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    Application of Hitachi converter in continuous annealing production line of
    发布时间:2014-10-28   来源:    【字体:

    China's energy consumption about 90% above is the energy consumption of the motor, the motor efficiency of the product data shows, Chinese 80% than the low level of foreign advanced two to three percentage points. The efficiency of the motor Y series are widely applied at home and the average value is eighty-seven point three percent; and the efficiency American motor with high efficiency average value is ninety point three percent. The efficiency of ultra high performance motor mean value is ninety-one point seven percent. So in addition to the motor development of high efficiency and energy saving, the key to the promotion and development of variable frequency speed control technology is also energy-saving. This paper is about application Hitachi frequency conversion technique in continuous annealing production line.
    1 Introduction to engineering
    The two phase of the project of Guangzhou JEF Steel Co. Ltd.: l pickling and cold rolling production line (PL - TCM), 1 continuous annealing production line, l galvanized wire (2#CGL), the overall design capacity is 1800000 tons, mainly in auto panels and home appliance plate as the main products. In the two phase of the project, the main production line design and equipment providers is Mitsubishi Hitachi Rail Corporation, the electrical part is Hitachi company contracted project construction period is three years.
    Introduction of 2 continuous annealing process
    The use of continuous annealing unit tower, from the process is divided into the cleaning (skim) and two parts of heat treatment, also can be divided into 3 stages: the exit section of population segment, segment, stove. The main technical parameters of the unit as shown in table one.

    3, process control
    The main production line motor (such as the uncoiler, leveler. Roller etc.) all use the vector control, the motor also uses vector motors; auxiliary equipment (such as wind) using VVVF control. The motor adopts frequency conversion motor (ordinary domestic manufacturing). There's a part (such as oil pump. Water pump etc.) with constant speed motor (domestic manufacturing). Here focuses on the application of frequency converter in Hitachi company vector control and VVVF control.
    3.1 vector control inverter
    The inverter we usually say, in terms of hardware consists of two parts: the rectifier and inverter part. In Hitachi drive system. The two part is separated to control, which has many advantages. For example, save the cost, reduce intermediate links, energy saving and efficiency increase, see below for detailed analysis.
    Hitachi frequency technology in CAL using two types of driving system, namely: the small and medium system, adopts the 2 level PWM control. Hitachi inverter also provides a large IGBT drive system, is used in the mill, then do not introduce. Whether it is large, medium or small system, driving system, include two main parts: the rectifier part, the inverter part (also known as the inverter part). The output waveform frequency part has been nearly completely close to sine wave.
    Typical IGBl driving system configuration is as follows:
    1) IG well rectifier transformer special;
    2) for the synchronous transformer control:
    3) IG Ni rectifier unit, to provide a stable DC power supply;
    4) IGBl converter unit, meet the speed control, current control.
    Hitachi drive system, using a public rectification unit. Then a plurality of vector control frequency converter used in the DC bus hanging unit.
    The use of this common DC bus system approach has many advantages:
    1) save equipment cost, because of the production line, there are a large number of roller drive control. The control requirements are very high, and the different position of the roller speed, the current is different. If the single inverter to control it, not only the control complexity increase, will be wasted due to improper selection of inverter allowance.
    2) to save electricity, for the traditional control method, which is l roller motor using 1 frequency converter drive, to use the brake resistor braking during deceleration, the excess energy consumption in the braking resistor. While the use of common DC bus, will produce some of the rollers motor braking electric energy feedback to the DC bus, used for other roller motor, so as to achieve the purpose of energy saving.
    3) on power system small disturbance, adopting 2 level PWM control, power factor is close to 1; while the use of synchronous voltage source and a pulse shift control to further reduce the interference of high harmonics to the power supply.
    4) stop to reduce equipment failure caused by. Using a common DC bus mode. Makes the control becomes simplified, DC common bus in the part of control is relatively simple, low failure rate of mature technology. In one part of the failure does not affect other frequency converter operation.
    5) spare parts management more simplified. Due to the rectifier and frequency part of separate control, so the spare parts more universal. In the vector control inverter, there are mainly two kinds of control mode: speed control and current control. In the speed control of its response to wc=10-30 rad. / s, current control, the response is wc= "100rad. / s. according to different needs with different control mode, for example. The need for high tension and rapid response of the coiler machine and other occasions usually uses the current control, time synchronization control in roller adopts speed control. But sometimes the speed and current control are used in combination to meet higher demand for control. Monitoring and data management of each inverter via industrial Ethernet network, more convenient to maintain and control.
    3.2 VVVF control inverter
    VVVF control frequency (VVVF control) fan, in the CAL in the production line is mainly used for example, preheating furnace circulating fan, heating furnace blower, the speed required accuracy is not very high, mainly in order to control the size of the circulating air flow rate through the valve control air. Avoid process can not meet the demand of. In the VVVF control inverter, using sinusoidal PWM control, using voltage source inverter in this project. Frequency control range: l:10, frequency response: 0.01Hz (at 50Hz). With overcurrent, overvoltage protection and under voltage protection function. Parameters can be set up and monitor the operation state of the inverter through the industrial Ethernet and fieldbus. VVVF control of variable frequency technology development has been very mature, and it is widely used in modern industry.

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