Tadashi Koshiduka

Investigation of Transformer Model for TRV Calculation by Using Frequency Dependent Inductance Model

The transient recovery voltage (TRV) of the transformer limited fault (TLF) current interrupting condition has been investigated with several transformers by using current injection (CIJ) method. A transformer model for the TLF condition is treated as leakage impedance and a stray capacitance with an ideal transformer in a computation by EMTP. By using the frequency response analysis (FRA) measurement, the transformer constants were evaluated at high frequency regions. FRA measurement graphs showed that the leakage inductance value of the test transformers gradually decreases along with the frequency. From these results, frequency dependent transformer equivalent circu it was constructed. The frequency response of the model was good agreement with measurement.

Investigation of EMTP transformer model for TRV calculation after fault current interrupting by using FRA measurement

The authors investigated to calculate the transient recovery voltage (TRV) after the transformer limited fault current (TLF) interrupting condition. Several transformers were used to measure TRV by means of a current injection measurement method. To simulate the TRV at TLF interrupting condition alternative transients program-electromagnetic transients program (ATP-EMTP) was used. The transformer equivalent elements, such as leakage inductance, stray capacitance and resistances were derived from frequency versus impedance graph obtained by frequency response analysis (FRA) measurements. Experiment procedure, results, consideration of transformer constants and constructed EMTP transformer models of current interrupting condition for TRV calculation of tested transformer are presented in this paper. The TRV obtained by the EMTP simulation gave agreeable results with the measured values of the experiment in each case, while a limitation was found by using a constant leakage inductance value which depends on a frequency.