A Method for the Modular Power Flow Analysis of Extensive Distribution Grids

The widespread deployment of distributed energy resources including volatile renewable generation raises the need for detailed distribution network analysis. In many cases, the vast system sizes make the joint analysis of multiple voltage levels computationally impracticable. Consequently, most studies focus on single or selected voltage levels and represent subordinate system portions by conventional static load models. Their parameters are usually identified by simplified aggregation methods that do not consider the effects of the network, i.e., network losses and spatial voltage variations. This approach involves inaccuracies and does not allow for validating compliance with the voltage and current limits inside subordinate system parts that are not explicitly represented in the model. In response to this challenge, this paper extends the static load model by including new parameters, i.e., the boundary voltage limits, and describes the associated component-based parameter identification method. Their combination paves the way for a modular power flow approach, which supports the separate investigation of different system portions without introducing considerable inaccuracies, enabling the systematic, precise, and computationally practicable power flow analysis and validation of voltage and current limit compliance in large distribution systems. The proposed concepts are applied to a synthetic distribution system to facilitate their use and showcase their usefulness.