Studies On Tripping Protection In A 10KV Distribution System

The lOkV capacity distribution system has widely been used in the power distribution and supply networks between urban and rural areas and its utilization ratio reaches up to 90%.Due to the late start of the application resear-ch on distribution system in China,the power supply protection techniques of the 10kV distribution system are not well developed,resulting in frequent and unpredictable circuit failures,which are undoubtedly detrimental to the daily use of electricity and industrial production.For the elimination of the tripping problems of the lOkV distribution system,it is imperative to take a lOkV distribution system as an example to analyze and summarize its detailed fault causes.Not only does it help to create technical proposals and settlement measures but also reduce the losses of power supply equipment,the scope of power failure,the time to deal with the tripping problems and the damages of industrial production.In this thesis,all of the operating circumstances of the GD power supply station are to be integrated.The tripping problems are to be analyzed by the retrospective analysis method for a lOkV distribution system chosen and the occurrence probability of the main faults is to be statistically documented.Based on the resultant statistical results,the three major factors that are responsible for the tripping problems of the 10kV distribution system are pointed out and these include lightning,bird damage,and short circuit.In terms of the quantitative analysis method,the lightning formation parameters and lightning occurrence times are estimated,leading to not only insightful understanding of the lightning activities around the GD power supply station but also a solid basis for the synthesis and design of the lightning protection scheme.With the close observations and repeatedly examinations of the effectiveness of a conventional bird damage prevention system,its drawbacks are found and modification measures are proposed,improving its performance and reducing the potential impact of bird damage.Through visiting the maintenance personnel of the GD power supply station,the influences of short circuits are pictured and the corresponding solutions are put forward.By means of the combinatorial use of the three measures outlined above,their reliability,effectiveness,and feasibility against lightning,bird damage,and short circuit are preliminarily demonstrated.Although the outcomes of the current thesis come from the detailed studies of the 10kV distribution system chosen,they are considered to have generally reference values and practical significance to the tripping protection of other 10kV distribution systems in China.