There are several factors which have to be considered for achieving optimal results from operations of a wind farm. These include understanding individual turbine performance and identifying frequent faults and assessing variance between actual and forecast energy production.

According to experts, one percent production loss on a 100MW wind farm can result in US$250,000 revenue loss. Overall, monitoring performance is critical in terms of obtaining maximum value from assets, to catch faults early, reducing the risk of catastrophic or downtime heavy failures, to prolong the life of all wind farm components and also to plan for scheduled downtime based on real wind farm behaviour.

As highlighted by the likes of Garrad Hassan, regular monitoring of operating wind farm data can identify unnecessary losses associated with individual turbine power performance and and frequent fault and other avaiability losses. One needs to break down turbine performance to component level showing what the significant issues on site are and how many hours of operation have been lost.

Through the monitoring of operating wind farm data, these lossess can be quantified.

But Scott MacKenzie, Asset Management, business manager, Natural Power recently told windenergyupdate.com that assessing the performance of a wind farm is for many owners a task performed at best on an annual basis with only the reports produced by the turbine manufacturers own SCADA system and metered output as a source of information. 

"This type of analysis is likely to overestimate turbine availability does not deliver the right information to the owner," said Mackenzie. "To gain an accurate picture of the site performance requires a more frequent and detailed analysis."

Specialists also refer to the fact that it is critical to determine not just hours of downtime but kWh of lost production. 

A company like Natural Power uses its wind analysis skills to determine what a wind turbine / site would have produced given the wind climate on site during any period of downtime. 

"This is an important element when it comes to reviewing budgets and  putting the performance in any one month into the context of the wind climate for that month. Also by analyzing the performance of each turbine it is possible to determine if turbines are delivering more or less energy than expected for that months wind climate as compared to the warranty power curve," said MacKenzie. 
 

Role of SCADA data

It is often said that for a wind farm, the SCADA system contains a wealth of information.

By automating this process, performance monitoring software saves time on analysis procedures and can lead to either yield improvements or simply the avoidance of losses. Powerful performance metrics immediately highlight areas which require attention.

An operational wind farm typically generates vast quantities of data. The SCADA data contain information about every aspect of a wind farm, from power output and wind speed to any errors registered within the system.

In the past, SgurrEnergy has highlighted that in general, the SCADA data are downloaded, however they are only used if some failure requires an analysis on a reactive bases. SCADA data may be effectively used to "tune" a wind farm, providing early warning of possible failures and optimising power output across many turbines in all conditions.

In terms of assessing availability, experts refer to run-time availability calculated based on SCADA data; establish if down-time correlated with high wind speed and if down-time correlated with loss of communications of the SCADA system, validate the manufacturer's reported availability figures and assess liquidated damages or availability bonuses.

Performance monitoring, which provides a snapshot of wind farm or turbine performance at a given time,  allows behaviour to be trended over time. Some of the important aspects of performance monitoring include Trending yield deficit with time; Met station data; Error code analysis; Performance metrics. Through a better understanding of the behaviour of a wind farm in a variety of conditions, it is also possible to schedule maintenance wisely, ensuring that the errors which impact most on power performance are fixed quickly.

According to SgurrEnergy, performance monitoring is at its most powerful, and most useful, when: It can be automated, reducing the time required for the analysis; provides a variety of information sources;  It can quickly indicate connections between data; It is interpreted by skilled and experienced personnel;

It indicates that an improvement of three percent could lead to £200,000 for a 50MW wind farm with a 30 percent capacity factor. A one percent mprovement would be worth £60,000 in a year.

Wind Energy Performance Optimisation Summit

windenergyupdate.com is scheduled to conduct Wind Energy Performance Optimisation Summit on 11th - 12th February 2009 in Hamburg, Germany.

For more information, click here: http://www.windenergyupdate.com/performance09/programme.shtml

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contact Tom Evans by email: tom@windenergyupdate.com