Aarhus, Denmark – December 2025 – Orsted A/S, the world’s largest offshore wind farm developer, has reported a 30% improvement in grid compliance and 25% fewer curtailment events after installing the ABB REF610C11HCNN01 protection relay at its 600MW Hornsea 3 offshore wind farm. The deployment, finalized in Q3 2025, solved longstanding challenges of voltage fluctuations and fault-induced curtailment that cost the company €2.3 million annually in lost energy revenue.
The Challenge: Grid Integration Pain Points for Offshore Wind
Orsted’s Hornsea 3 wind farm, located 120km off the Danish coast, faced unique grid integration challenges:
- Voltage Fluctuations: Turbine output variability (due to wind speed changes) caused grid voltage swings of ±8%, exceeding EU grid code limits (±5%). This triggered automatic curtailment, reducing energy delivery by 4.2% annually.
- Slow Fault Isolation: Legacy relays took 200ms to detect and isolate faults (e.g., cable short circuits), risking grid instability and triggering penalties from transmission system operators (TSOs).
- Corrosion & Environmental Stress: Offshore conditions (saltwater spray, humidity, extreme temperatures) caused legacy relays to fail every 2–3 years, requiring costly maintenance via service vessels (€80,000 per visit).
- Limited Visibility: The old system lacked real-time fault location data, forcing technicians to search 100km+ of subsea cables to identify issues—extending downtime by 2–3 days per incident.
“Offshore wind farms operate in the harshest environments and face strict grid code requirements,” said Lars Nielsen, Orsted’s Wind Farm Technical Director. “Our legacy protection system was holding back energy output and increasing costs. We needed a relay that could handle offshore conditions while delivering pinpoint fault detection.”
ABB REF610C11HCNN01: The Offshore-Grade Protection Solution for Wind Energy
After rigorous testing against marine-grade competitors, Orsted selected the ABB REF610C11HCNN01 for its offshore-specific design, fast fault response, and grid compliance features:
- Grid Code Compliance Engine: Automatically adjusts turbine reactive power output to maintain voltage within ±3% of nominal—eliminating curtailment from voltage fluctuations. Supports EU Grid Codes (EN 50160) and Danish TSO requirements for renewable integration.
- Ultra-Fast Fault Detection: Detects and isolates faults in 50ms (4x faster than legacy relays), preventing grid instability and TSO penalties. Built-in distance protection accurately locates faults within ±1km, reducing cable inspection time by 90%.
- Marine-Grade Durability: Corrosion-resistant aluminum alloy housing (ISO 12944-6 Class C5-M) and IP67-rated enclosure withstand saltwater immersion (up to 1m for 30 minutes) and temperatures from -40°C to +70°C. Mean time between failures (MTBF) exceeds 200,000 hours.
- Wind-Specific Protection Functions: Includes anti-islanding protection (prevents grid disconnection during outages) and turbine rotor overspeed protection, integrating seamlessly with Orsted’s Siemens Gamesa turbines via Modbus TCP.
- Remote Monitoring via ABB Ability™: Technicians access real-time relay data (fault logs, voltage profiles, health status) from onshore control centers, eliminating 80% of unnecessary offshore maintenance visits.
Results: Higher Output, Lower Costs, and Grid Stability
Five months post-deployment, Hornsea 3 achieved remarkable results:
- 30% Improved Grid Stability: Voltage fluctuations dropped from ±8% to ±2.5%, eliminating 90% of curtailment events and adding €552,000 in annual energy revenue.
- 25% Fewer Fault-Related Outages: Fast fault isolation reduced unplanned downtime from 12 to 9 days annually, saving €690,000 in lost production.
- 70% Lower Maintenance Costs: The REF610C11HCNN01’s marine-grade design eliminated corrosion-related failures, cutting maintenance costs by €240,000 annually.
- 90% Faster Fault Location: Precise fault positioning reduced cable inspection time from 3 days to 4 hours per incident, minimizing downtime.
“The REF610C11HCNN01 has redefined what we expect from offshore protection relays,” Nielsen said. “It’s not just durable—it’s intelligent. We’re now delivering more clean energy to the grid while reducing our environmental footprint and maintenance costs.”
Maja Andersen, ABB’s Global Product Manager for Renewable Energy Protection, noted the relay’s industry impact: “Wind energy needs protection solutions that are as robust as the turbines themselves. The REF610C11HCNN01 series is engineered to maximize renewable energy output while ensuring grid stability—critical for the energy transition.”
Orsted plans to install the ABB REF610C11HCNN01 at its upcoming 800MW Sunrise Wind farm (U.S.) and 700MW Baltic Sea Wind farm (Poland), targeting a 20% reduction in curtailment across its global fleet.
