Research and Application of Medium Voltage Drive System in Multi-stand Hot Continuous Rolling Finishing Mill

Abstract

Main drive system of multi-stand hot continuous rolling finishing mill has the characteristics of rapid loading and unloading, frequent acceleration and deceleration, multi-stand coupling and mutual interference, and has high requirements for the performance and reliability of frequency converter. Traditional drive system has some problems, such as complex transformer structure, high harmonic content in power grid measurement, slow motor control response, motor torsional vibration and so on. According to the application characteristics of multi-stand hot continuous rolling finishing mill, this paper proposes a high performance drive system solution. Compared with the traditional system, the proposed system has the advantages of unified circuit, low harmonic content in grid side, fast motor speed response, active suppression of motor torsional vibration and so on. It mainly introduces the main circuit scheme of the mill main drive system, the control principle of the grid side converter, and the vector control principle of the motor. Causes of torsional vibration are analyzed, and the suppression method of motor torsional vibration is introduced. The scheme has been verified by digital simulation and field performance evaluation. Experimental results show that the proposed main drive system has superior dynamic and steady-state performances, the voltage harmonic content is less than 4%, the motor torque can respond to the sudden change of load, multiple motors can work stably, and the transmission system can fully meet the requirements of field hot continuous rolling process.

Keywords

• main drive of rolling mill
• continuous rolling mill
• harmonics
• notch filter
• load observer
• torsional vibration