Every monitoring situation has challenges, but keeping tabs on a wind turbine presents a special list, one that includes extreme and varying weather, frequent load changes, and often in remote unmanned locations. The mechanical stresses that variable winds place on turbines demand real-time monitoring for the recognition, notification, and logging of failures as well as prevention of future failures through predictive logic based on a turbine’s monitored conditions and its history.
Sensors that monitor temperatures, pressures, vibrations, and more are one part of a condition-monitoring equation. Software to make sense of the signals is the other half. The software should install easily and then let users configure it for real-time monitoring, event detection, notification, logging, reporting, and presentation of measurement data and the abnormal condition events. This task may be simplified if the data and monitoring software support vendor-neutral protocols and interfaces such as OPC and SQL.
Condition monitoring software should be able to read the data, aggregate the data, and take action on it, action such as:
Current measurement and aggregate data monitoring. This capability requires detecting abnormal events defined by the behavior of data, while the required data may extend beyond the current measurements provided directly from instrumentation. Conditions may be defined by aggregated measurement values as well as aggregated event activity (e.g. event or alarm flooding – a high frequency of alarm activity).
Current measurement condition monitoring defects is the ability to monitor and recognize abnormal conditions of the current measurement values.
Aggregate-data condition monitoring determines abnormal conditions through the analysis of multiple values. The multiple values may be previously scanned values of a single measurement (recent history aggregate), or current values from multiple measurements.
Single-measurement aggregates provide calculated results using recent history of a single measurement. For example, vibration data can have wide swings of current value measurements. For example, TopView lets the user monitor calculated results such as “five-minute average” or “10 minute standard deviation” by caching recent history and calculating the desired aggregate value.
Multiple measurement aggregates are calculated on the current value of multiple measurements. These aggregates maintenance teams monitor data such as summations of multiple measurements and differences between measurements. For example, monitor the total load of five turbines or the load difference between two turbines.
Aggregate-event activity summarizes current and recent event activity as data values that can be monitored for abnormal behavior. These event statistics can be used to recognize higher-level events such as “more than five turbines currently have abnormal vibration measurements” or “there have been more than 10 temperature alarms in the last hour.” Such situations may be difficult to recognize without the proper condition monitoring tools, yet they provide significant value by monitoring overall health of the condition monitoring system.
Recognizing abnormal conditions
Once measurements and aggregates are available for monitoring, users can instruct the software to recognize abnormal conditions. These events may signal a current alarm condition, or warnings of potential alarms if the condition worsens. In addition to recognizing unexpected values of monitored data (greater than or equal to…) the conditions may include delays (exists for a period of time), deadbands, and blackout periods.
Examples of abnormal conditions: temperature above threshold for 2 minutes, power output too low for speed, acoustic volume too high for 5 minutes, and 5-minute average vibration trending up for one hour.
Log and notify
Once abnormal conditions (“alarms”) are recognized, they are logged and optionally sent as notification messages to ensure that the appropriate personnel are aware of them. Notifications can be sent through email, SMS/text messages, pagers, and phones. What’s more, if recipients do not acknowledge receipt of the notification, the message can be escalated to additional personnel to ensure that it is eventually received.
In addition to notification at the time of the event, the software provides multiple views of the monitored data and events.
A client application provides real-time displays of current values and alarms, audible signals of abnormal events, browsing of event history, and tools for performing event analysis (frequent alarm points or alarm flooding).
Alarm reports (event summaries over time) can be generated interactively or scheduled and emailed. Web-friendly HTML displays of current values and alarms can be stored, viewed, and published. RSS feeds of events allow combining event data into mobile devices and web pages.
Having the tools to successfully monitor abnormal wind turbine conditions, notify the appropriate personnel, and empower them to respond accordingly, can save a tremendous amount of time and money. TopView’s breadth of features and ease of use provides a powerful and versatile do-it-yourself solution that has been proven successful across many industries including multiple wind farms. WPE
By: Dane Overfield/Software Product Development Lead, Exele Information Systems Inc., www.exele.com
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