An integrated short-circuit current limiting scheme for Sichuan 500kV power grid considering Xinjiang power injection

“Xinjiang electricity sending outside” project as national energy security protection and solution for "natural electricity shortage" problem of the eastern and the central region in future is constructing step by step. Sichuan power grid as an adjacent network of Xinjiang, due to its abundant hydropower resource, has already become one of the largest outside sending scale provincial power grid and existed a structural contradictory problem of “redundancy in wet season and shortage in dry season", which contributes to Sichuan power grid with both power given and relay out duality between supply and demand. As an effective way to solve the problem above, “Sending Xinjiang electricity to Sichuan power grid" project has been included in the plan and in implementation. However the outstanding problems of Sichuan power grid is in being a comparative high level of short-circuit current in present, in order to ensure security and stability of the grid in future, how to limit the short-circuit current level has been the key issue of all. The most of existing methods of short-circuit current limiting was relatively single and some of limitation effect was not satisfied. So it was lack of proper guidance especial for Sichuan power grid which has a more complicated transmission way and voltage grade. Therefore basing on a brief introduction of the short-circuit current damages and its limiting measures at home and abroad, simulations about short-circuit current of Sichuan power grid before and after “”Xinjiang electricity sending outside" project implementation and comparative analysis about the effect of each main single limiting method were carried out in this paper. Then an integrated current limiting scheme suitable for Sichuan power grid development was putted forward. And validation of the scheme had been tested through simulation and analysis. The result showed that although the project would not improve the short-circuit level of Sichuan power grid, the scheme considering the developing plan and real situation was very necessary. And it also showed that the short-circuit current level decreased substantially and the high level current problem has been effectively controlled within the scheme. All of these had proved the validity of the scheme.