3.2.2. Operation and Maintenance Costs

*Copex.VSC* is obtained in Equation (8), and the A of the DC submarine cable equals to 0.5%, *n* is 20 years, and *i* is 5%, which were applied to this study.

3.2.3. Costs of Loss

The loss costs *Closs.VSC* consist of converter station loss *Csub.loss* and line loss *Cline.loss*. Converter station loss rate *Psub.loss* is the percentage of station power loss to the transmitted power. *Psub.loss* of two converter stations is 1.6–2.4%, and Zhen points out that *Psub.loss* is 1–2% [36]. The levelized loss rate of each substation is

$$P\_{\text{sub.loss}} = (\frac{1.6\% + 2.4\%}{2} + \frac{1\% + 2\%}{2})/2 = 1.75\% \tag{19}$$

Meanwhile, the line losses *Cline.loss* can be evaluated as

$$C\_{line\,Loss} = \left(P/\mathcal{U}\_{\rm DC}\right)^2 \cdot R \cdot 2L \cdot T\_f \cdot P\_{on-\,grid} \tag{20}$$

where *UDC* is the DC voltage; *R* is resistance.

The evaluation of *Closs.VSC* is described as

$$\mathcal{L}\_{loss.VSC} = P\_{sub\cdot loss} \cdot P \cdot P\_{on-grid} + \mathcal{L}\_{line\cdot loss} \tag{21}$$
