Reliable control and protection system for the Tian-Guang HVDC transmission project

The Tian-Guang HVDC power transmission system delivers 1800 MW over 960 km from converter stations (Bipolar 900 MW) at Tianshengqiao in Guangxi Province to the Guangzhou converter station in Guangdong Province. Both converter stations are connected to the respective AC networks through 220 kV buses. The HVDC transmission system is an important power link in the Southern China electric power network and transfers bulk power to Guangzhou area together with 500 kV AC lines in parallel. This paper describes the control and protection (C&P) system of the Tian-Guang HVDC power transmission project. All aspects regarding the used structure and redundancy are addressed. The C&P system includes also the communication system, the measuring system, the data acquisition systems (SER, TFR) and the master clock system. The complete design process including off-site and on-site tests is described as well. Special control functions and all new technologies which are used will be covered. Innovations like the decentralised I/O units with the redundant optical field bus, the hybrid optical measuring system, active DC filters and the new electrode tine monitoring system are introduced. The test results of the off-site tests and the field testing are discussed. Finally, operating experience from the first operation in December 2000 to the present, is reported as well.