Title :
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
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;
Conference_Titel :
India Conference (INDICON), 2011 Annual IEEE
Conference_Location :
Hyderabad
Print_ISBN :
978-1-4577-1110-7
DOI :
10.1109/INDCON.2011.6139518
