Cost evaluation of EHVAC offshore wind farm using intermediate shunt compensation: a parametric study

Very long distance connection of gigawatt‐size offshore wind farms: extra high‐voltage AC versus high‐voltage DC cost comparison

“…For the purposes of the present paper, the maximum distance over which a given AC CL can transfer the 1 GW target active power without resorting to intermediate compensation is defined as 'base' length, L Base ; keeping in mind the task of evacuating to shore the output of a 1 GW OWF and the results of previous studies [9,13,14], two EHVAC (420 kV-50 Hz) alternatives have been evaluated.…”

“…Switching-off of one of the two circuits with generation output below 50% of the OWF power rating (500 MW) is considered in order to enhance transmission efficiency [9]. The second component of total EYS can be assessed considering the probability that only one of the circuits undergoes an outage, i.e.…”

“…AC scenario #1 is based on a double‐circuit CL made of three‐core, 1400 mm 2 aluminium cables. As shown in [9], one circuit of such cable can transfer 500 MW at distances up to 90 km without intermediate shunt compensation ( L Base1 = 90 km). Transmission distances up to 180 km can be attained with one intermediate compensating station; two such stations are required in the (181–270)km range and three in the (271–360)km interval.…”

“…To calculate the total amount of the energy yearly supplied (EYS), the OWF yearly energy production is assessed as in [9], combining wind probability distribution data on an hourly basis from the wind atlas of the Dutch part of the North Sea and equivalent wind turbine power curves [32]. The OWF power output P is assumed variable from 10 to 1000 MW, with a 10 MW step Δ P Transmission losses over a year are calculated for all design alternatives as a function of OWF output.…”

“…to achieve a high active power loading, the line must be operated with a symmetrical reactive power profile (by means of appropriate terminal voltage control), thus maximising its active power transfer capability and minimising joule losses. Calculations show that in such an operating condition a single circuit of 420 kV three‐core cable could transfer up to 500 MW at 90 km distance [9].…”