Novel protection of the power collecting lines in PMSG wind farms

To enhance performance of traditional three-section overcurrent protection used in power collecting lines, a novel inverse-time overcurrent protection is proposed via analyzing the topology and faults characteristics of power collecting lines as well as the fuse protection features and PMSG's LVRT characteristics. Taking PMSG farm as the research object, traditional overcurrent protection is no longer applicable because it often causes small protection range, override trip and turbine tripping. The inverse-time overcurrent protection curve can be obtained according to the maximum current difference between power collecting lines and fuses. Finally the effectiveness of the novel protection is verified by simulations in EMTP-PSCAD environment. Results show that for power collecting lines, the novel protection approach overcomes the shortcomings of traditional methods and achieves better selectivity and speediness. In addition, it is insensitive to transient impedance, thus could be applied to engineering.