State Grid Economic and Technological Research Institute CO., Ltd., Beijing 102209, China
Compared with the previous projects, the main difficulties in the system design of Chongqing-Hubei project of China are that the engineering DC voltage is higher, capacity is larger, requirements for fault ride-through and AC/DC protection etc. are improved, but the transient stress level of fully-controlled power electronic devices is limited and the extreme mode of AC power grid deteriorates. In view of the limited transient stress level of the device, this paper proposes the accurate calculation method of rising rate for the arm fault current in the converter, the independent arm blocking strategy of overcurrent protection for valve base controller, the dynamic setting strategy of valve over-voltage protection. They solve the problem that the device safety and fault ride-through capability cannot be taken into account under the weak device capability. Aiming at the problems of high-frequency instability and weak-system instability of AC grid and flexible DC system in extreme modes, the instability mechanism and the practical engineering methods solving the instability are proposed. To meet the special requirements of AC breaker failure the protection and DC differential protection under the access of 500 kV AC power grid, the corresponding solutions and advices are proposed.
This work is supported by National Key R&D Program of China (No. 2016YFB0900905) and State Grid Corporation of China (No. SGSDJY00JHJS1900210).
|||PAN Ersheng, YUE Bo, MEI Nian, et al. System Design of ±420 kV Chongqing-Hubei Back-to-Back HVDC Project of China[J/OL]. Automation of Electric Power Systems, http://doi. org/10.7500/AEPS20200518007.|