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Case Study

Other applications

Application of Huafei High - power and Medium voltage Variable Frequency Drive in Metallurgical Synchronous Motor

2016-09-27 08:40:58 Bobo HUAFEI Group

Application of Huafei High - power and variable frequency drive" href="" target="_blank">Medium voltage Variable Frequency Drive in Metallurgical Synchronous Motor

I. Introduction

In recent years, the state's macro-control policies of the steel industry has been introduced one after another, of which the most important comes as energy-saving emission reduction, iron and steel industry is the largest energy-saving emission reduction industry, statistics show that the energy industry accounts for the country's total industrial energy More than 15% of consumption, energy-saving emission reduction in the work of great significance. Visible iron and steel industry is the field of many high-energy-consuming industries in the energy-saving emission reduction "top priority."

Project Overview

Tianjin Iron and Steel is a steel-based large-scale joint ventures, in the top 500 Chinese enterprises ranked 125, China's top 500 manufacturing 58, China's black metallurgy and rolling enterprises ranked No. 21, for many years out of Tianjin Top 100 private enterprises first.

Tianjin has a large sintering plant of four, has formed a production of 4.76 million tons of sinter, of which 200 square meters sintering machine system sintering fan and cooling fan power greater, respectively, 5000KW medium voltage synchronous machine and 3500KW medium pressure Synchronous machine, the initial design of the motor starts to rely on water resistance to start, and the air volume adjustment is the use of damper adjustment, after a period of operation and found that the use of air damper adjustment air volume there are a lot of limitations, mainly in:

1. The damper damper adjusts the air flow to change the resistance characteristic of the air duct, and the output power of the drive source motor has not changed, the throttle loss is quite big, the electric energy is wasted.

2. The damper adjust the air volume is the amount of wind consumed in the wind board, resulting in a large pressure difference before and after the wind board, damper easy to wear.

3. Fan motor running at full speed, vibration, noise, loss, bearing wear serious.

4. Adjustment accuracy is low, linearity is poor, dynamic response is slow.

5. Water resistance is only in the motor starts to play a role in regulating the air volume of the fan or rely on the damper adjustment, the motor energy consumption is still high, and water resistance to maintain a larger amount.

In response to these problems, and in response to national energy-saving emission reduction policies and guidelines to comprehensively improve the company's operating level and core competitiveness of a steel plant in Tianjin after a multi-research, comparison, and finally decided to Jiaozuo Huafei Electronics Co., Ltd. production Synchronous medium-pressure variable frequency drive, the sintering system 5000KW medium voltage synchronous machine and 3500KW medium voltage synchronous machine for frequency transformation.

Third, the field data

The frequency conversion project is a 5000KW sintering fan and a 3500KW cooling fan in a sintering furnace system of 200 square meters in a sintering plant in Tianjin. The motors are medium voltage synchronous motors produced by Shanghai Electric Machinery Co., Ltd. The parameters are as follows:

Fourth, the frequency conversion driver disposition

According to the field equipment parameters and process for customer matching two variable frequency drive" href="" target="_blank">medium voltage variable frequency drive, the technical parameters are as follows:

Fifth, the user load situation

Users of two medium-voltage synchronous motor power of 5000KW and 3500KW, respectively, and the motor and the fan shaft is not rigid connection, but by the snake-like spring connection, similar to the flexible connection, that is, through a coupling, the coupling of two The end is a separate part, which is tensioned in the middle by a serpentine spring. From the control system point of view, the entire motor load becomes a second-order inertia, and the second-order inertia of the damping is very small. In control theory, it is a very easy to shock system.

Which drives the variable frequency drive control, put forward high requirements. If the control is not good, the load mechanical jitter, and mechanical jitter will cause the torque jitter, synchronous motor torque jitter eventually becomes the excitation magnetic field and the rotor magnetic field angle of the shock, reaction to the inverter drive current shock. Inverter drive current shock is very likely to cause the inverter driver jump over voltage, over-current fault, which can not start the load.

The load graph is as follows:

Sixth, the frequency conversion system primary circuit transformation plan

Synchronous motor frequency control system mainly by the user switch, variable frequency drive, bypass cabinet, synchronous motor and excitation cabinet components. The variable frequency driver controls the excitation current of the excitation cabinet by signals to realize the synchronous motor start and stop control and realize the synchronous motor frequency conversion speed regulation. System control diagram is as follows:

Frequency control system by the user switch, manual bypass cabinet, water resistance counters, medium voltage inverter drive, medium voltage motor. Manual bypass cabinet is composed of three medium voltage isolating switches QS1, QS2, QS3. When the motor runs in inverter mode, QS1 and QS2 are closed and QS3 is open. When the motor runs at power frequency mode, QS3 is closed and QS1 and QS2 are open. Manual bypass cabinet in strict accordance with the "five anti-" interlock requirements design, frequency conversion output switch QS2 and frequency switching QS3 interlock, fully able to ensure the safe operation of frequency control system.

In the choice of starting mode, the use of synchronous start (that is, before the start of the converter excitation current into the excitation, making it directly in accordance with the synchronous machine to start), rather than the industry commonly used asynchronously activated (that is, before starting the converter excitation control cabinet After the start of the motor, the variable frequency drive will increase the excitation current slowly. When the excitation current reaches a certain level, the synchronous motor can start the motor according to the synchronous mode. If the excitation current does not exceed the excitation current, Speed ​​operation).

For synchronous start, start the link is simple, but the start of the control process demanding. The asynchronous start is just the opposite. Relying on the rich experience in the field of motor control, HuaFei electronic medium voltage drive fully support the load in such a complex way of direct synchronization start.

7, medium voltage variable frequency drive debugging operation

According to the characteristics of the load, HuaFei electronic technician chooses the optimal excitation current and voltage curve according to the characteristics of the load and adjusts the excitation current synchronously with the output voltage. The optimal excitation current curve is directly cured to Synchronous machine excitation cabinet, the voltage curve using multi-point V / F way, curing to the variable frequency drive parameters; and then use Huafei electronic medium voltage inverter drive unique vibration suppression technology synchronization, an effective solution to the Load start is not smooth, easy to shake, resulting in current oscillation problem, excellent completion of the two medium voltage synchronous motor start and stable operation, the two medium voltage variable frequency drive in November 13, 2011 into production continuous faultless stable operation.

After the commissioning is completed, the customer to the frequency conversion driver start stops, the movement stage of control, only adjusts the output frequency, starts stops for about, and the entire start stops, the movement process may complete in the central control room, the entire process also does not have to care about the excitation cabinet , Greatly reducing the intensity of the start-up phase, and reducing the complexity of the work to improve the production efficiency, but also reduce the possibility of error.

Two medium voltage variable frequency drives are in stable operation

Variable frequency drive room out of the wind and take dustproof, waterproof treatment

8, saving analysis

1) Medium voltage frequency conversion operation interface:

2) 5000KW cooling fan operation data analysis:

Calculated according to the above data, 5000KW sintering fan energy saving rate of 39%. The average annual cost of the equipment is 300 * 24 * (4111-2508) * 0.4 = 4.617 million yuan. The annual electricity cost is calculated as 0.4 yuan / kWh.

3) 3500KW cooling fan operation data analysis:

Calculated according to the above table data, 3500KW cooling fan energy-saving rate reached 24.8%, the average annual operation of the equipment more than 300 days, 24 hours a day basis, electricity to 0.4 yuan / kWh, the annual cost savings: 300 * 24 * (2150.9-2054.1) * 0.4 = 1.536 million yuan.

The overall energy saving effect is remarkable, moreover the performance is stable, the movement is reliable, the HuaFei electronic product obtains the user consistent high praise.

Nine, summary

The frequency conversion drive transformation, not only enhances the equipment the security reliability, enhances the technological process automation level, reduces the accident rate, more enterprise saves reduces the loss to enhance the economic efficiency to make the contribution, promotes the energy conservation in the country vigorously, reduces the environmental pollution policy instruction , The promotion and use of variable frequency drive will be a powerful measure to reduce energy consumption.


Jiaozuo Huafei Electronics Co., Ltd. production of medium voltage variable frequency drive in high-power synchronous motor on the successful operation, marking the Huafei Electronics has fully mastered the high-power medium voltage synchronous motor in the process of the start-up frequency conversion drag , As well as flexible connections, low frequency oscillation and other industry problems.


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