Weighted Dynamic Aggregation Modeling of Grid-Following Inverters to Analyze Renewable DG Integrated Microgrids

This article proposes weighted dynamic aggregation (WD agg) model for grid-following inverters and their controllers in applications such as photovoltaic (PV) farms or any renewable distributed generation (DG) integrated microgrids. The order and structure of the proposed WD agg model is similar to one inverter of the large-scale system. For example, the WD agg model of a PV farm becomes an equivalent single PV array, single inverter, and a controller with weighted average parameters, which hugely reduces the computational burden of the system studies. The parameter weights of each inverter are obtained based on the contribution of each unit in the overall dynamic behavior of the system. The proposed model can be used to mimic the steady-state, transient, and dynamics behavior of the system, and it can also be used to design controller and inverters parameters to ensure desirable performance of the large-scale system. The performance of the proposed method is simulated and experimentally evaluated by a small-scale PV farm consisting of three paralleled inverters with equal or unequal parameters in various inputs and stability conditions for a comprehensive study. The proposed model is also applied to CIGRE HV/MV 14-bus benchmark for renewable energies to show the functionality of the proposed model in large-scale and practical systems.