Study Of Low Voltage Reactive Power Compensation For Submerged Arc Furnace Based On PLC

Contraposing the problem that the power factor of submerged arc furnaces is generallylow in domestic refining industry, we develop a test control system of low voltage reactivepower compensation for submerged arc furnace based on PLC and HMI. The system achievesthe automatic control of reactive power compensation with shunt capacitors and improves thepower factor of submerged arc furnace.First this article analyzes the problem brought by low power factor in a submerged arcfurnace smelting process and clarifies the significance of reactive power compensation for asubmerged arc furnace. Then it compares the advantages and disadvantages of the existingreactive power compensation devices. On this basis, it advances the general scheme of thesubmerged arc furnace low voltage reactive power compensation control system contraposingthe characteristics of low-voltage and high-current. Finally it completes the design of systemhardware, system software and system debugging.The system hardware design is divided into three parts: the power part, the control partand the monitoring part. The power part use two AC voltage regulators to provide a stablepower supply to the control cabinet and the capacitor cabinet and intelligent voltmeter tomonitor the output voltage of voltage regulators. PLC is the master controller of the system, itcollects data from instruments and controls capacitors switching. HMI completes manyfunctions such as the power parameters display, the system parameters settings, and manualcontrol. The monitoring part consists of smart thermometers and temperature sensors,monitors the cooling water temperature of the copper pipe wire. If the temperature is too high,the system will trigger emergency stop to protect the system.System software design is divided into software design of PLC and software design ofHMI. PLC software completes the functions such as communication with the instruments tocollect the data of each instrument and automatic control of capacitors switching. The PLCprogram can also receive HMI control commands to manually switch capacitors and trigger emergency stop. HMI program includes three types of interface: data display interface,control interface and parameters settings interface. The data display interface displays thepower parameters in numerical and graphical way, facilitates staffs to view. The controlinterface completes many functions such as manual capacitors switching, system manual/automatic mode switching and triggering emergency stop. The parameters settings interfacewill write automatic control parameters to PLC data registers through the serial data line, asthe basis for the PLC automatic control.After completion the design of the system, three main functions of the system: powerdata collection, manual control and automatic control were tested. The results showed that thecontrol system meets the design requirements and runs stably and reliably. At present thesystem has been delivered to users.