Modernization of control systems for main drives of duo reversing mill stand 1000.
Modernization of control systems for main drives of duo reversing mill stand 1000 has been finished. This stand is a part of the hot rolling mill area in the long product rolling plant.
New digital control systems for top and bottom roll drives as well as a redundant set of equipment for control system have been implemented for Siemens DC motors (Pnom = 3500 kW; Unom = 997 V; Iarm_nom/Iarm_max = 3865/10630 A; Nnom/ Nmax = 60/150 rpm).
Digital drive control systems are designed and manufactured by ASC and based on Sinamics DCM control modules (by Siemens).
New control systems are used for Sitor reversing thyristor modules of armature circuits of the top and bottom roll motors. Sitor modules have not been revamped. An existing Sitor reversing thyristor module is dedicated for redundant automatic control system. Control pulses are sent to thyristors through pulse amplifiers designed and manufactured by ASC.
Motor field windings are connected to Sinamics DCM converters. These are digital exciters installed in the cabinets for new automatic control systems including redundant automatic control system. Digital exciters are connected to Sinamics of armature circuits via Sinamics Link.
Similar to analog automatic control system, the following functions are implemented in the digital automatic control system of the top roll: load sharing between rolls; ski formation control; calculation of rotary speed reference for the top and bottom roll motors implemented in the function of rolling speed and roll pass diameter references that are entered into automatic control system from the computer controlling mechanisms of the stand 1000 area.
Two independent (“virtual”) automatic control systems of the top and bottom roll drives are implemented in Sinamics of armature circuit and redundant automatic control system exciter. Redundant automatic control system can be activated instead of automatic control system either of the top or bottom roll by switching motor armature circuits and field windings with power disconnect switch, and on 10 kV side – with disconnect switches of transformers that feed armature circuits. Feedback signals, interlock signals and data signals for mill stand systems that have not been revamped (area control computer, MESSY — fault logging system etc.) are switched by software (digital automatic control systems are fitted with ET200M stations to make it possible). Selection of one “virtual” automatic control system out of two (top / bottom roll) is made in redundant automatic control system by switching groups of parameters of armature circuit and exciter Sinamisc DCM devices.
Main and redundant systems control as well as selection of the top and bottom roll drive circuits (both top and bottom roll can work either with the main or redundant automatic control system) is implemented by Simatic S7 PLC (CPU 3152DP). PLC is installed in the top roll automatic control system cabinet assembly and has individual power supply.
Operating personnel can quickly select drive circuits, carry out monitoring and diagnostics of all three drives from Siemens touch panel 12” TP1200 Comfort series installed on the front panel of the top roll automatic control system cabinet assembly. Operator control console is equipped with 9” TP900 Comfort series touch panel connected to PLC.
New control systems of mill stand 1000 are integrated with the old ones that have not been revamped.
Process data acquisition system ibaPDA has been installed. ibaPDA server is connected to PLC via Industrial Ethernet.
Temperature measurement system for motor armatures of the top and bottom roll has been developed. Data from the system are transferred to PLC and ibaPDA system via wireless gateway IE/WSN-PA Link.
Experience of ASC specialists in implementing similar revamping projects without major shutdown as well as hard work and assistance of skilled operating personnel of Oskol Electrometallurgical Plant and Customer’s professional work coordination made it possible to carry out demounting, erection and commissioning of complex equipment and systems within a scheduled 6-day overhaul.