BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//EE - ECPv5.10.0//NONSGML v1.0//EN
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:EE
X-ORIGINAL-URL:https://ee.iisc.ac.in
X-WR-CALDESC:Events for EE
BEGIN:VTIMEZONE
TZID:Asia/Kolkata
BEGIN:STANDARD
TZOFFSETFROM:+0530
TZOFFSETTO:+0530
TZNAME:IST
DTSTART:20240101T000000
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240410T093000
DTEND;TZID=Asia/Kolkata:20240410T113000
DTSTAMP:20260422T122306
CREATED:20240408T041654Z
LAST-MODIFIED:20240408T042412Z
UID:241429-1712741400-1712748600@ee.iisc.ac.in
SUMMARY:Colloquium On Investigation Of Direct Lightning Strike To High Voltage Transmission Lines
DESCRIPTION:Name of the Candidate :      Mr. Sukesh A \nDegree Registered :               Ph.D. \nTitle of the thesis :                 Investigation Of Direct Lightning Strike To High Voltage Transmission Lines \nTime and date :                     9.30 AM\, 10th April 2024 \nVenue :                                   High Voltage Laboratory Seminar Hall \nResearch supervisor :           Udaya Kumar \nABSTRACT \nLightning continues to be the single largest natural cause of line outages. With high voltage lines spanning millions of kilometres around the globe\, it has been a serious concern to transmission line engineers. Quite unfortunately\, the lightning performance of ultra-high voltage lines falls far below that estimated from the available models. There are two reasons for this difference\, namely\, inadequacy in the present standards in evaluating the lightning attachment process and in ascertaining the surge response of these tall lines. \nThe recent progress in simulating the attachment process is dealt with in the latest CIGRE technical brochure. It is shown that the simplified model proposed over there can account for the observed differences between estimated using older models and the field data. \nDifferent modelling approaches have been employed to evaluate lightning surge response. The most popular approach in power engineering is a lumped current source in parallel with an impedance. However\, there is no consensus among researchers regarding the value of impedance to be used in such models. Based on observations over tall towers\, it has been inferred that the peak value of the lightning current depends on the strike object. Importantly\, a seven years long study based on measurements on heavily instrumented UHV lines in Japan has provided additional information that is not in line with expectations. \nAn alternative modelling approach for evaluating the lightning surge response of lines is to make use of the return stroke models. Among the different categories of return stroke models available\, only the transmission line and electrodynamic models can\, in some sense\, be employed for modelling a direct strike to the transmission line. Even though current is not assumed in the transmission line models\, the mode of propagation is assumed as TEM mode\, which is not true on the channel\, at least in the initial stages of current evolution. Even though the mode of propagation is not assumed in electrodynamic models\, usually\, a lumped excitation is assumed. \nTherefore\, a model that does not assume the excitation and the mode of propagation is essential. A self-consistent return stroke model recently proposed by the group would be an ideal tool for the required investigation. It basically emulates basic essential physical processes along with accurate tracing of dynamic electromagnetic fields using time-domain thin-wire formulation. \nIn order to apply this model to simulate a direct strike scenario to a transmission line\, the field computation methodology had to be extended from the axisymmetric to a fully three-dimensional wire geometry. Further\, wire junctions need to be considered. These were achieved and for the latter\, spatial basic function is borrowed by the Numerical Electromagnetic Code. \nUsing this extended self-consistent return stroke model\, detailed simulations are carried out for a direct strike to the transmission line. The peak current during a strike-to-phase conductor and strike-to-ground (or simplified ground wire-tower structure) are deduced. Using this consistent modelling approach\, it has been clearly shown by modelling that the peak current value for the same conditions reduces to half of that for a strike to ground/ground wire-tower structure. The physical reason for this difference has also been identified. Furthermore\, the mode of propagation of the stroke current along the phase conductor is also assessed.  In summary\, this work has delved into some of the fundamental aspects of lightning strikes.
URL:https://ee.iisc.ac.in/event/colloquium-of-mr-sueksh-9-30-am-10th-april-2024/
LOCATION:HV seminar Hall
END:VEVENT
END:VCALENDAR