Real Time Multiphase State Estimation in Weakly Meshed Distribution Networks with Distributed Generation

Abstract

Recent research has presented a load scaling based real time state estimation (SE) approach for radial and multiphase distribution networks; the approach makes use of successive weighted least squares estimation and power flow to adjust forecasted load values so that they conform with the available real time measurements. This paper extends the load scaling based SE approach along two directions, while maintaining performance that is commensurate with real time computing requirements. First, the approach is extended to allow for meshes that are practically available in some distribution systems; this is achieved by embedding the power flow equations of the nodes that are part of the loops within the load scaling formulation. Second, a sensitivity-based technique is introduced to handle isolated line-to-ground voltage magnitude measurements in radial feeders; this technique is compatible with load scaling and is timely as many utilities have increased the monitoring of voltage measurements at pilot nodes to guard against voltage problems that are associated with distributed generation. The efficiency of the proposed estimator is demonstrated by comparison with the three-phase voltage based normal equations approach that handles both voltage magnitudes and meshes. © 2012 IEEE.