📋 Case Study

Hawaii Island Grid Modernization Project

Severe sub-synchronous oscillations during cloud-induced irradiance transients

🏗️ Project Overview

Integration of 220 MW solar + 100 MW BESS into isolated 230 kV radial grid

🎯 Challenge

Severe sub-synchronous oscillations during cloud-induced irradiance transients

🔧 Design Approach

Coordinated GFM-BESS damping control + adaptive PLL bandwidth tuning

📐 Key Calculations

Sub-Synchronous Mode Frequency

f = 1/(2π√(LC))

Result: 12.3 Hz

Triggered SSR at 11–13 Hz range

Damping Ratio Target

ζ ≥ 0.05 for modes < 25 Hz

Result: 0.062

Met NERC MOD-026 requirement

📊 Results

Eliminated SSR events; reduced frequency deviation by 78%; achieved 99.99% uptime during monsoon season

💡 Lessons Learned

• •Adaptive PLL design is essential for variable solar irradiance
• •GFM converter damping must be tuned against local grid impedance

✅ Key Takeaways

• 1Adaptive PLL design is essential for variable solar irradiance
• 2GFM converter damping must be tuned against local grid impedance