With respect to sensitivity,selectivity and speed of operation,the current differential scheme is a better way to protect transmission lines than overcurrent and distance-based schemes.However,the protection scheme ca...With respect to sensitivity,selectivity and speed of operation,the current differential scheme is a better way to protect transmission lines than overcurrent and distance-based schemes.However,the protection scheme can be severely influenced by the Line Charging Capacitive Current(LCCC)with increased voltage level and Current Transformer(CT)saturation under external close-in faults.This paper presents a new UHV/EHV current-based protection scheme using the ratio of phasor summation of the two-end currents to the local end current,instead of summation of the two-end currents,to discriminate the internal faults.The accuracy and effectiveness of the proposed protection technique are tested on the 110 kV Western System Coordinating Council(WSCC)9-bus system using PSCAD/MATLAB.The simulation results confirm the reliable operation of the proposed scheme during internal/external faults and its independence from fault location,fault resistance,type of fault,and variations in source impedance.Finally,the effectiveness of the proposed scheme is also verified with faults during power swing and in series compensated lines.展开更多
This paper formulates and solves a techno-economic planning problem of reactive power (VAR) in power transmission systems under loadings. The objective of the proposed research work is to minimize the combination of i...This paper formulates and solves a techno-economic planning problem of reactive power (VAR) in power transmission systems under loadings. The objective of the proposed research work is to minimize the combination of installation cost of reactive power sources, power losses and operational cost while satisfying technical constraints. Initially, the positions for the placement of reactive power sources are determined technically. Different cost components such as VAR generation cost, line charging cost etc. are then added in the total operating cost in a most economical way. Finally, the optimal parameter setting subjected to reactive power planning (RPP) is obtained by taking advantages of hybrid soft computing techniques. For the justification of the efficiency and efficacy of the proposed approach the entire work is simulated on two inter-regional transmission networks. To validate the robustness and ease of the soft computing techniques in RPP the responses of benchmark functions and statistical proof are provided simultaneously.展开更多
文摘With respect to sensitivity,selectivity and speed of operation,the current differential scheme is a better way to protect transmission lines than overcurrent and distance-based schemes.However,the protection scheme can be severely influenced by the Line Charging Capacitive Current(LCCC)with increased voltage level and Current Transformer(CT)saturation under external close-in faults.This paper presents a new UHV/EHV current-based protection scheme using the ratio of phasor summation of the two-end currents to the local end current,instead of summation of the two-end currents,to discriminate the internal faults.The accuracy and effectiveness of the proposed protection technique are tested on the 110 kV Western System Coordinating Council(WSCC)9-bus system using PSCAD/MATLAB.The simulation results confirm the reliable operation of the proposed scheme during internal/external faults and its independence from fault location,fault resistance,type of fault,and variations in source impedance.Finally,the effectiveness of the proposed scheme is also verified with faults during power swing and in series compensated lines.
文摘This paper formulates and solves a techno-economic planning problem of reactive power (VAR) in power transmission systems under loadings. The objective of the proposed research work is to minimize the combination of installation cost of reactive power sources, power losses and operational cost while satisfying technical constraints. Initially, the positions for the placement of reactive power sources are determined technically. Different cost components such as VAR generation cost, line charging cost etc. are then added in the total operating cost in a most economical way. Finally, the optimal parameter setting subjected to reactive power planning (RPP) is obtained by taking advantages of hybrid soft computing techniques. For the justification of the efficiency and efficacy of the proposed approach the entire work is simulated on two inter-regional transmission networks. To validate the robustness and ease of the soft computing techniques in RPP the responses of benchmark functions and statistical proof are provided simultaneously.
