Abstract:

For remote offshore wind farms, the diode rectifier unit (DRU) based HVDC system has received prominent interest. This is due to the fact that they provide higher efficiency, require a smaller footprint, high reliability, and lower costs. However, the problem of using DRU at the offshore substation is that they are unable to establish the offshore substation due to absence of voltage source. So, the wind turbine control system needs to change to grid forming control instead of the conventional grid following control. This control philosophy change is the main hindrance to the industrialization of the hybrid HVDC system. This paper proposes a novel GFM converter control based on the idea that the DC-link voltage can imply power differences similar to a synchronous machine frequency. To drive the converter frequency, the DC voltage, up to a certain constant factor, is used. Additionally, a nonlinear model is simulated in MATLAB/Simulink with the proposed and existing control techniques, and the results of simulations are compared. Furthermore, the proposed control technique is investigated for offshore wind farms. The proposed control technique is verified using simulation results in MATLAB/Simulink.

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