Application Of Three-level Inverter In Main Drive Of Ansteel Rougher Mill

Hot strip mill production line in steel production is the largest, highly technical, and relatively highly invested one. After nearly 30 years of construction, hot strip mill production line in China has made a great leap in quantity and quality. However, the problems are still very prominent. The development of the national economy demands the improvement of the steel in quantity and quality. The equipments of the early production line have a low productivity. The energy consumption does not meet the requirements of the national energy policy. The pollution to the environment is becoming increasingly serious. High-grade quality products can not be produced. Therefore, it is imperative for the iron and steel enterprises to have a large-scale technology reformation for the old production line.This paper makes a research on the problem of upgrading the second stand reversing rougher mill (Rougher mill 2) electric drive systems in the Ansteel 1780mm hot strip mill production line, relying on power electronic converter technology, power transmission technology, automatic control technology, as well as the rolling process automation technology. The upgrade is to achieve through the use of enhance electron injection gate transistor (IEGT) for the power element of the new three-level medium-voltage variable speed system TMdrive-70e2.Firstly, this article summarizes the main drive of hot rolling process requirements, describes the AC-AC frequency control system and AC-DC-AC frequency control system in the practical application of the rolling mill. Secondly, it determines the final technical proposal after analyzing two technical proposals in Ansteel Rougher mill main drive. Thirdly, analysis shows the characteristics of Rougher mill the old inverter MELVEC-3000N and the new inverter TMdrive-70e2. And researches are made on the characteristics of the gate turn-off thyristor (GTO) and an electron injection enhancement gate transistor (IEGT) power components, as well as the similarities and differences of its inverter units. Fourthly, it elaborates the structure and working principle of the three-level inverter and rectifier excitation, introduces the main application of TMdrive-70e2 debugging software, studies the Rougher mill main drive commissioning procedure. Fifthly, it describes in detail the Rougher mill frequency control device renovation process of debugging, analyzes and compares the debugging results. Finally, it summarizes the experience of revamping and debugging of rolling mill main drive, and puts forward some problems of the new equipment that needs to be solved.At present, the frequency control device has been in use. The static and dynamic technical indicators of the system are quite able to meet the requirements of the mill production process. It is running in good condition. The successful application proves that TMdrive-70e2 can completely replace MELVEC-3000N, therefore solves the current big problem in Ansteel hot strip rolling production line. It provides reference for domestic enterprises to upgrade the technology in hot strip rolling production line in the future.