Xiamen

The Xiamen HVDC project, also known as the Xiamen Island In-feed or Xiamen VSC-HVDC transmission demonstration project, is a high-voltage direct current (HVDC) transmission system located in Xiamen City, China. It was commissioned and put into operation on December 27th, 2015.

Technical Specifications

The Xiamen HVDC project is of bipole configuration, it has a voltage rating of ±320 kV and a power rating of 1000 MW. It is a MMC-HVDC (Modular Multilevel Converter-HVDC) system, connecting the Pengcuo and Hubian stations.

The transmission line consists of a 10.7 km underground cable, including subsea sections. The cable structure features copper cores, XLPE (Cross-Linked Polyethylene) insulation, grain aluminum flame retardant, and anti-termite PE sheath. The XLPE insulation thickness is designed as 26.0 mm, with a conductor cross-sectional area of 1800 mm².

System Components

The converter transformers are rated at (3+3) x 176.7 MVA. The AC substation operates at 220 kV with two transmission lines.

The project uses a metal return 10 kV connection model. The DC current is rated at 1600A, and each pole has a capacity of 500 MW.

Construction and Commissioning

The construction period for the Xiamen HVDC project was approximately 16 months. The project's development was approved by the State Electricity Regulatory Commission in 2014, with construction starting the same year. The system was commissioned in 2015.

Technical Advantages

The Xiamen HVDC project enhances the reliability of power supply for Xiamen Island and secures an additional power source for the growing demand. It has improved the strength of the Xiamen power grid and can satisfy future power demands in the region. The system allows for rapid adjustment of reactive power, significantly enhancing voltage stability and reliability of the Xiamen power grid.

Testing and Simulation

Before field commissioning, the project underwent extensive hardware-in-the-loop (HIL) real-time digital simulation testing. This testing used the RT-LAB platform to simulate the main circuit of the Xiamen MMC-HVDC project. The MMC valve was simulated in FPGA with a time-step of 250ns, while the rest of the main circuit was simulated in CPU with a time-step of 50μs. The State-space Nodal (SSN) interface was used to couple the models simulated on FPGA and CPU.

Equipment and Technology

All equipment used in the Xiamen HVDC project was manufactured in China with independent intellectual property rights. This includes the VSC-HVDC technology, which demonstrated China's capabilities in the emerging technology of MMC VSC at the time of construction