  In view of the trend towards extensive application of digital controllers in
the PV inverter of large-scale centralized photovoltaic (LSCPV) plant and the
increasing number of grid-connected LSCPV plants, this paper investigates in
detail the influence of the digital time delay of the inverter digital
controller on the stable grid-hosting capacity of LSCPV plant. The studies are
based on the Norton equivalent model of the grid-connected LSCPV system
considering the digital time delay when modelling the digital control system of
the PV inverter. Taking into account the actual situation in LSCPV plant, the
stable grid-hosting capacity of LSCPV is discussed for the cases in which the
PV inverters in the LSCPV plant have the same and different digital time delay
values by using the root-locus method. Simulation results of the digitally
controlled grid-connected LSCPV system model validates the theoretical
analysis.

Systems and Control