Research on commutation technology for HVDC transmission system

In the context of global climate change, countries have begun to pay attention to the construction and development of the energy industry, especially the power industry. The advantages of The High Voltage DC(HVDC) technology in long-distance and large-capacity power transmission make it a very important way of cross-regional power consumption in the future power grid. To find the most suitable converter technology for HVDC transmission, this paper starts with the topology and working principle of converter, comparing and analysing the technical characteristics and application scenarios of line commutated converter(LCC), voltage source converter(VSC), modular multilevel converter(MMC) and actively commutated current source converter(CSC). The research shows that although LCC technology is mature and low cost, it has commutation risk and needs reactive power compensation. VSC technology provides flexible voltage control, but it has higher losses and costs. MMC technology is superior to VSC in efficiency and harmonic control, but the structure is complex and expensive. CSC technology combines the advantages of LCC and MMC, has no commutation failure and the system is lightweight, but its technology is not mature. This paper compares and analyses the characteristics of the above converter technology, points out the application prospect and development direction of HVDC technology combined with the era background, and provides reference value for the progress of HVDC technology.