Response of MV-connected Doubly-Fed Induction Generator wind turbines and CHP-plants to grid disturbances

Notwithstanding the positive environmental impact, the increasing penetration of Distributed Generation (DG) units connected to the distribution network raises new topics concerning the expected response of these during outages. Grid disturbances especially at the transmission level can cause the unwanted disconnection of large amounts of DG, leading to undesired power imbalances causing line overloadings and/or voltage and frequency instability. This paper examines how transmission network faults can affect the operation of DG units connected on to the distribution network, how these units currently contribute to the voltage support and what are the consequences of actual and possible Fault Ride-Through (FRT) behaviors.