Comparison of Cost-effective Distances for LFAC with HVAC and HVDC in Their Connections for Offshore and Remote Onshore Wind Energy

For a cost-effective connection of large-scale longdistance wind energy,a low frequency alternating current(LFAC)transmission scheme(16.7 Hz or 20 Hz)is proposed as an alternative to the conventional high voltage alternating current(HVAC)transmission scheme(50 Hz or 60 Hz)and the recently popular high voltage direct current(HVDC)transmission scheme(0 Hz).The technical feasibility of the LFAC system is demonstrated but the basis for identifying the distance ranges for which LFAC would be preferable to HVAC and HVDC are not established and the dependence of this range on factors,such as power transfer rating,voltage rating and cable/line type,is not investigated.This paper presents an in-depth analysis for the overall cost of LFAC system and then provides an extensive comparison with HVAC and HVDC,to explore the distance ranges over which LFAC is cost-effective over both HVAC and HVDC in connections of offshore and remote onshore wind energy.The results demonstrate that the LFAC system does possess ranges in the intermediate distance for which it is more cost-effective than both HVAC and HVDC,and its overall cost advantage is generally larger in the overhead line(OHL)connection of remote onshore wind energy than the cable connection of offshore wind energy.