Study of series resonance overvoltage at LV side of transmission transformer during EHV cable energization

A series resonance between the leakage transformer inductance and HV cable capacitance can be excited by a voltage disturbance at the EHV side of the transformer. In this paper, the series resonance phenomenon is initially studied using lumped parameters to analytically obtain the resonance frequencies and estimate how each parameter affects the first series resonance as well as the harmonic content of the cable energization. For the load impedance two different configurations, consuming the same active and reactive power, are tested: parallel RL load and series RL load. It is concluded that the type of load model greatly affects the harmonic impedance of the system leading to different resonance behavior. The effect of the secondary circuit consisting of the transformer, the HV cable and the load is also investigated and is shown that it significantly affects the frequency of the harmonic content produced during EHV cable energization. In addition, the accuracy of the analytical formulas is assessed by modeling the basic circuit in PSCAD/EMTDC using the frequency-dependent phase model for cable and OHL modeling.

Study of series resonance overvoltage at LV side of transmission transformer during EHV cable energization (PDF Download Available). Available from: https://www.researchgate.net/publication/318348369_Study_of_series_resonance_overvoltage_at_LV_side_of_transmission_transformer_during_EHV_cable_energization [accessed Feb 01 2018].