Investigation Of A Novel CCVSC-DC Topology

The development of modern economy and the adjustment of global energy suppliers urgue the countries around the world to improve their power grids. The Smart Grid has been called up and is believed to be the main route for the grid mordernization. In order to keep up with the expansion of national ecnomics, the Chinese states grid has determind to upgrades itself to achieve the goal of a Roubust and Smart one. This requirement challenge the power transmission and distribution network nowadays to incorporate various power providers as well as provide safe, reliable, controllable and qualified electricity to the different coustomers.Voltage Sourse Converter (VSC) based High Voltage Direct Current (HVDC) is a substitute way for conventional HVDC in the fields of middle and small scale power transmission and distribution. It has been given great attention in last ten years. Based on a thoroughly review of different kinds of VSC topology, A novel Current Control (CC) VSC-DC has been proposed. The principle of the convereter has been disctibed, and the main parameters of the converter have been deduced. Also, the outer-loop and the inner-loop of the controller have been realized. The detailed mathematical models of the convereter and dule-ends CCVSC-DC have been constructed using Matlab Simulink. The output voltages and currents of the convereter have been analysised. The power transmission characters, the independent control of active/reactive power transimission and power reverse operation have been verified.Modularization of the inductor component has been introduced and a direct cooling superconducting inductor module has been constructed and the cooling test as well as the charging and discharging test have been carried out. The design scheme and the operation characters of the superconducting module have been verified.The applications of CCVSC-DC have been developed. The ac transmission capacity enhancement has been verified. The transient stability of the original ac system has been improved. Different system control strateges including PI Control, Linearize Optimal Control (LOC), Fuzzy Logic Control have been designed and the results have been compared. In the wind farm integration, CCVSC-DC can promote the wind farm's low voltage riding through ability. With the power fluctuating at the wind farm output power, the CCVSC-HVDC can mitigate the fluactuation, which make the wind farm more sutible to be integrated into the main gird.