Management of Fault Current Contribution of Synchronous DGs Using Inverter-Based DGs

Of the numerous types of distributed generators (DGs), synchronous DGs represent the most substantial contribution to fault currents and, consequently, have the greatest effect on the operation of the protection system. On the other hand, many types of DGs require power electronic (PE) interfaces at the points where they connect to the grid, which are normally left idle during fault conditions. This paper presents a novel idea for employing the PE interfaces of inverter-based DGs (IBDGs) as a means of managing the fault current contribution of synchronous DGs through the modification of the IBDG current phase angle during fault conditions. This operation enables synchronous DGs and IBDGs to be kept connected to the system during fault conditions but with their contribution to the current having no effect on the magnitude of the fault current. Constraints related to DG locations and capacities are thus relieved. More interestingly, it is demonstrated that larger-capacity IBDGs are more effective for managing the fault current contribution of synchronous DGs, which means that for systems that include synchronous DGs, the availability of more numerous IBDGs would be beneficial.