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Enron Mail |
For clarification, the "Vestas availability" you talk about is not specific
to Vestas nor is it based on any Vestas contractual availability. This availability is a multi- industry standard for simple "series component" availability. There is no credit for maintenance or repair time time which is why a 3-5% loss is considered acceptable for long term performance. The 3-5% loss includes maintenance. An availability metric that shows the turbine as available during repairs would be very objectionable to future owners. Pausing the turbine during maintenance may be acceptable if the long term goal is set accordingly. For example, if the turbine is always paused during maintenance then the long term system goal should be close to the 99.5% goal for grid availability. Hollis Kimbrough 05/15/2002 07:40 AM To: Mark Fisher/EWC/Enron@Enron, Mark V Walker/EWC/Enron@ENRON, Jeff Duff/EWC/Enron@ENRON cc: Subject: Calculating "Vestas Availability" Guys, In an earlier e-mail Ben made the statement: "Have you been able to determine what these numbers would look like using Vestas' definition of availability: Hours of Wind Turbine in Operation mode X 100 / Hours of Grid in Operation Mode." We now need to develop a methodology to calculate the Vestas definition using VisuPro data. I think this boils down to: Vestas Avail = (SOT+WOT+EST+RT+MT)/(ST-LOT) Where: SOT = System Okay Time EST = External Stop Time WOT = Weather Out Time LOT = Line Out Time DT = Down Time RT = Repair Time MT = Maintenance Time ST = SOT+EST+WOT+LOT+DT+RT+MT This calculation is based on an operating assumption that the current day machines are placed into "pause" mode during maintenance and repair time. As a result the availability counters will continue to increment even when the turbine is being serviced. Let's get together and discuss, Hollis
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