Comparative Analysis of Integral and Prefabricated Capsule Offshore Substations Based on Specific Sea Area

TTo select the optimal 220 kV offshore substation scheme for a 500 MW offshore wind farm, this paper compares the integrated and prefabricated cabin schemes across five dimensions: design management, structural economics, technical implementation, construction schedule, and full life-cycle cost. The results show that the integrated scheme adopts a single-point responsibility model, shortening the design cycle by approximately 2 months compared to the prefabricated cabin scheme. Its upper block weighs about 2500 tons, representing a 21.9% reduction and a 26.8% smaller footprint, demonstrating significant structural lightweighting advantages. Economically, the integrated scheme saves approximately 15.741 million CNY (a 7.54% reduction), primarily due to material optimization in the foundation and superstructure. Technically, the integrated scheme outperforms the prefabricated cabin scheme comprehensively in structural safety, lightning protection grounding, anti-corrosion, and cable routing, effectively mitigating risks such as deformation control difficulties and system fragmentation. Although the prefabricated cabin scheme offers a 1-month shorter construction period and reduces reliance on large-scale offshore fabrication bases, its high coordination costs and complex management interfaces result in significantly lower overall benefits. The study indicates that the integrated scheme, leveraging its comprehensive advantages in design coordination, structural economy, and operational reliability, is the preferred technical solution for current offshore substation construction.