New Fault Location Algorithms for Unbalanced Distribution Power Systems using Matrix Inverse Lemma in Fault Analysis

M.-S. Choi and S.-J. Lee (Korea)


Power system protection, Unbalance distribution system, Fault location


Unbalanced systems such as distribution systems due to single-phase laterals and loads have difficulties in fault locations. This paper proposes new fault locations developed by the direct 3-phase circuit analysis algorithms using matrix inverse lemma for the line to ground fault case and the line to line fault case in unbalanced systems. The fault location for balanced system has been studied using the current distribution factor, by a conventional symmetrical transformation, but that for unbalanced system has not been investigated due to high complexity. The proposed algorithms overcome the limit of the conventional algorithm using the conventional symmetrical transformation, which requires the balanced system applicable to any power system but useful for unbalanced distribution systems. Their effectiveness has been proven through many EMTP simulations.

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