Application of Localized FF Fieldbus Control System in Light Power Devices

1. Introduction Fieldbus was developed and developed in the late 20th century and is used for field intelligent device interconnection communication networks in the fields of process automation, manufacturing automation, and building automation. The Foundation Fieldbus (FF) has become a highly competitive bus technology with its advanced technology. After years of development, it has formed a mature, open, all-digital industrial communication system. The Fieldbus Foundation’s China Market Committee (FFCMC) mentioned in its report: “In China, according to incomplete statistics, several hundred large and medium-sized projects spread across large rivers, including world-class large projects such as Shanghai Secco Petrochemical and Guangdong Huizhou Zhonghai. The Shell petrochemical project and the Fujian Refining and Ethylene project have been shocked by the scale of the project, indicating that FF technology has entered a new stage of large-scale application in China."

The relevant domestic units have tackled the FF fieldbus technology earlier, and the technology level has been at the forefront of the world, including the research and development of chips, the research and development of protocol stack software, and so on. The application of products has also made continuous progress. Shenyang Zhongkebo Micro Automation Technology Co., Ltd. has completed the large-scale application of FF fieldbus control system on light power devices. The entire system has designed 36 FFH1 segments and 133 FF fieldbus meters. Among them, 21 bus current conversion instruments solve the bus access problem of traditional 4-20mA devices; multi-channel temperature acquisition instruments can collect 8 temperature measurement points. , saving instrumentation costs. The system completely adopts domestic independent products, and the engineering design, implementation and debugging are all completed by themselves. At present, the system has been successfully put into operation, and the system is stable and reliable. At the same time, the user is convenient in system maintenance and diagnosis management, and the cost is saved.

2. Introduction to process flow The light power plant includes a combustion chamber test stand, a compressor test stand, and a complete machine test stand. Combustion chamber test bench consists of test parts, turbine guides, air system, oil system, circulating water cooling system, etc., a total of 8 flow, 88 temperature, 55 pressure measurement points, through the measurement of data to complete the combustion chamber The performance study; compressor test rig consists of test parts, air system, speed increase box system, lubricating oil system, etc., a total of 2 flow, 26 temperature, 9 pressure measurement points, through the measurement of data to complete the compressor Performance study: The total test bench has 3 flow, 33 temperature, and 16 pressure measurement points. Through the data measurement, the engine performance study is completed. The measurement points of the light power devices are concentrated, and the safety and accuracy of the control loop are highly demanded. It is very suitable for the FF field bus control system.

Light power plant FF fieldbus control system adopts FF bus certification products of Shenyang Zhongke Bo Micro Automation Technology Co., Ltd., including networked control system supporting FF bus technology NCS4000, FF pressure transmission instrument, FF temperature instrument, 4-channel FF Current conversion instrumentation, 8-channel FF temperature acquisition instrumentation, as well as bus junction boxes, power supplies, and terminal matchers; bus cables are also supplied by domestic manufacturers, using Changzhou Bayi Type A cables.

3. Control Plan 3.1. Control System Structure
Figure 1 FF fieldbus control system structure diagram There are two control rooms at the scene, namely the East monitoring room and the North monitoring room, and the monitoring room is connected through the optical fiber. East monitoring and control room is equipped with a main engineer station and an engineer station, and 2 sets of control cabinets equipped with an NCS4000 are responsible for collecting the measurement data of the compressor and the combustion chamber test bench, while measuring the temperature, pressure, flow rate and other parameters of the auxiliary pipeline, and the valves, The frequency converter and other equipments are controlled; the north monitoring and control room is equipped with a master engineer station and a Chengshi station, and a set of control cabinets equipped with an NCS4000 is responsible for collecting the measurement data of the entire machine test bench.

(1) Control station: The whole system uses 3 sets of NCS4000 control stations that support the FFH1 access function. Each control station adopts controller redundancy and IO redundancy to ensure the safety and reliability of the system. Traditional IO module connects electromagnetic flowmeter, frequency conversion equipment, motor, oil pump and other signals through cables; FFH1 fieldbus communication module has 2 ports, ie two network segments, connected to fieldbus through fieldbus dedicated cable (backbone network) Junction box, fieldbus dedicated cable (branch network) to connect fieldbus instruments, each fieldbus junction box with up to 6 FFH1 smart meters. Several fieldbus junction boxes are distributed and installed on site.

(2) Control network: High-speed Ethernet is used as the communication medium between the main engineer station, the engineer station, and the control system. FFHSE protocol is used for data exchange. The control network is a redundant configuration that provides security and reliability for communications.

(3) FF field bus smart meter: The instrument used is Shenyang Zhongkebo Micro Automation Technology Co., Ltd. NCS-PT105IIS series diffusion silicon intelligent pressure transmission instrument, NCS-PT105II series intelligent differential pressure transmission instrument, NCS-TT108 intelligent temperature Transmission instrument, NCS-FI105 fieldbus current output transmission instrument, NCS-IF105 fieldbus current input transmission instrument. The control valve adopts the traditional 4-20mA signal valve and applies the NCS-FI105 fieldbus current output transmission instrument. The NCS-IF105 fieldbus current input transmission instrument can connect the traditional control valve to the FF fieldbus network segment, greatly reducing the The cost is beneficial to the application and promotion of FF field bus technology. At the same time, all the control loop PID functions are decentralized to the FF field bus meter to improve the control safety and accuracy, shorten the control cycle, and reduce the controller's operating load. This gives the controller more resources to perform advanced control functions.

3.2. FF bus segment design The design of FF field bus segment mainly considers the total current load of the segment, cable length, branch length, voltage drop, and the maximum number of devices connected to the fieldbus. At the same time, it is also affected by the network segment. Hazard and operability effects. The specific design is shown in Table 1.

Table 1 Segment Design Table
Bus power adopts 24VDC, 1A power supply; trunk length does not exceed 100 meters, branch length does not exceed 30 meters; communication speed is 0.5 seconds; intelligent instrumentation equipment in the control loop is designed in the same network segment, each network segment design at most A control loop; the network segment is designed as a star topology due to the relatively concentrated measurement data of the light power unit.

A total of 36 network segments are designed for the entire system. At present, 30 network segments are actually used, and up to 6 fieldbus meters are connected to each segment. A total of 133 FFH1 fieldbus meters are installed on each segment. On average, 3.7 field buses are connected to each segment. Instrument, leaving 2.3 fieldbus meter margin.

4. Summary The FF fieldbus control system of Shenyang Zhongkebo Micro Automation Technology Co., Ltd. has been applied in several sites such as the Yuanbaoshan Sewage Treatment Plant and the gasifier small-scale test device, and has achieved the expected results. The application of the FF fieldbus control system, FF intelligent equipment, and other hardware and software products independently developed on the lightweight power plant completes the practical application of the FF field bus engineering and realizes some advantages of the FF field bus technology: cable saving and Installation materials reduce the amount of work; can be calibrated by the instrument; function is better dispersed, and on-site control is achieved; accuracy of measurement is improved; all domestically produced products are used to save the cost for the user. At the same time, from the network segment design, FAT testing, project implementation, and on-site commissioning, FF fieldbus technology engineering experience has been accumulated and an important step has been taken on the FF fieldbus technology exploration road.