Research on main circuit and control strategy of the oil fracturing frequency converter

In view of the development trend of high-voltage and high-power oil field fracturing frequency converter, this article analyzes the typical application of oil fracturing conditions and compares the design concepts and ideas of the top domestic manufacturers. Finally, optimized and designed a 7000HP fracturing frequency converter with the highest single pump power, using a high-voltage cascaded main circuit topology structure. A sensorless vector control strategy for high voltage inverter based on carrier phase shift and full order flux state observer is proposed to significantly reduce the output voltage harmonics of the inverter, at the same time, the accurate estimation of motor speed and the accurate control of torque and current are realized to meet the control requirements of various conditions of oilfield fracturing operation, and further improve the oil and gas production efficiency. On the basis of theoretical analysis, the effectiveness of the control strategy is verified by simulation and experiment, reaching the engineering practical level.