At the end of December, 2020,the DC power supply system of Anhua Data Center in Dongguan, Guangdong ended its trial operation for one month,and the system was in good condition,symbolizing that the first megawatt-level full DC power supply data center was completed and put into operation!The full DC power supply scheme put forward by Tsinghua University was successfully applied for the first time!

Anhua Data Center in Dongguan, Guangdong

I. Research background

Energy consumption of data centers has increased rapidly in recent years, for example, the total electricity consumption of data centers in China in 2018 was 160.889 billion kilowatt-hours, above the total social consumption in Shanghai; In March 2020, data centers were listed as one of the seven major fields of Chinese "new infrastructure", entering the fast lane of accelerated development. However, the traditional AC power supply system of data centers are involved with high loss in multi-stage energy conversion and poor flexibility and controllability of power conversion, and the energy supply scheme of data centers must be improved.

DC power supply system, which is more suitable for the flexible access of distributed power supply, energy storage device and DC load because of its advantages such as fast and flexible control, high system efficiency, large power supply capacity, low line loss, high power quality and reactive power compensation capability, is an important orientation for the development of data center energy supply systems.

Comparison between a full DC power supply scheme and a traditional power supply scheme

II. Contribution of Tsinghua University

The DC Research Center of Energy Internet Research Institute, Large Capacity Power Electronics and New Power Transmission Research Center, Professor Zhao Zhengming's Team, Professor Zeng Rong, Associate Professor Yu Zhanqing and Associate Professor Huang Yulong's Team of EEA of Tsinghua University, and Guangdong Power Grid Co., Ltd., relying on the national key research and development program "Smart Grid Technology and Equipment" and the key special project "AC/DC Hybrid Distributed Renewable Energy Technologies, Core Equipment and Engineering Demonstration Research", have innovatively developed a full DC power supply scheme for data centers, which can improve the energy supply efficiency of the system by more than 15%, overcomes the theoretical basis, key technologies, core equipment and other difficulties of full DC power supply in data centers. The first megawatt full DC power supply data center has been completed and put into operation in Dongguan, contributing a technical path for the data center power supply system to achieve the goal of carbon peaking and carbon neutralizing.

(1) Breakthrough in the high efficiency and high power density DC conversion technology

Tsinghua University has internationally and initially developed a multi-function, multi-port megawatt power electronic transformer with a common high-frequency AC bus topology and a highest efficiency of 98.3%, and realized the strategy of "coordinated control based on energy balance", and improved the power electronic transformer with high power density and multi-function coordination to an internationally leading level.

Power electronic transformers in a data center power supply system

Power electronic transformers in a data center power supply system

The united project team proposed the AC/DC hybrid distribution system structure based on multi-port power electronic transformer for the first time, created a new distribution network operation mode of medium and low voltage closed loop and power electronic transformer "cluster", overcame the matching problems caused by diversity, time variation and dispersion of load storage in the source network, and improved the stability, reliability and efficiency of the system as well as complementary sharing through energy interconnection.

(2) Breakthrough in large capacity ultra-fast DC on/off technology

Tsinghua University and Zhuzhou CRRC Times have successfully developed a new generation of domestic on/off IGCT-Plus devices with a maximum breaking current of more than 10,000 amperes and international leading parameters; based on the breakthrough of ±375V solid-state ultra-high-speed DC on/off technology, the device can break in tens of microseconds, with a breaking capacity of more than 7.5MW and an on-voltage drop below 1V, protecting the safety of IT load in the data center.

Domestic IGCT-Plus device used in ±375V solid state DC circuit breakers

The project team creatively proposed the coupled negative voltage hybrid DC circuit breaker topology, broke through the key technologies such as low loss current flow, highly reliable commutation and ultra-fast on/off, solved the problems of large capacity and ultra-fast on/off of medium and low voltage DC systems, and successfully developed the 10kV hybrid DC circuit breaker, 10kV mechanical DC circuit breaker and ±375V solid-state DC circuit breaker with Taikai Group. It is the first time in the world to realize the integrated demonstration application of hybrid, mechanical and solid-state DC circuit breakers in the same project, which is another breakthrough of Tsinghua's independent innovation of DC breaking technology after Zhangbei 500kV DC circuit breaker and Zhuhai 10kV three-port DC circuit breaker were put into operation.

DC circuit breaker in the power supply system of a data Center

DC circuit breaker in the power supply system of a data Center

III. Conclusion

The application of Tsinghua's full DC data center program in Dongguan was a fruitful result of comprehensively deepening industry-university-research cooperation, and solved the problems of low efficiency and poor flexibility of AC energy supply in traditional data centers. The project achievement will promote the national production of large-capacity semiconductor devices and DC power grid equipment, provide key technical support and complete sets of solutions for the development of green data centers in China, and comprehensively bring China to the world peak of energy supply technology for data centers.

Brief about the DC Research Center

The DC Research Center of the Energy Internet Research Institute of Tsinghua University was established in 2015 under the leadership of Professor Zeng Rong, EEA of Tsinghua University. Relying on the superior scientific research strength of EEA, the Center has established a research team capable of high-level academic research, forward-looking technological innovation and practical industrial development. The DC Research Center takes the research and development of key technologies and equipment for DC transmission and distribution as the core task, focuses on the technical fields of HVDC transmission and medium-and low-voltage DC power distribution, carries out theoretical research, technical research and engineering construction at three levels of devices, equipment and systems, and strive to become the disseminator of the core concepts, the leader of theories and technologies, and the practitioner of standards and applications of DC power grid, so as to lay a solid foundation for the new energy revolution.

Website: http://dc.eiri.tsinghua.edu.cn

Brief about the Large-capacity Power Electronics Research Center

The Large-capacity Power Electronics and New Power Transmission Research Center of the Energy Internet Innovation Research Institute of Tsinghua University aims to integrate the basic theory of power electronics and new power transmission technologies and create an international first-class power electronics and new power transmission research team oriented to cutting-edge power transformation and transmission technologies in the energy Internet. The Center is positioned to walk with "two legs" of basic power electronics theory research and practical application technology research along the road of internationalization and intersection of power electronics and new power transmission research towards the energy Internet innovation research and personnel training. In the next few years, the Center will make breakthroughs in the basic theory of large-capacity power electronics supported by the Natural Science Foundation Project (2015-2019) on one hand, realize the key technologies of the power router system of the distribution network and the two-way wireless charging system of electric vehicles through the combination of basic theory and key technologies on the other hand, so as to solve the cutting-edge problems in the future energy network.