The Research On The Lightning Impulse Flashover Characteristics And Lightning Flashover Criterion Of 110kV Insulator

Lightning is the main reason of overhead transmission line tripping.The accuracy of the insulation flashover criterion have a great influence on the overvoltage calculation and backflashover level evaluation,and the actual lightning impulse flashover characteristics of insulators is the base of flashover criterion.The lightning overvoltage on the insulators is related to lightning form and its wave tail falls rapidly in the case of backflashover.However,the insulator flashover characteristics of different materials under the short-tail wave are not clear yet.What's more,in the actual operation of the circuits,the influence of altitude on the impulse discharge voltage of insulator can not be neglected.Therefore,the paper reaserached on the flashover characteristics and the flashover criterion under the different lightning impulse voltage of insulators on the real tower model placed in the high altitude area.Firstly,basd on the PSCAD/EMTDC electromagnetic transient simulation program,the short-tail waveform and its influence factors on the insulator of the 110kV double-circuit transmission lines were analyzed.Secondly,the test circuit was designed and the test platform was set up at National Engineering Laboratory of UHV Engineering?Kunming?.Next,the discharge test of the composite insulator and the glass insulator on the 110kV real tower model under the standard lightning impulse and short tail wave at the high altitude area is carried out.On the basis of insulator U_50%,volt-second data and discharge image,the flashover characteristics of insulators are analyzed by comparing the factors such as tower type,insulator material and voltage waveform.Then,combined with the physical mechanism of long air gap discharge and the test data,the parameters k,E₀ of the Leader Development Model were corrected,and the model applicability was verified within a certain margin of error.Last but not least,based on the modified Leader Development Model,the flashover level of the typical110kV double-circuit transmission line was calculated based on PSCAD/EMTDC program,and the flashover level of different flashover criteria was compared and analyzed.The results show that the modified Leader Development Model can reflect the flashover level of the high altitude area,and it is more suitable for the flashover criterion of long air gap in high altitude area than the Regulations Method and the volt-second characteristic.