Improved techniques for modelling fault arcs an faulted EHV transmission systems

A realistic simulation of fault arcs is extremely important in the successful design and development of alternative and improved transmission system equipment such as adaptive auto-reclosure and novel protection schemes. It is also particularly important in relation to the design of single pole switched systems. This paper discusses, in some detail, techniques that have been developed to model fault arcs more realistically than has been achieved hitherto. A time dependent dynamic resistance representation of the primary arc is proposed with emphasis on an empirical approach which is used to determine the parameters concerned. In particular, significant improvements have been made to the dynamic conducting characteristic of secondary arc models. The paper concludes with a presentation of some interesting studies relating to typical 400 kV single circuit and double circuit systems when the new are models are incorporated into the electromagnetic transients program (EMTP)