IEC TS 61400-13-2001 pdf free.Wind turbine generator systems – Part 13: Measurement of mechanical loads.
The measurement programme involves collecting both a comprehensive statistical database arid a set of time series, which define the behaviour of the turbine in certain specific situations. In this clause, a system of measurement load cases (MLCs) is defined to determine the wind turbine loads in conditions corresponding to a selection of design load cases (DLCs) of IEC 61400-1. The MLCs may directly be used for documentation of the load in relation to the DLCs. or the MLCs may provide a basis for the validation of calculation models at specific and well-defined external conditions. Subsequently, the models can be used to estimate the loads at the design conditions. This clause also provides specifications for the quantities to be measured.
3.2 Measurement load cases (MLCs)
3.2.1 General
This subclause describes how to build up load measurement campaigns from a number of well-defined MLCs. The MLCs are defined in relation to the DLCs, described in IEC 61400-1. Hence, not all DLCs can be reasonably verified by measurement.
The MLCs define the main external conditions and the operational conditions of the turbine during the measurement campaigns. The external conditions include meteorological parameters such as wind speed, turbulence intensity and air density. The operational conditions include operational parameters such as rotational speed. yaw error electrical power and blade pitch angle. The operational conditions depend on the wind turbine configuration and shall be specified for each particular case.
Due to the stochastic character of the external conditions, measurements of each MLC have to be repeated several times in order to reduce the statistical uncertainty. The minimum number of measurements at each MLC is specified in this subclause.
Some of the DLCs of IEC 61400-1 and covered by MLCs defined in this specification are specified at external conditions that are difficult to achieve during a measurement campaign. In particular, the high wind speeds for those DLCs are difficult to obtain during the measurement campaign or at a specific site. For example, it is not possible to forcefully apply the extreme coherent gust to the turbine. In such cases, these load cases shall be assessed at wind speeds which are as high as possible.
The measured time histories are classified in two ways: one considering steady-state operation (SO) and one considering transient events (TE). In this way. all measurements can be classified in measurement load cases which relate to the lEG 61400-1 DLCs.
Tables 1 and 2 show the MLCs that are recommended to be recorded. The MLCs defined in the tables may not be complete. Additional MLCs may be necessary depending on the wind turbine concept and control and safety strategy.
3.2.2 MLCs during steady-state operation
Power production During power production, measurements shall be performed in the wind speed range from cut-in to cut-out and in a range of turbulence intensity levels described in the following subclause.IEC TS 61400-13 pdf download.