Fault Current Control of Distributed Generations Equipped with Synchronous Generator to Coordinate Protective Relays

The presence of distributed generation sources (DGs) will affect the extent and duration of system failures. This will inevitably require the need to review the functioning of the system of protection and re-coordination of the relevant equipment. Because the lack of an appropriate coordination between the DG units connected to a distribution system could lead to the exchange of power between these units and the system's instability, improper operation of the system of protection or the unintended islanding of a part of the system. Due to the fact that synchronous machine type DGs (SMDGs) are the most problematic for system coordination (over-current relays) than other types of DGs; in this paper, controlling the output current of generators Synchronization is proposed by tap changer of the transformer connected to it. In this method, the SMDG's participation in the flow of error is limited by the control of the pincer. Before the fault occurred and in accordance with the system conditions, the transformer tapping device connected to the synchronous generator has been changed and it reduces the flow during an error. This strategy, in addition to reducing the generation error of the generators and transformer assembly installed as a dispersed generation source, also increases the permeability coefficient of these sources. The proposed technique is implemented on a sample distribution system in the ETAP software; the results of the simulation show the effectiveness of the proposed method.