Accurate Unbalanced Fault Location Method for Multi-Ended Multi-Tapped Structures

Abstract

The accurate fault location is an important criterion for protection system. Accurate and fast fault location decreases the outage time, consumers dissatisfaction and operation cost. Different methods have been proposed to determine the fault location. The impedance-based methods are usually used to protect power systems. The accuracy of these methods depends on system parameters and the structure of power systems. Also, these methods require an iterative process, the phase alignment and a high volume of data. Another algorithm has been newly presented based on negative sequence parameters, which is not iterative and the amount of data communicated between relays is small. Besides, this algorithm is not affected by pre-fault load flow, zero-sequence mutual coupling and fault resistance. This algorithm has been applied for one-tapped systems. But, that method is not applicable for multi-ended structures with more than one tap. In this paper, a new algorithm is introduced to extend the negative sequence method for multi-ended structures with more than one tap. This new algorithm covers a larger area of the power system. Hence, it improves the reliability of power systems. It decreases the amount of relays necessary for the fault location. So, it can noticeably reduce the costs. Also, in this paper, a new idea is presented to reduce the time of the fault location process. The proposed methods are implemented in PSCAD/EMTDC and MATLAB software. The results of simulations will show the effectiveness and accuracy of proposed methods.