Study of Multi-converter Aggregation with Improved Equivalent Parameters

Grid-connected converters act as an interaction between the new energy and the power grid, and provide a certain amount of inertia to support and increase the stability of the system. This paper considers the complexity of analysis when multiple virtual synchronous generators (VSGs) are connected to the grid. It is necessary to aggregate and reduce the order of the multi-converter model to simplify the circuit and facilitate the analysis of the mechanism. Based on the working principle and the coherency criteria, the VSGs aggregation condition was designed: virtual power angle change curve classification. Equivalent models were built in the PSCAD/EMTDC and integrated into the power grid simultaneously. The correctness and effectiveness were verified. By improving the capacity weighted equivalence of aggregated parameter values, the aggregation effect is more accurate compared to parameter aggregation without considering the capacity of virtual synchronous generators.