A low-observable distribution system has insufficient measurements for conventional weighted least-squares state estimators. Matrix completion state estimators have been suggested

but their computational times are prohibitive. In this letter

a novel and efficient power-flow-embedded projection conic matrix completion method is proposed

which is customized for low-observable distribution systems. This method can yield more accurate state estimation (2-fold improvement) in a much shorter time than other methods. Case studies on different-scale systems have demonstrated the effectiveness of the proposed method when applied to the state estimation problem of low-observable distribution systems.