Performance Analysis of Extra High Voltage 765 kV and 400 kV Hydro Power fed Transmission Lines

The extra high voltage transmission lines are preferred for their high active and reactive power transfer capability. To further increase the power transfer capacity of extra high voltage transmission lines fixed and thyristor-controlled series compensation is used. The series compensation also reduces reactive power transmission loss and provides better transient stability by damping oscillations. The extra high voltage lines charged at 765 kV and 400 kV are compared based on active power and reactive power transfer capacity, transmission line power loss, series compensation requirement and operation during transient conditions. The series compensation device optimum location is equally important for its efficient use. The sensitivity indexes based on power loss are used here for finding optimum location for the series compensation device. The analysis is performed using MATLAB/SIMULINK environment for 1400 MW Hydro power plant at Tehri Koteshwar complex connected to load by extra high voltage transmission lines.