Study of Impacts of Two Types' Distributed Generation on Distribution Network Voltage Sags

Distributed generation (DG) has impacts on the performance of connected distribution network. DG is usually not requested to participate in voltage regulation of the distribution network and will be disconnected from the distribution network quickly enough when a fault occurs in it for eliminating DG's negative influence. But in this way it will also limit the capability of DG to suppress the voltage sag of distribution network in faulty condition. In this paper, two typical DG models, i.e. synchronous generator and VSC-type inverter based DG models, are established focusing on the different effect on voltage sag in different scenarios with different models, fault locations, control modes and reactive power reserves etc. It is concluded that synchronous generator based DG has low effect on suppressing the voltage sag, while VSC-type inverter based DG has certain capability of suppressing voltage sag, depending on factors such as control strategies, reactive power reserve and fault locations etc.