| At present, beam pumping unit is the widely used in the most of the oilfield, it has a simple structure, high reliability, easy manufacture and convenient maintenance, and this feature make it become the preferred oil production equipment, but its low efficiency and the problem of large energy consumption is the limitations in oilfield production level of ascension. The number of beam pumping unit in domestic oilfield is numerous, but the operation of the pumping unit efficiency is very low in fact, and it has a big gap with foreign in this aspect. As is known to all of us, energy saving production is an important way of oilfield sustainable development, if we can enhance the overall efficiency of the pumping system, the power saving of space will be very big every year, and it’s meaningful for the oilfield to mining cost and improve economic. In order to improve the overall efficiency of pumping system, this article using a new switched reluctance motor which has an excellent comprehensive performance replace the traditional one. The retrofit scheme not only has great feasibility and promotion space but also is more affordable for improving the efficiency of the pumping system.The research object of this paper is CYJY12-4.8 type pumping unit, using the designed 45 KW three-phase(6/4) switched reluctance motor as its driver. The essence reason why the pumping system inefficient is that the volatility of periodic load don’t match the general motor which is designed and manufactured at constant load According to the principle of beam pumping unit, the load characteristic is similar to sinusoidal waveform figure. At first, the pumping unit will be influenced by an expansion cycle alternating load, and it has an impact on drive motor efficiency under the rated load. The way of direct load startup requires the motor has a higher starting torque. Rush time reasonable adjustment also has certain influence to improve the oilfield production. Cost, stability and loss of the motor must also be considered when choosing the motor. And the switched reluctance motor is a good comprehensive properties of new one, it has some characteristics such as simple structure, high reliability, low cost, good startup and so on, and it can adapt to frequent start. It can maintain the characteristics of high efficiency and also satisfy the pumping speed stepless regulation of many virtues and exert its advantages in energy saving reconstruction.The overall efficiency of pumping system is the data which the pumping unit transmission efficiency multiplied the motor running efficiency.Therefore, the paper analysis the load characteristics, mechanical conditions and switched reluctance motor control mode. Especially analyzed the working principle of pumping unit and the load characteristics, switched reluctance motor control strategy and their matching problem. Make a mechanics analysis to the pumping unit and then we got the load characteristics of pumping unit. Designed a switched reluctance motor matching the power of CYJY12-4.8 type with a 45kw three-phase(6/4) according to the amount of three-phase asynchronous motor and its own characteristics. Establish the two dimensional motor model and analysis the static magnetic field with ANSOFT, then we obtain the motor flux, the inductance of the static magnetic field and torque angle of characteristic curve, provide a precise value to establish a 45kw three-phase(6/4) switched reluctance motor model. Completing the task of building the mathematical model of the pumping unit and the power matching model of the switched reluctance motor.Although switched reluctance motor has excellent comprehensive properties and u-nique advantages, but the torque ripple is a very prominent SRM shortcomings, not only have serious effects on motor performance and pumping unit efficiency, thus the overal 1 efficiency of the pumping system will have a huge impact. And the traditional position, current chopping control and voltage control methods all have their own limitations and unable to suppress the effect of the torque ripple of motor. Then it is significant particularly important to suppress the torque ripple in the aspects of motor control strategy. Build the mathematical model of CYJY12-4.8 type pumping unit and 45kw three-phase (6/4) encapsulating module of switched reluctance motor, using the strategy of direct torque control (DTC) to set up a simulation model include the pumping unit match the switched reluctance motor pumping. The result shows that the motor torque ripple is suppressed very well and the motor running more smoothly under the control of the DTC strategy, it has a faster response time than the traditional control method in aspect of motor speed, and also can achieve stability in a very short time with small fluctuations. According to the above analysis, the matching simulation of pumping unit and switched reluctance motor through the direct torque control can suppresses the torque ripple effectively,make the motor run more smoothly and more matching with pumping unit. To reducing the electromagnetic torque for saving energy. It is great significance for the oilfield sustainable development. |
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