Take the 2730/400 multi-cylinder box paper machine electric drive control system of a project as an example

This system uses DC bus power supply. The system uses Renault inverter, Siemens S7-400, KP1200 touch screen to form a communication network. (PCS7). Dell Industrial PC uses Siemens software to communicate with PLC via Industrial Ethernet. PLC is used as the main workstation, KP1200 is used as the terminal display interface, and the inverter is used as the actuator. In addition, the system can also be used as a sub-workstation of the entire network to realize the communication network with the factory, realize real-time monitoring, and meet the needs of the development of automation control. The system adopts full digital speed setting, remote data communication, speed/torque control load distribution, speed chain, traction settings, protection and diagnosis functions, fault alarm, tension control, load distribution control, and the system is equipped with a backup interface. This article introduces the paper machine drive control system, which has functions such as phase loss monitoring and voltage monitoring, overcurrent, overload protection, lubricating oil station failure alarm, communication failure alarm, etc., which better protects the safety of people and equipment.

Principle of control system:

Transmission technical characteristics: The system has 46 main transmissions with many transmission points. Each transmission point requires high precision for synchronization and speed stability. The speed difference control must be accurate. Transmission points such as the mesh, press, sizing, and drying sections require load. The distribution is balanced. We combine the practical experience of designing, debugging and analyzing the electrical control system of other paper machines of the same type, and put forward the electrical configuration and control technical scheme suitable for the paper machine based on the principles of reliable control, technology, simple operation and convenient maintenance.

The frequency converter adopts RNB8 series drive frequency converter, PLC is Siemens S7-400 type programmable controller, Siemens KP900 touch screen, constitutes Profibus-DP network communication control, upper computer adopts DELL industrial computer, communicates with PLC through industrial Ethernet, and software adopts Siemens WCC upper computer monitoring software. PLC exchanges data with each transmission point through the high-speed Profibus-DP interface, forming an network system. PLC is the master station of control, KP900 is the terminal display operation interface, and the inverter is the actuator. In addition, this system can be used as a sub-workstation of the whole plant network control, and realize the communication network and real-time monitoring with the whole plant to meet the needs of the development of factory automation control.

System Features:

◆TSPMC-3000- DC multi-network, high-speed network control system;

◆TSPMC-3000-DC load distribution part adopts a sub-frequency conversion drive system powered by DC bus;

◆The main operation and monitoring of the console is completed by the SIMATIC KP900 intelligent operation terminal;

The entire control core of the paper machine is controlled and monitored by Siemens’ distributed control center S7-400 and display workstation (industrial computer). The network used is: PROFIBUS-DP, EtherNet, etc., as well as the remote I/ which is necessary for DCS and QCS. The O modules are all controlled by the network; the management network adopts the industrial Ethernet, the DELL industrial computer, and the SIEMENS WIN CC monitoring software for on-site data management, and the on-site situation can be browsed through the ordinary Internet browser.

Technical  index:

1. Environmental conditions

Location: Indoor

Altitude: Below 1000m AMSL without derating

Humidity: 5% to 95%, non-condensingStor

age temperature: -40℃ to +65℃

Ambient temperature: -5℃ to +40℃

2. AC power supply:

Voltage error: +/-15%, maximum

Frequency error: +/-5%, maximum

Phase imbalance: +/-2%, maximum

3. Grid frequency: 50HZ

4. Voltage:

Incoming cabinet input voltage: 380V, 3-phaseCo

ntrol voltage: 220V, single phase

DC bus: 512V DC

5. Paper machine performance index:

Product Variety: Double Noodle Box Board Paper

Quantitative: 170~330g/㎡

Paper machine width: 2730mm

System type: AC variable frequency sub-drive

Installed capacity: main drive 2245.5KWDe

sign speed: 420m/min

Working speed: 400m/min

Crawling speed: 30m/minPaper

machine form: right hand phone

6. Electrical performance indicators    Electronic Quota:

1) Transmission form: all digital AC frequency converter transmission

2) Control method: three-level network control

3) Power supply mode: the factory provides three-phase AC 380V power supply, and the rectifier cabinet public DC bus inverter power supply

4) Feedback mode: open loop

5) Transmission accuracy: stable speed accuracy ≤0.01%

6) System control accuracy: 0.01%

7) Dynamic accuracy: 0.02%

8) Load control accuracy: ±1%

9) Tension control accuracy: ±2%

10) Inverter overload capacity: 150% 60 seconds

11) Speed response: 1000r/30ms

7. Control accuracy:

1) Static control accuracy (>24 hours)

--Speed control accuracy relative to rated speed 0.01%

----Control accuracy of the relative speed difference between two adjacent branch groups 0.01%

2) dynamic control accuracy

----Short-term speed deviation when there is interference (such as torque change) 0.05%

----Short-term tension control accuracy during constant speed during acceleration and braking 1%

----Tension control accuracy for transition from constant speed to acceleration or braking state 4%

3) The range of basic parameter deviation

----Torque (load): 20%

----Supply voltage: 10%

----Frequency: 2Hz

4) Speed control

The fluctuation of the grid voltage does not exceed ± 15%.

The fluctuation of the grid frequency does not exceed ± 3%.

The load fluctuation does not exceed ±30% of the maximum rated load.

Temperature change does not exceed  10%