Design Of Control System And Research On Control Method For Electroslag Furnace Based On The Power Supply Of The Scott Transformer

Electroslag furnace which is based on the electroslag remelting technique is a kind of extensive applied smelting-equipment in the province of special metallurgy. Considering the power equipment is complex, actual requirements and equipment investment, most of the electroslag furnace use single-phase ac power supply currently. This method is simple in design, less in investment, but if the former level of power load capacity and single-phase load capacity are close, it must bring the problem of unbalanced three-phase to the first winding of transformer. If the problem is serious, the loss of transformer will be increased even broken, and it can reduce allowable volume, and it will make three-phase output voltage unbalance. So it needs enough electric capacity, or forming large-scale production. If not it will bring the problem of unbalanced three-phase seriously. For the small scale and capacity How to solve the power of three-phase equilibrium is an urgent problem.According to the properties of Electroslag furnace, the thesis choose the Scott transformer that is low voltage and high current to be the power supply. According to the theorem of Scott transformer, it can realize three-phase equilibrium when the current of transformer secondary side is size of the equivalent and phase difference of90degrees. According to the different composition of power supply circuit, it how to ensure the power system is always meeting the three phase control method in the smelting process is studied and discussed.The background of the thesis is the20+20-Ton switching electroslag furnace computer automatic control system in steel mill. According to the rapid industrial growth and requests of increasingly precise control accuracy, the paper developes a two-grade computer control system based on superior computer and PLC controller.The redundant hardware configuration on inferior computer is based on S7-300of SIEMENS Corporation. It controls the entire smelting process by adopting STEP7Programming software. By using WinCC configuration software in redundant operator station, to complete designing monitoring program, which realizes the field data real-time recorded, storage,and printing the monitoring, and provides real-time tracking curves of processing parameters.