- Email: [email protected]
A Sustainable Approach to Process Optimization through Integrated Advanced Control Software Standards
13th Symposium on Automation in Mining, Mineral and Metal Processing Cape Town, South Africa, August 2-4, 2010
A Sustainable Approach to Process Optimization through Integrated Advanced Control Software Standards D.J de Clerk*, P.G.R de Villiers **, G Humphries*** *Process Control Technology Specialist, Anglo Platinum, Control and Instrumentation Department, Johannesburg, South Africa (Tel: +2711-3736622; e-mail: [email protected]) **Lead Process Control Engineer, Anglo Platinum, Control and Instrumentation Department, Johannesburg, South Africa (Tel: +2711-3736449; e-mail: [email protected]) ***Head of Technology, Anglo Platinum, Control and Instrumentation Department, Johannesburg, South Africa (Tel: +2711-3736503; e-mail: [email protected]) Abstract: Anglo Platinum’s process control department has succeeded in establishing a robust, sustainable advanced control architecture that facilitates the rapid expansion of its automation and optimization strategy across its concentrator, smelter and refinery operations. This paper discusses the various components of this architecture that led to and contributes to the widely recognized impact that it has on driving Anglo Platinum’s mission to be the world’s number one producer of safe, profitable Platinum. Keywords: Advanced Process Control, Integrated Expert Systems, Platinum Processing control systems, require a solid foundation, support structure and monitoring philosophy in order to make them sustainable. Consequently Anglo Platinum embarked on a journey to identify and fill all the gaps that were hindering its vision. It took several years, but the rapid increase in the control footprint over the last three years has made it all worthwhile.
1. INTRODUCTION In the early 1990’s, Solomon Associates2 conducted a study to determine the key factors that influence the profitability of oil refineries. Somewhat surprisingly it was found that the only two factors with high statistical significance were the staff’s education level and the degree to which advanced process control (APC) was utilized. Consequently, approximately 15 years ago, Anglo Platinum4 started with a vision to achieve optimal plant performance through continued expert supervision. This vision has driven the evaluation of several control related technologies, and has provided the motivation to keep going despite some setbacks. Throughout these years it became clear that technology is no longer the barrier to successful APC implementation, but rather the way in which it is applied. By combining the bestof-breed features found in various technologies, Anglo Platinum has derived an integrated product suite that provides all the tools required by its small group of control engineers to design, deploy and support an ever growing control footprint. These tools, that is centered on a Gensym G26 based Expert System, is known as the Anglo Platinum Expert Toolkit (APET) product suite.
Fig. 1. APC count at Anglo Platinum’s operations over the past thirteen (13) years.
1.1APC Footprint at Anglo Platinum
2. ARCHITECTURE OVERVIEW
Figure 1 shows the number of advanced controllers that have been successfully deployed throughout the various Anglo Platinum operations over the past 13 years. Most of these controllers have an uptime exceeding 95%. Evident from Figure 1 is the initial downward trend in the number of deployed controllers utilized by the operations. This emphasized the fact that control systems, especially advanced 978-3-902661-73-9/10/$20.00 © 2010 IFAC
Figure 2 demonstrates the various layers and components that make up and support the APET product suite. Each layer of the schema contributes in a unique manner to the APET functionality. APET forms the “middle layer” between the Programmable Logic Controller (PLC) and the Operational
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Performance Monitoring (OPM) layers. The effective functioning of each layer is dependent on the performance of the layer that feeds into it. The functionality provided by the APET middle layer ensures a robust and holistic approach to process optimization. This paper will discuss some of these in more detail with a specific focus on the G2 based APET.
2.1.3 Subversion (SVN) In a rapidly developing and expanding environment like the APET footprint, effective and reliable version control is critical. Anglo Platinum operates a central SVN3 repository that is used to ensure all modifications to all applications are always made to the latest version and can always be tracked and/or reverted. SVN also doubles as a backup architecture in that all modified applications are automatically pushed to the repository on a daily basis. Furthermore it serves as a deployment tool through which the latest version of APET is deployed to all operations on a daily basis. In order to maximize the potential of SVN and to cater for certain characteristics of G2, a G2 based SVN client has been developed that facilitates the integration with this exceptionally powerful and useful open source product.
OPM
Central
(OSI AF, PI, Matlab, Statistica)
PMDB + AMDB (Excel + MSSQL)
ACM (G2)
SVN APC Dashboard
MPC
Historian
(DMC+, Prime)
APET (G2)
(InSQL, PI)
(Excel, Matlab)
APC Database
Site
(J5)
2.1.4 iDX and Unifig
iDX + Unifig SCADA (WinCC, Citect)
Anglo Platinum standardized on using iDX7 to facilitate the communication between various components of the APET product suite. iDX is a South African developed middleware product. As illustrated in Figure 3, it is centred on a collection of data slots that each contains a single current value along with an associated timestamp and quality. Surrounding this slot collection are one or more driver modules that can read from and/or write to these slots. Each driver module can in turn collect data from or send data to an external system.
PLC (Siemens, Rockwell, Moore)
Fig. 2: APET product suite. 2.1 Site Layer The lower part of the illustrated schema is currently implemented on several concentrator, refinery and smelter operations within Anglo Platinum. This consists of:
iDX Components
G2
2.1.1 PLC/DCS and SCADA
DB
Realtime or DB
HDD
SQL
Driver Modules External Systems
As a result of the numerous operations of different types, age and background where APET is deployed, it is inevitable that different PLC (programmable logic controller), DCS (distributed control system) and SCADA (supervisory control and data acquisition) platforms need to be accommodated. Generally, communications to higher level applications is done via the SCADA layer, however, it is also possible to communicate directly with the PLC. Similarly, most communications are OPC11 based, but where required, custom protocols have been deployed. Over the years, Anglo Platinum has refined and consolidated its PLC coding standards, but unfortunately it has seldom been economically viable to reengineer existing PLCs. Hence it is also unavoidable that APET should cater for varying code structures at this level.
G2 Client
Data Logger
OPC Client J5, DMC, Prime, Other iDX
HDD Data Playback
OPC Server
SLOTS TCP Client TCP Server Other iDX
TCP Server
OPC Client
TCP Client Custom
Other iDX, iDX MC
OPC Server PLC/SCADA, Analyzers, Other iDX
Various
Fig. 3. iDX architecture. While iDX is utilized in a continuous real time fashion, Unifig is utilized in a periodic offline manner. Unifig has the ability to query the structure of a PLC and then expose the information to external systems. Unifig can be used to automatically configure the plant historian with all the desired tags that exist in the PLC and automatically tag up the various objects in APET. This results in a perpetually current standardized historian configuration saving time, resources and reducing errors associated with manual configuration.
2.1.2 Historian When Anglo Platinum first embarked on its process control vision, few of the sites had proper historians. This had to be corrected as the historian provides vital information needed to perform proper operational performance monitoring (OPM) and analysis. Once again different historians have been deployed to the different operations and site specific needs are catered for. Typically the historians collect their data from the PLC/SCADA layer via the same OPC server utilised by APET.
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any controller implemented in APET. From here the user can view and interrogate all the relevant controller data, states, messages, and tuning parameters at a single glance. Once again, as a result of the integrated nature of the APET products, there is no need for manual configuration of these dashboards. All configurations, like controller layouts and various tag allocations, are simply read from the preconfigured APET structure.
2.1.5 Anglo Platinum Expert Toolkit (APET) Through several years of development and refinement by Anglo Platinum and various partners, APET has matured into an exceptionally powerful tool that stands at the centre of many of Anglo Platinum’s control department’s successes. APET, which was originally built on SGS’ MinnovEX Expert Technology (MET)10, is based on Gensym’s G2 and enables its users to rapidly capture the asset model of an operation in a very strong relational, object-orientated and visual environment. The core original intention of APET was the implementation of advanced controllers. However, due to its logical and intuitive structure, it fast became the reference point for several other applications. Instead of configuring various applications individually with essentially the same information, APET is now able to auto configure them based on its own configuration. This leads to a single point of configuration, and one version of the truth. APET will be described in more detail in section 3.
2.1.7 Model Predictive Control (MPC) Internally to APET it is possible to implement various different control algorithms, including fuzzy, rule and model based control. Certain other control algorithms require more dedicated software.
2.1.6 APC Database – J5 The data found in the historian makes it possible to monitor operations’ performance. However, for APC design, monitoring and tuning, more detailed information is required that cannot be stored cost effectively in the plant historian. Therefore, Anglo Platinum has standardized on installing a J515 historian alongside each APET site instance. Like iDX, J5 is a South African product that has been developed in close collaboration with Anglo Platinum. It is developed in the Python13 programming language and used to populate a Microsoft SQL Server database with data collected from iDX via OPC. Over the years it has been refined and integrated with the APET product suite to such an extent that it is essentially completely auto configured. The data that is captured by J5 is stored on site, but also rolled-up and stored centrally. All of this data is made available to various components of the APET product suite such as APET itself and OPM, but also externally to other clients like Matlab9 and Microsoft Excel.
Fig. 4: APC dashboard example showing a controller with 4 input fuzzy membership functions and 2 outputs. Anglo Platinum selected two MPC1 partners5,14. Both of their platforms interface with the plant via APET. All data is received and validated by APET before passing it on to the MPC algorithms via iDX. The necessary setpoint changes are then calculated and returned back to APET. Depending on various process states and conditions these setpoint changes are then propagated to the PLC or discarded. Wrapping the MPC algorithms inside of APET in this manner provides for rapid deployment of new MPC controllers that forms part of a bigger robust hybrid solution.
2.1.7 APC Dashboard
2.2 Central Layer
The APC Dashboard has been developed to allow external interrogation of the advanced controllers within APET without unnecessary access to the rest of the APET application. The APC Dashboard is deployed on two platforms, Excel and Matlab, each communicating with APET via the Gensym ActiveX-Link. The Excel based dashboard provides a configuration frontend that makes use of Excel’s powerful user-interface to capture various tuning parameters and configurations used by the different control algorithms implemented in APET. Since Excel is readily available and used by site metallurgists, it provides a cost effective interface into APET for adjusting control limits and targets.
The upper part of the schema shown in Figure 2 is implemented at Anglo Platinum’s head office in Johannesburg that has a network link to all Anglo Platinum’s operations. This layer consists of: 2.2.1 APET Central Monitor (ACM) Given the number of APET installations across Anglo Platinum’s operations, it made sense to develop a central monitoring tool to focus mainly on the infrastructure health (Figure 5). ACM is also a G2 based application that has a fulltime G2to-G2 connection to each one of the APET instances on the operations. It immediately highlights whenever any of the APET instances becomes unreachable, and it also provides the facility to query all APET instances for various bits of
The Matlab based dashboard capitalizes on Matlab’s superior trending capability. This application, which has been locally developed by Anglo Platinum and its partners, provides the user with a neatly consolidated, real time view (Figure 4) of 117
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information like which sites are currently running, how many controllers are currently on and how are they performing.
2.2.2 Asset Model Database (AMDB) and Process Model Database (PMDB) Historically, the operational performance monitoring (OPM) application was configured manually by means of Matlab scripts. This proved to be tedious and error prone and the configuration was subsequently moved to a database (PMDB) based structure. This still required lots of manual configuration of information that was already neatly captured in the APET applications. Hence the AMDB was developed to store the asset models that were captured in APET. Now queries against AMDB are used to populate PMDB from which OPM collects its configuration. AMDB also contains lots of additional information that will be used in future versions of the monitoring packages. 2.2.3 Operational Performance Monitoring (OPM) The OPM subdivision of Anglo Platinum’s control department plays a vital role in identifying optimization opportunities as well as monitoring existing controllers’ performance.
Fig. 5: ACM front page listing all APET instances overlaid on a map of the Platinum Rich Bushveld Ignenous complex. ACM subsequently grew into the role of asset model collector. Here its purpose is to collect the asset models from the various sites, make them available for inspection (Figure 6) and also export them to the asset model database (AMDB). Finally ACM was enhanced with the APET quality assurance (AQA) module. This module is capable of starting each of the APET site applications on an offline server, using the latest version of APET, and then compiling a report based on various metrics and diagnostic checks. This essentially performs automated beta testing and greatly reduces the risk of upgrading the APET site applications to newer versions of APET that contains new or enhanced functionality and/or bug fixes.
Fig. 7: OPM daily report example showing the stability analysis on one of the sensors This is realized by utilizing several tools, of which the Matlab and OSI PI AF12 components are the biggest beneficiaries of the APET product suite. These systems receive their configuration from APET (via ACM and AMDB), and based on this information generate automated periodic reports (Figure 7). These reports are used to guide the operations’ management and control engineers to achieve optimal performance from Anglo Platinum’s assets. 3. ANGLO PLATINUM EXPERT TOOLKIT (APET) Gensym G2 is a fourth generation object orientated programming environment that combines a real time inference engine within a graphic environment to facilitate rapid application development and deployment. APET is a modularized layered G2 application that has been developed to fully exploit its powers in order to optimize Anglo Platinum’s assets. Some of its features will be described in this section.
Fig. 6: ACM asset model tree example showing the various S88/S95 layers
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3.1 Utilities Some of the other utilities in turn are focused on integration with external systems. These include command line driven applications like SVN, ActiveX controls in programs like Excel and Matlab, and other G2 applications like ACM.
Anglo Platinum has designed and developed several generic utilities, which are not necessarily part of the standard G2 installation, to help improve the development and user experience of APET and other G2 applications like ACM. These tools play a vital role in ensuring a small effective but efficient base that can support the maximum possible number of closed-loop controllers.
3.2 Graphical Rules Toolset (GRT) GRT is an important foundation module in APET that provides for the construction of easy to follow data flow logic diagrams (Figure 9).
Fig. 8: Dynamic popup menu example indicating how connection stubs are created while considering the allowable connection types. Code that assists with layout, organization and standardization of objects provides structures that are easy to follow and navigate. Various code execution management features ensure that developers and users are always aware of what is happening, while prioritized event queuing and logging control execution sequences and avoid unnecessary duplicated processing.
Fig. 9: GRT logic example that shows how the internal attributes of an instrument is calculated and represented. The ever growing library of GRT blocks offer data collection from external systems, single and multiple input calculations, data qualification, filtering and much more. The GRT engine has been highly optimized and a typical APET application performs several thousand GRT executions every second.
Substantial effort has gone into providing an efficient, intuitive user interface that is focussed and responsive even over slow long distance networks. Dynamic overhead and popup menus (Figure 8) have been designed that not only provide the user with quick access to relevant functionality, but also provides useful information on the selected object.
3.3 Communications The communications (comms) module is another critical foundation module in APET. It provides several communication masters that establish and maintain, with auto recovery, links to external systems that typically also run as windows services like iDX, J5, SQL, and other G2 applications. Furthermore, it contains all the class definitions and code that enables thousands of data points to be read and written every second to and from iDX. It is from this module that integration with most other components of the APET product suite is driven. This module compiles all configuration files for the various iDX services, setup the tags within the J5 database, facilitates communication with the MPC programs and determines the relevant historian tags for OPM purposes.
Highly efficient dialog utilities have been created to facilitate user input and configuration operations. All of these are integrated with the user authentication system that restricts users’ actions as required. To supplement the version control gained through the integration with SVN, all editing of code structures are recorded as an additional backup. Code copyright is preserved through appropriate text stripping without hampering troubleshooting ability. Performance and health of an APET application are continuously monitored and reported. This is complemented with a set of predefined, categorized diagnostic checks that report on any unexpected settings or configuration. These ensure that all standards are adhered to, that all references are intact and that no error condition goes unnoticed.
3.4 Schematic The schematic provides invaluable structure and context to all the objects and data in an APET application. It is used to capture (explicitly and implicitly) several important relationships between the various assets present on an operation. This relational asset model forms the basis of most of the reasoning and referencing in APET as well as the source of the exported OPM configurations.
The system provides useful tools to manage, preserve and trend variable history with minimal performance impact. Used in conjunction with a periodic screen capture feature, these play a key role during operation monitoring and controller tuning. 119
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The reuse of pre-existing templates is strongly encouraged and well supported by APET. It is possible to copy-andpaste entire sections of existing schematics without the need for major reconfiguration and therefore engineering time is substantially reduced, especially given the large number of similar processes across Anglo Platinum’s operations.
(Figure 12). All objects in the schematic are automatically named according to a predefined naming convention that only expects a unique ID. The internal logic of the objects is represented by special subclasses of the GRT blocks that have been combined in predefined templates. Throughout these steps, the various comms slots need to be tagged in order to establish communications with the PLC and other external applications. This process is simplified through the use of the APC-Dashboard and Unifig integration.
Constructing the schematic consists of a couple of steps and is in many ways an iterative process as shown in Figure 10.
Fig. 12: Example of equipment, instruments and basic controllers found in a process cell At this point, the APET application closely resembles the site SCADA (as well as P&IDs) which means site engineers and operators find it easy to relate to. The schematic contains vast amounts of information that is elegantly presented through the use of dynamically coloured icons, connections and attribute displays. In addition, it can now be exported to configure initial OPM reports that will facilitate pre-APC analysis and identification of optimization opportunities.
Fig.10: The APET schematic development process First the S88/S958 containers (Site, Area, Process-Cell, Unit) are created and connected to one another (using appropriate directional connections to indicate material types) to represent the high-level process flow (Figure 11).
3.5 Advanced Process Control (APC) Implementation of APC was the original motivation for developing APET and it still remains part of its core focus. Internally to APET it is possible to deploy fuzzy, rule and model based controllers. The Mamdami-type fuzzy controllers are supported by the Fuzzy Inference System (FIS) module that has been developed to closely integrate with the Matlab Fuzzy Logic Toolbox. It provides powerful membership function editors and viewers that assist with the tuning of these systems (Figure 13).
Fig. 11: Example of process cells found in an area Next, the various equipment (Mills, Reactors, Sumps, Pumps, Valves, etc) are added and assigned to their respective units. These are also connected up to represent the process flow. Field instruments (Flow, Temperature, Pressure, Weight, Status etc) are now added and connected (directly or inline) as appropriate. These instruments collect measurements from the PLC, validate and filter the values before making them available for trending, calculations and control. This is followed by derived instruments that are used to calculate various inferential values. Several calculations are configured automatically while the others can either be procedural or graphical. Either way, all calculations support relative referencing to improve reusability. All instruments are assigned with the appropriate engineering unit and some unit conversions are also available. The final step, before APC implementation is commenced, is the addition of base layer control objects to represent the PID and other controllers that reside in and are executed by the PLC/DCS
Fig. 13: Fuzzy membership functions monitoring showing the functions, overlaid with recent data that are used to classify the rate of change of an instrument’s reading.
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As indicated before, APET also supports the implementation of external control algorithms like MPC. APC controller objects are also added to the schematic and connected to the appropriate objects to clearly indicate its controlled and manipulated variables as shown in Figure 14.
4. SUMMARY An integral key element in Anglo Platinum’s control vision of achieving successful and sustainable optimal plant performance is the APET product suite. This product suite has evolved over many years, over which many lessons have been learned that justify the current approach and methodologies. The continued expert supervision strategy is actively endorsed at the highest management levels and made possible by the wide deployment of APET across all its operations. Oversight is provided by a multidisciplinary team of very capable and motivated engineers that endeavours to build key partnerships with various members of the process control industry. These partners provide a solid support base for the APET product suite, enable rapid enhancement of various components and ensure adherence to Anglo Platinum standards. Investing in a proper industrial IT infrastructure has not only guaranteed reliable communications at site level but also made it possible to access the system from anywhere in the world. This greatly improves the effectiveness with which a small team of engineers can maintain multiple systems across a large geographical area.
Several predesigned templates exist that ensure that a new controller can be deployed within a matter of hours. Once loaded, some of these templates will auto configure based on existing relationships found in the schematic while others are easily configured through simple drag-and-drop operations. During a controller setup all of its trends, additionally required GRT blocks, message queue and relationships are automatically created and/or configured. This provides for properly standardized controllers that are easy to maintain.
The APET contains several features that enhance reliability and sustainability of deployed applications. These features include: A dynamic visual environment that exploits the power of intelligent schematics to represent the asset model and control logic. Templates that make it possible to reuse predefined structures and modules. Automated configuration, that leverages the strengths of the relational object orientated environment, allows for increased speed in application deployment and also reduces user error. Automated diagnostic checks that guarantee valid system configurations and optimal performance. Integrated solutions that provide for a single point of configuration. A holistic automated version control system that facilitates backups, distribution of updates, work synchronization and record keeping.
Fig. 14: Example of an APC implementation. This APC controls the sump level and discharge density by supplying set points to the make-up water and discharge flow PID controllers. 3.6 Process States and Key Performance Indicators (KPI) Another key ability of APET is the calculation and monitoring of equipment and controller states and objectives. All of which can also easily be added to the schematic by selecting from sets of predefined templates. Process states are prioritized and used to govern the controller with respect to what is currently happening on the process, like detecting a significant upset condition. Depending on the active process state, the frequency and/or magnitude of the control actions may be adjusted, or an alternative control algorithm may be implemented all together. These states are logged in the historian for categorization of the data during analysis. Key performance indicators, such as stability and specific energy consumption, are defined for most equipment and rolled up to the respective advanced controllers. These are combined to form the objective functions for the controllers that are used to measure the controller success and benefits.
REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.
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en.wikipedia.org/wiki/model_predictive_control solomononline.com subversion.tigris.org www.angloplatinum.com www.bluesp.co.za www.gensym.com www.idxonline.com www.isa.org: ISA-TR88.95.01 www.mathworks.com www.met.sgs.com/advanced_process_control_met_ www.opcfoundation.org www.osisoft.com www.python.org www.randcontrols.co.za www.sjsoft.com
A Sustainable Approach to Process Optimization through Integrated Advanced Control Software Standards D.J de Clerk*, P.G.R de Villiers **, G Humphries*** *Process Control Technology Specialist, Anglo Platinum, Control and Instrumentation Department, Johannesburg, South Africa (Tel: +2711-3736622; e-mail: [email protected]) **Lead Process Control Engineer, Anglo Platinum, Control and Instrumentation Department, Johannesburg, South Africa (Tel: +2711-3736449; e-mail: [email protected]) ***Head of Technology, Anglo Platinum, Control and Instrumentation Department, Johannesburg, South Africa (Tel: +2711-3736503; e-mail: [email protected]) Abstract: Anglo Platinum’s process control department has succeeded in establishing a robust, sustainable advanced control architecture that facilitates the rapid expansion of its automation and optimization strategy across its concentrator, smelter and refinery operations. This paper discusses the various components of this architecture that led to and contributes to the widely recognized impact that it has on driving Anglo Platinum’s mission to be the world’s number one producer of safe, profitable Platinum. Keywords: Advanced Process Control, Integrated Expert Systems, Platinum Processing control systems, require a solid foundation, support structure and monitoring philosophy in order to make them sustainable. Consequently Anglo Platinum embarked on a journey to identify and fill all the gaps that were hindering its vision. It took several years, but the rapid increase in the control footprint over the last three years has made it all worthwhile.
1. INTRODUCTION In the early 1990’s, Solomon Associates2 conducted a study to determine the key factors that influence the profitability of oil refineries. Somewhat surprisingly it was found that the only two factors with high statistical significance were the staff’s education level and the degree to which advanced process control (APC) was utilized. Consequently, approximately 15 years ago, Anglo Platinum4 started with a vision to achieve optimal plant performance through continued expert supervision. This vision has driven the evaluation of several control related technologies, and has provided the motivation to keep going despite some setbacks. Throughout these years it became clear that technology is no longer the barrier to successful APC implementation, but rather the way in which it is applied. By combining the bestof-breed features found in various technologies, Anglo Platinum has derived an integrated product suite that provides all the tools required by its small group of control engineers to design, deploy and support an ever growing control footprint. These tools, that is centered on a Gensym G26 based Expert System, is known as the Anglo Platinum Expert Toolkit (APET) product suite.
Fig. 1. APC count at Anglo Platinum’s operations over the past thirteen (13) years.
1.1APC Footprint at Anglo Platinum
2. ARCHITECTURE OVERVIEW
Figure 1 shows the number of advanced controllers that have been successfully deployed throughout the various Anglo Platinum operations over the past 13 years. Most of these controllers have an uptime exceeding 95%. Evident from Figure 1 is the initial downward trend in the number of deployed controllers utilized by the operations. This emphasized the fact that control systems, especially advanced 978-3-902661-73-9/10/$20.00 © 2010 IFAC
Figure 2 demonstrates the various layers and components that make up and support the APET product suite. Each layer of the schema contributes in a unique manner to the APET functionality. APET forms the “middle layer” between the Programmable Logic Controller (PLC) and the Operational
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Performance Monitoring (OPM) layers. The effective functioning of each layer is dependent on the performance of the layer that feeds into it. The functionality provided by the APET middle layer ensures a robust and holistic approach to process optimization. This paper will discuss some of these in more detail with a specific focus on the G2 based APET.
2.1.3 Subversion (SVN) In a rapidly developing and expanding environment like the APET footprint, effective and reliable version control is critical. Anglo Platinum operates a central SVN3 repository that is used to ensure all modifications to all applications are always made to the latest version and can always be tracked and/or reverted. SVN also doubles as a backup architecture in that all modified applications are automatically pushed to the repository on a daily basis. Furthermore it serves as a deployment tool through which the latest version of APET is deployed to all operations on a daily basis. In order to maximize the potential of SVN and to cater for certain characteristics of G2, a G2 based SVN client has been developed that facilitates the integration with this exceptionally powerful and useful open source product.
OPM
Central
(OSI AF, PI, Matlab, Statistica)
PMDB + AMDB (Excel + MSSQL)
ACM (G2)
SVN APC Dashboard
MPC
Historian
(DMC+, Prime)
APET (G2)
(InSQL, PI)
(Excel, Matlab)
APC Database
Site
(J5)
2.1.4 iDX and Unifig
iDX + Unifig SCADA (WinCC, Citect)
Anglo Platinum standardized on using iDX7 to facilitate the communication between various components of the APET product suite. iDX is a South African developed middleware product. As illustrated in Figure 3, it is centred on a collection of data slots that each contains a single current value along with an associated timestamp and quality. Surrounding this slot collection are one or more driver modules that can read from and/or write to these slots. Each driver module can in turn collect data from or send data to an external system.
PLC (Siemens, Rockwell, Moore)
Fig. 2: APET product suite. 2.1 Site Layer The lower part of the illustrated schema is currently implemented on several concentrator, refinery and smelter operations within Anglo Platinum. This consists of:
iDX Components
G2
2.1.1 PLC/DCS and SCADA
DB
Realtime or DB
HDD
SQL
Driver Modules External Systems
As a result of the numerous operations of different types, age and background where APET is deployed, it is inevitable that different PLC (programmable logic controller), DCS (distributed control system) and SCADA (supervisory control and data acquisition) platforms need to be accommodated. Generally, communications to higher level applications is done via the SCADA layer, however, it is also possible to communicate directly with the PLC. Similarly, most communications are OPC11 based, but where required, custom protocols have been deployed. Over the years, Anglo Platinum has refined and consolidated its PLC coding standards, but unfortunately it has seldom been economically viable to reengineer existing PLCs. Hence it is also unavoidable that APET should cater for varying code structures at this level.
G2 Client
Data Logger
OPC Client J5, DMC, Prime, Other iDX
HDD Data Playback
OPC Server
SLOTS TCP Client TCP Server Other iDX
TCP Server
OPC Client
TCP Client Custom
Other iDX, iDX MC
OPC Server PLC/SCADA, Analyzers, Other iDX
Various
Fig. 3. iDX architecture. While iDX is utilized in a continuous real time fashion, Unifig is utilized in a periodic offline manner. Unifig has the ability to query the structure of a PLC and then expose the information to external systems. Unifig can be used to automatically configure the plant historian with all the desired tags that exist in the PLC and automatically tag up the various objects in APET. This results in a perpetually current standardized historian configuration saving time, resources and reducing errors associated with manual configuration.
2.1.2 Historian When Anglo Platinum first embarked on its process control vision, few of the sites had proper historians. This had to be corrected as the historian provides vital information needed to perform proper operational performance monitoring (OPM) and analysis. Once again different historians have been deployed to the different operations and site specific needs are catered for. Typically the historians collect their data from the PLC/SCADA layer via the same OPC server utilised by APET.
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any controller implemented in APET. From here the user can view and interrogate all the relevant controller data, states, messages, and tuning parameters at a single glance. Once again, as a result of the integrated nature of the APET products, there is no need for manual configuration of these dashboards. All configurations, like controller layouts and various tag allocations, are simply read from the preconfigured APET structure.
2.1.5 Anglo Platinum Expert Toolkit (APET) Through several years of development and refinement by Anglo Platinum and various partners, APET has matured into an exceptionally powerful tool that stands at the centre of many of Anglo Platinum’s control department’s successes. APET, which was originally built on SGS’ MinnovEX Expert Technology (MET)10, is based on Gensym’s G2 and enables its users to rapidly capture the asset model of an operation in a very strong relational, object-orientated and visual environment. The core original intention of APET was the implementation of advanced controllers. However, due to its logical and intuitive structure, it fast became the reference point for several other applications. Instead of configuring various applications individually with essentially the same information, APET is now able to auto configure them based on its own configuration. This leads to a single point of configuration, and one version of the truth. APET will be described in more detail in section 3.
2.1.7 Model Predictive Control (MPC) Internally to APET it is possible to implement various different control algorithms, including fuzzy, rule and model based control. Certain other control algorithms require more dedicated software.
2.1.6 APC Database – J5 The data found in the historian makes it possible to monitor operations’ performance. However, for APC design, monitoring and tuning, more detailed information is required that cannot be stored cost effectively in the plant historian. Therefore, Anglo Platinum has standardized on installing a J515 historian alongside each APET site instance. Like iDX, J5 is a South African product that has been developed in close collaboration with Anglo Platinum. It is developed in the Python13 programming language and used to populate a Microsoft SQL Server database with data collected from iDX via OPC. Over the years it has been refined and integrated with the APET product suite to such an extent that it is essentially completely auto configured. The data that is captured by J5 is stored on site, but also rolled-up and stored centrally. All of this data is made available to various components of the APET product suite such as APET itself and OPM, but also externally to other clients like Matlab9 and Microsoft Excel.
Fig. 4: APC dashboard example showing a controller with 4 input fuzzy membership functions and 2 outputs. Anglo Platinum selected two MPC1 partners5,14. Both of their platforms interface with the plant via APET. All data is received and validated by APET before passing it on to the MPC algorithms via iDX. The necessary setpoint changes are then calculated and returned back to APET. Depending on various process states and conditions these setpoint changes are then propagated to the PLC or discarded. Wrapping the MPC algorithms inside of APET in this manner provides for rapid deployment of new MPC controllers that forms part of a bigger robust hybrid solution.
2.1.7 APC Dashboard
2.2 Central Layer
The APC Dashboard has been developed to allow external interrogation of the advanced controllers within APET without unnecessary access to the rest of the APET application. The APC Dashboard is deployed on two platforms, Excel and Matlab, each communicating with APET via the Gensym ActiveX-Link. The Excel based dashboard provides a configuration frontend that makes use of Excel’s powerful user-interface to capture various tuning parameters and configurations used by the different control algorithms implemented in APET. Since Excel is readily available and used by site metallurgists, it provides a cost effective interface into APET for adjusting control limits and targets.
The upper part of the schema shown in Figure 2 is implemented at Anglo Platinum’s head office in Johannesburg that has a network link to all Anglo Platinum’s operations. This layer consists of: 2.2.1 APET Central Monitor (ACM) Given the number of APET installations across Anglo Platinum’s operations, it made sense to develop a central monitoring tool to focus mainly on the infrastructure health (Figure 5). ACM is also a G2 based application that has a fulltime G2to-G2 connection to each one of the APET instances on the operations. It immediately highlights whenever any of the APET instances becomes unreachable, and it also provides the facility to query all APET instances for various bits of
The Matlab based dashboard capitalizes on Matlab’s superior trending capability. This application, which has been locally developed by Anglo Platinum and its partners, provides the user with a neatly consolidated, real time view (Figure 4) of 117
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information like which sites are currently running, how many controllers are currently on and how are they performing.
2.2.2 Asset Model Database (AMDB) and Process Model Database (PMDB) Historically, the operational performance monitoring (OPM) application was configured manually by means of Matlab scripts. This proved to be tedious and error prone and the configuration was subsequently moved to a database (PMDB) based structure. This still required lots of manual configuration of information that was already neatly captured in the APET applications. Hence the AMDB was developed to store the asset models that were captured in APET. Now queries against AMDB are used to populate PMDB from which OPM collects its configuration. AMDB also contains lots of additional information that will be used in future versions of the monitoring packages. 2.2.3 Operational Performance Monitoring (OPM) The OPM subdivision of Anglo Platinum’s control department plays a vital role in identifying optimization opportunities as well as monitoring existing controllers’ performance.
Fig. 5: ACM front page listing all APET instances overlaid on a map of the Platinum Rich Bushveld Ignenous complex. ACM subsequently grew into the role of asset model collector. Here its purpose is to collect the asset models from the various sites, make them available for inspection (Figure 6) and also export them to the asset model database (AMDB). Finally ACM was enhanced with the APET quality assurance (AQA) module. This module is capable of starting each of the APET site applications on an offline server, using the latest version of APET, and then compiling a report based on various metrics and diagnostic checks. This essentially performs automated beta testing and greatly reduces the risk of upgrading the APET site applications to newer versions of APET that contains new or enhanced functionality and/or bug fixes.
Fig. 7: OPM daily report example showing the stability analysis on one of the sensors This is realized by utilizing several tools, of which the Matlab and OSI PI AF12 components are the biggest beneficiaries of the APET product suite. These systems receive their configuration from APET (via ACM and AMDB), and based on this information generate automated periodic reports (Figure 7). These reports are used to guide the operations’ management and control engineers to achieve optimal performance from Anglo Platinum’s assets. 3. ANGLO PLATINUM EXPERT TOOLKIT (APET) Gensym G2 is a fourth generation object orientated programming environment that combines a real time inference engine within a graphic environment to facilitate rapid application development and deployment. APET is a modularized layered G2 application that has been developed to fully exploit its powers in order to optimize Anglo Platinum’s assets. Some of its features will be described in this section.
Fig. 6: ACM asset model tree example showing the various S88/S95 layers
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3.1 Utilities Some of the other utilities in turn are focused on integration with external systems. These include command line driven applications like SVN, ActiveX controls in programs like Excel and Matlab, and other G2 applications like ACM.
Anglo Platinum has designed and developed several generic utilities, which are not necessarily part of the standard G2 installation, to help improve the development and user experience of APET and other G2 applications like ACM. These tools play a vital role in ensuring a small effective but efficient base that can support the maximum possible number of closed-loop controllers.
3.2 Graphical Rules Toolset (GRT) GRT is an important foundation module in APET that provides for the construction of easy to follow data flow logic diagrams (Figure 9).
Fig. 8: Dynamic popup menu example indicating how connection stubs are created while considering the allowable connection types. Code that assists with layout, organization and standardization of objects provides structures that are easy to follow and navigate. Various code execution management features ensure that developers and users are always aware of what is happening, while prioritized event queuing and logging control execution sequences and avoid unnecessary duplicated processing.
Fig. 9: GRT logic example that shows how the internal attributes of an instrument is calculated and represented. The ever growing library of GRT blocks offer data collection from external systems, single and multiple input calculations, data qualification, filtering and much more. The GRT engine has been highly optimized and a typical APET application performs several thousand GRT executions every second.
Substantial effort has gone into providing an efficient, intuitive user interface that is focussed and responsive even over slow long distance networks. Dynamic overhead and popup menus (Figure 8) have been designed that not only provide the user with quick access to relevant functionality, but also provides useful information on the selected object.
3.3 Communications The communications (comms) module is another critical foundation module in APET. It provides several communication masters that establish and maintain, with auto recovery, links to external systems that typically also run as windows services like iDX, J5, SQL, and other G2 applications. Furthermore, it contains all the class definitions and code that enables thousands of data points to be read and written every second to and from iDX. It is from this module that integration with most other components of the APET product suite is driven. This module compiles all configuration files for the various iDX services, setup the tags within the J5 database, facilitates communication with the MPC programs and determines the relevant historian tags for OPM purposes.
Highly efficient dialog utilities have been created to facilitate user input and configuration operations. All of these are integrated with the user authentication system that restricts users’ actions as required. To supplement the version control gained through the integration with SVN, all editing of code structures are recorded as an additional backup. Code copyright is preserved through appropriate text stripping without hampering troubleshooting ability. Performance and health of an APET application are continuously monitored and reported. This is complemented with a set of predefined, categorized diagnostic checks that report on any unexpected settings or configuration. These ensure that all standards are adhered to, that all references are intact and that no error condition goes unnoticed.
3.4 Schematic The schematic provides invaluable structure and context to all the objects and data in an APET application. It is used to capture (explicitly and implicitly) several important relationships between the various assets present on an operation. This relational asset model forms the basis of most of the reasoning and referencing in APET as well as the source of the exported OPM configurations.
The system provides useful tools to manage, preserve and trend variable history with minimal performance impact. Used in conjunction with a periodic screen capture feature, these play a key role during operation monitoring and controller tuning. 119
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The reuse of pre-existing templates is strongly encouraged and well supported by APET. It is possible to copy-andpaste entire sections of existing schematics without the need for major reconfiguration and therefore engineering time is substantially reduced, especially given the large number of similar processes across Anglo Platinum’s operations.
(Figure 12). All objects in the schematic are automatically named according to a predefined naming convention that only expects a unique ID. The internal logic of the objects is represented by special subclasses of the GRT blocks that have been combined in predefined templates. Throughout these steps, the various comms slots need to be tagged in order to establish communications with the PLC and other external applications. This process is simplified through the use of the APC-Dashboard and Unifig integration.
Constructing the schematic consists of a couple of steps and is in many ways an iterative process as shown in Figure 10.
Fig. 12: Example of equipment, instruments and basic controllers found in a process cell At this point, the APET application closely resembles the site SCADA (as well as P&IDs) which means site engineers and operators find it easy to relate to. The schematic contains vast amounts of information that is elegantly presented through the use of dynamically coloured icons, connections and attribute displays. In addition, it can now be exported to configure initial OPM reports that will facilitate pre-APC analysis and identification of optimization opportunities.
Fig.10: The APET schematic development process First the S88/S958 containers (Site, Area, Process-Cell, Unit) are created and connected to one another (using appropriate directional connections to indicate material types) to represent the high-level process flow (Figure 11).
3.5 Advanced Process Control (APC) Implementation of APC was the original motivation for developing APET and it still remains part of its core focus. Internally to APET it is possible to deploy fuzzy, rule and model based controllers. The Mamdami-type fuzzy controllers are supported by the Fuzzy Inference System (FIS) module that has been developed to closely integrate with the Matlab Fuzzy Logic Toolbox. It provides powerful membership function editors and viewers that assist with the tuning of these systems (Figure 13).
Fig. 11: Example of process cells found in an area Next, the various equipment (Mills, Reactors, Sumps, Pumps, Valves, etc) are added and assigned to their respective units. These are also connected up to represent the process flow. Field instruments (Flow, Temperature, Pressure, Weight, Status etc) are now added and connected (directly or inline) as appropriate. These instruments collect measurements from the PLC, validate and filter the values before making them available for trending, calculations and control. This is followed by derived instruments that are used to calculate various inferential values. Several calculations are configured automatically while the others can either be procedural or graphical. Either way, all calculations support relative referencing to improve reusability. All instruments are assigned with the appropriate engineering unit and some unit conversions are also available. The final step, before APC implementation is commenced, is the addition of base layer control objects to represent the PID and other controllers that reside in and are executed by the PLC/DCS
Fig. 13: Fuzzy membership functions monitoring showing the functions, overlaid with recent data that are used to classify the rate of change of an instrument’s reading.
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As indicated before, APET also supports the implementation of external control algorithms like MPC. APC controller objects are also added to the schematic and connected to the appropriate objects to clearly indicate its controlled and manipulated variables as shown in Figure 14.
4. SUMMARY An integral key element in Anglo Platinum’s control vision of achieving successful and sustainable optimal plant performance is the APET product suite. This product suite has evolved over many years, over which many lessons have been learned that justify the current approach and methodologies. The continued expert supervision strategy is actively endorsed at the highest management levels and made possible by the wide deployment of APET across all its operations. Oversight is provided by a multidisciplinary team of very capable and motivated engineers that endeavours to build key partnerships with various members of the process control industry. These partners provide a solid support base for the APET product suite, enable rapid enhancement of various components and ensure adherence to Anglo Platinum standards. Investing in a proper industrial IT infrastructure has not only guaranteed reliable communications at site level but also made it possible to access the system from anywhere in the world. This greatly improves the effectiveness with which a small team of engineers can maintain multiple systems across a large geographical area.
Several predesigned templates exist that ensure that a new controller can be deployed within a matter of hours. Once loaded, some of these templates will auto configure based on existing relationships found in the schematic while others are easily configured through simple drag-and-drop operations. During a controller setup all of its trends, additionally required GRT blocks, message queue and relationships are automatically created and/or configured. This provides for properly standardized controllers that are easy to maintain.
The APET contains several features that enhance reliability and sustainability of deployed applications. These features include: A dynamic visual environment that exploits the power of intelligent schematics to represent the asset model and control logic. Templates that make it possible to reuse predefined structures and modules. Automated configuration, that leverages the strengths of the relational object orientated environment, allows for increased speed in application deployment and also reduces user error. Automated diagnostic checks that guarantee valid system configurations and optimal performance. Integrated solutions that provide for a single point of configuration. A holistic automated version control system that facilitates backups, distribution of updates, work synchronization and record keeping.
Fig. 14: Example of an APC implementation. This APC controls the sump level and discharge density by supplying set points to the make-up water and discharge flow PID controllers. 3.6 Process States and Key Performance Indicators (KPI) Another key ability of APET is the calculation and monitoring of equipment and controller states and objectives. All of which can also easily be added to the schematic by selecting from sets of predefined templates. Process states are prioritized and used to govern the controller with respect to what is currently happening on the process, like detecting a significant upset condition. Depending on the active process state, the frequency and/or magnitude of the control actions may be adjusted, or an alternative control algorithm may be implemented all together. These states are logged in the historian for categorization of the data during analysis. Key performance indicators, such as stability and specific energy consumption, are defined for most equipment and rolled up to the respective advanced controllers. These are combined to form the objective functions for the controllers that are used to measure the controller success and benefits.
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en.wikipedia.org/wiki/model_predictive_control solomononline.com subversion.tigris.org www.angloplatinum.com www.bluesp.co.za www.gensym.com www.idxonline.com www.isa.org: ISA-TR88.95.01 www.mathworks.com www.met.sgs.com/advanced_process_control_met_ www.opcfoundation.org www.osisoft.com www.python.org www.randcontrols.co.za www.sjsoft.com