Unsynchronized fault-location technique for two- and three-terminal transmission lines

What is it about?

a novel fault-locator technique for two- and three-terminal power transmission lines is introduced. Unsynchronized three-phase current and voltage measurements of all line ends are processed for estimating the required synchronization angle/s and the fault location via exploiting the initial conditions of each fault type. To realize this target, the computations of the required synchronization angle/s are initially accomplished independent of the fault location via considering a lumped charging current at the reference terminal which is selected arbitrarily. Consequently, the initial fault location is determined via equating the deduced equations of the positive-sequence voltage at the faulty point from two sides of the faulted segment as a function of the measured data after their correction. The previous obtained fault location is, then, utilized as an input for the next iterative computations, where the distributed line model is used to update the charging current. This process is repeated until the change rate of the obtained fault location becomes negligible.

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Why is it important?

The presented technique can be easily incorporated with the existing IEDs because all of the calculations are carried out using unsynchronized measurements. Further, the proposed unsynchronized fault-locator technique uses only the post-fault data and does not need the source impedance value. Finally, the presented technique is represented as a faulty segment identifier and fault locator. However, it can not be applied under three-phase fault conditions due to an absence of any healthy phase and then the synchronization operator expression cannot be obtained.

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