Solution for Modular Design and Rapid Deployment of High-Voltage Transformer

Project Background

Core Pain Points

• Severe Voltage Fluctuations: Rapid changes in the output of renewable energy sources lead to frequent voltage limit violations at transformer terminals.
• Elevated Resonance Risks: Dynamic impedance mismatch between inverters and transformers tends to trigger wide-frequency resonance under weak grid conditions.
• Insufficient Voltage Support: Traditional transformers struggle to provide effective reactive power support under low SCR conditions, resulting in frequent grid disconnection accidents.

Solution

2.1 Equipment Design and Technical Adaptation

• Wide-Frequency Impedance Adaptive Transformer: Adopting the coordinated control of adjustable magnetic shunt and on-load tap changing (in compliance with IEC 60076-7), it realizes dynamic matching of equivalent impedance within the frequency band of 10Hz–2.5kHz, resolving the inverter-transformer resonance issue. Verification from Nordic offshore wind power projects shows that it can lower the minimum SCR tolerance limit from 1.5 to 1.0.
• Integrated Subsynchronous Oscillation Suppression Device: Built-in FACTS-based SSO damping controller (in reference to IEC 61400-21) suppresses subsynchronous power oscillation in the 10–50Hz range by switching thyristor-controlled series compensation modules. Drawing on the experience of Indian solar parks, it has successfully eliminated the risk of torsional vibration in wind turbine shafts.
• Configuration of High-Frequency Harmonic Filter Modules: Integrated with third-order passive filters and active power filters (APF) (meeting the harmonic limits specified in IEC 61000-4-7), it achieves a harmonic attenuation rate of over 40dB for high-frequency harmonics ranging from 2–150kHz, which is fully compatible with the switching frequency characteristics of photovoltaic inverters.

2.2 Intelligent Control and System Optimization

• AI-Powered Real-Time Stability Control Strategy: A deep reinforcement learning (DRL)-based prediction-decision model is deployed to conduct real-time analysis of renewable energy output fluctuations and grid strength indicators, dynamically optimizing transformer tap positions, reactive power compensation capacity, and filtering parameters (in compliance with the IEC 61850 communication protocol). After application in a wind-solar hybrid base in Spain, the voltage qualification rate has been increased to 99.98%.
• Modular Plug-and-Play Architecture: Drawing on the design experience of HVDC converter transformers, it adopts standardized interfaces and a digital twin pre-commissioning platform, enabling quick replacement of SSO suppression modules and filtering units, and cutting the on-site installation cycle by 50%.

2.3 Global Localized Implementation

• Cross-Regional Standard Adaptation: The solution complies with multiple international standards, including IEC 62271 (high-voltage equipment) and IEEE 1547 (grid-connected inverters). Its reliability across different climate zones has been verified through projects such as Hydro-Québec in Canada and NEOM New City in Saudi Arabia.
• Full-Lifecycle Services: Jointly established a global fault database with institutions like DNV and CIGRE, providing harmonic spectrum analysis and impedance scanning services to predict potential resonance risk points.

3.Implementation Results

3.1 Project Verification (Retrofit Case of a 10-Million-Kilowatt Wind Power Base)

Core Parameter Optimization

• Grid disconnection rate reduced by 90% (from 12 times per year to 1.2 times).
• Total current harmonic distortion (THD) decreased by 60% (from 8.7% to 3.5%), which is better than the IEC 61000-4-30 Class A limit.
• SCR adaptation range extended to 0.8–10, supporting the stable operation of the power system with 98% renewable energy penetration.

Key Indicator Improvement

• The fluctuation range of transformer hot-spot temperature reduced by 70%, and the insulation service life extended to 40 years (up from the original design of 25 years).

3.2 Benefit Analysis

• Increased Renewable Energy Consumption Rate: The curtailment rate of wind and photovoltaic power in weak grid areas decreased from 15% to 4%, adding 2.3 TWh of clean energy generation annually.
• Avoided Duplicate Grid Investment: Eliminated the need for additional investment in SVC/STATCOM required by traditional solutions (saving $120 million per GW) and delayed the demand for transmission grid upgrading.
• Economic Viability Verification: The investment payback period shortened to 6 years. Referring to the experience of the Hornsdale Energy Storage Project in Australia, combined with revenue from the ancillary service market, the internal rate of return (IRR) reaches 14%.

Conclusion