System impacts evaluation of a single-phase traction load on a 115 kV transmission system

The system impact of a new transit substation may include harmonic distortion, voltage unbalance and flicker. Measurements were taken at a similar substation, and system simulations were performed for the planned substation. It was found that the Metro North train load produced significant levels of third harmonic current. Resonances in the 115 kV system were simulated and found to be at frequencies which are not critical. The decision as to whether to install a harmonic filter is a difficult one. Unbalance and flicker were found to be negligible.