Effect of PLC on the impedance and stability of converter dominated DC microgrids

This paper investigates the influence of power line communication signals on the impedance and the control of a dc distribution grid. In a dc distribution grid, PLC is affected by the impedances of the cables and converters. The time variant converter impedance is affected considerably by the terminal capacitor of a converter at higher PLC frequencies. Different approaches are implemented to make the grid impedance time invariant for PLC applications. The use of decoupling inductors at each source and load in a dc distribution grid is one of the common approaches to substantially decrease the influence of terminal capacitors. The influence of the parasitic capacitance of the added decoupling inductor on the converter impedance is investigated. Moreover, the effect of decoupling inductances on the stability of the dc distribution grid for different load conditions, especially when the grid is dominated by constant power loads, is studied. The influence of a source and a load modeling (constant power load) on the dc distribution grid stability is also investigated. This paper shows that the system's voltage stability depends on the value of decoupling inductors, grid capacitance and the complexity of the dc grid.