Transmission line fault location based on three-phase state estimation framework considering measurement chain error model
In this paper, a wide-area integrated method including a number of algorithms for transmission lines fault location, faulty line discrimination, fault type and faulted phase(s) identification is suggested. The proposed method is based on extension and modification of state estimation formulation. Thus, the method is applicable to both symmetrical and asymmetrical networks as well as all fault types including symmetrical and asymmetrical ones. The method exploites the capacities of the state estimation formulation and the solution algorithm of weighted least squares (WLS) to reduce the effect of inherent error measurement chain on the fault location accuracy and detection and elimination of bad data in the measurement vectors. For this purpose, an error model of the measurement chain including instrument transformers and PMUs is proposed. This model is used to design measuring errors covariance matrix in the state estimation formulation. The performance of the proposed method has been investigated through numerous fault events simulated on different locations of all transmission lines of the 39-bus IEEE test system.