Application of FGI FD5000 MV Drive for Raw mill fan in cement

1. Introduction

Raw mill fan in cement industry carries gas and raw meal. The pressure drop in raw mill fan is very high. If a vertical roller mill is used for raw grinding in cement industry then a large raw mill fan is installed. Usually cement industries use centrifugal fans to carry out this process.

2. Original control system analysis

Before the reconstruction of Ambuja cement (Bhatapara) , the slip power recovery system(SPRS) used . However, there are the following disadvantages:

(1) For reliable thyristor commutation inverter firing angle kept less than 180°.

(2) To improve power factor, capacitor is introduced into stator or rotor sides 3.Energy consumption is also high.

3. Project reform

The project adopts FD5000 series MVD independently developed and produced by FGI Science and Technology Co., Ltd. . The MVD is a medium voltage variable frequency speed regulating device of vector control H bridge series multi-level technology. The original old system can still be used at present, so it will not be dismantled temporarily, and will be reserved as the backup system.

4. VFD principle

FGI FD5000 series VFD is a high-tech energy-saving product, which adopts advanced IGBT power unit multi-level technology, digital control technology and SPWM pulse width modulation technology. It has the advantages of high power factor, high efficiency, energy saving, high stability, etc, and has the rated power energy feedback ability.

Each phase of the VFD is composed of six power units in series, and the three-phase Y is connected to the output. The output adopts the SPWM wave superimposed by 9 power units in 11 kv of each phase to form high-quality output waveform, which is supplied to the motor.

Optical fiber communication is adopted between control cabinet, power unit cabinet, transformer cabinet and bypass cabinet to prevent electromagnetic interference. Achieve complete isolation of high and low voltage, improve safety.

The input side of the power unit is composed of fuse, rectifier and filter parts, and the rectifier part is composed of six IGBT. The inverter consists of four IGBT H bridge inverter outputs, and the motor is driven by the unit series.

5. Application advantages

(1) High reliability

The FD5000 series inverters of FGI have perfect protection functions, such as overcurrent, overvoltage, overload, stall and other protection functions.

(2) Small start-up current

The impact current in the process of starting and accelerating is small, and the maximum starting current in the process of accelerating does not exceed 1.9 times of the rated current.

(3) Wide range of speed regulation

VFD system belongs to the stepless speed regulation, the motor control in the process of acceleration and deceleration is stable, The speed regulation is soft.

(4) Production efficiency is high

The stability of the FGI FD5000 series VFD is high, and the speed does not change with the change of the load. The VFD can control the motor to run stably at a given speed. 

6. Complimentary Close

The practice has proved that the in Raw mill fan runs well after the technical transformation of VFD, the energy consumption of the fan of Raw mill fan is reduced and the power factor of the power grid is also improved. Facts have proved that the Medium Voltage VFD has superior product performance, in the cement industry in the energy saving transformation application can create huge economic benefits, in the energy saving and environmental protection has played an important role. It can completely replace the traditional control mode and has very high promotion value.