Study On Compact Arrangement And Lightning Inrush Overvoltage In 220kV Substation

In recent years,industrial parks in our country have developed rapidly.With growing power demands of industrial parks,transmission and distribution projects are proposed and implemented at accelerating pace.In industrial parks,due to the high land price,complex terrain and concentrated load,substations with hybrid switchgear such as HGIS and AIS+GIB have great advantages over traditional AIS,GIS based substations.However,due to the late start of compact layout study,especially after the layout change of traditional substations,the overvoltage problems need further study.Since lightning accident is a major threat to the safe operation of substations,the research on lightning overvoltage in compact substations is of great importance.Therefore,this paper focuses mainly on the layout optimization for compact substations with HGIS and AIS+GIB switchgear and lightning inrush overvoltage in these substations.The main contents and contributions of this thesis are as follows:(1)The characteristics of HGIS and AIS+GIB and the advantages of using HGIS and AIS+GIB in substations in industrial parks by comparing them with AIS and GIS are analyzed.By comparative analysis of various typical designs of 220 kV substation of State Grid,the layout optimization for substations are studied with the aforementioned two kinds of switchgears and a way to achieve overall compact layout is presented through both size compression and wiring simplification,and an idea of overall compact layout of HGIS and AIS+GIB substations is proposed.(2)The substation in a certain economic development zone of Hubei Province is considered as an example,its accurate equivalent EMTP-ATP model(including multi-wave impedance lossless line tower model considering wave velocity variation and a pilot model method for simulating flashover process of insulator string)including the incoming lines and in-station units(including HGIS and AIS+GIB)is presented,and the parameters of the model are calculated.Based on this,the insulation coordination level and the insulation safety margin are studied.(3)Based on the equivalent model of the incoming lines and in-station units,the overall model of the substation under lightning invasion is built at its 220 kv and 110 kv sides using EMTP-ATP.The overvoltage levels are simulated and analyzed under lightning counterattack with different operation modes and different lightning arrester allocation plans,the more optimized arrester allocation plan than the traditional allocation plan of 220 kV substation is obtained according to the guaranteed insulation level and the cost,which is to arrange arresters at both outgoing side and bus bar side and omit the transformer-side arrester.Meanwhile,the overvoltage levels of the system are simulated under lightning shielding failure with the same arrester allocation plan and the result shows that the overvoltage levels are lower than those under lightning counterattack.(4)The overvoltage levels are simulated considering a series of influencing factors(including simulation model selection,impulsive corona,power distribution layout,length of insulation chains,lightning invasion location)of compact substation,and they are compared with those without the factors considered.The impacts of the aforementioned factors by the comparison and analysis are obtained.