Simulation Research On The Region Grid Voltage Stability Affected By HVDC

Modern power systems are moving towards large grid, large units, ultra voltage and long-range, AC/DC transmission direction. Because of the low cost, high-capacity, long-distance, such as the advantages of flexible and particularity that AC transmission control can not be compared, HVDC has been widely used in the power system gradually. In order to adapt to the rapid growth of China’s economy and demand for electricity, the State Grid and China Southern Power Grid Company Limited propose to accelerate the construction of±800kV HVDC system-level power grid as the core strategic objectives of strong grid. Nuozadu-Heshan±800kV HVDC project is a key project of China Southern Power Grid Company Limited, it is not only to continue promoting the development of the west and the West to East strategies and to achieve important initiatives win for both Eastern and Western, but also to achieve a concrete manifestation of the scientific development for China Southern Power Grid Limited, it has significant role model for subsequent construction of HVDC project. Many incidents of AC/DC system voltage instability occur worldwide, for the problems of AC/DC system voltage stability, the long-distance HVDC project inverter station is the most serious. Nuozadu HVDC project has long distance transmission, large transmission capacity and the inverter station is located in the load center of Jiangmen grid, study on the voltage stability of Jiangmen region affected by it has important practical significance.Focus on the present situation that simulation and research of domestic and diplomacy AC/DC system voltage stability are insufficient, this article uses power system software PSCAD/EMTDC and combines typical data of guangdong power grid closely to built the simulation model of Nuozadu-Heshan HVDC and inverter side AC system in Jiangmen, from the aspect of SCR/ESCR、VSI、DC system control modes、 converter station reactive power compensation and AC/DC system fault to research on How HVDC impact on the regional power grid voltage stability; Discusses some key problems of the AC/DC system voltage stability; And propose preventive measures for AC/DC systems voltage instability incidents.The conclusions by studying are as follow, region power grid affected by Nuozadu HVDC project in jiangmen are strong AC system, it can give adequate support to the DC system when fault occur and enable the system to restore normal operation quickly, it also have a positive effect on voltage stability of guangdong power grid; In terms of the DC system control modes, the voltage stability that rectifier side constant current inverter side constant voltage control is the best, followed by that rectifier side constant current inverter side constant extinction angle control; and the worst is that rectifier side constant power inverter side constant extinction angle control;220kV and above grid frame of jiangmen power grid is strong enough that jiangmen power grid is able to maintain stable operation when monopolar block fault、bipolar block fault and AC system fault occur, voltage fluctuations can be maintained within the allowable range, and voltage instability does not occur.