Neutral grounding reactors for shunt compensated EHV transmission lines

Single Pole Reclosing is a widely accepted practice for improving the transient stability in EHV transmission systems. Successful single phase reclosing requires some means of ensuring interruption of the secondary arc currents produced by capacitive and inductive coupling with the two energized phases of the same circuit or with the parallel circuit in case of double circuit lines. One of the ways to achieve successful reclosure is to use a Neutral Grounding Reactor in the already available line connected shunt reactors to reduce the magnitude of the secondary arc current, thereby ensuring its rapid extinction. Steady state and transient system studies help in selection of properly sized NGR. This paper discusses the results of studies carried out for selection of an optimal sized NGR for a typical 765 kV single circuit and double circuit line.