Today, Derun Electric's editor will talk about the role of low voltage frequency conversion cabinet in coal-fired power plant.

In general, the core role of * * LV frequency conversion cabinet in coal-fired power plant is "energy conservation and consumption reduction" and "optimal control". **By changing the power supply frequency and voltage of the motor, it can accurately control the rotating speed of the motor and finally realize the intelligent and efficient regulation of large auxiliary machines such as fans and water pumps.

The following is a detailed breakdown of its specific role:

###1 Core role: energy conservation and consumption reduction (this is the most important and direct economic benefit)

In traditional coal-fired power plants, a large number of fans (such as induced draft fan, forced draft fan and primary air fan) and water pumps (such as condensate pump and circulating water pump) usually operate at constant speed. When the air volume or water volume needs to be adjusted, it is realized by * * throttling * *, for example:

*Fan * *: adjust the opening of air valve and baffle.

*Water pump * *: Adjust the opening of the valve.

In this way, it is like when driving at high speed, the speed is controlled by pressing the brake all the time, the energy is wasted on overcoming the resistance of the valve and baffle, but the motor is always running at high speed at rated power, which is very power consuming.

**Energy conservation principle of frequency conversion cabinet:**

The drive motor of frequency conversion cabinet adopts the principle of "* * supply as required * *". It detects the actual demand of the system through sensors (such as pressure and flow sensors) and then automatically adjusts the speed of the motor.

*Load characteristics of fan and water pump * *: its power is directly proportional to the third power of rotating speed ('Pn ³ '). That is, if the rotating speed is slightly reduced, the power will be greatly reduced.

*Example * *: If the required air volume is reduced to 80% of the rated value and the motor speed is reduced to 80%, the power consumption can theoretically be reduced to ` (0.8) ³=0.512 `, i.e. 51.2% of the rated power! Extremely significant energy saving effect.

The auxiliary equipment of the power station (especially the induced draft fan and condensate pump) is the "big user" of the plant power. The frequency conversion transformation can greatly reduce the * * plant power consumption rate * * and directly improve the power supply efficiency and economic benefits of the power station.

ABB low-voltage frequency conversion cabinet manufacturer asked Anhui Derun Electric.

###2 Optimize process control and improve operation stability

*Smooth soft start/soft stop * *: frequency conversion start is the "soft start" gradually increasing frequency and voltage, the starting current is small (usually less than the rated current), and the impact on the power grid and mechanical equipment is greatly reduced. Avoid large current impact during direct start (up to 5-7 times of rated current), protect motor, cable and circuit breaker, and reduce voltage fluctuation to power grid. Smooth soft stop also avoids water hammer effects (for pumps) and mechanical shocks.

*Precise control * *: Frequency control can realize very accurate speed control, so as to make the process parameters such as air pressure, water pressure and flow more stable, and improve the automation level and operation stability of the whole generator unit. For example, the condensate pump can accurately maintain the water level of condenser hot well and reduce fluctuation after adopting frequency conversion control.

###3 Protection of equipment for extended life

*Reduce mechanical wear * *: Soft start/stop and stable operation speed greatly reduce the impact and wear on mechanical parts such as water pump, fan, bearing, valve and pipe, extend the service life of equipment and reduce the maintenance cost.

**Motor protection * *: The frequency converter usually has built-in rich protection functions, such as overcurrent, overvoltage, undervoltage, overload, overheating and phase loss, providing comprehensive protection for the motor.

###Main application situations

In coal-fired power plants, low-voltage frequency conversion cabinets are generally used for the following auxiliary equipment:

Condensate pump * *: one of the most typical variable frequency application cases with the most significant energy conservation effect.

Circulating water pump * *: Adjust the cooling water flow according to the season and load change, so as to save energy.

Various fans * *: including * * induced draft fan * *, * * forced draft fan * *, * * primary fan * *, etc.

Mortar pump, slag removal pump * * and other auxiliary water pumps.

Other auxiliary equipment required to regulate flow or pressure.

###Summary of Summary

For coal-fired power plant, low-voltage frequency conversion cabinet is far more than a simple electrical control equipment, it is a key * * energy conservation technology * * and * * process optimization technology * *. The benefits include:

*Economic benefit * *: greatly reduce the auxiliary power consumption, save the electricity cost and have high return on investment.

*Technical benefits * *: improve the automation level, optimize the control process, and make the unit operate more stably and flexibly.

*Equipment benefit * *: reduce equipment loss, extend equipment life and reduce maintenance cost.

*Environmental benefits * *: indirectly reduce the coal consumption and carbon emission caused by the power consumption of the power plant, which conforms to the development direction of green power plant.

Therefore, in the design and transformation of modern coal-fired power plants, the installation of frequency conversion devices for large auxiliary machines has become a standard configuration and an inevitable trend.