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Glossary

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50-year extreme wind speed Extreme wind speed event With regards to site classification, wind turbine design and stability it is important to also assess extreme wind speed situations. The maximum wind speed statistically occurring once in 50 years has been taken as base for such assessment, as described in IEC 61400-1 Ed3. ISO / IEC 61400-1 Ed.2 ISO / IEC 61400-1 Ed.3 Wind Resource and Energy Yield Assessment Analyses of turbulence intensity, site classification and extreme wind speed events Representative Turbulence Intensity Characteristic turbulence intensity
Bankable Bank's conform A term describing the acceptance by banks and investors. In most cases and for sure the experienced banks in wind project financing, do test and approve project compliance with internationally accepted standards as the IEC 61400-12-1 and other national standards and guidelines as respected by mayor (scientific) wind energy nations. Hence a project that is bankable in that sense does comply with such standards to a minimum extend. Therefore banks do accept these projects for financing, which become "bankable". Also the way of data processing and documentation by the experts is taken into account for proving bankability. Consultants should be accredited in order to objectively prove independence and high working standards following best practices and internationally accepted norms and guidelines as minimum standards of the quality management system and policy of the individual consultants. Non compliance to internationally accepted standards may lead to less certainty, higher risks and uncertainties for the bank, meaning they request a higher share of equity capital and higher interest rates. At a given point, if quality of the project documents and assessments is too poor, a bank may not accept the project for reasonable financing and the project becomes "not bankable". The other way around: the better the project documents, the higher the certainties and the lower the uncertainties, the more attractive will be the capital services offered by the financing bank. ISO / IEC Guide 98-3:2008: Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement ISO / BIPM "Guide to the Expression of Uncertainty in Measurement" (GUM) DIN V ENV 13005 (1999-06): Leitfaden zur Angabe der Unsicherheit beim Messen FGW Part 6 (Assessment of Wind Resource and Energy Yield) Rev. 9 ISO / IEC 61400-12-1 Wind Resource and Energy Yield Assessment Uncertainty Assessments of Wind Resource and Energy Yield Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control Power Performance Measurement and Power Curve Verification Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events Wind Resource and Energy Yield Assessment Uncertainty Assessments of Wind Resource and Energy Yield Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control Power Performance Measurement and Power Curve Verification Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events
Characteristic Turbulence Intensity characteristic turbulence, characteristic turbulence level IEC 61400-1 edition 2 defines the characteristic turbulence intensity as the mean plus standard deviation of random ten-min measurements. Load cases are defined by the characteristic turbulence intensity at 15 m/s, called I15. It is unlikely that manufactures will obtain new certificates for older turbine types and hence often among manufacturers and for older turbines it is still referred to the definition as given in Ed.2, though, since 2005 the edition 3 was published with an amendment in 2010. ISO / IEC 61400-1 Ed.2 ISO / IEC 61400-1 Ed.3 EN 1991-1-4:2005+A1:2010 DIBt Guideline "Richtlinie für Windenergieanlagen - Einwirkungen und Standsicherheitsnachweise für Turm und Gründung" (Regulation for wind turbines – influences and structural safety proves for tower and foundation) Analyses of turbulence intensity, site classification and extreme wind speed events" service Wind Resource and Energy Yield Assessment Site Prospection, Spatial Analyses and Site Selection Fatigue Loads Representative Turbulence Intensity Wake Decay Rate Spatial Efficiency
Commissioning Start of Operation Defines the official start of operation of a wind turbine once the wind turbine is erected, tested and all commissioning documents are filled and signed by the wind turbine manufacturer, the client (or his owners engineer with a power of attorney). With commissioning the technical warrantee period given by the wind turbine manufacturer starts, normally lasting two years. Within that two years of technical warrantee, the wind turbine manufacturer is taking care for regular inspections, repairs and irregular maintenance. Our Services Owners Engineer Lenders Engineer Wind Turbine Performance Warrantee Wind Turbine Sales Contract Guarantee
Expectation Value Average Value, Mean Value, P-50, P50 The long-term value that mostly is used as reference for the annual energy yield (AEY) or annual energy production (AEP). It is the standard result output of energy prognoses calculations. The chance that this value is over- or underestimated in either case is 50%, assuming a bi-nominal distribution around this average value. The level of confidence is 50% that this value of annual energy yield is over- or undermatched on long term. The uncertainty attached to this expectation value is an indicator determining how much a change of the confidence level (e.g. assuming 40% (P40) or 60% (P60)) would change the value of the long-term energy generation for that level of confidence: the lower the uncertainty attached, the more narrow any P values are distributed around the P50 value and the less the risk of energetic derivation from a given average value at P50. ISO / IEC Guide 98-3:2008: Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement ISO / BIPM "Guide to the Expression of Uncertainty in Measurement" (GUM) Download DIN V ENV 13005 (1999-06): Leitfaden zur Angabe der Unsicherheit beim Messen FGW Part 6 (Assessment of Wind Resource and Energy Yield) Rev. 9 ISO / IEC 61400-12-1 Wind Resource and Energy Yield Assessment Uncertainty Assessments of Wind Resource and Energy Yield Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control Level of Confidence Bankable Uncertainties
Fatigue Loads Exhaust, Tiring, Weariness Weakening of a material caused by repeatedly applied loads. Fatigue damage of a turbine component is the accumulated effect of multiple load cycles. The damage of similar cycles is proportional to their number and their load range raised to a power m called the Wöhler exponent. The combined effect of different load cycles may be described by the equivalent number of load cycles and a reference load range. ISO / IEC 61400-1 Ed.2 ISO / IEC 61400-1 Ed.3 EN 1991-1-4:2005+A1:2010 DIBt Guideline "Richtlinie für Windenergieanlagen - Einwirkungen und Standsicherheitsnachweise für Turm und Gründung" (Regulation for wind turbines – influences and structural safety proves for tower and foundation) Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events Wind Resource and Energy Yield Assessment Site Prospection, Spatial Analyses and Site Selection 50-Year Extreme Wind Speed Representative Turbulence Intensity Characteristic turbulence intensity Spatial Efficiency Wake Decay Rate
Lenders Engineer Bank's Engineer Banks and other investors often may lack technical understanding of all the aspects relevant during a wind farm project. Therefore it may be the case that they engage an expert that is taking care of the interests of the bank resp. investor. Such called banks engineer has the function to supervise works, performance, progress and to detect any shortcomings or deficits the bank or investor may need and want to know. They are approving milestones for payments, do keep control and perform reporting to the bank or investor in order to inform about all project details and compliance or non-compliance of project realization and progress. Our Services Owners Engineer Take Over Commissioning Wind Turbine Performance Warrantee Wind Turbine Sales Contract Guarantee
Level of Confidence Confidence Level, Confidence Coefficient, Quantile of Probability Distribution, p-Quantile The level of confidence is used to describe the percentage of instances (frequencies of occurrences) that the observed interval (an interval could be e.g. 90% of the time) contains a parameter (power generation) determined.
The level of confidence of the corresponding confidence interval (specific range of values) would indicate the probability that the confidence range captures a value given a distribution of samples. This value is represented by a percentage. For example: "On long-term average for 90% (level of confidence) of the time the wind turbine / wind farm will generate at least 'xyz' kWh (confidence interval) of electricity per year". This amount of 'xyz' kWh/a in fact is the P90 value of an energy yield prognosis. Meaning that only a 10% chance exists that the wind turbine (s) will not generate this electricity on long-term average per year.

Banks and investors for their risk analysis do frequently take the P90 value into account when they analyse project risks. By that they get to know the range of energy generation (lower 'xyz' kWh) that on long-term only happens with a probability of 10%, hence it is unlikely to happen and hence forms an acceptable risk. Meaning that if a wind farm with the P90 value is still financially viable, a bank would take the risk and provides a loan.

The P50 value in that aspect does describe the energy level that has a chance (probability) of 50% to be under- or overmatched as average energy generation per year on long-term. Hence this is the actual true expectation value, the usually called AEP (annual energy production) or AEY (annual energy yield) value.		 ISO / IEC Guide 98-3:2008: Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement ISO / BIPM "Guide to the Expression of Uncertainty in Measurement" (GUM) Download DIN V ENV 13005 (1999-06): Leitfaden zur Angabe der Unsicherheit beim Messen FGW Part 2 (Determination of Power Curves and standardized Energy Yields) Rev. 16 Expectation Value Bankable Uncertainties
Linear Weibull Fit Analysis Approach WASP Weibull Fit The weibull fit performed by WASP, a standard accepted procedure, introduces an uncertainty that hardly is respected during uncertainty assessments of the energy yield prognoses. On the other hand side accurate measurement of the wind speed with low uncertainty is the most important parameter to yield low uncertainty. Therefore ProfEC Ventus has been developing a procedure to assess the uncertainty of the WASP weibull fit and to qualify, if this standard method tends to over- or underestimate the true, measured wind speed regime on site. Our linear Weibull fit approach lets derive the quality of an individual WASP Weibull fit and permits determination of introduced uncertainties.
The fit of the Weibull distribution function by WASP is weighted on the higher wind speeds, maintaining two principles: 1. the total energy in the fitted Weibull distribution and the measured distribution are the same. And 2. the frequency of occurrence of wind speeds higher than the observed average wind speed are the same for the fitted Weibull distribution and the measured distribution. Latter means that the Weibull fit is done in a way respecting the optimal fit for V > Vmean. This first only leads to the determination of the scale parameter 'k' and subsequently the scale parameter 'A' is calculated as function of 'k'. 		ISO / IEC Guide 98-3:2008: Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement ISO / BIPM "Guide to the Expression of Uncertainty in Measurement" (GUM) Download DIN V ENV 13005 (1999-06): Leitfaden zur Angabe der Unsicherheit beim Messen ISO / IEC 61400-12-1 FGW Part 2 (Determination of Power Curves and standardized Energy Yields) Rev. 16 FGW Part 6 (Assessment of Wind Resource and Energy Yield) Rev. 9 Uncertainty Assessments of Wind Resource and Energy Yield Wind Resource and Energy Yield Assessment Level of Confidence+E65 Bankable Uncertainties WASP Weibull Fit
Long-term Alignment Long-term Correction, Long-term Correlation Wind measurements often are taken for a period of one to a few years. Knowing about the inter-annual fluctuations of wind, one must respect that this "measurement period" is not always or not entirely representative for the long-term (approx., 30-35 years) wind climate valid for the considered measurement site. Therefore with statistical means the short-term measurement period is aligned to the assessed long-term valid wind climate. The result enters usually the flow models for energy yield assessments. The uncertainty of this alignment is taken into account, thereby investigated in particular the following cases:
1. how representative is the short-term measurement period if compared to the long-term valid wind climate at the site.
2. how representative is the long-term period compared to the financing period of a wind farm (often 12-15 years)
3. how representative is the long-term period compared to the operational period of a wind farm (usually 20 years).
Consideration of the according uncertainties leads to a solid long-term wind speed assessment on site an offers owner and investors certainty and reliable planning figures.		 ISO / IEC Guide 98-3:2008: Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement ISO / BIPM "Guide to the Expression of Uncertainty in Measurement" (GUM) Download DIN V ENV 13005 (1999-06): Leitfaden zur Angabe der Unsicherheit beim Messen ISO / IEC 61400-12-1 FGW Part 2 (Determination of Power Curves and standardized Energy Yields) Rev. 9 FGW Part 6 (Assessment of Wind Resource and Energy Yield) Rev. 9 Uncertainty Assessments of Wind Resource and Energy Yield Wind Resource and Energy Yield Assessment Level of Confidence Bankable Uncertainties
Meso-Scale Meso Scale; Mesoscale Meso scale is describing a scale of about 500m*500m to 10,000m*10,000m raster width. Models with such wide resolution are typically used for macro-spatial purposes. Weather models as WRF, MM5 and others are forming the essence of such meso-scale calculations, often used for coarse geographic wind mapping of entire countries or subsequent down-scaling with micro-scale models. BWE Recommendations on Wind Mapping Open Foam - CFD WFR - Mesoscale Re-Analysis Meso Scale Wind Maps Micro Scale Wind Maps Micro-Scale
Micro-Scale Micro Scale; Microscale Micro scale is describing a scale of about 10m*10m to 1000m*1000m raster width. Models with such high resolution are typically used for micro-siting purposes, up to regional wind map generation. CFD, 3-dimensional and 2-dimensional (as WASP) models are forming essence of related calculation methods. As input serve high resolution geo-data, which may be derived from meso-scale models within a break-down procedure. BWE Recommendations on Wind Mapping Open Foam - CFD WFR - Mesoscale Re-Analysis Meso Scale Wind Maps Micro Scale Wind Maps Meso-Scale
V.Mac Virtual Measurement Access Virtual Measurement Access: a service developed by ProfEC Ventus that enables customers to instantaneously review and access any measurement data connected at measurement stations and sent to the V.Mac - Server (including data loggers and measurement services provided by third parties). V.Mac enables advanced features such as data and report sharing, establishing of sub-accounts with limited access, data comparison, data checking, energy production estimates, alert setting if any measurement thresholds are reached and much more. V.Mac V.Mac Access Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control
Owners Engineer Client's Engineer A technical supervisor engaged by a project owner in order to control and supervise processes of any sub-contractors, EPC contractors and others involved to deliver services or hardware. Owners of a project often are strategic investors knowing well management, laws, contracts and accounting for project implementation but often lack scientific experience on such on wind energy project implementation.
Therefore project owners often rely on the expertise of an independent company or expert that supervises and approves any deliverables from third parties and who warrants the performance on time and on scope. The owners engineer controls if work and tasks are implemented according to contracts and agreed deliverables and he defends the (mostly technical) interests of the project owner.		 Our Services Lenders Engineer Commissioning Take Over Wind Turbine Performance Warrantee Wind Turbine Sales Contract Guarantee
Point of Common Coupling PCC The point at which a electricity generating set is connected to the utility network / to the electricity network. Usually at this point the electricity meter should be installed to count the injected amount of electricity accounting for any internal losses on side of the gen-set. ISO / IEC 61400-12-1 FGW Part 2 (Determination of Power Curves and standardized Energy Yields) Rev. 16 FGW Part 6 (Assessment of Wind Resource and Energy Yield) Rev. 9 Power Performance Measurement and Power Curve Verification Assessment of Losses Power Curve
Power Curve P-V curve, Wind Turbine Power Performance Characteristics Describes the functional relationship of the power generated by a wind turbine in dependence of the wind speed the wind turbine is facing at hub height. The power curve usually is measured in accordance to the internationally accepted IEC 61400-12-1 standard and in some cases in compliance to MEASNET standard. Compliance with these standards ensures comparability of different wind turbine power performance characteristics with each other. The P-V curve also is used for commercial sales and marketing purposes, within sales and purchase contracts as well as for prototype measurements. Hence, it is of crucial importance to measure the wind turbine power uttermost precisely. Therefore the wind measurement aspects within the IEC 61400-12-1 standard also are seen as international standard for best practices of wind measurements. ISO / IEC 61400-12-1 FGW Part 2 (Determination of Power Curves and standardized Energy Yields) Rev. 16 MEASNET Power Performance Measurement Procedure Power Performance Measurement and Power Curve Verification Wind Turbine Performance Warrantee Wind Turbine Sales Contract Guarantee
Remote Sensing The term typically describes scanning of physical characteristics by sensors that can scan an item of interest over a large distance and return back the data, too. Examples of remote sensing in the context of wind energy are: orography data (or othertopographic characteristics) scanned and transmitted by satellites same as scanning conditions of the atmosphere. Typical remote sensing techniques are LIDAR, SODAR, etc. Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control
Representative Turbulence Intensity Representative Turbulence, Representative Turbulence Level IEC 61400-1 edition 3 defines the representative turbulence intensity as the mean + 1.28 times standard deviation of random ten-min measurements. Load cases are defined by the reference turbulence intensity Iref. which is equal to the mean turbulence intensity at 15 m/s. It is unlikely that manufactures will obtain new certificates for older turbine types certified in the past and hence often for older turbines it is still referred to another definition of the representative turbulence intensity as given in edition 2. ISO / IEC 61400-1 Ed.2 ISO / IEC 61400-1 Ed.3 EN 1991-1-4:2005+A1:2010 DIBt Guideline "Richtlinie für Windenergieanlagen - Einwirkungen und Standsicherheitsnachweise für Turm und Gründung" (Regulation for wind turbines – influences and structural safety proves for tower and foundation) Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events Wind Resource and Energy Yield Assessment Site Prospection, Spatial Analyses and Site Selection Fatigue Loads Characteristic Turbulence Intensity Wake Decay Rate Spatial Efficiency
Rotating Mast Mast Hopping A technic to mimic a measurement mast during so called "site verification". Based on comprehensive matrix calculations for different atmospheric situations of stability, classified by directional wind shear parameters.
A rotating mast replaced costs for additional measurement mast installed.		 Wind Resource and Energy Yield Assessment Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control
Spatial Efficiency Specific Power, Areal Efficiency Describes the amount of installed power (rated capacity or nameplate capacity) per unit of surface (e.g. ha). Investigations have shown that in Germany, between about 1990 and 2004 the average specific power per square kilometre wind farm area on average was 0.05 km2/MW. In modern wind farms, spatial efficiency even may become 0.01 - 0.25 km2/MW. The optimal spatial efficiency depends on the wind turbine thrust curve, the available space of the planned wind farm area, topographical characteristics and turbulence intensity levels. Dena Netzstudie (dena Grid Study) Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events Wind Resource and Energy Yield Assessment Site Prospection, Spatial Analyses and Site Selection Fatigue Loads Characteristic Turbulence Intensity Wake Decay Rate Representative Turbulence Intensity
Take Over End of Warrantee Term Normally two years after commissioning the warrantee period expires. That moment is the take over, as the wind turbine manufacturer transfers the full responsibility of maintenance and inspection to the client. Any technical warrantee claim becomes void afterwards. Therefore very often short before take over, a final check of the wind turbines is performed on behalf of the client and proven regarding any warrantee matters and degradations. In case of any matters of technical warrantee, claim must be made before take over. Our Services Lenders Engineer Owners Engineer Wind Turbine Performance Warrantee Wind Turbine Sales Contract Guarantee
Uncertainties Indication for Trustability of Measurement Results Uncertainties are the doubt that exists regarding the trustability of a measurement result. I.e. if measuring wind, the uncertainties are an indicator for the degree that the measurement data are reflecting the real observation. Several components do influence the wind speed measurement as the sensors, tower structure, topography, etc. and therefore they cause uncertainties that are attached to the measurement data if comparing them to the true wind speed data. Uncertainties also may be introduced by the data processing methods and the flow models used. The uncertainties are important to be assessed in a bankable way, as they in fact do determine the difference between the energy generation values at different levels of confidence. Hence they are an indicator for the scatter around the P50 value and do directly influence the risk level that a bank / Investor does analyse. ISO / IEC Guide 98-3:2008: Uncertainty of measurement – Part 3: Guide to the expression of uncertainty in measurement ISO / BIPM "Guide to the Expression of Uncertainty in Measurement" (GUM) Download DIN V ENV 13005 (1999-06): Leitfaden zur Angabe der Unsicherheit beim Messen FGW Part 6 (Assessment of Wind Resource and Energy Yield) Rev. 9 ISO / IEC 61400-12-1 Wind Resource and Energy Yield Assessment Uncertainty Assessments of Wind Resource and Energy Yield Banks Conform Configuration of Wind Measurement Systems, Equipment, Masts and V.Mac Data Control Power Performance Measurement and Power Curve Verification Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events Expectation Value Level of Confidence Bankable
Wake Recovery Rate Wake Recovery, Wake Rehabilitation, Wake Recuperation Describes the rate, within which the reduced wind speed behind the wind turbine (within a wind turbine wake) recovers towards the same undisturbed average free wind speed as present before passing the vertical rotor swept area of a rotor. High turbulences do increase the rate, within which the wake wind speed recovers towards free wind speed. The thrust curve describes the wind turbine blocking effect. Spatial efficiency balances infrastructure costs and wake recovery rate to maximize energy yield. ISO / IEC 61400-1 Ed.2 ISO / IEC 61400-1 Ed.3 EN 1991-1-4:2005+A1:2010 DIBt Guideline "Richtlinie für Windenergieanlagen - Einwirkungen und Standsicherheitsnachweise für Turm und Gründung" (Regulation for wind turbines – influences and structural safety proves for tower and foundation) Site Prospection, Spatial Analyses and Site Selection Analyses of Turbulence Intensity, Site Classification and Extreme Wind Speed Events Wind Resource and Energy Yield Assessment Fatigue Loads Characteristic Turbulence Intensity Representative Turbulence Intensity Spatial Efficiency
Wind Turbine Performance Warrantee Contract Warrantee; Performance Warrantee The wind turbine performance warrantee is considering the minimum assured technical performance and availability of a wind turbine. Wind turbine power performance is very important for investors, financiers and the wind turbine manufacturer. The warrantee of a wind turbine performance (often) is (becomes) an essential contractual matter. ISO / IEC 61400-12-1 FGW Part 2 (Determination of Power Curves and standardized Energy Yields) Rev. 16 MEASNET Power Performance Measurement Procedure Power Performance Measurement and Power Curve Verification Our Services Lenders Engineer Owners Engineer Commissioning Wind Turbine Sales Contract Guarantee
Wind Turbine Sales Contract Guarantee Contract Guarantee, Performance Guarantee The wind turbine sales contract guarantee is considering the financial guarantee assured by the technology provider to the client regarding compensations in case of underperformance of a wind turbine. Wind turbine sales contract guarantees are very important for investors and financiers. The guarantees of a wind turbine performance often become an essential contractual matter. Power Performance Measurement and Power Curve Verification Our Services Lenders Engineer Owners Engineer Commissioning Wind Turbine Performance Warrantee

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