Renewable source integrated transmission line protection by novel time-domain computation of line voltage drop

• A novel time-domain computation of line voltage drop is proposed for the protection of renewable source integrated transmission lines (RSITL). • Line voltage drops computed using sending and receiving end signals are nearly 180° out of phase unlike two terminal currents in which this phase relation deviates significantly due to line-charging current. • This unique characteristic of line voltage drops is exploited to derive indices for detection of fault direction and faulty phases. • Its ability for single-pole tripping following a phase to ground fault helps to achieve better stability, reduce power outage area and enhance power utility. • The method has better dependability and security compared to existing methods for protection of RSITL under different fault conditions. Due to presence of power electronic converters, the renewable source integrated transmission lines (RSITLs) show quite different fault-signal characteristics compared to the transmission lines having only conventional sources. This may lead to poor reliability in the traditional protection schemes when they are applied in RSITLs. To improve the reliability, a novel technique is proposed based on time-domain computation of two voltage drops across the line using sending end and receiving end signals. The unique characteristic that these two line voltage drops are nearly 180° out of phase, is exploited to derive the indices for directional protection of RSITLs and segregation of faulted phases. The ability of the scheme for single-pole tripping (SPT) following a phase to ground fault is also examined to achieve better stability, reduce power outage area and enhance power utility. The proposed protection scheme is found highly dependable and secured against all types of internal faults and external events when it is tested for fault resistances up to 300Ω, severe noise, asynchronization and line parameter variations. In comparison to similar existing pilot protection schemes applied in RSITLs, the proposed scheme is superior with respect to different protection aspects including SPT, dependability and security.