A three-phase algorithm for state estimation in power distribution feeders based on the powers summation load flow method

• This work proposes a three-phase state estimation approach exploring radiality feature of distribution systems.
• The feeder is divided into reduction sections, in order to estimate state variables, section by section, from substation to the laterals, like a forward sweep algorithm.
• The proposed methodology reduces significantly the computational effort to perform the estimation, since it works with gain matrices of small dimension.
• The methodology was tested successfully for large and real distribution feeders.

State estimation approaches for use in transmission systems are common in the literature, however, there are few algorithms intended for distribution systems. This occurs, mainly, due to the small amount of measurement data available in real time and topological complexity of these systems. In this context, this paper proposes a new three-phase state estimation algorithm for radial distribution feeders, which is based on adjustment of loads from a dynamic utilization and imbalance factors, in order to model pseudo-measurements of powers, and take into account the imbalance of loads, frequently presents in feeders. The method performs the estimation by section, starting from the substation toward the loads, where estimated quantities in a section are used as pseudo-measurements to estimate the subsequent section. This procedure provides a computational optimization for real-time methodology presented here. Tests were performed in distribution feeders from a Brazilian power company and the results show satisfactory performance of developed state estimator in respect to adjustment of estimated values compared with corresponding real-time measured quantities.