Electricity And Voltage Decoupling Method Study And Control System Design For DC Ladle Furnace

The ladle furnace is the most popular refine way in the domestic and foreign. The ladle furnace usually uses the three phase AC arc to heat. Along with the development of the DC arc furnace technology, the ladle furnace also uses DC arc to heat, and has the various merits, has the enormous superiority in particular in the fire-proof material consumption index aspect. This project uses single bar bottom positive electrode, which takes a graphite electrode in the slag level that has the certain resistance, maintains the certain distance between the graphite negative electrodes and the metal molten bath. When DC voltage is added to the electrode, the negative electrode produces the electric arc. The DC constitutes loop through the electrode, the electric arc and the electricity slag, to achieve the goal to heat up the molten steel.This article aim at some Iron & Steel Corporation Steel Corporation group technology center pilot plant newly built project of 2t DC ladle furnace system, design distributed computer control system which is based on the PROFIBUS-DP. It controls the entire smelting process by using Siemens S7-300 and ET200S series PLC. Using Siemens's WinCC configuration software, to complete monitoring software configuration, to realizes the field data real-time recorded and the monitoring. Having designed smelting time, recording inquiry, read-write parameter and so on. Those have the dynamic operation picture of the Windows style.In the ladle furnace, heating speed and the temperature of the molten steel completely lie on the electricity control system and the DC voltage control system. The electricity control is plying by the rise and fall speed and the infixed depth of graphite electrode. The voltage control is plying by the output voltage regulation on the DC power supply. But the infixed depth of graphite electrode make effect on the electricity, at the same time it also influenced the voltage. So it made great coupling. The thesis aim at the bad control impact made by the voltage and the electricity coupling in the DC ladle furnace, take into account the characters of the ladle furnace:non-linear, time-variation, inaccurate mathematic model. Design one kind of PID neural network decoupling controller. It combined the conventional PID method and the neural network, decoupling the electricity and the voltage of the ladle furnace, accordingly to have good dynamic and static characteristic, meet the control demand.