Implementation of some digital computer algorithms for power system protection

Previous researchers have concentrated their effortson the theoretical development of digital protectionalgorithms. This thesis deals with the practical applicationof some of these algorithms in "stand-alone" digitalprotection schemes.The schemes described are a transmission line digitaldistance protection scheme and a transformer digital differentialprotection scheme. The software and hardware structuresof these are detailed with emphasis being given to theoperational aspects of these units in a power system situation.The performance studies of these protection schemes wereconducted on a power system model in the Power Department,the School of Electrical Engineering at the University ofNew South Wales. This model is described and its specificationsare given for reference. In the case of the digital distanceprotection these operational studies have been extended to anexperimental computer facility at Sydney West Substation, a330 KV substation in the Electricity Commission of New SouthWales high voltage network.The limitations of both protections were investigatedand modifications to each scheme developed by the author toenhance the operations of the protection are discussed. Inthe digital distance protection case these limitations concernprinciply the detection and correct discrimination of resistiveearth fau1ts.A significant addition to the experimental resultsobtained for the digital distance protection are the faultoccurrences described in Appendix 4. A zone 1 fault and aresistive earth fault occurred on the monitored line and thedigital protection scheme's response to these faults is analysed