The quality standards for power supply are nearly the same in ENTSO-e and UPS of Russia, but the control principles are different. The differences are basically originating from the architecture of the power grids. The European grid mainly consists of short transmission lines. The UPS of Russia is characterized by the prevalence of long and weak interconnections. The project concerning the possibility of integrating ENTSO-e and UPS of Russia started more than 10 years ago. Such integration requires using the same or nearly the same control principles. Geomagnetic disturbances are the so-called high-impact low-frequency events. They affect large geographic areas and provoke simultaneous outage of several network elements. The strengths and weaknesses of the control methods employed by ENTSO-E and UPS of Russia for ensuring stability during geomagnetic disturbances have been analyzed in the article.