Techno-Economic Study of Series Current Limiting Reactor and Its Impact in the 11KV Network with Harmonic Pollution

Abstract

Survey & selection of oil filled fault current limiting  series reactor  for limiting short circuit  fault  currents from 40KA to 22KA at 11KV level in an existing distribution substation due to change of source substation.  The impact of source X/R ratio variation, maximum & minimum short circuit currents on the acceleration times of the 11KV motors and variance in voltage regulation due to change(s) in the conventional Series reactor impedance is studied. Impact of power factor improvement capacitors on the short circuit level and on series reactor impedance is assessed. Expected harmonic pollution due to VSD’s is estimated and its influence on the series reactor impedances is assessed for resonant conditions.  Transient Recovery Voltage and Rate of Rise of Recovery Voltage are studied for verification of circuit breakers’ ability to isolate the fault conditions.  Techno - economic evaluation of series reactor(s) impedance(s) for cost effectiveness along with the ability of reputed international testing houses for testing is assessed. The study results reflect that the constraints of test laboratories to test the specified series reactors will have an impact on the selection of series reactor impedance.  While higher impedance selection will be useful from the short circuit point of view, it will pose difficulties with reference to physical dimensions of the equipment, cost and other related issues.

Keywords: Current Limiting Reactor (CLR), Short Circuit Current, Harmonics, Cost