Developments in the simulation of long-distance single-pole-switched EHV systems

The simulation of secondary arcing is extremely important in relation to the design and planning of single-pole-switched EHV systems; but, until quite recently, it has not been possible to simulate this complex phenomenon. The paper extends earlier work on digitally simulating short uncompensated systems employing single-pole autoreclosure (SPAR) to long-distance applications. In the latter case, it is commonly necessary to employ arc suppression arrangements, to reduce the secondary-arc current to levels commensurate with satisfactory extinction times. The paper, therefore, first describes work performed to suitably characterise the extinction processes associated with secondary arcs in long-distance applications. The new methods developed are then employed in the simulation of a 500 kV application similar to the Winnipeg-Twin Cities interconnection, and a comparison with the results of some actual fault-throwing tests is made. An extensive series of general studies of long 500 kV interconnectors is then summarised, and it is shown that the techniques can be used to adequately quantify both the dead times for satisfactory SPAR and the effect thereon of such factors as the degree of compensation and conductor transpositions. The paper concludes by summarising the results of studies of conventionally compensated untransposed applications