WTT Control Systems & SCADA 3 — Questions and Answers
Question 1: A technician notices a turbine's SCADA shows frequent 'grid voltage fluctuation' faults. Which component should be investigated first?
- The pitch controller calibration
- The main circuit breaker and grid monitoring relay (Correct answer)
- The nacelle anemometer
- The yaw position sensor
Correct answer: The main circuit breaker and grid monitoring relay
Grid voltage fluctuation faults point to the grid monitoring relay and main breaker, which monitor voltage levels and disconnect the turbine when grid quality falls outside acceptable limits.
Question 2: What is the function of a 'watchdog timer' in a wind turbine controller?
- It monitors wind speed trends to predict gusts
- It resets the controller if the main program fails to execute within a set time period (Correct answer)
- It tracks the cumulative operating hours for maintenance scheduling
- It monitors the temperature of the control panel enclosure
Correct answer: It resets the controller if the main program fails to execute within a set time period
A watchdog timer resets the controller if the main control program does not periodically reset the timer, indicating a program crash or hang.
Question 3: In IEC 61400-25, what standard does it define for wind turbine communication?
- Mechanical load testing procedures for turbine blades
- Communication standards for monitoring and control of wind power plants (Correct answer)
- Grid connection requirements for offshore wind farms
- Safety requirements for wind turbine electrical systems
Correct answer: Communication standards for monitoring and control of wind power plants
IEC 61400-25 defines communication standards and data models specifically for monitoring and control of wind power plants.
Question 4: A wind turbine's power curve shows actual output consistently 8% below the reference curve at all wind speeds. What is the most likely cause?
- A faulty rotor speed sensor
- Blade contamination, erosion, or pitch angle offset error (Correct answer)
- A malfunctioning SCADA data logger
- An incorrect transformer tap setting
Correct answer: Blade contamination, erosion, or pitch angle offset error
A consistent underperformance across all wind speeds on the power curve typically indicates blade surface degradation or a systematic pitch angle offset affecting aerodynamic efficiency.
Question 5: What does the term 'setpoint ramp rate' mean in the context of active power control for wind turbines?
- The rate at which the turbine increases rotor speed during startup
- The maximum rate at which the power output setpoint can be changed per unit time (Correct answer)
- The speed at which pitch angles change during emergency shutdown
- The time constant of the low-pass filter on the wind speed signal
Correct answer: The maximum rate at which the power output setpoint can be changed per unit time
Setpoint ramp rate limits how quickly the power output target can change, preventing rapid power fluctuations that could destabilize the grid.
Question 6: Which of the following best describes 'curtailment' in wind turbine operations?
- Intentional reduction of turbine output below its maximum potential (Correct answer)
- Emergency shutdown triggered by excessive vibration
- Automatic restart procedure after a grid fault
- The process of feathering blades during high wind conditions
Correct answer: Intentional reduction of turbine output below its maximum potential
Curtailment is the intentional reduction of a wind turbine's power output below its maximum potential, typically due to grid constraints, noise restrictions, or operator commands.
Question 7: In a fiber optic communication network used for wind farm SCADA, what is the primary advantage over copper Ethernet?
- Lower installation cost per meter
- Immunity to electromagnetic interference and longer transmission distances (Correct answer)
- Higher data refresh rates for real-time control
- Compatibility with legacy Modbus RTU devices
Correct answer: Immunity to electromagnetic interference and longer transmission distances
Fiber optic cables are immune to electromagnetic interference from generators and power cables, and can span much longer distances without signal degradation.
WTT Control Systems & SCADA 3
A technician notices a turbine's SCADA shows frequent 'grid voltage fluctuation' faults.
Which component should be investigated first?