Design and development of megawatt wind turbines - Wind Power Generation and Wind Turbine Design - page 203

Figure 8: Rated rotor speed for the industry study set.
To best illustrate the range of MW WT design parameters and how they infl u-
ence technology choices for turbines and WPPs using value analysis methodology,
a 10-turbine analysis group was prepared by aggregating the trends (e.g. P / A , rotor
diameter, rated rotor speed, etc.) from the industry study set. Table 1 contains the
summary listing for this value analysis group. Many of the results shown in the
remaining sections of this chapter are based on this uniform group of basic
MW WT design parameters.
3.7.3 Infl uence coeffi cients and functional relationships
The design wind conditions and market settings are fi rst entered into the value
analysis tool and sweeps of turbine design cases yield trends for the output per-
formance and fi nancial merit parameters. These trends, and their corresponding
sensitivities to variation, are next used to assess the relative merits for compo-
nent technology decisions. This process is repeated for combinations of compo-
nent technologies to arrive at conceptual design proposals that are further vetted
by all the various groups within the organization. Once a number of these studies
have been performed, a pattern of infl uence coeffi cients (ICs) and functional
relationships result. These provide a convenient guideline for the WT design TC
and market conditions of prime interest, and can be quickly applied to assess
emergent component technologies without the need to go through the rigorous
value analysis calculation. However, use these parameters with caution, always
keeping in mind the assumptions that were used to generate them. If the main
assumptions are different enough, revert back to full sweeps using the value
analysis tool. Over time, this process of developing “rule of thumb” ICs will
emerge again and again, with better appreciation across the organization as more
people gain experience using them.