Characterisation of flicker emission and propagation in distribution networks with bi-directional power flows

With the increasing penetration levels of intermittent and fluctuating energy sources such as wind generating systems in the electricity grid, resulting voltage fluctuations and flicker can be expected to become an important power quality considerations. Due to significant bidirectional power flows resulting from large renewable power generation systems connected to downstream, voltage fluctuations may propagate from downstream to upstream. The work presented in this paper investigates and characterises flicker emission and propagation resulting from fluctuating generating sources connected to a distribution network. Mathematical models are developed for flicker emission under different generator control strategies and flicker propagation to upstream network. These emission and propagation characteristics are investigated and verified using a test network comprised of a wind farm. The study has revealed that flicker emission characteristics are influenced in a detrimental manner by the reactive power control strategy of the generator and the flicker attenuation characteristics are influenced by the various load types connected to the distribution feeder.