Distributed Generation for Mitigating Voltage Dips in Low-Voltage Distribution Grids

The presence of synchronous and induction generators has a positive effect on the retained voltage (the lowest rms voltage during the event) during voltage dips in high voltage networks. The impact of converter-connected distributed-generation (DG) units has been reported to be negligible, as most converters operate at unity power factor, and the currents injected in the grid are limited to the nominal current of the converter. However, the impact of DG units on the distorted grid voltage is strongly dependent on the voltage level, and thus the grid impedance, of the concerned grid. This paper investigates and compares the effects of converter-based DG units, synchronous and asynchronous generators on the retained voltage during voltage dips in low voltage distribution grids.