Unsynchronized Fault-Location Technique for Double-Circuit Transmission Systems Independent of Line Parameters

In this paper, a new double-end fault-location technique is proposed for parallel transmission lines depending on unsynchronized measurements of both line ends without using line parameters. The proposed technique is based on profiling the correlation between the unknown synchronization angle and the fault distance to accurately estimate the fault point. The positive-sequence network with lumped parameter line model is first utilized in order to facilitate pinpointing the required synchronizing angle between both line ends. The least square error method is used to solve the equivalent positive-sequence network of the line using unsynchronized double-end measurements. Then, an accurate estimation of the fault distance can be realized for all fault types depending on the positive-sequence network of the faulty line. The performance of the proposed locator is thoroughly investigated using a detailed simulation of a selected 150-mi overhead parallel transmission system using the Alternate Transients Program/Electromagnetic Transients Program package. A wide variety of faulty conditions is covered in order to exploit the benefits of using double-end data even with very high fault resistance and untransposed transmission lines.