methods.In the parameters of the medium filter,I / F open-loop control is selected as the motor starting and low-speed control method of the synchronous reluctance motor.After studying the influence of the step-up transformer in the system,the improved I / F control method is used to prevent the transformer from being in the motor.Magnetic saturation occurs during the starting process,and a frequency stable closed loop based on instantaneous active power feedback is used to reduce the impact of load disturbance during the I / F open-loop starting process.Secondly,in the study of the switching process from synchronous reluctance motor open-loop I / F control mode to vector control mode,this paper introduces a dual dq coordinate system switching mode to instantaneously switch between the two control modes,which is different from the traditional Compared with the switching method of this method,this method ensures a stable and smooth switching process,at the same time,the switching speed is faster and the ability to resist load interference is stronger.Finally,a simulation model of a low-voltage inverter and a step-up transformer driven underground synchronous reluctance motor is built under MATLAB / Simulink environment,and it is verified that the improved I / F control method can prevent the saturation phenomenon of the transformer when the motor is open-loop starting,and The control switching method based on the double dq coordinate system is simulated to verify the feasibility and effectiveness of the switching scheme.