الفهرس | Only 14 pages are availabe for public view |
Abstract This thesis presents enhanced ultra high speed (UHS) protective scheme that is based on the travelling wave rrw: technique. It includes two main fault detection units; the first is analogue for primary protection and the second is digital for secondary (backup) protection. The two units are combined in an integrated protective scheme with the appropriate logic. The algorithm is proposed based on simulation studies that are achieved by using standard power system simulation software namely electromagnetic transients including DC (EMTDC). The information contained in the travelling waves has been used to discriminate between internal and external faults. The analogue unit will respond directly after fault inception, however the digital unit requires analogue-to-digital (AID) conversion in addition to algorithm processing time and may be delayed by a suitable backup time. Therefore, the operation of the analogue unit will be faster. It has a fault detection operating time of 2-3 ms, The final trip decision is to transmit the trip signal to the output interface if the fault incidence IS confirmed by the analogue unit or confirmed by the digital unit. The prototype hardware of the analogue unit was implemented and tested by a laboratory tests and its performance is found to be accepted. The algorithm of the digital unit was presented. The performance of proposed integrated protective scheme for protecting extra high voltage (EHV) transmission lines has been tested using the simulation data and confirmed to be satisfactory |