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Li et al. Complex Eng Syst 2023;3:1 https://dx.doi.org/10.20517/ces.2022.46 Page 5 of 15

capacity is small, and scenery output fluctuations do not cause a negative influence on the power grid.
However, as the scene is increasingly connected to the electricity grid capacity, the influence of randomness,
volatility, and intermittent scenery output characteristics on the safety and stability of power system
operation is more and more significant, greatly reducing the power quality. It considerably affects the grid
connection of wind power generation and the frequency modulation and peak regulation of the power grid.
The development of energy storage technology makes it possible to solve the output fluctuation of wind
power generation.

Ning et al. introduced the basic principle of energy storage to smooth the output fluctuation of wind-power
generation , expounded the research status of energy storage system control methods when wind-power
[20]
generation fluctuation is smooth, and summarized the similarities and differences of various existing
methods. Zhao and Cui introduced the photovoltaic system capacity ratio analysis optimization calculation
using the leveling of the KWH cost concepts. The optimal energy storage system configuration and the
project yield of this method were verified when compared with the optical storage system under different
storage configurations and the existing load power and PV systems under the optimization calculation .
[21]
Gao et al. established eight kinds of wind-wind-load composite Copula models by combining the actual
offshore wind farm power, photovoltaic power plant power and grid load, and proposed a hybrid time-
varying Copula model based on rattan structure, which can more accurately describe the high-dimensional
[22]
wind-wind-load dependence structure . Sun et al. established the coordination relationship model between
[23]
photovoltaic and energy storage systems , carried out the coordination optimization of energy storage
devices under different output conditions of renewable energy, and proposed the voltage stability control
method of regional power grid based on the coordination of distributed photovoltaic and energy storage.
Recent studies in [24,25] proposed a method for different photovoltaic units and hybrid energy storage units to
cooperatively suppress the bus voltage fluctuation and keep the load side voltage stable.

Although the floating power supply platform is predicted to have great development prospects, various
limitations prevent the technology from being used commercially on a large scale. The near harbor is a
complex environment that requires a consideration of the external environment such as geographical
factors, climatic environment, solar emissivity, and so on, and requires the components to be able to
withstand saltwater, strong ocean currents, waves, and wind. The current low maturity of the industry leads
to a lack of direct reference standards for design in port environments. However, the industry can look to
more established industries such as offshore oil and gas, or offshore renewable energy (MRE) such as
offshore wind.

3. TOPOLOGICAL STRUCTURE DESIGN OF MICROGRID SYSTEM NEAR PORT
In the past decade, maritime transport has been responsible for nearly 90% of the world’s overseas trade and
logistics, accounting for 3% to 5% of total greenhouse gas emissions. This could rise to 18% by 2050,
according to research by the International Maritime Organization (IMO). There is an urgent need for a
more efficient maritime transport system, improving the efficiency of all the subsidiary energy subsystems.
Today, seaport microgrids are seen as a viable way to improve overall system flexibility as well as mitigate
growing environmental concerns. However, with the trend of electrification, the connection between port
and ship is no longer limited to logistics but extended to power, which makes future maritime transport
management a complex transport-power multi-microgrid coordination problem. Seaport microgrid is a
representative and promising technology for shaping future green maritime transportation.