CONDITION MONITORING
FEATURE SPONSOR
ADVANCED ANALYSIS OF CONDITION MONITORING DATA
Ventech Systems specialises in the provision of condition monitoring products and services to the wind industry. Its portfolio is based on an innovative approach to data analysis, derived from many years of experience developing advanced condition monitoring technology for the aerospace sector.
PROBLEMS WITH COMPLEX DATASETS Multichannel vibration measurements captured from rotating machinery provide a very rich source of information regarding the health of the system. However, the complexity of this type of data means that the datasets generated, quickly become very large. For this reason, all such systems employ a front end which automatically ‘screens’ the data (normally on a channel by channel basis) and generates alerts if certain criteria are exceeded. When an alert is triggered, a more detailed analysis of the underlying is undertaken manually to assess the situation.
One of the fundamental problems faced by any system of this type is how to configure the algorithms which undertake this screening process. This involves a tricky balancing act in terms of the sensitivity of the settings; too sensitive and it will produce a plethora of false alarms, making the job for the analyst very difficult; not sensitive enough and there is a risk that potentially catastrophic faults will be missed.
WIND TURBINE ISSUES
Unfortunately, these problems become
particularly acute when applied to wind turbines. The primary reason for this is the extremely variable loading regime that a turbine will experience during its
operational life. This creates
a much greater degree of variability in the measured vibration data, which consequently makes the development of reliable screening algorithms even more difficult than normal.
This both increases the cost of the analysis and reduces the effectiveness of conventional approaches to the screening problem. One consequence is that wind turbine CMS are particularly prone to false alarms, which substantially increases the workload on the operator.
GREATER LEVEL OF AUTOMATION To address this difficulty, Ventech Systems has developed a new approach to the automated screening process. The main difference between this and more conventional approaches is that, in addition to considering the channels of data individually, the analysis also takes into account the relationship between them.
HARMONIC MONITORING FOR WIND FARMS
Resonant circuits within wind farms can be stimulated by harmonic currents arising either from individual turbines or from the local distribution network. At higher levels these can cause the turbines to be shut down by their own internal harmonic protection schemes. Obviously this should be avoided at all costs since manual intervention will be required to restart, leading to lost production.
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www.windenergynetwork.co.uk IDEAL SOLUTION
Wind turbine manufacturer Nordex found the ideal solution for monitoring harmonics at their wind farm sites across the UK and Ireland in the
Sub.net monitoring system manufactured by Embedded Monitoring Systems Ltd in Lisburn, Northern Ireland.
NATURAL FIT
Initially designed to monitor utility substations the
Sub.net has proved a natural fit for monitoring harmonics in wind farms. The
Sub.net constantly computes harmonic content and creates an event report if the THD level exceeds a preset level.
This means that a much higher level of interpretation is provided automatically, considerably simplifying the task for the analyst.
BENEFITS
The advantages of this approach are two- fold. Firstly having a computer do more of the work means that the work itself can be done a lot more thoroughly. As a result, the quality of the output, in terms of reliability of fault detection, is significantly improved. At the same time reducing the workload on the human analyst reduces costs.
This approach has been trialled using data from operational turbines and has proven successful in identifying drive train faults. Ventech Systems is currently engaged with a number of operators regarding future deployments of the system.
Ventech Systems
This report is automatically emailed directly to key staff who can take immediate action if required. An alarm output can also be sent to the operator’s SCADA system which can then automatically ‘back off’ the turbines (or disconnect a resonant component such as a switched capacitor). Since the
Sub.net processes its own data and does not require any centralised Master Station the response time is ideal for this critical application.
CONTINUOUS TREND REPORTS Harmonic measurements up to the 50th are aggregated over 10 minutes to create continuous trend reports. A
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