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Sieyuan supplied three 66 kV amplitude-phase corrector sets for the ±500 kV VSC-HVDC system at the Yangjiang Sanshandao Offshore Wind Farm, mitigating high-frequency resonance on the low-voltage side of the interconnecting transformers.
Stabilizing Offshore Wind VSC-HVDC Systems with 66 kV Amplitude-Phase Correctors
For the Yangjiang Sanshandao Offshore Wind Farm Project, Sieyuan Electric supplied three tailor-made 66 kV amplitude-phase corrector sets for the VSC-HVDC transmission system. Installed on the 66 kV low-voltage side of the 500 kV interconnecting transformers, the amplitude-phase correctors were designed to mitigate high-frequency oscillation risks. The solution combines impedance adaptation, offshore environmental protection, and mechanical reinforcement to support stable operation under demanding offshore conditions.
Project Overview
Sieyuan supplied three 66 kV amplitude-phase corrector sets for the ±500 kV VSC-HVDC system at the Yangjiang Sanshandao Offshore Wind Farm, mitigating high-frequency resonance on the low-voltage side of the interconnecting transformers.
Project Background
±500 kV VSC-HVDC transmission risks high-frequency resonance as offshore distances grow.
Key Challenges
Resonance risk, severe offshore corrosion exposure, and high dynamic transport loads.
Sieyuan Solution
Impedance-reshaping correctors with offshore-hardened design and a triangulated sea-fastening system.
Technical Highlights
Impedance-based resonance suppression validated for 0.2g offshore transport and lift loads.
Project Overview
Project Background
The Yangjiang Sanshandao Offshore Wind Farm Project uses a ±500 kV VSC-HVDC transmission system to deliver bulk power over long subsea distances. As offshore wind farms extend farther offshore, VSC-HVDC technology is increasingly adopted for high-capacity, long-distance transmission. However, interactions among the MMC control system, system impedance, and harmonic excitation may introduce negative damping and high-frequency resonance risks. These oscillations can reach several thousand hertz and affect the stable operation of converter valves and transformers.
Key Challenges
High-Frequency Resonance Risk — The interaction between negative damping, system impedance, and harmonic excitation can lead to high-frequency resonance and oscillation.
Severe Offshore Environment — High salinity, humidity, and salt spray require the equipment to meet pollution class IV requirements while maintaining insulation performance and corrosion resistance.
Transportation and Dynamic Loads — During marine transportation and offshore installation, the capacitor assemblies are exposed to motion, vibration, and acceleration forces. The equipment must withstand horizontal and vertical accelerations of up to 0.2g while maintaining structural integrity during transportation, lifting, and subsequent platform operation.
Sieyuan Solution
Impedance Adaptation — Sieyuan designed the 66 kV amplitude-phase correctors with capacitors, reactors, resistors, and current transformers to reshape the harmonic impedance of the AC/DC interface. The adapted impedance provides positive damping or a high-impedance barrier across critical frequency ranges, helping interrupt oscillation build-up.
Offshore-Hardened Electrical Design — The equipment incorporates enhanced creepage distances and anti-corrosion treatments for pollution class IV offshore conditions.
Sea-Fastening and Mechanical Restraint — Four steel cables were evenly arranged around each capacitor rack at 360° intervals and secured from the middle longitudinal frame to designated anchor points. Turnbuckles were used to tension the cables, forming a rigid triangulated restraint structure. Structural simulations under horizontal and vertical accelerations of 0.2g were conducted to validate the mechanical integrity of the complete assembly during transportation, lifting, and platform operation.
Technical Highlights
Impedance-Based Resonance Suppression — The amplitude-phase correctors reshape the harmonic impedance of the AC/DC interface, providing positive damping or high-impedance barriers across critical frequency ranges to mitigate high-frequency resonance.
Offshore Environmental Protection — Pollution class IV design, enhanced creepage distances, and anti-corrosion treatments support reliable operation in high-humidity, high-salinity, and salt-spray environments.
Mechanical Protection for Offshore Transportation — The dedicated sea-fastening and restraint system, validated under horizontal and vertical accelerations of 0.2g, supports the structural integrity of the capacitor assemblies during marine transportation, lifting, and platform operation.
