Hardware-in-the-Loop Test Bench for Flexible DC Distribution Networks Using RT-LAB and eFPGAsim

The Company

Shenzhen Power Supply Bureau, part of China Southern Power Grid (CSG), collaborated with Tsinghua University and Zhejiang University on the research project “Key Technology of Flexible DC Based Smart Distribution.” The project focused on improving power quality, integrating distributed generation and energy storage systems, and advancing flexible DC distribution technologies.

The Challenges

• Limitations of Offline Simulation: Traditional offline simulation tools could not effectively simulate protection system behavior or identify hardware implementation issues.
• Complex Power Electronics Modeling: Real-time simulation of MMC voltage source converters and high-frequency solid-state transformers remained technically challenging.
• High-Speed Simulation Requirements: Accurate testing required sub-microsecond simulation steps and nanosecond-level switching signal resolution.

The OPAL-RT Solution

• FPGA-Based Real-Time Simulation: OPAL-RT’s eFPGAsim platform and eHS solver enabled real-time simulation of complex power electronic circuits.
• Multi-Rate System Modeling: eFPGAsim was seamlessly integrated with RT-LAB to combine high-speed power electronics simulation with larger power system models.
• Hardware-in-the-Loop Testing: Keliang developed a flexible DC distribution network model and performed HIL testing of control and protection systems under various fault conditions.

The Results

• Flexible DC Network Validation: The project validated the modeling of key equipment and the protection strategies of flexible DC distribution systems.
• First HIL Platform in China: Shenzhen Power Supply Bureau built China’s first HIL test platform based on a typical four-terminal flexible DC distribution network.
• Advanced DC Distribution Research: The platform enabled research on network structures, control and protection schemes, DC transformers, and energy management strategies.
• Successful Project Completion: The project was successfully completed and approved by the acceptance group of the Ministry of Science and Technology of China.

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