Simulation Analysis of Split Connection Mode System Control for XiMeng to TaiZhou UHVDC Project

XiMeng to TaiZhou (abbr. XT) ±800kV UHVDC (Ultra High Voltage Direct Current) transmission project, with rated power 10000MW, is the first HVDC project high voltage and low voltage converter spilt connection to 500kV and 1000kV power grid. In view of the rectifier and inverter side AC system weak characteristics of in the primary operation stage, the converter station bus voltage control strategy puts forward before and after the HVDC system deblock by system simulating calculation analysis in the primary operation conditions. For split connection mode control function, it is analyzed that is the basic control performance of high and low voltage converter split connection to 500kV/1000kV AC power grid, the simulation calculation model is established. The performance of the deblock, power/current step response, AC/DC line ground fault and monopole start/stop in reversed power direction has been carried out simulating research. The XT UHVDC system and equipment performance and the secondary control protection function got verified, the improved control strategy of commutation failure in inverter side was put forward. Through the simulation analysis and test, it is suggested that reversed power direction mode temporarily not arrange because the XiMeng side system is very weak and AC/DC voltage and current fluctuate greatly. Those research results are used in the process of XT project system test, in order to provide technical support for system stability operational stage in primary operation stage.