PLC, Simulation Training Helping Personnel Cope With Growing Complexity Of China's Pipelines

Aug. 10, 1998
Organizational overview [38,676 bytes] Main regions of pipeline activity [45,852 bytes] Langfang and vicinity [67,842 bytes] PLC training system [32,229 bytes] Simulation training system with dataviews [32,110 bytes] Dataview system overview [44,953 bytes] Jingbian initial station flow diagram [52,681 bytes] Shaan-Jing pipeline pressure and flow [55,353 bytes] Shaan-Jing blockage at km393 [57,796 bytes] Simulation training system with RSView32 [33,547 bytes] Adapted from a paper presented at
Chang Dahai
Staff and Workers College of the China Petroleum Pipeline Bureau
Langfang, China

Andrew Wike
Stoner Associates Inc.
Houston

Adapted from a paper presented at the ASME International Pipeline Conference in Calgary, June 7-11, 1998.

There are more than 7,000 km of crude oil pipelines and more than 8,000 km of natural gas pipelines in China.

Although there are few products pipelines in China today, the growth of this industry is anticipated, fueled by the rapid development of the economy there.

The China Petroleum Pipeline Bureau is the largest pipeline operator in China, accounting for more than 6,000 km of crude oil and natural gas pipelines. The Langfang-based Staff and Workers College (known simply as the Pipeline College) is a unit of the China Petroleum Pipeline Bureau (Cpplb). Students at the Pipeline College include full-time engineering students and short-term trainees. In general, the short-term trainees are management and operator-level staff who attend the Pipeline College for more advanced training. Having a lack of effective training tools, it has been almost impossible for the Pipeline College to provide a really effective training experience, particularly in actual pipeline operations.

In 1996, the Pipeline College developed plans to embrace advanced training tools in order to increase the effectiveness of the training courses it offered. The focus was in two areas: pipeline operations and programmable logic controller (PLC) set-up and maintenance. To achieve an effective training environment for pipeline operations, a simulation training system was set up using commercially available pipeline simulation software from Stoner Associates; the PLC training is based on Allen-Bradley equipment.

The operations training center computer systems were configured to accommodate 10 trainees simultaneously running their own independent training sessions. The first training courses delivered by the Pipeline College using their new tools were presented in summer 1997.

This article covers the development of the pipeline industry in China as a background to the operation of the Pipeline College, training center hardware and software configurations, and the Pipeline College's first experiences in using these advanced training tools and their plans for the future development of the training center.

Background

The economy in China is developing rapidly.

The $20 billion trade surplus reported in 1997 almost doubled that of the previous year. While the Southeast Asia region's weakened economies will make China's exports less price-competitive, the potential for further, albeit less rapid, growth is evident.

One of the primary enabling factors of economic growth is the adequate supply of affordable energy.

Pipelines are a major mode of transporting hydrocarbons from their source to the industries they feed, and the pipeline infrastructure in China is developing rapidly to meet the energy demands of its industry.

Pipeline organizations in China

China National Petroleum Corp. (CNPC) is mainly responsible for the exploration, production, and transportation of onshore oil and natural gas in China. There are now more than 15,000 km of oil and gas transmission pipelines for which CNPC is responsible.

China National Offshore Oil Corp. (Cnooc) has traditionally been the only company charged with the development and exploitation of offshore oil and gas resources.

However, late in 1996, China National Star Petroleum Corp. (Cnspc) was founded to end the prior dominant upstream positions of CNPC and Cnooc. Cnspc is authorized to market oil and natural gas to domestic customers, subject to government constraints, and to conduct cooperative exploration, development, and production with foreign companies.

Under CNPC are to be found many pipeline operating companies, such as: the Sichuan Petroleum Authority, responsible for the natural gas network in Sichuan province; Cpplb, responsible for the oil and gas transmission pipelines in North, East, and Northeast China; several companies operating pipelines in both the Xinjiang autonomous region (which includes the Tarim basin) and in Qinghai Province.

There are few product pipelines in China today, perhaps the most notable being the Fushun-Yingkou pipeline in Liaoning province operated by China National Petrochemical Corp. (Sinopec), whose main responsibility is for operating refineries rather than pipelines.

The CNPC also has three operating units responsible for the survey, design, and construction of pipelines that are organized under the Cpplb, while China Petroleum Engineering & Construction Corp. (Cpecc) provides general contractor services.

It is worth noting that a restructuring of China's petroleum sector, currently under way, will provide CNPC with a greater downstream presence and Sinopec with a greater upstream presence (see related article, p. 00).

New pipeline projects

There have been several new pipeline projects in recent years, such as the 500-km Jingbian-Xi'an pipeline and the 840-km ShaanJing pipeline to Beijing to transport natural gas production near Jingbian in Shaanxi Province to market.

In the Xinjiang autonomous region, the Tarim Oil & Gas Transportation Co. is extending the network of oil and gas pipelines it operates between Tazhong, Donghetang, and Mozhan, with a hub in Lunnan.

Development is not merely internal. Major new proposed projects could bring oil and/or gas from the Caspian Sea region and Turkmenistan, via Kazakh stan, into West China, while yet another project could bring Siberian gas through China to the Korean peninsula (see map, OGJ, July 20, 1998, p. 29).

CNPC also has international project interests. Its Cpecc unit continues to be heavily involved in the reconstruction of the pipeline infrastructure in Kuwait following the Persian Gulf War, and CNPC has a 40% interest in the Muglad basin oil development project in southern Sudan, which includes a major crude oil export pipeline to a port on the Red Sea.

China Petroleum Pipeline Bureau

The largest of the CNPC operating companies is Cpplb, which operates pipelines predominantly in North, East and Northeast China.

The first pipeline under the responsibility of the Cpplb began operation in 1971. Today, Cpplb owns a formidable network of over 6,000 km of oil and gas pipelines with diameters ranging from 300 mm to 720 mm. This network traverses 14 provinces, metropolitan areas, and autonomous regions. While this network is both operated and owned by the Cpplb, the company also assists in operating pipelines owned by its sister companies under CNPC, such as the new ShaanJing natural gas pipeline owned by Beijing Gas Transmission Co., and several pipelines in the Xinjiang autonomous region.

Through its own pipelines, Cpplb transports oil and gas from 10 producing fields (owned by Cpplb) to 4 oil marine terminals, 3 train-loading racks, and 15 refineries and petrochemical plants. The Cpplb has the capacity to transport 110 million metric tons/year of oil and 400 million cu m/year of natural gas. The crude oil transported by Cpplb accounts for more than 60% of the entire volume of oil transported in China.

Initially, all of Cpplb's pipelines were run manually. However, beginning in the mid-1980s, PLC-based station control systems and full pipeline Scada systems were introduced. Today, all three modes of operation are still in use.

Ensuring that their staff have the necessary skill levels required to operate pipelines has always been a major emphasis for the Cpplb. To focus this emphasis, the Cpplb established the Pipeline College to provide the appropriate learning environment.

The Pipeline College

The Pipeline College is located in Langfang, Hebei Province, as is the administration of Cpplb, and other Cpplb units such as the Pipeline Survey and Design Institute and the Pipeline Science Research Institute.

With the majority of its pipeline operations in North and East China, Beijing would have been an ideal location for Cpplb's base of operations. However, given the crowding in Beijing, Cpplb selected the town of Langfang for its base. Langfang is about 60 km southeast of Beijing and about half way between Beijing and China's third-largest city, Tianjin (see map, p. 00).

The Pipeline College incorporates several laboratories, including an instrument and process control laboratory, a small-scale pipeline loop (200 m of 50 mm pipe), and an oil properties and rheology test center, among others.

Students attending the college fall generally into one of two categories: full-time students enrolled for a 3-year study course (much like a community college in the U.S.) and short-term students, typically management and operator level staff, who attend the Pipeline College for more advanced training.

With the increasing focus on automation of pipeline operations, both at the local station control level and at the overall pipeline supervisory control level, the traditional "blackboard and chalk" methods used in the past were becoming increasingly less and less effective. These methods can be used quite effectively for the more-relaxed manual operations. However, with pipelines running at the higher pressures permitted under automated operations, any pressure surges can have very serious and costly consequences, and hydraulic properties influence pipeline operation to a greater degree than ever before. These new modes of operation demanded a new approach to training operations staff.

Consequently, in 1996, being faced with the challenge of ever-increasing operational complexity of its pipelines, the head of Cpplb decided to establish a simulation training center at the Pipeline College to maintain and enhance the skill levels of the Cpplb operations staff to meet these new challenges.

In addition to the simulation training center to be used for overall pipeline operator training, the Pipeline College also established a training environment for the local station control systems.

PLC training system

In order to train the staff responsible for setting up and programming the local station control systems, and to train those responsible for operating those systems, a PLC training system based on Rockwell Automation's Allen-Bradley equipment was set up.

A PC running Rockwell Software's RSLogix ladder-logic programming software provides the person-machine interface to both a PLC-5 family programmable logic controller and an SLC 500 family small logic controller. Both the PLC-5 and the SLC 500 are interfaced with a pump station process diagram board designed by the Pipeline College.

Equipment (pumps and valves) on the process diagram board are represented by lamps that illuminate to indicate their respective status, while the selected pipeline flow paths are also illuminated.

The student compiles his process control ladder logic in the PC using the RSLogix tools, with the resultant control logic being downloaded into the PLC-5 and SLC 500 units. The correct operation of the student's ladder logic is shown by appropriate illumination on the process diagram board.

This system is also used to train the students in the diagnosis of possible faults in the PLC-5 and SLC 500 units.

System requirements

Perhaps the most important aspect of a training simulation system is the interaction of the student operator with the simulation.

There are various alternatives that can be considered for this interaction, the choice of the specific alternative being dependent on the specific objectives for the system. Some of these objectives were encapsulated by Matthews and Wike (1995) as:

  • All personnel who work in pipeline operations are to understand the effects of pipeline operations on pipeline hydraulics.
  • All personnel who operate the pipeline in the control center are to understand the effects of pipeline operations on the pipeline they operate.
  • All personnel who operate the pipeline in the control center are to recognize various unusual operating conditions for the pipeline they operate when viewed using all the control center's operations tools and to understand how to return the pipeline system to safe, stable operation.
Clearly, in the environment of the Pipeline College, with many different pipelines being the subject of training and the different levels of operator control being exercised, all of these objectives were deemed necessary. The specific goals of individual training courses depend on the specific requirements of the staff-and their skill levels-attending the training. The selected system needed to address the training goals across this entire spectrum.

Other capabilities of the software on which the system was to be based were considered by the Pipeline College to be important, such as:

  • The system should be able to simulate gas pipelines, crude oil pipelines (including the non-Newtonian behavior of heavy crude oils), and refined products pipelines.
  • The system should be able to simulate the operation of local equipment control systems and the effect of the equipment operation on pipeline hydraulics.
  • The system should support multiple (up to 10), concurrent training sessions, with each student having his own simulated pipeline and equipment to operate.
  • The system should provide the instructor with the ability to monitor, and interact with, each of the multiple student's simulation sessions.
Following the review of a large number of papers on pipeline simulation and an extensive investigation into available technologies, the Pipeline College selected Stoner Associates' SPS/Trainer software as the technology base for its simulation training system.

System configuration

Hydraulic simulation is a computer-intensive software application.

The requirement to run 10 concurrent, yet independent, training simulations mandated the use of a powerful computer server at the core of the system. The system selected was Sun Microsystems' Ultra 2, a 64-bit architecture, dual-CPU system supplemented by 384 Mb memory and 4.2 Gb hard disk capacity.

The students sit at their own 133 MHz Aptiva PCs running Windows NT. Each PC has 32 Mb memory and a 1.6 Gb hard drive. The PCs are linked to the Ultra 2 computer server through a Catalyst 1900 switch from Cisco Systems. The Catalyst 1900 provides an Ethernet connection (100 base T) to the Ultra 2 server, with a dedicated, high bandwidth 10 base T (10 Mbps) connection to each of the 10 trainee PCs. The switch facilitates the communications between the many student PCs and the single server, coupling a high transfer rate (so the students perceive a responsive individual connection to the server) with more transparent network management functions, such as packet collision avoidance and flooding control.

To gain access to the Solaris operating system of the Ultra 2, each PC is loaded with the eXceed X-emulation software from Hummingbird Communications Ltd. This effectively turns each PC into an X-terminal linked to the Ultra 2.

The SPS/Trainer hydraulic simulation software resides on the Ultra 2 server. The SPS/Trainer software provides the instructor with the capability, among others, to:

  • Configure models of different pipeline networks and equipment, including natural gas, crude oil, and petroleum product pipelines, and to assert either idealized or detailed control on the equipment.
  • Create standard pipeline control exercises for the students.
  • Create upset conditions to which the student operator is challenged to respond.
  • Create reports and plots of the student training simulations.
  • Replay student training exercises during counseling sessions.
  • Eavesdrop onto any of the student simulations in-progress to monitor progress or to inject further complexity into the current scenario to challenge the student even more.
Through the SPS/Trainer interface, the instructor has complete access to all simulation devices and all simulation controls. However, the student operators, when in the field, will have no such access; their access will be limited to the controls available on the actual equipment and to the pipeline variables monitored by the installed Scada system. Controls and displays will normally be through some sort of Scada-system specific graphical interface.

To provide this graphical student interface to the simulation training system, the Pipeline College selected the DataViews interface option to the SPS/Trainer. Using this package, Scada-like screens are built with a variety of user-defined symbols to represent equipment and a wide repertoire of object dynamics are available to signal changing equipment status or pipeline conditions. In the simplest case, for example, a valve may change color and/or rotate to show its current position.

System set-up

However, merely bringing the training tools in-house does not make a training program. In order to be able to use the tools effectively, the instructors needed to be trained in the use of the tools. The Pipeline College dispatched eight of its staff to the vendor's Houston offices for an intensive 3-week training course in model and display building. The Pipeline College had already selected the first subject pipeline for training, the 840-km Shaan-Jing natural gas pipeline, so the training had a strong emphasis on this pipeline.

Upon their return to Langfang, these staff were then charged with continuing to develop the pipeline models and displays to be used during the training sessions they were to deliver. A few weeks following the staff's return, the vendor dispatched client support staff to Langfang for a final week of training and assistance in system set-up.

Even with the models and displays prepared, this still did not determine how these tools were to be woven into an overall training program. The Pipeline College staff prepared a training course based on the simulation training system that covered:

  • Normal operation of the pipeline, including rudimentary control operations.
  • Operator response to emergency conditions.
  • Analysis of the survival time of the pipeline.
  • How to use the information available from the simulation, such as profile, trend, and current data.
  • Peak-day analysis.
  • Start-up and shut-down analysis.
  • Analysis of leak situations.
With the models, displays, and the training curriculum prepared, the Pipeline College was prepared to commence training other staff.

Initial experiences

As mentioned, the initial focus of the training program was the newly constructed 840-km Shaan-Jing natural gas pipeline from Jingbian to Beijing, owned by Beijing Gas Transmission Co. (BGTC). On this pipeline, Cpplb staff were to assist in field operation of the equipment and control systems, while the overall pipeline control was to be scheduled by BGTC staff in their Beijing control center.

The Cpplb staff were brought into Langfang and trained. At the end of training, the students had been given a broad base of understanding in the operation of the Shaan-Jing pipeline, including transient and steady-state operations, and in set point control and the consequent effects on overall pipeline hydraulics and operation.

One of the simulation training exercises centered on the survival time of the Shaan-Jing pipeline. For example, a normal operating scenario would call for pressures of 45 bar and 16 bar at Jingbian and Beijing, respectively, and a flow rate of 178,000 cu m/hr.

If the mainline valve, 393 km from Jingbian, is closed and the flow rate at Beijing lowered to 100,000 cu m/hr, it will take 42 hr for the pressure at Beijing to reach 10 bar, and 115 hr to reach 5 bar.

For BGTC staff, the appropriate operational response to compressor trips was also included in the training demonstrations and exercises. Later in the year, staff operating the Lunku natural gas pipeline in the Xinjiang autonomous region were trained using the simulation training system configured with a model of their pipeline.

At yearend, Cpplb technical staff responsible for operating crude oil pipelines were trained on the system, this being the first "hands-on" use of the system for training liquids pipeline operators. The training course introduced the students to the real-world consequences of unanticipated closure of mainline block valves, pump trips, control system malfunction, and more, but all within the safe confines of a training environment. Students were challenged to recognize the symptoms of the malfunction, to identify the cause of the problem, and subsequently to return the pipeline to a safe operating equilibrium.

Future developments

Clearly, the training courses to date have not had as their goal the third training objective identified by Matthews and Wike (All personnel who operate the pipeline in the control center are to recognize various unusual operating conditions for the pipeline they operate when viewed using all the control center's operations tools and to understand how to return the pipeline system to safe, stable operataion).

Instead of using "all the control center's operations tools"-most significantly the Scada system interface- the Pipeline College has been using the DataViews Scada-like screens for the student interface.

A rather unique capability of the simulation software selected by the Pipeline College is the ability to interface it with a duplicate of an operational Scada system. The way this is done is to provide an emulation of the Scada host to field PLC communications. "Field" measurement data are extracted from the simulation and sent to the duplicate Scada host, while equipment commands from the host are converted into the equivalent commands recognized by the simulation software and injected into the simulation in progress. With this configuration, the student has available all the operations tools normally available in the control room during live operation, because the student is operating a copy of the Scada system.

McCracken (1991) describes this system architecture in some detail, while Rosser and Wike (1997) describe the experiences of a specific implementation.

The Pipeline College currently is building an interface between the simulation training system and Rockwell Software's RSView32 Scada software. Here, rather than use the PCs as X-terminals into the UNIX simulation server, the PCs will run the RSView32 Scada software and use the Scada-to-PLC protocol emulation to connect at the data level with the simulations running on the Ultra 2. Once in place, training sessions with the third objective as their goal can be realized.

When this configuration has been established, the Pipeline College will be able to run concurrent training sessions using either the DataViews interface or the RSView32 interface.

Another area of future development is in the operation and control of refined products pipelines. With growth anticipated in demand for refined products, plans are being formulated to establish a pipeline network for the transportation of these products. Pipeline College staff will use the simulation training system to research product pipeline design and operation. Prior to offering instruction in the operation of these systems, however, the Pipeline College staff must be fully conversant in the technology and hydraulics involved, and the simulation training system will be used to ensure the instructors have the appropriate skill levels.

Bibliography

Bridgewater, G.W., 1988, "Utilization of a Pipeline Simulator for Operator Training," Proceedings, 1988 API Pipeline Cybernetics Symposium, pp. 26-37.

Labrunie, C.S., 1996, "Uso de Simuladores de Processo No Treinamento de Operadors," Proceedings, 6th Congresso Brasileiro de Petr?leo.

Levine, D., Manney, G, and Anderson, P.N., 1990, "Training Oil Movements Controllers at Shell," Proceedings, 1990 Pipeline Simulation Interest Group, paper 9004.

Matthews, S.A., and Wike, A., 1995, "Control Center Training Systems: Configurations and Benefits," Proceedings, 3rd Congreso Latinamericano del Gas.

McCracken, G.E., 1991, "A Scada-Interfaced Gas Controller Training System," Proceedings, 1991 American Gas Association Operating Section Conference, paper 91-DT-84.

Meadows, T.A., 1995, "Building a Pipeline Trainer at Columbia Gas Transmission," Proceedings, 1995 American Gas Association Operating Section Conference, paper 95-OP-098.

Pringle, A., 1991, "Development of Simulator Training and Real Time Modeling," Proceedings, 1991 American Gas Association Operating Section Conference, paper 91-DT-55.

Rachford, H.H. Jr., Weber, M.V., Archer, D., Gearhart, R., and Litterell, H., 1982, "A Pipeline Dispatcher Training Model," Proceedings, 1982 Pipeline Simulation Interest Group.

Rosser, M., and Wike, A., 1997, "New Computer Models Help Train Product Pipeline Operators," Pipeline & Gas Industry, Vol. 80, No. 5, May 1997, pp. 41-45.

Schultz, D., 1991, "Benefits of a Pipeline Training Simulator," Proceedings, 1991 Pipeline Simulation Interest Group, paper 9102.

Smayda, M.L., 1995, "IPLT's Pipeline Operations Training Program: The Importance of Being Earnest," Proceedings, 1995 Pipelines, Terminals and Storage Conference.

The Authors

Chang Dahai is Director, Pipeline Transportation Department of the Staff and Worker College of the China Petroleum Pipeline Bureau at Langfang, Hebei, China. He has a BS in mechanical engineering from Fushun Petroleum Institute, Fushun, China. Since graduation, he has worked on staff training and research related to pipeline transportation issues at the Pipeline College.
Andrew Wike is Director, Business Development for Stoner Associates' Energy Transmission division, based in Houston. His main focus is international business development for Stoner's pipeline simulation software. Before joining Stoner in 1988, he was General Manager of Logica Energy Systems, also in Houston, and for 9 years prior to that he served in several positions, ranging from programmer to business center manager, for Logica BV, Rotterdam. Wike has an Honours degree in Computer Science from The Polytechnic, Wolverhampton, England.

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