A detailed network model for distribution systems with high penetration of renewable generation sources

One of the most important aspects that characterizes smart grids is the widespread integration of loads and renewable-based generators connected to the distribution network. In general, sequence or phase based network models have included the effect of ground return on equivalent phase and neutral impedances using the Kron's reduction and Carson equations. Under unbalanced grid operation, these traditional models can produce inexact results being inadequate for advanced grid analysis and optimization. This paper presents a detailed and compact formulation for the analysis of multi-grounded distribution systems. The key contribution of the paper is to introduce a detailed representation of the ground loops in the distribution system model suitable to be applied under different analysis methods as power flow, optimal power flow, state estimation and network pricing in an integrated manner. This contribution is meaningful since it allows to analyze future electrical systems with severe unbalanced operation due to high penetration of single-phase renewable and load sources. The ground parameters can be adjusted in the context of a state estimator that integrates ground voltages and currents. The proposed model is tested using illustrative and real-world large-scale test cases. Results reveal significant differences when compared with system analyses using standard three phase network model approach.