Protection of Transformers against Fast Transient Resonance

In modern power grids, integrating renewable energy sources (RESs) increases the system's number of fast transients (FTs). FT occurs in the power system because of either a lightning strike to the power equipment or frequent switching of RES.

Currently, there is plenty of detailed research on single objects of the power system which face fast transient. However, there are limited solutions for protecting crucial devices of the power system against the FT, considering their interaction.

This section of the project aims to study the state of the art of protection devices against FT and extract the already utilized components' positive and negative aspects. And then, a new protection device will be experimentally developed to preserve transformers against FT and resonance overvoltage. Fundamentally, the protection device will be designed based on the ferromagnetic features of the material, and its behavior will be totally frequency dependent. The proposed device imposes meager series resistance during system low-frequency operation and, in contrast, imposes very high resistance throughout FT occurrence. Therefore, the designed frequency-dependent protection device (FDPD) provides features as follows:

•    Almost no effects during low-frequency operation of transformer
•    Negligible power loss in transformer low-frequency operation 
•    Protection of transformer in the frequency domain of FT
•    Providing economically cost-effective device 

As the final step of the project, the collaboration between other project researchers, the interface will be developed, including an accurate model of the transformer, ground, cable, and the designed protection device to evaluate the protection of the transformer against fast transient very close to reality.