Average-value model of micro gas turbine systems and its application to online validation of service restoration schemes

Distributed generators (DGs) within distribution systems can be used as emergency sources to restore critical loads during a major outage caused by extreme events. Since the capacity of DGs is limited, the dynamic performance of DGs needs to be validated by simulations before executing restorative strategies. Currently, many DGs use power electronic converters for grid connection. Therefore, electromagnetic transient (EMT) simulation is needed to study their transient characteristics for feasibility evaluation of service restoration plans. However, the detailed models of converters, which model each individual switch, are time consuming for EMT simulation, unsuitable for the purpose of online validation. This study first develops a simplified model of micro gas turbine (MTG). Then the dynamic average-value modelling technique is used to construct the average-value model (AVM) of grid-connected converters. Finally, the MTG generation system model is integrated into a distribution system model for feasibility evaluation of restoration strategies. A radial test system including three MTG generation systems is utilised to validate the effectiveness of the proposed model. The numerical simulation results indicate that compared with the detailed model, the AVM improves the efficiency of simulation while still accurately predicts the transient behaviours of MTG generation systems. The proposed model is applicable for the online validation of restoration strategies.