Offshore wind power attracts intensive attention for decarbonizing power supply in Japan, because Japan has 1600 GW of offshore wind potential in contrast with 300 GW of onshore wind. Offshore wind availability in Japan, however, is significantly constrained by seacoast geography where very deep ocean is close to its coastal line, and eventually, nearly 80% of offshore wind resource is found in an ocean depth deeper than 50 m. Therefore, power system planning should consider both the location of available offshore wind resource and the constraint of power grid integration. This paper analyzes the impact of power grid integration of renewable resources including offshore wind power by considering the detailed location of offshore wind resource and the detailed topology of power grid. The study is performed by an optimal power generation mix model, highlighted by detailed spatial resolution derived from 383 nodes and 472 bulk power transmission lines with hourly temporal resolution through a year. The model identifies the optimal integration of power generation from variable renewables, including offshore wind, given those predetermined capacities. The results imply that, together with extensive solar PV integration, total 33 GW of offshore wind, composed of 20 GW of fixed foundation offshore wind and 13 GW of floating offshore wind could contribute to achieve 50% of renewable penetration in the power supply of Japan, and that scale of offshore wind integration provides a technically feasible picture of large-scale renewable integration in the Japanese power sector.

海上风电在日本的脱碳电源方面引起了广泛关注，因为日本的海上风电潜力为1600 GW，而陆上风电为300 GW。但是，日本的海上风能受到海岸地理的严重限制，因为沿海地理非常深的海洋靠近其海岸线，最终，近80％的海上风能被发现在深度超过50 m的海洋中。因此，电力系统规划应同时考虑可用海上风资源的位置和电网整合的约束。本文通过考虑海上风电资源的详细位置和电网的详细拓扑结构，分析了包括海上风电在内的可再生资源对电网整合的影响。该研究是通过最佳发电混合模型进行的，通过从383个节点和472条大功率输电线路获得的详细空间分辨率（一年中每小时的时间分辨率）来突出显示。在给定预定容量的情况下，该模型可以确定各种可变可再生能源的最佳发电整合，包括海上风能。结果表明，再加上广泛的太阳能光伏集成，由20 GW固定基础海上风电和13 GW浮动海风组成的33 GW海风将有助于实现日本电力供应中50％的可再生能源渗透率，海上风电整合的规模为日本电力行业的大规模可再生能源整合提供了技术上可行的图景。