Effects of low amplitude oscillatory switching transients on EHV grid transformers

Author

Mitra, Poulomi ; De, A. ; Chakrabarti, A.

Author_Institution

Dept. of Electr. Eng., St. Thomas Coll. of Eng. & Technol., Kolkata, India

fYear

2011

fDate

16-18 Dec. 2011

Firstpage

1

Lastpage

5

Abstract

A section of the Eastern Regional Power Grid in India has been simulated in this paper using Alternative Transient Program (ATP) for the purpose of defining high frequency transient voltages which may occur during various switching events. The investigation reveals that such oscillatory voltages could excite natural frequencies of a 400/220/132 kV power transformer which closely match with the terminal excitation frequencies. Short Time Fourier Transform (STFT) has been used to analyze the frequency contents of the voltage response of the windings. Results of the STFT confirmed the presence of resonant frequency in the 400 kV main winding of the transformer. Reduction in winding voltage stresses under resonance is possible by deploying some remedial measures which have also been suggested in this paper.

Keywords

Fourier transforms; power grids; power transformers; switching transients; transformer windings; EHV grid transformers; Eastern Regional Power Grid; India; alternative transient program; high frequency transient voltages; low amplitude oscillatory switching transients; oscillatory voltages; power transformer; resonant frequency; short time Fourier transform; terminal excitation frequencies; transformer winding; voltage 132 kV; voltage 220 kV; voltage 400 kV; voltage response; Coils; Inductors; Power transformer insulation; Resonant frequency; Transient analysis; Windings; Oscillatory over voltage; Power system transient; Transformer winding;

fLanguage

English

Publisher

ieee

Conference_Titel

India Conference (INDICON), 2011 Annual IEEE

Conference_Location

Hyderabad

Print_ISBN

978-1-4577-1110-7

Type

conf

DOI

10.1109/INDCON.2011.6139518

Filename

6139518