  Solar activities may disturb the geomagnetic field and impact the power grid
via geomagnetically induced currents. We study active and reactive powers as
well as the power factor of Iran's power grid transformers (230 kV and 400 kV)
and their correlations with geomagnetic disturbances indices (SYM-H < -30 nT
and sizable horizontal geomagnetic field fluctuation) from 19 March 2018 to 20
March 2020. Out of 128,627 cases with a transformer power factor of less than
0.7, we observe that 12,112 samples correlated with SYM-H. Our investigation
shows that about 4 percent of two years, the SYM-H has values less than -30 nT.
Analysis of high-performance transformers (a power factor greater than 0.7 at
95 percent of working time) shows at least a 55 percent correlation of power
factor less than 0.7 and SYM-H less than -30 nT. We observe that the
transformers' power factor of Rafsanjan-Kerman and Sarcheshmeh-Kerman (wye
connection on 230 kV side) substations decreased to less than 0.7 and
correlated with SYM-H. We show that the reactive power of the Sefidrood-Guilan
and Shahid Beheshti-Guilan transformers (wye configurations) increased
considerably on 9 January 2020 and positively correlated with SYM-H may produce
large GICs at this part of the grid. We observe that the increase in reactive
power at the Shahid Beheshti-Guilan substation correlated with the sizable
changes in the horizontal field recorded by the Jaipur station. However, more
details (temperature and current of transformers) need records to estimate the
impact of geomagnetic induction current on the power grid.
