چكيده به لاتين
Abstract
The impact of FACTS (Flexible Alternating Current Transmission System) Devices on distance protection is investigated in this Thesis. In order to investigate the impact of FACTS devices on distance protection, firstly the model of each FACTS device is presented and then the general model of FACTS devices is introduced, which has the capability of modeling all FACTS devices. In order to investigate the impact of FACTS devices on distance protection, among the two existing analytical and simulation methods, the analytical method is selected, which is not frequently used due to its difficulty. In this method the measured impedance at the relaying point by distance relay is calculated and then the distance relay tripping characteristic is presented, which is the locus the measured impedance in the impedance plan. The measured impedance in the presence of general model of FACTS devices as well as each FACTS device is presented. The measured impedance is calculate for FACTS devices installation on single line transmission line, on near end of the next line as well as the line behind, on the first circuit of double circuit transmission line as well as the second circuit while the FACTS devices are installed at the near and far end of the line. Investigating the distance relay characteristic in the presence of FACTS devices in the mentioned cases, the impacts of FACTS devices leading to distance relay mal-operation could be observed. According to the changes in distance relay characteristic, some solutions are presented to decrease as far as possible or completely solve the problems aroused in the presence of FACTS devices, leading to distance relay mal-operation in the both cases of operating when it should not operate as well as not operating when it should operate. The proposed solutions are: changing the connection point of the relay measuring transformers in the case of FACTS devices installation at the near end of the line, modifying the input signals and impedance calculation procedure in a distance relay in such a way that the calculated impedance would be the real value, proving order connection between the relays over the network, adaptive and modified distance protection.
