TIGER

Tiger Oh

Knowledge Based Gas Turbine Condition Monitoring

Summary of Functionality

Contact Details

 

Sermatech Intelligent Applications

1 Michaelson Square

Livingston

West Lothian

Scotland.  UK

EH54 7DP

Tel: +44 (0)1506 47 20 47

Fax: +44 (0)1506 47 22 82

Email: ia@intapp.co.uk

WWW: http://www.intapp.co.uk

The Tiger knowledge based gas turbine condition monitoring system uniquely provides on-line continuous diagnostic interpretation of data available from a gas turbine controller. Not only does this provide early warnings of any developing problems, but also a rapid diagnosis of any trips or unexpected failures. Furthermore, because Tiger performs continuous diagnostic analysis, the Tiger system builds up a complete picture of all the faults and problems that have occurred on a gas turbine. This includes any momentary blips or minor problems or other small deviations which might be the only warning of a future problem.  This provides the information needed to enable condition-based maintenance. Other approaches only give a periodic snapshot of the state of the gas turbine.

Tiger's knowledge based analysis makes an assessment of the condition of the gas turbine based on its behaviour while operating. This unique interpretation of the dynamic behaviour and reactions to changes provides a very powerful diagnostics view of the health of the gas turbine. Tiger also complements other approaches to condition monitoring.

Maintenance

Corrective Including Emergency Maintenance

Planned Maintenance

Preventive Maintenance

Scheduled Maintenance

Condition Based Maintenance

Condition Monitoring

Unplanned Maintenance

Behaviour Monitoring

Tiger: Condition Assessment

Vibration Monitoring

Oil Analysis

Visual Monitoring

 

This document gives a short summary of the main functionality of Tiger from the users viewpoint. When the Tiger system was developed considerable thought was given to the range of functionality and support an engineer would require to understand the state of the gas turbine and to troubleshoot any problems. As a result, Tiger provides a wide range of functionality not available in other systems.

OPERATING MODE

Tiger Overview Screen

The Tiger system continuously collects and analyses data from the gas turbine controllers. A diagnostic analysis of the gas turbine is performed every second. This analysis is viewed through reading the Fault Manager diagnostics messages instead of having to graphically review data. Any events can be replayed for later analysis and investigation. The full functionality of Tiger can easily be access remotely. Time is saved since one can initially download diagnostics, not data. A remote Tiger connection can also be used to monitor the gas turbine operation live. Depending on the configuration of the computer, the on-line Tiger system can store at least four months of continuous, once per second data on the local hard disk. At monthly intervals, backups are made so that all data is permanently retained. Tiger also continuously builds overview trends and calculates the performance of the turbine (assuming the appropriate instrumentation is fitted.)

The other main operating mode for Tiger is the off-line data replay mode. Using this mode, the user can enter the time of an event and Tiger will replay the once per second data for that time interval. Data of interest can also be selected visually from the trend graph and by a few simple mouse clicks, unusual events can be selected and replayed with the complete diagnostics.

Tiger Compressor Sub-System Overview Screen

The replay mode allows the user to replay and analyse over and over again the same data set that is of interest. It also includes a single step facility to allow the user to step through the data one second at a time. This includes the ability to freeze the data replay to allow the user to examine the data from different viewpoints.

USER INTERFACE 

The Tiger system uses a state of the art user interface, organised in such a way to give the operator a rapid understanding of the state of the gas turbine. Uniquely within Tiger, this includes mimic views of the main sections of the turbine, as well as engineering schematic views of the critical sub-systems. The operating diagrams include over a dozen displays of the main sub-systems of the gas turbine such as: 

Tiger Exhaust Spread Overview Screen with Diagnosis

q  compressor                                                                                                                                                

q  fuel system

q  exhaust temperature spread                                                                                                            

q  wheelspace thermocouples

q  vibration measurements                                                                                      

Each screen is organised to give a clear understanding of the critical parameters affecting that part of the system.

Tiger Gas Fuel System Schematic Screen

The optional engineering schematics give a schematic view of the primary sub-systems of the gas turbine to allow the engineer to understand, at his level, the current state and follow the operation of the gas turbine. This includes schematics for systems such as: 

q  cooling air             

q  cooling water

q  hydraulic system   

q  inlet guide vanes

q  starting means      

q  steam injection system

q  fuel system           

q  lube oil system

 

Tiger trends ISO Corrected Performance & Heat Rate

Performance

The Tiger system includes information about the performance of the gas turbine including a generator performance curve display and a continuous calculation of the gas turbine efficiency, if the appropriate instrumentation is available.

NOx Emission Levels

NOx Levels

The Tiger system can report on NOx emission compliance and indicate whether the turbine is above the consent or maximum allowed level.

TIGER DIAGNOSTICS

The heart of the Tiger system is its on-line continuous diagnostics. Given the complexity of a gas turbine, it is impossible to precisely diagnose everything. Faults that have been anticipated or seen by Tiger before, will have diagnostic analysis in place and will give, as clear as possible, a conclusion to the end user. However, because of the complexity of a gas turbine system, many problems which will occur, no one has seen before.

In this situation, Tiger does the best job it can to consolidate the fault detection and low-level diagnostic messages. With this strategy, Tiger is always helpful from identifying that something unusual has happened by focusing on the sub-system where the problem occurred to, in many cases, providing a clear and concise diagnosis.

The Tiger fault manager in a hypertext format presents the diagnostic output. A quick examination of the top level display of the fault manager gives the user a rapid summary of the state of the gas turbine and whether any important incidents have taken place. All messages are colour coded to indicate their importance as well as the areas they apply to, for example:

Tiger Fault Manager Output

q  High level diagnostic conclusions    

q  Critical fault indications

q  Warning indications        

q  Summaries of faults related to a specific sub-system

q  Low level fault detection messages                

The diagnostics are organised as a hypertext tree so that initially the user only sees the top-level conclusion. By using the mouse, the user can examine the events leading to that conclusion and continue down to the lowest level of detailed messages. In addition, the fault manager contains a complete time oriented summary of all the messages so the user has the choice of seeing all the Tiger fault detection and diagnostic messages in time sequence, or seeing them organised logically by the diagnostic process.

The Tiger diagnostic system is organised with several levels of hierarchy.

q  Fault Detection

Tiger Fault Manager Explanation of a High Level Conclusion

The purpose of this level is to detect any abnormalities or unusual events on the gas turbine. Tiger uses a variety of proprietary techniques and currently within the Tiger system, there are over 4000 fault detectors checked every second. These vary from simple context sensitive limit checkers to specialised mechanisms to ensure the dynamic response of the turbine is as it should be.

q  Diagnostic Rules

Using techniques from knowledge based systems, Tiger uses diagnostic rules to specify the correct interaction of parameters and sub-systems within Tiger, and determines whether they are functioning properly or not. This provides a very sophisticated ability to detect whether the working of the turbine is correct. This mechanism uses temporal reasoning techniques to track sequences of events over time.

q  High Level Rules

The Tiger fault manager uses temporal reasoning to combine the results of the fault detection and diagnostic rule levels into higher-level conclusions. Tiger combines the literally thousands of diagnostic checks it performs in a hierarchical fashion so that the user sees a single fault conclusion for a major incident.

q  Accounts For

Once a problem has been identified, the existence of this problem accounts for many other diagnostic messages. Tiger organises the wide range of phenomena that occurs when a problem exists through the ‘accounts for’ set, so that a single conclusion can account for many consequent results. This organises the many events, very simply for the user, and reduces the alarm explosion that can occur during a major incident.

Diagnostic Query

q  Areas 

When it is not possible to provide a concise diagnosis, the fault detection and low level diagnostic conclusions are grouped by areas (sub-systems), such as all the outputs related to the fuel system or the inlet guide vanes or the combustion system. This allows an experienced engineer to rapidly focus on the core problem area and gives him support in determining what problem has just occurred.

q 

Example Page from Tiger's on-line Manuals

Diagnostic Query

Often it is important to identify how often a problem is occurring, or list the most frequent problems.  To identify the most frequently occurring problems, to summarise the diagnostics at a higher level and to provide an easy way to identify the dates and times particular events have occurred, Tiger provides a Diagnostic Query.  The user specifies the date and time range to be queried, any text or message string and optionally a priority level.  Tiger then does a complete search of the diagnostics.  Above is an example of a query of all Critical Level faults in the Gas Fuel systems for the month of November.

ON-LINE MANUALS

In order to support the engineer in the troubleshooting process and understanding the state of the gas turbine, Tiger optionally includes an extensive set of on-line manuals. Currently, there are over 1000 pages of manuals on-line containing the primary operating and sub-system descriptions of the gas turbine.

The on-line manuals are linked directly to the diagnostic output. This means that when the operator sees a diagnostic conclusion of interest, by a simple click of the mouse, he has been taken directly to the appropriate section of the on-line manuals. The manuals themselves are interlinked with hypertext, so the user can navigate and follow a chain of detail in order to determine what he requires.

Tiger Graph Display

GRAPHICAL ANALYSIS OF DATA

Engineers always like to verify their fault conclusions, by examining the raw data related to an incident directly. Tiger provides a sophisticated graphical display facility for this purpose. Tiger collects approximately 600 measurements at once per second intervals, and all this data is permanently retained. Using the data replay facility, the engineer can go back to any past event and examine this once per second data through the user interface or the graph displays. In on-line mode, the Tiger graph is also available to give a live display of the key parameters.

Tiger Trend Screen Showing 24 Hours of Data

The Tiger graph contains six windows that can display up to ten channels simultaneously in each window. The entire graph, or the windows individually, can be displayed at normal resolution, x 2, x 10, allowing the engineer to zoom in on the precise details and timing of any incident.

For ease of use, the Tiger graph normally contains four minutes worth of once per second data. The ‘value’ facility lets the engineer identify the precise value of a parameter and the time in order to permit the rapid identification of the sequence of events for a particular problem.

Associated with the graph facility, and also the primary user interface, is a print facility so that the engineer can print the graphical display of data related to a specific incident. This can then form a permanent record of a specific incident.

 

TREND SYSTEM

A key aspect of any condition monitoring system is the ability to trend the operation of the turbine over a long period of time. The Tiger system contains an innovative and flexible trend construction and display facility. Any of the 600 analog or digital parameters can be trended over any time period specified by the user. These are then displayed through the graph facility, which has the ability to display six graphical windows with up to ten parameters per window. This facilitates examination and comparison of trends across several parameters. 

The Tiger trend can be constructed in a variety of ways. Visually these provide a rapid overview of events on the gas turbine, allowing the user to rapidly detect any unusual spikes, changes or oscillations. The Tiger system automatically builds a trend graph for each 24-hour interval.

An important capability of the trend system is the ability to replay the once per second data directly from the presentation of the trend graph.

The trend graph provides a very powerful way to overview any pattern of response or deteriorations over time intervals from a few minutes, a few hours, a day, week, month, or even a year.

Tiger's functionality has been proven through over 50 fired years of gas turbine analysis and becomes the window into the behaviour of the gas turbine, enabling condition-based maintenance.

Tiger is a Trademark of Intelligent Applications Ltd