Fusion Engineering and Design 89 (2014) 595–599
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Fusion Engineering and Design journal homepage: www.elsevier.com/locate/fusengdes
Design and development of a device management platform for EAST cryogenic system Zhiwei Zhou ∗ , Xiaofei Lu, Ming Zhuang, Liangbing Hu, Genhai Xia Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui, China
h i g h l i g h t s • A device management platform for EAST cryogenic system based on DCS is designed. • This platform enhances the integrity and continuity of system device information. • It can help predictive maintenance and device management decision.
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Article history: Received 24 May 2013 Received in revised form 9 February 2014 Accepted 11 March 2014 Available online 31 March 2014 Keywords: EAST Cryogenic system DCS Device management Maintenance techniques
a b s t r a c t EAST cryogenic system is one of the critical sub-systems of the EAST tokamak device. It is a large scale helium cryoplant, which adopts distributed control system to realize monitoring and control of the cryogenic process and devices. However, the maintenance and management of most field devices are still in the corrective maintenance or traditional preventive maintenance stage. Under maintained or over maintained problems widely exist, which could cause devices fault and increase operation costs. Therefore, a device management platform is proposed for a safe and steady operation as well as fault diagnosis and predictive maintenance of EAST cryogenic system. This paper presents the function design and architecture design of the cryogenic device management platform. This platform is developed based on DeltaV DCS and acquires monitoring data through OPC protocol. It consists of three pillars, namely device information management, device condition management, and device performance monitoring. The development and implementation of every pillar are illustrated in detail in this paper. Test results and discussions are presented in the end. © 2014 Elsevier B.V. All rights reserved.
1. Introduction EAST cryogenic system is one of the critical sub-systems of the EAST tokamak device for cooling of the superconducting magnets and other cold components. As shown in Fig. 1, it is a large-scale helium cryoplant including large number and variety of cryogenic devices, which consists of a 2 kW/4 K helium refrigerator and the cryogenic distribution sub-system [1]. The helium refrigerator is composed of the compressor station, cold box, valve box and 10,000 L Dewar. All heat exchangers, adsorbers and four turbines are installed in the cold box. The cryogenic distribution sub-system includes a cryogenic valve box on which four supercritical helium circulating pumps and all cryogenic valves are installed.
∗ Corresponding author. Tel.: +86 551 65593285. E-mail addresses:
[email protected] (Z. Zhou),
[email protected] (X. Lu),
[email protected] (M. Zhuang),
[email protected] (L. Hu),
[email protected] (G. Xia). http://dx.doi.org/10.1016/j.fusengdes.2014.03.023 0920-3796/© 2014 Elsevier B.V. All rights reserved.
EAST cryogenic control system was designed and developed based on the DeltaV distributed control system (DCS) from Emerson process management Corporation [2,3]. It provides a fine operator interface, and has realized historical data archive and analysis; alarm detection and safety interlock protection, automatic control of different operational modes. The past 8 experiments have proved DeltaV DCS is highly efficient to monitor and control cryogenic process and devices [3]. EAST cryogenic system has been put into operation for 8 experiments since 2005. With the increase of operation time, the maintenance and management of field devices have become a focus. As EAST now requires the cryoplant availability to be 96% rather than the previous 90%, the devices maintenance management requires be more robust. The Emerson Corporation has a suit of commercial software AMS (Asset Management System) Suite, which is an aimed solution to decrease device maintenance cost and promote the operation efficiency of the whole factory. However, we did not get this commercial software suit with the additional
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Fig. 1. Simplified flowchart of the EAST cryogenic system.
functionality because of the cost limitation. Instead, a device management platform for the EAST cryogenic system was designed and developed based on our actual operation needs to help the devices’ fault diagnosis and predictive maintenance. 2. Function design of cryogenic device management platform According to the operation requirements of the engineers and process operators for the eight experiments, the EAST cryogenic device management platform is designed into three pillars, namely device information management, device condition management, and device performance monitoring. Fig. 2 shows the diagram of device management function. Device information management includes device prophase management and operation management. The prophase information is the devices’ static information which depends on the manufacturer and has no need to modify unless the device is updated. The operation information including the device operation and maintenance records is the dynamic information which needs to be updated frequently. Device condition management is designed to have the function of monitoring running condition, diagnosing system fault and predictive maintenance. Device performance monitoring calculates and displays the performance of cryogenic system as well as its kernel components like compressors and turbines. The platform is custom, but the design and implementation are made in a generic way. Some functions such as device information management could be used for monitoring other systems or shared with other facilities. But some other function like device performance monitoring just adapts to the EAST cryogenic system. 3. Architecture and software structure design This platform adopts a Client/Server software structure to realize device management. C/S mode has strong interaction, fast data processing and high reliability. The basis of device management is building an integrated database to accumulate device information and monitor device condition. Based on the DeltaV DCS, all realtime data of devices and process are sampled by the Input/Output
(I/O) modules per second. Fig. 3 shows the architecture and software structure of this platform. DCS monitoring modules play a role of communication server, which is configured on Professional plus Station of the DCS. It periodically executes command to acquire the online condition and real-time data of the cryogenic devices, and sends the management information to the OPC (OLE for Process Control) Server. OPC Server is installed on the Application Station. It provides an OPC Data Access 2.0 Standard to read/write the runtime data. Data Server takes charge of data access from OPC Server through OPC Custom Interface written in C++ as well as the database operation, and response to data request of the device management client. The Device Management Client, Data Sever and OPC Server compose two layer of C/S structure. The integrated database adopts relational database MySQL based on Structured Query Language (SQL) and multithreading to manage the information related to devices. All devices information is stored into different data tables in database, and relates to each other with the device number. The operators or system maintenance engineers can interact with the device management platform through the graphical user interface (GUI). 4. Platform development and discussions The device management platform has been developed as an OPC client. It is designed under Microsoft Windows XP environment. An integrated development environment (IDE) Qt Creator has been used to provide a comfortable human-machine interface. Qt is a cross-platform C++ graphic user interface application frame. Its signal-slot communication mechanism between objects and its powerful GUI design tool help to promote development of the platform. VC++ was considered to be an alternative software tool, but its GUI development is not as convenient as the Qt which has the Quick UI technology. 4.1. Device information management The devices in the EAST cryogenic system can be divided into four types: mechanical devices, process devices, instrumentation and valves. Fig. 4 is the interface of prophase information management of screw compressors. The left tree lists all the function
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Fig. 2. Diagram of device management function.
of the device management platform. Through the left tree, the corresponding function interface can be opened. Device information management records all the lifetime information of every device.
As shown in Fig. 4, the prophase information data table has five fields including device number, basic property, technical property, capability property and operation time. The platform supports entering device information through these buttons designed on the
Fig. 3. Software architecture of device management platform.
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Fig. 4. Interface of device information management.
interface and keeps all the records automatically in the integrated database. The operation time is designed for all of the mechanical devices, such as screw compressor, turbine, circulating pump and so on. It is monitored and calculated in the DCS, and transfers to the client for planned maintenance alarm. Here applies a time-based maintenance strategy [4]. Pressing the Operation Information button can open the operation information management interface. It has a friendly GUI to renew the information. The operation records and the maintenance records were stored into different data tables with different data fields in the integrated database. The operation table records the next planned maintenance time which can be used to trigger the maintenance alarm, while the maintenance table records the fault symptom, fault cause and the solutions, which are helpful to build the fault trees for fault diagnosis. 4.2. Device condition management Device condition management is used to display and analyze the running condition of field devices. Fig. 5 is the operation condition monitoring interface of screw compressors. The mechanical devices in the cryogenic system have each important operation conditions that should be rigorously supervised, but among which still have some similar operation condition signals like running status and emergent stop status, as Fig. 5 shows. Monitoring operation condition is essential for fault diagnosis. The common malfunction in cryogenic system is attributed to thermodynamic performance which presented the pressure or temperature of the system is abnormal or machine dysfunction which behaved as abnormal noises and vibration. DeltaV DCS supervises the cryogenic process in real time, and monitors the data streams such as temperature, pressure, and mass flowrate. It executes the computation and sends out alarm or fault signals by means of detecting the fault symptoms every 5 s. This platform is developed on the basis of the cryogenic fault diagnosis expert
system, which can help operators to locate the possible fault causes in time and give rational operation suggestions [5]. This platform also adopts a condition-based maintenance strategy, also known as predictive maintenance, which is the most modern and popular maintenance technique [4]. This predictive maintenance method utilizes reliability factor of fault diagnosis results, which reveals degradation evolvement of the system’s devices caused by incipient fault [5]. 4.3. Device performance monitoring The device performance monitoring is designed to have five main parts as Fig. 2 shows. All of the performance parameters are calculated by the client program, which reads necessary process variables per minute from the DCS and stores the calculation results into the integrated database. The management interface displays the latest several performance parameters, while the history performance used for system analysis can also be queried. The MySQL database adopts the InnoDB engine. The present data records in the device information data table at most do not exceed 10,000 lists, so the average execution time of remote concurrent access is less than 1 ms. Because the device condition scan rate is set as 5 s and the performance calculation san rate is 1 min, their data records in each data table have exceeded 1 million lists and 100 thousand lists separately. So the execution time arrived at about several milliseconds. 4.4. Test results and discussions The developed function of this platform has been tested preliminarily. The security issues have been considered in the system design. The device management platform provides the supervisory and alarm function without any account permit. But some functions like updating device information, querying the historical device performance need to login with a valid account.
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Fig. 5. Interface of device condition management.
Device condition management can help operators to master the runtime operation condition of cryogenic devices and find abnormal situations in time. It is the base of fault diagnosis and prediction. Device performance monitoring provides useful runtime data to analyze and optimize the cryogenic system and its core components. The time-based combining with the condition-based maintenance alarm is effective for the cryogenic devices maintenance. It helps in making maintenance plans. However, the platform still has some problems to be solved. Because of the present I/O cards in the DeltaV DCS can not support the Fieldbus protocol and the field intelligent devices were limited in number, the device information can not be automatically acquired. This manual entering manner of device information management consumed much time and manpower. The vibration monitoring for mechanical devices is not sufficient in the cryogenic system to diagnose or predict the possible fault. All of these problems need us to upgrade the cryogenic control system for a better operation and maintenance. 5. Conclusions In this work, a device management platform for the EAST cryogenic system based on the DeltaV DCS was designed and developed with the Qt Creator IDE and MySQL database for decreasing device maintenance cost and promoting the operation efficiency of the whole cryoplant because of the current control system lack of these functions and the devices maintenance management becoming more and more important. The cryogenic device management
platform enhances the integrity and continuity of system device information. Besides, it can help predictive maintenance and device management decision as well as the fault diagnosis. In the future work, with the upgrade of cryogenic control system, via reading DD (device description) files the device management platform can directly diagnose and manage the instrumentation based on HART (Highway Addressable Remote Transducer) protocol such as the pressure transmitters or other FF-based (Foundation Fieldbus) intelligent field devices. Acknowledgements Financial support from the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. Y05FCQ1124) and the Application & Development Project of the Institute of Plasma Physics (Y35ETY130G) are gratefully acknowledged. References [1] H. Bai, Y. Bi, P. Zhu, Q. Zhang, K. Wu, M. Zhuang, et al., Cryogenics in EAST, Fusion Eng. Des. 81 (2006) 2597–2603. [2] Y. Jin, X. Shao, M. Zhuang, H. Bai, EAST cryogenic supervisory and control system based on Delta-V DCS, Plasma Sci. Technol. 7 (2005) 3013–3016. [3] M. Zhuang, L. Hu, Z. Zhou, G. Xia, The cryogenic control system of EAST, Fusion Eng. Des. 87 (2012) 2007–2011. [4] R. Ahmad, S. Kamaruddin, An overview of time-based and conditionbased maintenance in industrial application, Comput. Ind. Eng. 63 (2012) 135–149. [5] Z. Zhou, M. Zhuang, X. Lu, L. Hu, G. Xia, Design of a real-time fault diagnosis expert system for the EAST cryoplant, Fusion Eng. Des. 87 (2012) 2002–2006.
