Final Flashcards
Which is usually greater, generator or turbine inertia?
Generator
In the equation for starting a turbine, what is the inertia term?
Combined generator and turbine inertia
When does maximum performance occur? and what is this called?
When dCp/da=0
Betz’ limit
When does maximum power occur in a turbine?
When dW/dΩ=0
How is Reynold’s number affected by turbine size?
The smaller the turbine, the lower the Reynold’s number
How can you adjust pitch angle based on wind speed and tangential velocity?
- FOr small U (large rΩ), Pitch angle must be small
- For small rΩ (large U), pitch angle must large
What are some sources of generator inefficiency?
- Copper losses in the wiring.
- Iron losses due to rotor being magnetized and demagnetized
What is beam radiation?
solar radiation direct from the sun without scattering in the atmosphere, sometimes called direct radiation
What is diffuse radiation?
Sunlight direction changed by scattering in atmosphere. Some PV cells do not respond to diffuse radiation
Irradiance?
Rate at which energy falls on surface (W/m^2)
Irradiation?
incident energy on surface (J/m^2)
What is the azimuth angle?
polar direction of PV module. South or North can be zero
What is declination?
Value of altitude angle at solar noon each day
WHat is Rb that can be calculated?
Ratio of beam radiation on titled surface to that on horizontal surface at solar noon
What is penetration?
Total renewable capacity/average grid demand
