The National Development and Reform Commission of China formally gave its authorization for the construction of a "Back-to-back HVDC grid interconnection" between the Southwestern province of Chongqing and the Central province of Hubei. This authorization was approved on the 26th
December, 2016.
Currently the interconnection between Chongqing and Hubei is through two 500kV AC transmission lines (Jiupan-Longquan & Zhangjiaba-Enshi) with the two systems connected and operating synchronously. Aiming to improve the stability of power transmission and the two systems , as well as to ensure the increasing
electricity output from Southeast China, the State Grid Corporation of China (SGCC) decided to change the synchronous interconnection between the two systems into an asynchronous interconnection
using HVDC.
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| Chinese main power grid |
The interconnections will be built using Voltage Source Converters (VSC) based on Modular Multilevel (MMC) converter technology. Compared with the ‘classic Current-Source Converter HVDC’, VSC-HVDC allows flexible control and fast response on both active power
and reactive power respectively allowing decoupling and independent control of active and reactive power (PQ decoupling), avoids commutations failures typical with larger thyristor based systems and avoids the use of large reactive power compensators at the end of the HVDC lines.
Each of the VSC-HVDC stations will be rated at 2*1250 MW with a DC transmission line voltage of ±400kV, it will be the one of highest voltage
and largest capacity Back-to-back VSC-HVDC worldwide. With regards to
technical parameters of the project, the converter station in the north lane located in Yichang
city, Hubei province, will comprise two converter units at 1250 MW each and will be built in the second stage of the project with an overall capacity of 2500MW. The B2B converter station in the south
lane will be located in the City of Enshi, and will be of identical size and capacity to the North one. The AC system around the HVDC converters is of 500kV.
The total cost of the project is estimated at 6.5 billion RMB (1.3 Billion AUD)
The following is a single line diagram of the proposed B2B VSC-HVDC station on the north transmission line:
The total cost of the project is estimated at 6.5 billion RMB (1.3 Billion AUD)
The following is a single line diagram of the proposed B2B VSC-HVDC station on the north transmission line:
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| Geographical map of Project |