The paper analyzes “polar” substorms observed at high geomagnetic latitudes (>70° MLAT) in the absence of substorm-like disturbances at lower latitudes. The analysis is limited to the longitudinal sector of the IMAGE network (~108-114 Mlong), in this case “polar” substorms develop over the Svalbard archipelago. The “polar” substorms are usually observed under quiet geomagnetic conditions, but the question remains open whether “polar” substorms can develop under extremely quiet conditions, when the geoeffective parameters of the space weather are extremely small. We studied 92 “extreme geomagnetic quiet” intervals in 2010- 2020, associated with the intervals of extremely slow solar wind (ESSWs, V < 300 km/s). It is found that ”polar” substorms were observed even under an extremely slow solar wind, however, with the appearance of the negative Bz component of IMF; there were established 32 such events at the longitudinal sector of the IMAGE network in the 17 ESSW intervals (~19% of all ESSW intervals). It is shown that “polar” substorms during ESSW exhibit the main features of ordinary substorms, namely they accompanied by Pi1B geomagnetic pulsations, positive subauroral or mid-latitude magnetic bays, a poleward moving of the westward electrojet and auroras during its expansion phase. Besides, it was found that the most events (~82%) of ”polar” substorms during ESSW were isolated events, developed only in the pre-midnight sector, without substorm disturbances in other longitudinal sectors. Several “polar” substorm events have been studied in detail.