Investigation of Transformer Model for TRV Calculation by EMTP

摘要

Due to an increase of electric power consumption a capacity of electric power system is increasing. Large capacity power transformers have been used in high voltage power transmission systems especially above 200 kV. As they have a small leakage impedance, when a fault occurs in a power system, the transformer limited fault (TLF) current became to exceed an interrupting current of the condition defined in the relevant IEC standard. The TRY should be investigated carefully at the TLF condition as a transformer is generally simulated as an ideal transformer with aleakage impedance at a power frequency. A detailed analysis was conducted on the 4 kVA, two windings low voltage transformer by using a frequency response analysis (FRA) measurement. The TRV calculated by EMTP using the model showed a good agreement with one obtained by the experiment with a current injection method. The transformer model for the EMTP calculation is derived.