Design and Simulation Implementation of All-DC Offshore Wind Power System

Abstract

With the continuous advancement of the goal of “carbon neutrality” and “carbon peaking”, renewable energy sources such as solar energy, wind energy, and hydropower have developed rapidly. Compared with onshore wind power, offshore wind power has natural advantages such as abundant wind energy resources and no land occupation. However, due to the charging current of submarine cables, the traditional AC transmission method is only suitable for short-distance, small-capacity offshore wind farms. For this reason, full DC offshore wind power technology came into being. This paper analyzes and studies the principle of the high-voltage direct current transmission system of the offshore wind farm. In the full direct current offshore wind power system designed in this paper, the low-voltage alternating current generated by the wind turbine is converted into low-voltage direct current through a diode rectifier bridge and further passed through the isolated DC-DC converter, the low-voltage direct current is converted into high-voltage direct current and be transmitted using submarine cables. To effectively adjust the voltage of the DC transmission system, we use a proportional-integral controller to close-loop control the phase shift angle of the DC-DC converter. Next, the high-voltage DC power is converted into a civil AC power distribution system by the onshore inverter, and the output AC power is adjusted in real-time by the integral controller. Finally, the correctness and effectiveness of the proposed control method are verified by building the corresponding simulation model in Matlab/Simulink.