Wind Farm Operating Conditions Under Geomagnetic Disturbance

This paper investigates the potential impacts of geomagnetically induced current (GIC) on the wind farm operating conditions. A comprehensive harmonic analysis within the EMTP-RV program is done for the exposure of different components of the studied system to the generated harmonics due to GIC. In particular, the GIC effects on the wind farm main output transformer (MOT) and the doubly fed induction generator are investigated. A thermal analysis is also conducted to estimate the hot-spot heating of the MOT, when subjected to the GIC benchmark waveform with various magnitudes. The effects of a harmonic filter for limiting the harmonic distortions are investigated and compared with the case of using GIC blocking devices and the IEEE 519 standard limits. The simulated hot-spot heating due to GIC in the MOT structural parts and windings is also investigated and the simulation results are compared with the standard emergency temperature limits. The simulation results reveal that the hot-spot temperature of the MOT winding increases beyond the maximum standard level of 180 °C, when the peak of the benchmark GIC exceeds 70 A/phase. Thus, a loading capability curve is derived for the safe operation of MOT, during the geomagnetic disturbance.