📋 Case Study
Wind Farm Grid Connection
Subsynchronous resonance (SSR) risk and weak-grid-induced control instability during low-load conditions
🏗️ Project Overview
350 MW offshore wind farm connecting via VSC-HVDC to 400 kV mainland grid
🎯 Challenge
Subsynchronous resonance (SSR) risk and weak-grid-induced control instability during low-load conditions
🔧 Design Approach
Tuned SSR filters, grid-forming converter control architecture, and coordinated DC voltage droop + AC frequency support
📐 Design Diagram
AI-generated project design illustration
📐 Key Calculations
SSR Modal Frequency
f_ssr ≈ 1/(2π√(L_eq × C_turbine))
Result: 32.7 Hz
Within turbine shaft torsional mode range—requires mitigation
Short-Circuit Ratio (SCR)
SCR = S_sc / S_wind
Result: 1.8
Classified as 'weak grid'—dictates GFMI requirements
📊 Results
Zero SSR events over 2-year commissioning; achieved ±0.15 Hz frequency regulation within 1.2 s; passed all ENTSO-E Dynamic Performance Tests💡 Lessons Learned
- •SCR < 2 mandates grid-forming capability—not just grid-following
- •SSR filter design must consider harmonic interaction with turbine controls
- •HVDC control loops require co-simulation with EMT models
✅ Key Takeaways
- 1SCR < 2 mandates grid-forming capability—not just grid-following
- 2SSR filter design must consider harmonic interaction with turbine controls
- 3HVDC control loops require co-simulation with EMT models
📐 Prerequisites
Understand these before this topic
🔗 Engineering Applications
See how this applies across industries