Wind turbines and Voltage Flicker
Wind turbines can contribute to voltage flicker in several ways, primarily due to the inherent variability in their power output. Here’s how they play a role:
Sources of Voltage Flicker
- Wind Speed Variations: Changes in wind speed lead to fluctuations in the power output of wind turbines. This causes voltage fluctuations at the point where the turbine connects to the grid (Point of Common Coupling, or PCC).
- Generator Oscillations: Wind turbines, especially those with doubly fed induction generators (DFIGs), can cause power converter oscillations around frequencies of 8.8 Hz, contributing to voltage flicker.
- Tower Shadow and Blade Movement: Although primarily related to visual flicker, the movement of turbine blades and tower shadows can indirectly influence grid stability if these patterns affect generator performance over time.
Impact on Voltage Flicker
- Voltage Variations: The fluctuations in wind speed cause the turbine’s output to vary, resulting in voltage changes in the grid. This can be measured using the flicker severity index (Pst), with limits typically set below 0.3 for most grid connections.
- Flicker Effects: While the primary focus is on power quality, the visual effect of shadow flicker can also be disruptive, especially in low sunlight conditions.
Mitigation and Measurement
- Measurement Standards: The IEC-61000-4-15 standard provides guidelines for flicker meter measurements, helping assess the power quality in grid-connected turbines.
- Operational Controls: Variable-speed turbines tend to produce lower flicker levels than fixed-speed ones, suggesting operational parameters can influence flicker emissions.
In summary, wind turbines contribute to voltage flicker mainly through power output fluctuations caused by wind speed variations and generator dynamics. Understanding and mitigating these effects are crucial for maintaining grid stability and power quality.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/what-role-do-wind-turbines-play-in-causing-voltage-flicker/
