Inclusion of classic HVDC links in a PMU-based state estimator

This article presents a PMU-based state estimator algorithm that considers the presence of classic HVDC links. A hybrid AC/DC network model is developed to combine the AC network and DC links. The algorithm assumes that DC link measurements can be sampled synchronously, are time-stamped and reported at the same rate as PMU measurements. Then, by applying the weighted least squares algorithm, a linear state estimator can solve for both AC and DC states simultaneously. To validate the algorithm, a state estimation model is built for a 9-bus and the KTH-Nordic 32 systems, for both AC-only and hybrid AC/DC networks. In addition, the influence of losing DC measurements and effects of measurement noise on the state estimator are briefly discussed.