IEC 61400-12:1998 pdf download – Wind turbine generator systems -Part 12: Wind turbine power performance testing

IEC 61400-12:1998 pdf download – Wind turbine generator systems -Part 12: Wind turbine power performance testing.
This part of IEC 61400 specifies a procedure for measuring the power performance characterishcs of a single wind turbine generator system (WTGS) and applies to the testing of WTGS of all types and sizes connected to the electrical power network, It is applicable for the determination of both the absolute power performance characteristics of a WTGS and of differences between the power performance characteristics of various WTGS configurations.
The WTGS power performance characteristics are determined by the measured power curve and the estimated annual energy production (AEP). The measured power curve is determined by collecting simultaneous measurements of wind speed and power output at the test site for a period that is long enough to establish a statistically significant database over a range of wind speeds and under varying wind conditions. The AEP is calculated by applying the measured power curve to reference wind speed frequency distributions, assuming 100% availability.
The standard describes a measurement methodology that requires the measured power curve and derived energy production figures to be supplemented by an assessment of uncertainty sources and their combined effects.
1.2 NormatIve references
The following normative documents, through reference In this text, constitute provisions of this part of IEC 61400. At the time of publication, the editions indicated were valid. All normative documents are subiect to revision, and parties to agreements based on this part of IEC 61400 are encouraged to Investigate the possibility of applying the most recent editions of the standards indicated below. Members of lEG and ISO maintain registers of currently valid International Standards.
IEC 60044-1:1996, Instrument transformers — Part 1: Current transformers
lEG 60186:1987, Voltage transformers Amendment 1(1988).
Amendment 2 (1995).
lEG 60688:1992. Electrical measurrng transducers for converting a.c. electrical quantities to analogue or digital signals
ISO 2533:1975, Standard atmosphere
Guide to the expiession of uncertainty in measurement. ISO information publications, 1995,
110 p. ISBN 92-67-10188-9
1.3 Definitions
For the purposes of this part of IEC 61400, the following definitions apply.
1.3.1
accuracy
closeness of the agreement between the result of a measurement and a true value of the moasurand
1.3.2
annual energy production
estimate of the total energy production ol a WTGS during a one-year period by applying the measured power curve to different reference wind speed frequency distributions at hub height. assuming 100% availability
1.3.3
availability
ratio of the total number of hours during a certain period, excluding the number of hours that the WTGS could not be operated due to maintenance or fault situations, to the total number of hours in the period, expressed as a percentage
1.3.4
complex terrain
terrain surrounding the test site that features significant variations in topography and terrain obstacles that may cause flow distortion
1.3.5
data set
collection of data that was sampled over a Continuous period
1.3.6
distance constant
indication of the response time of an anemometer, defined as the length of air that must pass the instrument for it to indicate 63 % of the final value for a step input in wind speed
1.3.7
extrapolated power curve
extension of the measured power curve by estimating power output from the maximum measured wind speed to cut-out wind speed
1.3.8
flow distortIon
change in air flow caused by obstacles, topographical variations. or other wind turbines that results in a deviation of the measured wind speed from the free stream wind speed and in a significant uncertainty
1.3.9
free stream wind speed
speed of the undisturbed natural air flow, usually at hub height
1.3.10
hub height (wind turbines)
height of the center of the swept area of the wind turbine rotor above the terrain surface
NOTE — For a vert.cal aids wind turbine the hub height is the height at the equator ptane.