HVDC power transmission line can be constructed in many configurations like monopolar, bi-polar, tri-polar, back to back and many more. Their advantages and disadvantages has been discussed in [28] among them multi-terminal, multi-infeed or mesh type configuration is the better choice for aplications because of higher flexibility and efficiency. In a AC power grid several DC lines can be connected with existing AC line in this configuration with additional converters & inverters connected with grid as shown in Fig. 7. Fig.7 Mesh type combine AC-DC network In a multi-terminal high voltage grid, some HVAC & HVDC network is connected though converter and inverter respectively. Parallel or simultaneous AC-DC long distance power transmission is possible by using this configuration. The system operator can automatically select the optimal set of ac/dc transmission lines parameter for satisfying TEP criteria i.e. supplying load forecasts, minimizing investment costs, and optimizing market operations that becomes suitable for practical application.
VII. MODELING OF A 12 PULSE CONVERTER Fig.8 shows the configuration of a 12-pulse unidirectional power converter. It can be operated with or without filter…show more content… In [34] authors has designed a new types of transformer less three-phase three-level NPC based power converter which performance has been analyzed in 2.64–4.16 kV DC, 5.1–12.8 kW. It’s performance like DC link voltage, efficiency & THD profile was acceptable. The authors assumed that this converter will be suitable for 15kV grid voltage. Converter switching circuit has been designed in SiC (Silicon Carbide) IGBT & Diodes as shown in Fig.18. So, this converter can be re-designed for medium or high voltage with SiC
