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Reference: ISH2015_216

Type:
ISH Collection
Title:

Simulation and Experimental Validation of Protective Level of Complete Surge Arresters

 

Abstracts

Lightning arrester is a very important power system network element since it protects various substation equipment from the over voltages caused due to lightning and switching surges. It is very essential to properly design these arresters yielding sufficient protective margins between the arrester protective levels and the BIL of the equipment to be protected. The utilities determine the required protective level of the arrester for a given application by performing simulation studies with system contingencies yielding maximum over voltages at the location of the arrester. However, if the simulation studies are not done accurately either due to unavailability of proper arrester data or due to factors that are not generally considered during simulation (steepness of incoming current, lead length separation distance effects etc.), the actual protective margin between the arrester and the BIL of equipment reduces at site conditions as compared to the predicted values at the time of selecting the arrester. The system simulations studies are also important while studying the cause of failures of equipment that are protected by arresters. Thus it is essential to have very accurate models of arresters for simulation studies which are validated thoroughly using measured data. The models thus developed are also useful for testing laboratories in declaring the residual voltage of the complete arresters at currents exceeding the generator capacity. This necessitates accurate measurements and computations of protective levels of arresters. The authors have carried out simulation studies by modelling the generator circuit and by using the arrester data measured at lower currents. By using the above concept, 198kV and 398 kV arresters is modelled using Electro Magnetic Transients Program (EMTP). Residual voltage of each arrester obtained from simulation is experimentally validated by applying lightning and switching surges of different current magnitudes. The simulation results tally quite well with measurement results.
 

File Size: 766,7 KB

Year: 2015

 
 
 
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