The "Twelfth Five-Year Plan" policy promotes the development of VFD (Variable-frequency Drive)

A few days ago, the "Twelfth Five-Year Plan for Energy Conservation and Emission Reduction" issued by the Chinese state clarified the requirements for industrial energy conservation. The proportion of total industrial output value has risen from 68.1% to 70.9%. High energy consumption and high emission industries have grown too fast, and the goal of structural energy conservation has not been realized. Therefore, the management of industrial energy consumption must be strengthened.

The "Twelfth Five-Year Plan" policy promotes the development of VFD (Variable-frequency Drive)

Since the research and development of VFD (Variable-frequency Drive), frequency conversion technology has achieved remarkable energy-saving effects in many production processes. Chinese national "12th Five-Year Plan for Energy Conservation and Emission Reduction" requires the implementation of energy-saving renovation projects. Energy-saving motor systems are one of the main projects. System operation and control, improve the overall operating efficiency of the system. The plan proposes that the operating efficiency of the motor system in 2015 will increase by 2 to 3 percentage points compared with 2010, and an electricity saving capacity of 80 billion kWh will be formed during the "Twelfth Five-Year Plan" period.

Therefore, since the "Twelfth Five-Year Plan", energy conservation and environmental protection have been the core of Chinese industrial economic development. While pointing out the direction for the sustainable development of Chinese industry, it is also effectively promoting the sustainable development of Chinese VFD (Variable-frequency Drive) industry. Make Chinese VFD (Variable-frequency Drive) industry continuously expand the market share of the industry, and rely on its strong development force to become an important basis for Chinese industrial economic development.

Frequency conversion energy saving is mainly used in occasions where it is necessary to change the speed of the AC motor and change the characteristics of the driving machinery to meet the requirements of the production process, and it is mostly used in fans and water pumps. When the motor can only run at the rated speed, its driving machinery can only run at a certain rated speed.

When the production process requires adjustment of the process parameters, the flow rate can only be changed by increasing (decreasing) the system resistance, and the motor is always running under the rated condition, resulting in a waste of electric energy. Such as fans, pumps and other equipment, the traditional speed regulation method is to adjust the outlet (or inlet) baffle and valve opening to adjust the air supply and water supply. the probability of system failure. When using frequency conversion speed regulation, if the flow requirement is reduced, the requirement can be met by reducing the pump or fan speed.

On the whole, VFD (Variable-frequency Drive) mainly achieves energy saving effect through power factor compensation and soft start. In terms of power factor compensation, since reactive power will increase line loss and heat generation of equipment, coupled with the reduction of power factor, the active power of the grid will decrease. Among the large reactive power consumption lines, the equipment use efficiency is low and the waste is serious. After using the frequency conversion speed control device, the VFD (Variable-frequency Drive) internal filter capacitor acts, thereby reducing the reactive power loss and increasing the active power of the grid.

In terms of soft start and energy saving, the hard start of the motor will have a serious impact on the power grid, and at the same time, the requirements for the capacity of the power grid are too high. When a large current and vibration are generated during start-up, the damage to the baffle and valve will be great, and the use of equipment and pipelines will be greatly damaged. Life expectancy is extremely unfavorable. The use of the soft start function of VFD (Variable-frequency Drive) will make the starting current start from zero, reduce the impact on the power grid and the requirements for power supply capacity, prolong the service life of equipment and valves, and thus save equipment maintenance costs.

However, it should be noted that the problem of "small horses and large carts" should be avoided in the use of VFD (Variable-frequency Drive). The reason for this problem is based on the limitation of working conditions when the design was put into production at that time, so that in order to save money during design and installation, many places have adopted the setting that the frequency conversion power is less than the rated power of the motor. However, with the development of technology and changes in process and production conditions, the problem of "small horses and large carts" will inevitably appear, resulting in the failure of VFD (Variable-frequency Drive) to operate normally.

Therefore, during the trial period of the frequency conversion device, in order to prevent problems before they happen, detection and adjustment should be carried out in advance to avoid the above problems. In addition, after 6 to 10 years of normal use, VFD (Variable-frequency Drive) tends to enter a period of high incidence of failures, and failures such as component burnout, failure, and frequent activation of protection functions often occur, seriously affecting its normal operation.

Energy-saving VFD (Variable-frequency Drive) selection of 10 principles

At the same time, when choosing VFD (Variable-frequency Drive) speed regulation or energy saving, the following 10 principles should be followed as the prerequisite for deciding on the plan. If the local electricity price is high, the economic benefits will be greater when the same amount of electricity is saved, which is also something that must be considered.

1) There are certain conditions for VFD (Variable-frequency Drive) to save power. Under the condition of not affecting the use, after changing the working condition parameters appropriately, the power consumption of unreasonable operating parameters can be saved, and the general operation can be transformed into economical operation.

2) To save energy, the frequency must be reduced. The greater the drop, the more power will be saved. Without lowering the frequency, VFD (Variable-frequency Drive) cannot save power in principle.

3) It is related to the load rate of the motor. When the load rate is 10% to 90%, the power saving rate is at most about 8% to 10%, and the lower load rate corresponds to a higher power saving rate. However, the reactive power saving rate is about 40% to 50%, which is not included in the electricity bill.

4) It is related to the reasonableness of the original operating condition parameter values. For example, it is related to the adjustable value of pressure, flow rate, speed, etc. If the adjustable amount is large, the power saving rate will be high, otherwise it will be the opposite.

5) It is related to the original adjustment method. It is not economical to adjust operating parameters by means of import or export valves, but it is economical and reasonable to change to VFD (Variable-frequency Drive) speed regulation. After using the VFD (Variable-frequency Drive) to adjust the speed, it can save 20% to 30% more electricity than using the manual valve to adjust the operation method.

6) It is related to the original speed regulation method. For example, the slip motor was originally used for speed regulation, because the speed regulation efficiency is low, especially at medium and low speeds, the efficiency is only below 50%, which is very uneconomical. After changing to VFD (Variable-frequency Drive) speed regulation, this part of electric energy Saved. At present, in light industry, textile, papermaking, printing and dyeing, plastics, rubber and other industries, most of them still use slip motors, so using VFD (Variable-frequency Drive) to achieve energy saving, technical transformation is a top priority.

7) It is related to the working mode of the motor. For example, the power saving is different for continuous operation, short-time operation, and intermittent operation.

8) It is related to the length of time the motor is started. For example, if the power is turned on 24 hours a day and 365 days a year, the power saving will be large, and vice versa.

9) It is related to the power of the motor itself. Under the same power-saving rate, the energy-saving value of high-power motors is large, and the economic benefits are large. Even if the power-saving rate is lower than that of small-power motors, the actual benefits are greater.

10) It is related to the importance of each unit's production process design. First of all, it is necessary to select products with high power consumption, high product cost, and the current speed regulation method is not economical and reasonable, and then modify them. After switching to VFD (Variable-frequency Drive), there will be immediate results and twice the result with half the effort.