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Analysis of LC Oscillation Presence and Its Impacts in 765 kv Line Connected With Non-Switchable Shunt Reactor

S. Vignesh, S. Chandrasekar, A.R. Agastheeshwaran, V. Rajakani, S. Rajalakshmi



The transmission lines are one of the most important parts of the power system. The number of line faults in transmission line is more compared with the total number of faults in the whole power system. Distance protection is commonly used in long transmission lines. It works on the basis of increase or decreases in predetermined value of circuit admittance, impedance, or reactance. Shunt reactors are connected in high voltage systems to compensate the capacitive effect of long transmission line. Non-switchable reactor is a type of shunt reactor, which is always connected in the line and cannot be switched. These are commonly used in long lines and the same is taken here for analysis along with a 765 kV line, which is connected between the source and load with necessary distance protection at both the ends. Oscillation in the transmission line is produced due to the effect of capacitance distributed throughout the line and inductance offered by the line and reactor when the breaker is opened. When a single- or double-line-to-ground fault occurs the transmission line experiences a three-pole trip in case of three-phase breaker, the healthy phase(s) will experience resonance between the shunt reactors and the shunt capacitance of the line. Circuit unbalance caused by the fault at the instant opens the breaker. LC oscillations are produced at that instant and their frequency is below the nominal 50 Hz of the system, typically between 35 and 45 Hz [1]. Due to the presence of LC oscillations the selectivity of the protection devices gets reduced. Finally, it affects the stability of the system. In this paper, we have analyzed the presence of LC oscillation in transmission line along with reactor and their impacts in protection.

Keywords: Distance protection, non-switchable reactor, selectivity

Cite this Article

Agastheeshwaran AR, Rajakani V, Vignesh S et al. Analysis of LC Oscillation Presence and Its Impacts in 765 kv Line Connected With Non-Switchable Shunt Reactor. Trends in Opto-Electro & Optical Communication. 2016; 6(1): 20–24p.

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