Automatic collection and storage of treatment facility data continues to increase in importance in the water wastewater industry. This data is critical to supporting the increasing needs of EPA/compliance reporting and is the basis for driving operational performance improvements. The advent of historian products extends the ability of a traditional system to effectively store data and efficiently make use of the data.
History on historians
HMI and scada systems are a major source of water treatment data and have been performing the role of application historian at many water plants. Traditional HMI/scada systems used a proprietary data target, ODBC interface to a relational database (RDB), or a simple file format (*.mdb) to allow for manipulation with office automation products. The modest performance of these solutions is suitable in terms of supporting simple operator queries such as viewing recent value trends in flows, temperature, or other analog values.
Although RDBs offer a great deal of flexibility, they can require significant custom engineering for each defined access and can have comparatively slow performance when the queries cover large data sets or associated periods of time. The application historians tend to be tightly linked to the application at hand and do not provide for integration of data from external systems such as LIMS, HVAC/facility control, and/or security systems.
The relatively recent advent of plant-wide or enterprise historian technologies dramatically changes the capability of accessing critical stored data. Enterprise historian products such as Proficy Historian from GE Fanuc are specifically designed to provide high performance from a single, central repository of massive volumes of historical data. An enterprise historian such as Proficy Historian is a high-performance system designed to access up to 100 000 different data points per server, with the capability of transferring 20 000 events per second in and out of the system. This performance exceeds rates that are possible with typical HMI/scada application historian. In addition to raw performance, an enterprise historian allows for easily applied calculated extensions and aggregation of the recorded data at the time of data storage.
Better, faster data
Obviously very little in a water plant changes 20 000 times per second, and this very high data transfer rate may seem excessive or unnecessary. However, the performance of the enterprise historian technology changes the effectiveness of the valuable process data that has been stored.
A simple example would be the need to plot for an entire month the hourly average, value minimum, and maximum value for several inter-related process parameters such as flow rate, turbidity, and pH. These values and their associated tags may be recorded at different logging intervals, and there may even be gaps in the data from device downtime.
This kind of query would be virtually impossible with traditional RDB technology without a tremendous amount of pre-engineering of background software and the development of complex SQL statements and associated table joins. Enterprise historian technology has been specifically designed for optimum delivery of these types of queries and other needs that are based on the real day-to-day dynamically changing requirements. The retrieval and display of critical operational data from a plant historian can be done in a fraction of the time of what could be expected from standard RDB technology. The reality is that in many cases the effort required with traditional RDB technology is such a large obstacle that this type of analysis is never done.
The performance capability of products such as Proficy Historian also allows for the retention of important data for much longer periods of time. Enterprise historians through optimised data compression are able to more efficiently store time-streamed data than RDB through the elimination of unnecessary overhead. This additional data is retained and stored in the enterprise historian without any loss of performance in retrieval. A tremendous amount of energy and integration engineering is expended managing RDB file size and archiving procedures that are not necessary with enterprise historians. Common questions such as the comparison of water quality and rainfall values from this July versus last July are accomplished without jumping through complicated hoops involving data restoration and merging.
Enterprise historians also add capability in terms of data security. Traceability and auditibility are integrated into the data storage technology. The audit trail for the storage and the detailed identification of any data changes to the data are stored with the data itself. RDB technology would typically require extensive custom coding to accomplish the same level of data protection. The end result is that the critical operation data has a higher level of integrity and assures complete compliance with potential EPA audits.
Open for business - enabling the entire system architecture
Built on open architectures, enterprise historians deliver all of this extended capability while being completely compatible with the balance of a water system's IT infrastructure. This starts with the protection of historic investment in scada and existing data retention schemes. Existing historic data can be imported from current repositories including standard RDBs to immediately take advantage of performance capabilities. Enterprise historian software extends the information capabilities of HMI/scada for water wastewater historians like Proficy Historian also have open interfaces allowing runtime data from disparate systems like LIMS and HVAC to be dynamically inserted into a single, secure performance data engine. Finally, existing systems that need to be fed data can access the enterprise historian through standard IT enablers such as OPC, OLE DB and Web-based tools.
A functional architecture depicted in figure 1 highlights the open orientation that is enabled across the enterprise by the use of an enterprise historian. The enterprise historian is served by a series of high-performance collectors. A collector is a high-performance layer of software that aggregates, concentrates, and delivers data into the enterprise historian based on user-configurations.
The following highlights three different collector scenarios:
1. Some of the collectors can be based on the batch import of data through a file-based collector. This allows disparate systems to pass data in a very standard format. The data collector can perform a configurable data aggregation and/or calculations on the incoming data to normalise it with other data in the database and prepare it for optimum access in terms of reporting and manipulation.
2. Proficy Historian is a high performance data engine capable of accepting large volumes of data at comparatively high speeds. Correspondingly, a series of industry standard dynamic data collectors can be configured to accept data directly from runtime support devices such as PLCs, PACSystems, RTUs, and DCSs. Proficy Historian is open-standards based so range of vendors and connections is wide and proven and certainly well beyond GE Fanuc offerings.
3. Proficy Historian does have optimised data collectors specifically for interface to the advanced HMI/scada applications that are prevalent in the manufacturing and industrial environments. These collectors have been specifically integrated into the capabilities available in Proficy HMI/scada for both iFIX and Cimplicity. The robust capability of realtime data monitoring and alarming provides a rich source of data for the enterprise historian application. Proficy Historian does support the collection of information from other HMI/scada products and with open-standards collectors such as those described above for PLCs and other run time systems.
Figure 1 depicts a single centralised enterprise historian server that is receiving data from a wide variety of data collector and associated data sources; this is the simplest of architectures. Historian software extends the information capabilities of HMI/scada for water and wastewater - architectural flexibility that is often necessary for enterprise historian applications. The historian database could alternatively be supported by a number of historian servers that are local to the respective data collectors. These servers can then be networked back to a central enterprise instance of the entire historical database. Proficy Historian provides additional 'store and forward' capability between servers and collectors. If direct network connection is interrupted for any reason, the local collectors will automatically store/queue the data and forward it to the target server when connectivity is returned.
Harvesting the power of readily-accessible data
Much of the discussion to this point has been focused on the aggregation capability and the delivery of a centralised repository of information in the enterprise historian. Clearly the point of storing this data is to foster the effective use of the data for reporting and continuous improvement. Proficy Historian is claimed to provide unprecedented access to this aggregated data in terms of simplicity as well as in terms of access techniques.
To achieve the maximum effectiveness possible, the enterprise historian must provide ready access to the data in easily configurable ways. Proficy Historian allows for runtime applications such as HMI to use stored data in the same way that these applications would use data from RDBs or customised data sources. This historian also provides for access to mainstream, non-IT users through the use of Excel plug-ins into the Microsoft Office environment. Standard reporting capability is provided through standard database access techniques such as OLE DB. The variety of the access and the ease with which it is executed changes the very nature of what is and can be executed.
There have long been technical and organisational barriers to ready access to this data without having to engage large amounts of IT or specialised resources. The removal of these barriers delivers great potential for deriving valuable benefits from the historical data. Because the historian has performed a powerful level of assimilation and aggregation much of what would have been complex data presentation becomes nearly trivial.
Proficy Real-time Information Portal is a utility designed for rapid creation of Web-based access to the information in enterprise historians as well as other data sources. Customised views of the data can be rapidly created for each organisational group across the plant. A supervisor view can be created to allow for overviews of volume data and flow totals.
An operator view can be created that shows critical process variables and associated limits or trends. A compliance view can be created that can act as the format for EPA reporting or state mandated requirements. This data may include a mix of data that originally was collected from a runtime scada system and from manual testing in the laboratory system. Because all of these views are web-based, the user can access them from standard browsers and/or thin-clients such as handheld, mobile PDA computers.
In summary, as the data accountability demands on water treatment facilities continue to increase, enterprise historian technology meets these demands by driving performance, assuring data integrity, and reducing overall implementation costs through off-the-shelf capability. The associated data access can be liberating in terms of usefulness of the data and the resulting benefits derived from rapid analysis.
For more information contact Daniel Coetzee, GE Fanuc Automation, 031 583 2602, [email protected], www.gefanuc.com
© Technews Publishing (Pty) Ltd | All Rights Reserved
printer friendly version