Complex sentence: HVDC also allows transfer of power between grid systems running at different frequencies, such as 50 Hz and 60 Hz; this improves the stability and economy of each grid, by allowing exchange of power between incompatible networks.
Split into simpler sentences: HVDC also allows transfer of power between grid systems running at different frequencies, such as 50 Hz and 60 Hz. This improves the stability and economy of each grid, by allowing exchange of power between incompatible networks.