Analysis And Research On 500kV Yongshengyu Transformer Station 220kV Shirt Circuit Bus Bar

Nei Monggol Autonomous Region Power Grid(For short,West Inner Mongolia Power Grid)locates in the north of North China Grid,it is the important component and main transmitting end of North China Grid.There are abundant coal,wind and photovoltaic resources.In recent years,with the development of power grid construction,strengthening of the power grid structure and a lot of power grid connection,problems of transformer station short circuit and above-norm current reveal prominently.Short circuit current level of some transformer stations will be beyond the rating interrupting capacity of existing switching equipment.According to different power grid structure,there are about three solutions of solving West Inner Mongolia Power Grid short circuit above-norm current at present: One,retrofit small reactor on main transform neutral point;Two,retrofit current-limiting reactor on circuit;Three,adopt splitting mode to run 500 kV transformer stations 220 kV busbar.500kVPermanent Sanctuary Transformer Station is the first comprehensive automatic of 500 KVhub transformer station of West Inner Mongolia Power Grid.It plays a very critical and important role in the power grid structure from West Inner Mongolia Power Grid to North China Power Grid.According to regional planning of power grid construction,two power grids will be connected with Permanent Sanctuary Transformer Station by direct or indirect connection.After connecting,short circuit current level on side of 220 kV will be beyond the rating interrupting capacityof existing switching equipment,which is 50 kA.By comparison of several projects,it considers of connecting long-term power grid construction in this paper,and ensures to make transform permanent sanctuary into 220 kV side splitting running.At that time,220 kV side three-phase of PermanentSanctuary Transformer Station,single phase short circuit current will both decrease to around 36 KA.Because 500 kV PermanentSanctuary Transformer Station 220 kV busbar is type of dual busbar single segment connecting,it has no condition for main transformer 220 kV side splitting running,and needs to do perfect transformation on 220 kV busbar.The transformation involves the primary and secondary devices of power transformation.Because PermanentSanctuary Transformer Station was built in an early age,220 kV bus bar protection and main power transformation of No.500kV1 are both unsuitable for running mode of 220 kV which has been transformed.Replacement is needed in the process of transformation,the time of transformation is long,the transformation is difficult,and the risk of power grid is high.220kV busbar connecting mode within the maintenance area of ultra high voltage power supply bureau has been counted in this paper.Combining to transformation project,considering from view of stable operation of power grid and cost of transformation,It suggests to directly design 220 kV busbar of new voted transformer station into dual bar bus dual segment connection mode,which has a great practical significance on adapting to and solve problems of short circuit and over-norm current that power grid development brings in the future.