Effect of accurate modelling of converter interfaced generation on a practical bulk power system

With increased penetration of converter interfaced generation (CIG) in power systems, the suitability of modelling approaches and models dependent on the system conditions has to be studied. However, their suitability has yet to be systematically analysed. In this study, the authors first develop a methodology for identifying the maximum penetration of aggregated rooftop sources that can be represented as negative loads in both the steady state and dynamic analysis. Then they verify the suitability of a positive-sequence performance-based model and a detailed electromagnetic transient (EMT) model for utility-scale photovoltaic (PV) plants under different fault conditions. Based on the results, they perform dynamic simulations on a large practical system with both positive-sequence transient stability (TS) and EMT-TS hybrid simulation. This study shows that positive-sequence performance based PV plant model is more suitable for study cases with faults relatively far away from the point of connection. In addition, the results indicate that positive-sequence models and TS simulation approach can produce comparable results with reference to the EMT-TS hybrid simulation with EMT detailed models for normally-cleared single-line-toground faults, but the inadequacy of positive-sequence based model and simulation approach becomes obvious for prolongedtripping of unbalanced faults in the proximity of the PV plants.