Hierarchical State Estimation Architecture Based on State & Topology Coestimation Performed at Substation Level

This paper presents a hierarchical structure for decentralized power system state estimation whose lower level is conducted at each power network substation. Local level real-time modeling is based on a nonlinear state & topology coestimation algorithm which not only provides the nodal state variables, but also determines the correct substation topology. The higher hierarchical level, performed at the regional control center, coordinates the local estimates by processing power flow measurements taken on the network branches that interconnect the substations, followed by a second estimation stage that adds the contribution of synchrophasor measurements provided by phasor measurement units deployed in the network. In addition to other benefits, the proposed decentralized architecture allows a substantial reduction of the amount of data transmitted from substations to control centers, and also demands less computational effort than conventional centralized schemes. A number of case studies performed on an IEEE test system whose substations are represented at bus-section level are employed to evaluate the performance of the proposed state estimation architecture.