LLC resonant type boost converter for HVDC interconnection of PV generation facility

In recent years, the introduction of renewable energy generation facilities has been increasing all over the world. However, renewable energy generation often requires long-distance power transmission. Because it is widely distribution in all around. When the electric power is transmitted over a long distance, high voltage direct current (HVDC) power transmission is suitable. The HVDC transmission lines can reduce the transmission losses and equipment costs as compared to the AC system for a long distance power transmission. If the renewable energy generates a DC power, the HVDC transmission lines will improve the power system efficiency. However, it is not easy to boost a DC systems. This research proposes a DC power converter with a high step-up performance. The DC-DC converter modules are cascaded to achieve high voltage and large capacity. The LLC resonance type DC-DC converter is used for the DC-DC converter module. Soft switching can be achieved with a simple circuit configuration, and switching loss can be reduced. In addition, high frequency transformers in the converter ensures insulation from the transmission system. The operation of the proposed converter is verified by the simulation using MATLAB / Simulink. From the simulation results, the proposed method can reduce the cost and losses for a grid connected HVDC system.