A unified three-phase power-flow analysis model for electronically-coupled distributed energy resources

Summary form only given. This paper develops and presents a unified and generic three-phase, steady-state, hl{fundamental-frequency,} sequence-frame-based model of the voltage-sourced converter (VSC) for power-flow analysis of VSC-interfaced Distributed Energy Resource (DER) units. The model is unified since it represents (i) three-wire and four-wire VSC configurations, (ii) balanced and unbalanced power-flow scenarios, (iii) various VSC control strategies and options, and (iv) operating limits and constraints of the VSC and its host DER unit. Based on the developed model, a new power-flow algorithm in the sequence-component frame is also developed. To achieve numerical and computational efficiency, the interface-VSC operating limits are accommodated in the power-flow algorithm as an interleaved step. The accuracy of the developed model and the computational efficiency of the power-flow algorithm are demonstrated based on several case studies, and where applicable the results are validated based on comparison with the exact time-domain solution, using the PSCAD/EMTDC software tool.