Research On Sensorless Speed Detection In Electrical Submersible Pump

Electric submersible pump technology in oil field operations is dominant in the world and its reliability and capability is important to assure the high yield of the oil field. The proposed of this paper is to get a simple method of the sensorless speed detection by analyzing some methods and some conditions. The background of this paper is oil pumping equipment-electrical submersible pump in the Dagang Oil Field.Considering the operation environment of the electrical submersible pump, the cost and reliability advantages of eliminating mechanical sensors and cabling for the measurement has led to development of methods commonly termed "sensorless" or "self-sensing" control. The mothed based on high frequency injection can be geted by the analysis of some information about speed detection in motor. Everyone knows that the rotor of submersible motor has many blocks, now we can take one block of rotor and change it's winding in order to achieve yielding saliencies. Owing to some saliencies, we can get a quasi-continuous rotor speed signal by injecting a high-frequency flux wave into the stator. The research can be divided into two parts. The first is to get a simulation model of induction motor with some saliencies on the basis of the Park equation and change to a library model, which makes the simulation of induction motor easy, modularize and universal. Owing to the variable rotor leakage inductance between the q-axis and d-axis, a quasi-continuous rotor speed signal can be acquired by injecting a high-frequency flux wave into the stator. This method enhances the ability of protection for motor and improves the performance of transducerless submersible motor drives, especially for low-speed operation. The second is to realize the system by modern DSP technology. The simulink model of speed detection system can be converted to VHDL (Very High Speed Integrated Circuit Hardware Description Language) form by using Dspbuilder.The results of simulation confirm the validity of this simple method of the sensorless speed detection. It has accurate and high dynamic speed information without sensor at very low speed, which is important for Electrical Submersible Pump. In addition, the author explains the shortcomings and requisite amelioration of the system, on which the author should undertake further research and improvement in the future.