This paper presents a novel formulation of the Distribution System State Estimation (DSSE) optimization model. For a given electric three-phase circuit feeder, network models are built using a quasi-symmetric impedance matrix TRX representing the entire structure and topology of the radial network. As a key contribution, the state variables of demands and generators connected to large-scale distribution grids are obtained by using a convenient matrix reduction technique. As a result, the size of the optimization problem is considerably reduced with respect to the jacobian formulation by considering radial and weakly meshed exploitation and elimination of interconnecting nodes. Results and comparative analysis are presented using the IEEE 4-, 13-, 37-, 123-, and 8500-node test systems.

Summary This paper analyzes the well‐known short‐circuit current distribution problem in electric distribution facilities from a new perspective. Fault current distribution, temporary overvoltages, and ground potential rise profile are determined according to a detailed network model based on 5×5 primitive matrices. Despite the use of a 5×5 network model entails additional data with respect to the traditional approach based on Carson's assumptions, the main advantage of the method lies on the enhanced representation of the ground loop. Thus, short‐circuit current distribution can be determined either by using any existing closed‐form expression for the ground loop representation or by incorporating impedance parameters adjusted from dynamic state estimation based on synchronized measurements. The proposed method was illustrated in a simple radial two bus and also applied on a large‐scale 115/12 kV system with 360 buses. Results were compared and validated with the nodal admittance approach provided by the OpenDSS platform.