Investigations on the surge withstand capability of SCALED System

Abstract

Simple resistor-capacitor (RC) circuit theory is extended in developing Supercapacitor Assisted (SCA) technique by placing supercapacitor (SC) in series with the useful load. Part of wasted energy in a RC loop is utilised by this useful load resulting in increased overall efficiency of the circuit. In Supercapacitor Assisted Light Emitting Diode (SCALED) converter, developed for a DC microgrid system, two SC banks with LEDs form the modified RC loops. A complete SCALED system prototype is in field trial at Ports of Auckland Limited (POAL). Target of this project was to test transient surge withstand capability of SCALED system so that its vulnerability to lightning surges could be minimised. Noiseken LSS-6110 Lightning Surge Simulator (LSS) was used to generate high voltage transient surges as per IEEE C62.41 standards. Surge propagation through different parts of SCALED was studied stage by stage with PV panel providing two different paths for surge energy to travel. Tests revealed that SCALED itself is able to withstand limited transient surges due to the buffer SC bank connected across its input ports. However, some operational time delay was observed which is due to processing circuits sensitive to transients. Thesis provides an initial approach towards developing surge protected SCALED system.