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August 5, 2010


PI Information Article

Thanks to Mesalands College in New Mexico for publishing this PI summary article.  This is an excellent overview of the PI system and the tools used to access the data it collects.  The diagrams included in the poached article below are relevant, since they descibe the tools I use and trouble-shoot on a day-to-day basis.  Immediately below is a great comprehensive summary of (OSIsoft) PI System at a high-level.

OSIsoft PI System

  • PI stands for Process Information, which is an intentionally nebulous term designed to describe any and all information generated by any type of process system comprised of electrical or mechanical equipment. 
  • The amount of PI generated by an industrial facility can be enormous, and special software and systems are required to compile it into a useful form.  Several software companies have been successful in marketing PI management systems, including the notable example of OSIsoft, which found its beginnings in the data intensive and data driven petrochemical industry.   
  • Using OSIsoft PI systems, scientific research on the behaviors any type of machinery and equipment can efficiently conducted, as could energy efficiency studies and other critical industrial cost saving measures such as predictive maintenance.
  • In contrast to petrochemical and other large scale industrial facilities, early commercial wind turbines were relatively simple machines, often with vague modes of operation limited to conditions as simplistic as “Run” and “Faulted.”   Modern commercial wind turbines, however, may possess system complexities rivaling those of small factories, with literally thousands of sensors and operational conditions. 
  • With this added complexity, it becomes possible to form a sophisticated picture of the detailed inner workings of the machine during operation and when faulted, provided that the data is collected and made accessible. 
  • SCADA systems (Supervisory Control And Data Acquisition) have existed in the wind industry for over two decades in one form or another, often employing proprietary technologies and custom built equipment and software.  These deployments often interface via multiple communication standards, delivering various formats of data which must then be translated into useful forms by specialized software or human beings. 
  • The shortcomings of these pre-existing data collection and control systems are becoming more and more evident as the maturing wind industry discovers the enormous value of comprehensive data collection in diagnosing existing faults and preventing costly new ones.  As a result, PI management software is gaining acceptance in the wind industry and is providing attractive features to engineering and management figures alike.
  • In simplistic terms, the PI system is usually PC based, and interfaces with industrial equipment that is capable of gathering sensor data and status messages from automated “smart” machines. 
  • The inherent customizability of most PI systems is one of their biggest assets, as data points (known as “tags”) can be generated by customers to represent just about any kind of available process information.  Tags may be written that account for individual temperature, pressure, and vibration sensors, or entire arrays of sensors.  Tag databases are expandable and upgradable, with data points existing in numbers of hundreds, thousands, or even hundreds of thousands, capable of monitoring literally millions of inputs simultaneously and in real-time.
  • Aside from tags that draw from raw sensor data, tags can also be created that utilize status conditions calculated internally by the industrial field equipment being interfaced with.  In a commercial wind turbine, for example, an excessively high electrical current reading may not be of concern unless it occurs in concert with another high reading elsewhere in the machine.  Such a combination of events would trigger a special fault condition in the turbine, and a customized PI tag could be written that accounted for only that event, as opposed to the data provided by the individual current sensors.
  • Once tags are written, the resultant collected data can be archived for as long as the customer wishes to maintain it.  This data is archived in a unified data point standard that enables corporations to share process data with any position within the company (provided they have the proper clearance levels). 
  • The same data accessed by field technicians can be drawn upon by executive corporate management, and every position in between.  One way this data becomes so universally accessible is through the ability of most PI systems to export process information to popular and highly standardized interactive data analysis software like Microsoft ProcessBook and Excel, and speak standardized programming languages like Structured Query Language and Visual Basic.  These abilities alleviate the need to purchase expensive proprietary software suites and retrain employees on how to use them.  Additionally, in this age of global computer networking, it is naturally implied that any PI system is capable of being accessed from any point on the planet via the internet, again, provided that proper clearance levels are granted.
  • PI Software suites like those produced by OSIsoft make it possible to build incredibly comprehensive and highly accessible data management systems that are tailor-made to the specialized demands of the wind industry.   Such process information management is already having positive impacts in commercial wind, as engineers utilize the wealth of new data to improve the reliability of failure-prone and expensive components like gearboxes, and the energy gathering abilities of wind turbine blades.
  • The NAWRTC PI System is capable of tracking 26,000 tags. The GE SCADA system monitors 590 elements, some are value, some are on/off, and some are state (return value correlates to state or condition such as shutdown or maintenance mode)


Typical network connection for OSIsoft PI System.


PI Process Book


PI System Process Explorer Showing Tags


Import into Excel


SQL Data can be accessed by Visual Basic

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