| As the power systems continue to grow in size, large interregional AC/DC hybrid grids come into being, ultrahigh-voltage long-distance power transmission lines and ultra-large-capacity generation units are gradually put into operation, and the series capacitor compensators and High Voltage Direct Current systems are adopted to improve the power system stability and transmission capability. Therefore the subsynchronous resonance/oscillation problems and the stability problems in the large-scale AC/DC hybrid power systems resulting from these factors will necessarily become the problems in the secure operation of the grids that can't be ignored.;This dissertation contributes to the research work and engineering practice in the following aspects: an unique Prony Identification approach to designing additional controller of SVC, a novel implementation algorithm on the modulation and control signal of the phase-controlled reactors together with a special connection manner to connect the SVC to suppress sub-synchronous resonance at the HV bus, a new composite control structure used for multiple sets of parallel SVCs or STATCOMs that are controlled automatically and independently, and finally the principle and implementation of the decoupled control of the cascaded STATCOM. All the above methods were verified with simulation study and real power system parameters and data were used in most of the simulations.;Both the static voltage stability and transient stability of the AC/DC hybrid power transmission systems in China Southern Power Grid were analysed and simulated. The SVC models were included in study and proved to be effective to provide dynamic reactive power and voltage support.;The SVCs and STATCOMs designed according to these theories and methods have been successfully applied to the 210Mvar SVC at 500kV Wuzhou Substation in China Southern Power Grid, the four sets of SSR-DSs in Guohua Jinjie Power Plant, the 240Mvar SVCs at Chuxiong Converter Station of the Yunnan-Guangdong +/-800kV ultrahigh-voltage DC power transmission project in China Southern Power Grid, and the +/-200Mvar STATCOMs at 500kV Dongguan Substation in China Southern Power Grid. |
