ELEN7056: Power Electronics Project - Power Electronic Device options for VSC HVDC Schemes
Nowadays, the HVDC is being widely used all around the world. Until as of late HVDC based thyristors, which is called conventional or classic HVDC has been used for conversion from AC to DC and vice versa. HVDC converter bridges together with lines or cables can be arranged in a number of configurations, i.e. monopolar HVDC system, bipolar HVDC system, homopolar HVDC system, back-to-back HVDC system, and multiterminal HVDC system , .
A new type of HVDC has become available which make use of the more advanced semiconductor technology instead of thyristors for power conversion between AC and DC and vice versa. The HVDC converters are voltage source converters (VSCs) which operate with high switching frequencies (1-2kHz) utilising pulse width modulation (PWM). The technology is commercial available as HVDC Light  or HVDCPLUS (Power Link Universal System)  .
This project report is structured by providing the operating principles of VSC HVDC in Section 2, the investigation of semiconductors devices used in VSC HVDC schemes by comparison between the VSC semiconductors in Section 3, establishing the devices maximum available voltage and current ratings in Section 4, demonstrating how the devices are specified in Section 5 and determining issues associated with the devices, and lastly, the conclusion in Section 7.