REP Wind Power Technologies 3 — Questions and Answers
Question 1: What is the Weibull distribution used for in wind energy analysis?
- Designing tower structural profiles
- Statistically describing the frequency distribution of wind speeds at a site (Correct answer)
- Calculating transformer losses in wind farms
- Estimating blade erosion rates over time
Correct answer: Statistically describing the frequency distribution of wind speeds at a site
The Weibull distribution is the standard statistical model used to characterize the probability distribution of wind speeds at a given location for energy yield assessments.
Question 2: Direct-drive wind turbines eliminate which major component compared to conventional turbines?
- Rotor blades
- The gearbox (Correct answer)
- The transformer
- Pitch actuators
Correct answer: The gearbox
Direct-drive turbines connect the rotor shaft directly to a low-speed generator, eliminating the gearbox and its associated maintenance requirements and failure modes.
Question 3: Which IEC wind turbine class designation indicates the highest wind speed design environment?
- IEC Class I (Correct answer)
- IEC Class II
- IEC Class III
- IEC Class S
Correct answer: IEC Class I
IEC Class I turbines are designed for high-wind sites with average wind speeds up to 10 m/s, while Class III covers lower-wind sites up to 7.5 m/s average.
Question 4: What phenomenon causes the 'three-per-revolution' (3P) excitation in a three-bladed wind turbine?
- Generator pole-pair frequency
- Each blade passing the tower once per revolution, creating periodic loading (Correct answer)
- Gearbox tooth mesh frequency
- Transformer electromagnetic vibration
Correct answer: Each blade passing the tower once per revolution, creating periodic loading
Each of the three blades passes the tower once per revolution, creating three structural load pulses per revolution known as 3P excitation.
Question 5: What is the primary advantage of variable-speed wind turbines over fixed-speed designs?
- Lower blade manufacturing cost
- Ability to operate at optimal tip-speed ratio across a wider wind range (Correct answer)
- Simpler electrical grid connection
- Reduced need for yaw control systems
Correct answer: Ability to operate at optimal tip-speed ratio across a wider wind range
Variable-speed turbines adjust rotor speed to maintain optimal tip-speed ratio as wind speed changes, capturing more energy across a broader range of wind conditions.
Question 6: In wind resource assessment, what does P90 production estimate mean?
- The turbine produces at 90% nameplate capacity
- There is a 90% probability that actual production will meet or exceed this value (Correct answer)
- The project earns a 90% return on investment
- 90% of wind measurements are above the mean
Correct answer: There is a 90% probability that actual production will meet or exceed this value
P90 is a conservative energy yield estimate with a 90% probability of exceedance, commonly used by lenders to assess financial risk in wind projects.
Question 7: What is the purpose of a SCADA system in a wind farm?
- Structural component analysis and design automation
- Real-time monitoring, data collection, and remote control of turbines (Correct answer)
- Supply chain and delivery administration for spare parts
- Scheduling contract and deadline administration
Correct answer: Real-time monitoring, data collection, and remote control of turbines
SCADA (Supervisory Control and Data Acquisition) systems provide operators with real-time turbine performance data, alarms, and remote control capabilities across the wind farm.
REP Wind Power Technologies 3
What is the Weibull distribution used for in wind energy analysis?