Fault Location in Multitapped Transmission Lines Using Unsynchronized Data and Superposition Theorem

Lines with several taps are frequent and involve a large number of small towns and customers. With the need for costs reduction, this solution has been adopted in Brazilian utilities, with measurements only at the two terminal substations of the main line. The relevance of the problem is related to the long time for fault location when there are several secondary tap lines, depriving a large number of customers of energy during this period. Since there is not yet an adequate approach for this configuration, without additional hardware and measurements in tap lines, this paper presents a low-cost solution focusing on the synchronization of data measurements and the fault location in the main line or in the tap lines. The algorithm can handle the critical condition of zero-sequence infeed of star-delta transformers connected to tap lines, detecting the faulty section through the superposition theorem and finally obtaining the fault distance. Simple and accurate enough expressions were developed for fault location in order to help computer implementation of the algorithm. The algorithm also enables fault location in double-circuit main lines with several tap lines. The results, considering various line configurations and fault types, are presented, showing the accuracy and efficiency of the proposed method.