Emulation of Auto-Reclosing Scheme with Adaptive Dead Time Control for Protection of Series Compensated Transmission Line

Series compensation plays an important role in smart power grid to improve power transfer capacity and voltage profiles. Majority of faults occurring in grid are transient in nature. However, discrimination between transient fault and permanent fault are contemporary problems in the field of distance protection of transmission line. Auto-reclosure is one of the foremost solutions for the same. This paper demonstrates implementation of auto-reclosing scheme using Modified Full Cycle Discrete Fourier Transform with adaptive dead time control. The fault detection logic is based on monitoring impedance trajectory in the R-X diagram of distance relay. The reclosing instance is identified by examining differential voltage across the contacts of circuit breaker. During transient fault condition, based on the time by which the breaker voltage retarded to normal value (below preset threshold) is used to set adaptive dead time of reclosure. Software validations have been performed with the variation in fault location, fault resistance, and fault location with varying line compensation level. Real time validation is also performed using digital signal controller on laboratory prototype. The outcome of simulation and emulation indicates substantial reduction in dead time indicating effectiveness of the developed scheme.