The hottest MM440 frequency converter is used in 2

Application of MM440 inverter in the control of the 2400/160 paper machine

application of MM440 inverter in the 2400/160 paper machine

application of the MM440 inverter in the control of the 2400/160 paper machine

Chi Nianhu of Shanghai zhongyun electrical equipment Engineering Co., Ltd.

Abstract:

in the ordinary paper machine transmission control system, based on speed control, according to the process requirements, in the Department, press department Sizing and other parts need to be combined with distribution control

Abstract:

The motor-drive system in the paper machine is based on the speed control, including the load-sharing control when the machine is on demand.

key words: speed control load share control PID Technology controller

overview

1 Requirements of paper machine for automatic control of electric drive

1.1 requirements for stable speed:

the paper machine needs to go through multiple divisions from pulp to paper, so it is a multi unit speed coordination system, and the speed requirements between each division are strictly coordinated. According to the process flow, there is generally the following relationship: as long as the speed of one of the divisions is unstable, it will not be able to maintain production, and the paper web will break during "1035", Is to relax. If the speed of the whole paper machine is unstable, the quantity of paper (the weight of pages per square meter) cannot be guaranteed to remain unchanged. Therefore, all parts of the paper machine are required to be able to stabilize the speed. However, in the actual operation, there are many interference factors that destroy the stability of speed, such as the fluctuation of electric voltage, the change of frequency, the fluctuation of load, the change of temperature and so on. The requirement for the automatic control of electric drive is to overcome the influence of these interference and ensure the stability of vehicle speed. Different paper machines have different requirements for speed stability accuracy, so the requirements for electrical transmission are also different. Generally speaking, thin paper or large high-speed paper machines have higher requirements

1.2 requirements for speed change:

when the paper machine works normally, the range of speed change due to technological changes is small, generally only about 10-15%. When the paper machine is adjusted, such as checking the copper, changing the blanket at the press, changing the cloth at the dryer or preheating, it needs to crawl at a low speed, and the speed will be reduced to about 20 m/min. at this time, there is no requirement for stable speed

1.3 requirements for smooth starting:

some parts of the paper machine require smooth starting, for example, if the part starts too fast, copper will be damaged; The transmission inertia of the drying cylinder and calendering parts is relatively large, and too fierce starting will twist the mechanical coupling, so the whole system is required to start smoothly, and each part should be able to start and stop independently

1.4 requirements for speed regulation of each division:

as shown in Figure 1, the process flow chart of the paper machine, the paper on the paper machine is under the action of traction, and the longitudinal elongation of the paper will continue at the beginning of the cadre. When the water content of the paper is reduced, the longitudinal elongation and deformation of the paper will be reduced. When the paper enters the calender and winder, the paper will be pulled and stretched again, so in the whole paper machine production line, The speed of each segment is different, which can maintain the paper tension. At the same time, the speed of each part of the paper machine must be adjustable, so as to avoid the head breakage caused by the relaxation or tension of the paper web. The speed adjustment range of each part is ± (10-15%)

since the paper machine does not need to be started frequently, and the speed change range required by the process is not large, achieving stable speed is the main goal of electric drive automatic control

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2. Overview of 2400/160 paper machine

2400/160 paper machine produces thin paper with a ration of 17-30g/m2. The design speed is 160 m/min. The paper web is formed in the middle of the length, dehydrated by composite pressing, and then dried by five groups of drying cylinders. The paper web is cut after being cooled in the cylinder, and rolled into a master roll by the paper reeler. The paper machine is divided into partial drives, with a total of 15 transmission points, and the total installed capacity is 202kw. As shown in Figure 2, paper machine transmission diagram

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system configuration

in the control system, S7-200 series PLC is used to control MM440 frequency converters of different divisions by using USS protocol communication, and MM440 variable frequency speed regulation of the motor, so as to achieve the control of paper machine transmission, which is operated by the console control button. The specific configuration is as follows:

cpu226

Di module

do module

bus connector

shielded twisted pair

MM440 frequency converter (Software version: v1.16)

incoming reactor

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characteristics of three MM440 frequency converters

1 Rich control functions:

can meet the drive control requirements of various industries. In this control system, vector control mode is used to drive each branch motor

2. Powerful communication function:

it has a standard RS485 interface to facilitate the communication of the upper computer. The Profibus communication option can hook the MM440 on the open and fast DP to realize what impact will the uneven installation of the left and right force measuring parts have on the indication? High performance communication control

3 Free function block and BICO Technology:

MM440 has the free block and BICO technology that are different from general-purpose frequency converters, which can realize flexible configuration design and complete the control requirements of complex processes

4. Various parameter setting methods:

parameter setting is carried out through the basic operation board and advanced operation panel, and parameter setting can also be carried out by using simovis and drivemonitor debugging software. At the same time, the debugging software can be used to monitor the process value in control

electrical control of four 2400/160 paper machines

1 Paper machine speed chain

because each segment transmits the paper in the production process, according to the requirements of papermaking process, the proportion of linear speed between segments is required to be coordinated (the linear speed ratio between adjacent two segments should be kept constant). Maintaining this proportion coefficient with high precision and reliability is an important condition to ensure product quality and normal production operation. If this proportion coordination is damaged for any reason, the product quality will be reduced. At the same time, this speed proportion coordination relationship of the paper machine should continue to be maintained when the speed is changed or the machine is restarted after shutdown, without readjustment. Secondly, the pressure testing machine should achieve such acceleration every time it impacts the battery. This proportion coordination should have a fine-tuning function to adjust the speed difference between the adjacent two parts, so as to avoid the relaxation and tension of the paper in the transmission process. The speed fine-tuning should be sensitive and reliable, and there should be no obvious lag in the adjustment process. The proportional coordination relationship is as follows:

N1 = K1 (N0 + dn0) N2 = K2 (N1 + DN1) N3 = K3 (N2 + DN2) N4 = K4 (N3 + DN3)

in the 2400/160 paper machine, the USS protocol communication combined with PLC program is used to complete the control of the speed chain, avoiding the signal drift of the given link of the speed chain of the operational amplifier and improving the stability