Arc flash Protection in Wind Turbines

Wind turbines are typically located in remote areas, making it difficult to respond quickly to incidents. The height of wind turbines also presents challenges for maintenance and emergency response. Additionally, variations in wind speed can cause rapid fluctuations in power load, potentially triggering arc flash incidents. Arc flashes are high-temperature electrical faults that can damage equipment, injure personnel, or cause fires. Therefore, to prevent or mitigate arc flash events, wind turbines can be equipped with arc flash protection relays to enhance safety and ensure the proper functioning of the equipment.

Problem Overview

Due to multiple arc flash incidents in recent years, a large power company conducted an arc flash risk assessment for over 50 power plants under its management. As a result, they decided to implement protection measures for one of their power plants, which operates more than 150 wind turbines.

Blue Jay Wind Turbine Arc Flash Protection Solution

Based on our extensive experience in the wind power sector, we recommend a comprehensive arc flash protection solution for the wind turbine system. The solution is outlined as follows:

Blue Jay AFR-4 Arc Flash Relays

4 channels for arc sensors

High accuracy Current & light sensing

upstream circuit breaker tripping, Zone & Tie breaker tripping

Arc Flash Protection for High and Low Voltage Sides, and Inverters

We recommend the company install arc sensors on the high-voltage side, the low-voltage side, and inside the inverter of the wind turbine’s electrical box. Additionally, a current transformer should be placed inside the inverter. These sensors will constantly monitor the electrical system for any signs of an arc flash and ensure that potential faults are detected quickly.

Coordination Between Arc Flash Relays and Medium Voltage Switchgear

Install an arc flash relay in the tower control cabinet. This relay will receive signals from the arc flash sensors and current increment signals. When the current increment or arc flash sensor signal is triggered, the relay will send a disconnection command to the medium voltage switchgear, quickly disconnecting the wind turbine from the grid to prevent the arc flash from escalating.

Arc Flash Protection Relay for Transformers

We also recommend installing arc flash relays to protect the transformers within the wind turbines. Transformers are crucial components of wind turbine systems, and protecting them from arc flash events will further ensure the stability and safety of the entire system.

Monitoring and Real-time Data Feedback

Implement remote monitoring using SCADA (Supervisory Control and Data Acquisition) systems for real-time data feedback. This ensures that in the event of an arc flash, the operator can quickly respond and take action.

Basic knowledge about wind turbine arc flash

Why Wind Turbines Present a Heightened Arc Flash Risk?

1. High incident energy levels in wind turbines, which typically operate at significant voltages (690V to 34.5kV), are a major concern because faults in these systems can release immense energy, with high voltage increasing the likelihood of electrical arcing by exceeding the air’s insulating capacity.

2. Proximity to high-voltage networks with substantial fault current levels increases the risk of severe arc flash incidents in wind turbines, as these networks can supply large fault currents and even feed them back into the turbine during a fault.

3. The confined and densely packed electrical equipment within wind turbine nacelles makes maintaining safe clearances difficult and increases the likelihood of potential arc flash.

4. Harsh weather and frequent lightning strikes common to wind turbine locations degrade electrical components and increase the risk of faults and arc flashes.

5. Infrequent maintenance on wind turbines, often performed near live electrical systems, coupled with the potential for human error during these procedures, elevates the risk of accidental contact and arc flash incidents.

6. The extreme heat generated by an arc flash can easily ignite combustible materials within the nacelle. Without a fire suppression system, controlling a fire in a wind turbine can be very difficult.

Which area needs arc flash relay in wind turbines?

Arc flash relays are primarily used for arc flash protection in transformers, switchgear (including cabinets with power converter equipment), interrupting devices, and cable or bus terminations within wind turbines.

Are arc flash relays useful for all Renewable Energy Systems？

Yes, Are arc flash relays useful for all Renewable Energy System. They are useful for wind energy, solar energy, inverters, battery energy storage system, etc.

Are there other arc flash mitigation methods for wind turbines?

1. Remotely monitoring wind turbines in real-time using SCADA reduces potential arc flash incidents.

2. Implementing effective grounding systems across the entire wind farm lowers arc flash risk.

3. Regularly inspecting slip rings, which transfer power from the rotating nacelle to the fixed tower, reduces the chance of arc flash events.

4. Using arc-resistant switchgear in the turbine’s electrical system helps control and redirect arc flash energy away from personnel.

5. Designing turbines with features that allow for safe electrical component maintenance.

Do you know arc flash incident in wind turbines？

2009, USA: A worker got hurt by an arc flash when they touched a power bar while checking wires in a US wind turbine’s bottom cabinet.

2012, Germany: A wind turbine in Germany burned down. The fire started with an arc flash in the harmonic filter box because a wire was loose.

2012, Spain: An arc flash started a fire inside a Spanish wind turbine’s top section (nacelle). A worker fixing something in the control box got burned on their hands and face and had to go to the hospital right away.

2015, Germany (Meinerzhagen): There was a fire in a wind turbine in Meinerzhagen, Germany. It started in the turbine’s electrical box.

2018, USA (Maine): A nine-year-old wind turbine in Maine, USA, had an arc flash that caused an electrical fire.

Conclusion

Arc flash protection is crucial for wind turbines to ensure the safety of personnel and equipment, as well as the reliability of the power generation system. Given the high voltages, confined spaces, and challenging environmental conditions, wind turbines are prone to arc flash incidents. Installing arc flash sensors, relays, and implementing real-time monitoring systems can effectively mitigate these risks, quickly detecting faults and enabling swift responses. These protective measures help reduce downtime, prevent equipment damage, and enhance the overall safety and efficiency of wind turbine operations.