  This paper proposes a novel strategy for the current injection based control
for distributed energy resources connected to weak grids through a voltage
source converter experiencing faults. The current injection controller is no
longer synchronized with the point of common coupling at which the measured
voltage signal can be severely affected by faults in the weak grid, but with
the strong grid point at which the voltage is rigid. It is shown that the phase
difference between the voltage source converter and the strong grid voltages
caused by the long power lines does not affect the power control. Furthermore,
a time delay compensation method which tolerates communication time delay
introduced by the transmission of the synchronization signal from the strong
grid point is proposed. The performance of the proposed control strategy is
verified with an RTDS Technologies real-time digital simulator using switching
converter models.
