Nancal 10kV/10KV, 6200kW MV converter used in BinXin steel

Input voltage: 10kV
Output voltage:10kV
Rated capacity: 6200kW
Function: soft starter and soft stop
1 drive 4 

NC HVVF series is a new generation high performance high reliability medium voltage AC drive with proprietary intellectual property made by Shanghai Nancal Electric. NC HVVF adopt voltage source cell cascade topology, with high performance vector control.
This article introduces Nancal HVVF series AC drive used in BinXin steel Jiangsu factory (BinXin steel) for blower of sintering machine. The power of sintering blower is as big as 6200kW, Nancal adopt 1drive4 solution (including reserved expansion), can realize functions of speed adjust, soft start, soft stop and synchronous transfer etc.
2-Applications in BinXin steel factory
BinXin Steel adopts AC drives to soft start the blower motor then transfer to grid. Nancal provides a complete Medium voltage AC drive upgrade and transformation solution. The original system are used as backups. The new AC drives are completely configured according to 4motors. After 3# and 4# motors are expanded, the converter can be put into use without any adjustment. The system diagram is as follows:
There are 4sets of 6200kW sintering blower synchronous motors(including reserved expansion). The original AC drive is imported brand consists of 7.2kV converter and step-up transformer. The new NC HVVF AC drive is 10kV high-voltage input and 10kV high-voltage output directly, no additional step-up transformer needed.
When the steam turbine is not put into operation, NC HVVF will soft start the motor and adjust the speed. When the steam turbine is put into operation, motor is driven by HVVF drive and the steam turbine together. Control cabinet is responsible for coordinating the works between high and low voltage power distribution cabinets, frequency converter, synchronous motor excitation system, blower and auxiliary system and steam turbine parts, and provide complete system monitoring function. And start the sintering blower, realize the frequency and speed control, and to realize the safe operation of sintering blower control according to the operating mode of steam turbine.

Loading: 4*6200kw synchronous motors for sintering fans.
Nancal products: NC HVVF Series 10kv VFD, 10kv input, 10kv output. No need any step up transformer.
The main features that the new solution can achieve:
1) Complete the soft start and speed control operation of the motor
2) Detection and Monitoring functions of all the relative auxiliary systems including high and low voltage power distribution, excitation system and lubrication system etc. And realizes the safety interlock and necessary protection for the startup and operation of the sintering blower.
3) It has the monitoring function coordinated with the steam turbine system, can coordinate the work of the steam turbine and automatically adapt to the operating state of the steam turbine, and control the AC drives to ensure the safe operation of the sintering blower.
4) Well-equipped indicator device for status indication, alarm, shutdown, etc.
5) Configure the touch screen to implement system parameter setting, monitoring operation, status display, data storage and query functions.
The waste heat generated by the sintering blower is used to drive the turbine, then the steam turbine drives the motor together with Nancal AC drive. Compared with the normal energy saving cases, the control is more complex and the stability requirements is higher.
When the steam turbine is out of operation, the Nancal HVVF drive will start the motor and control the speed. When the steam is under operation, the motor is drive by both frequency converter & steam turbine.