Research on Key Technical Problem of System Commissioning of Sutong GIL Utility Tunnel Project

Sutong GIL utility tunnel project is a significant part of Huainan-Nanjing-Shanghai UHV AC transmission project. Sutong GIL connects 1000kV over-head transmission lines from Taizhou and Suzhou stations, and its length is about 5.5km. High voltage and large power flow of UHV AC transmission lines produce large induction current, which will cause difficult-extinguished secondary arc and reclosing failure.To solve the above problem, induction current rapid release devices are installed at both sides of Sutong GIL. Thus, there are four grounding devices for the same loop of Taizhou-Suzhou transmission lines, and the induction voltage and current are different under various grounding conditions, which should be concerned during system commissioning. Sutong GIL project divides Taizhou-Suzhou transmission lines into two parts, and the both open-looped over-head parts are earlier completed. This may cause voltage control and electromagnetic transient problems in system commissioning of the over-head parts of Huainan-Nanjing-Shanghai UHV AC transmission project. This paper focuses on key technical problems of system commissioning Sutong GIL utility tunnel project as well as Huainan-Nanjing-Shanghai UHV AC transmission project. Simulation studies have been carried out, and corresponding measures have been proposed, which have been applied in field commissioning.