On June 29, 2020, ± 500kV Zhangbei VSC-HVDC grid project (referred to as "Zhangbei project") was successfully put into commercial operation.
Zhangbei converter station
The Zhangbei project is a major landmark project carried out by the State Grid Corporation of China for promoting energy technology revolution, large-scale development and utilization of renewable energy sources, serving clean and low-carbon 2022 Winter Olympics and supporting the transformation of national energy structure.
Zhangbei project is a cutting-edge DC grid and the first project deploys DC breakers for DC line faults clearance. Four converter stations including Zhangbei, Kangbao, Fengning and Beijing will be built in the project with rated capacities of 3000MW,1500MW,1500MW and 3000MW respectively Zhangbei and Kangbao stations are power sources, Beijing station is the load center and Fengning station connects to a pump storage plant for regulating renewable power fluctuation. Besides, 666km of ± 500kV overhead DC transmission lines and neutral overhead line will be built.
After commercial operation, 14 billion KWh of renewable energy can be delivered every year, realizing 100% clean energy power supply for Beijing Winter Olympic venues.
Schematic diagram of ± 500kV four terminal VSC-HVDC power grid
NR Electric is selected as major supplier for Control and Protection system, ± 500kV/3000MW converters, DC breakers and DC measurement equipment.
± 500kV/3000MW converter valve
NR innovatively proposed a bridge rectifier type hybrid DC breaker, which has overcome the key technologies such as IGBT valve group strong current switching off, mechanical switch ultra-high speed breaking and high potential energy supply. All DC breakers supplied by NR Electric have passed the manual DC line grounding fault testing successfully. With extremely fast and reliable breaking capacity, they have strived for a wider stable boundary for the whole DC grid.
±500kV DC breaker of NR
At the same time, the control and protection system provided by NR overcome the problems, likenew energy access to bipolar island control, coordinated control of multiple converter stations, ultra-high speed protection and fast recovery control of DC grid, safeguard the successful operation of the DC grid.
Control and protection system
In addition, according to the demand of ultra-high speed measurement and response of DC grid, NR has developed a new generation of measurement device with high accuracy, the step rise and delay time could achieve dozens of microseconds.
In order to ensure the delivery of Zhangbei project, during the equipment production, NR strictly controlled the equipment production, type test, quality control and other processes in line with its mature standards, finally all equipment was delivered on schedule with high quality and high standard.
Field installation and commissioning of DC breaker
During site commissioning, ± 500kV VSC-HVDC converter valves have been tested by heavy load operation test and 7 times of artificial AC grounding test at near end, the converter valves are in reliable operation under all these tests; the ± 500kV DC breaker has successively completed air closing line, steady-state current breaking and reclosing test, with the action accuracy rate of 100%, and experiencing 10 times of artificial grounding energy impact, all equipment are correctly disconnected and reclosed.
All the equipment supplied by NR is stable and reliable, which provides strong support for the smooth implementation of commissioning tasks, and lays a solid foundation for the successful operation of Zhangbei project.
Site test of DC breaker
On June 10, Zhangbei project completed manual grounding short circuit test on DC line. The DC circuit breakers was disconnected and reclosed within 2.8 ms, clearing DC line fault successfully.
Site artificial DC line grounding test
On June 25, the Zhangbei project successfully passed 168 hour trial operation, and the project was put into commercial operation on June 29.
The operation of Zhangbei project marks the formal arrival of the era of DC grid and also shows the strong role of NR in construction of cutting-edge HVDC field.