4.3.4. Costs Components Comparisons with Different P

Components comparisons of different *P* are carried out to acquire a view for investors. Taking the 25 km wind farms as an example, a sensitivity analysis was conducted, and the results shown in Figure 6.

It can be seen that there is an obvious advantage of the GIL system, as the capital costs of the GIL transmission system changed the least compared to the other systems, even when the capacity reached 900 MW. That means it is less sensitive to transmission capacity. However, the HVAC system and HVDC systems are so sensitive to capacity, which should be considered in OWF planning.

**Figure 6.** Costs components comparisons with different *P* (*L* is 25 km): (**a**) shows the HVAC system; (**b**) shows the VSC-HVDC system; (**c**) shows the GIL system; (**d**) shows the Hybrid HVDC system.

#### **5. Conclusions**

This paper investigates the four electrical transmission options for current and future Western Guangdong offshore wind farm implementation, including their technical characteristics, application status, and economic costs. Based on the component-resolved evaluation model, the capital costs, OPEX, and loss costs of four concepts of electrical transmission were studied, with the results showing that capital costs are the major component. The capital cost of the DC-type transmission technology is mainly related to the converter investment, while the cost of the AC type and GIL transmission technology is mainly related to the line and compensation cost. Meanwhile, the analysis also indicates that the offshore distance and capacity have an important impact on the capital costs of the four types of transmission. The sensitivity analysis of the four transmission solutions regarding transmission distance and capacity recommends the powerful competitive alternative of the HVAC transmission concept if the transmission system is less than 50.48 km for Yangjiang offshore wind farms, and VSC-HVDC and hybrid HVDC transmission for longer distances and larger capacities. For future planning, the GIL transmission system should be the preferred option in near sea and large-capacity wind farms, and the hybrid HVDC transmission possesses significant economic potential with a wide range of transmission distances and capacities.

**Author Contributions:** Q.J. performed the conceptualization, formal analysis and original draft preparation; B.L. provided methodology and reviewed the manuscript; T.L. supported the funding acquisition. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Science and Technology project of State Grid Corporation of China "Cloud energy storage framework-based AI dispatching strategy of renewable energy integration and contingency response", grant number 5100-202199274A-0-0-00.

**Data Availability Statement:** Data available on request due to privacy restrictions.

**Conflicts of Interest:** The authors declare no conflict of interest.
