Research On Application Of SVC In UHV AC Power Grid Voltage Stability

The Ultra High Voltage power grid is the emphasis of China’s power grid construction, and the inevitable trend of China’s power gird development. The series compensator can improve the reactive power and reactive power of the line, improve the stability of the transmission system, improve the transmission capability and restrain the over-voltage of the system. For Ultra High Voltage power grid, the increase of voltage grade makes charging power increases,1000 kv UHV AC line charging power is about 500 kv line 4 times. As a result, more necessary installation of reactive power compensation device in UHV power grid to provide a large number of dynamic reactive power compensation, in order to enhance the grid voltage support, and improve the line transport capacity, reduce the electric network loss.Ultra High Voltage power grid’s key substation reactive power compensation device when installation, can effectively improve the voltage of the grid of UHV power transmission channel support capabilities, and play a positive and effective role in UHV power grid safe and stable operation. As a new type of flexible AC transmission equipment, static var compensator SVC has been widely used in reactive power compensation, voltage stability and power load characteristic improvement. According to the national grid company "twelfth five-year" planning, "three China" UHV AC power grid will form in 2015. During the period of "much starker choices-and graver consequences-in", will build more back to+1000 kv UHV DC transmission projects, China will gradually form of super-large scale UHV AC/DC mixed across regions interconnected power grid, the future combined type SVC in uhv grid will have broad prospect of application.The technology of static var compensation in UHV power grid will be the new field of development and application of the var compensator.In this paper, the parameters and transmission characteristics of UHV AC transmission system are analyzed in detail. The classification and working principle of the static var compensator SVC has been introduced in this paper. A new application of different TCR+FC+TSC in the UHV power network by SVC has been put forward.Based on this, the simulation model of combined SVC is built by PSCAD/EMTDC software. The Jindongnan-Nanyang-Jingmen UHV AC 1000kV system has been used as an example, the reactive power demand of UHV power grid three different SVC configuration schemes are proposed. The SVC control strategy for UHV power network is proposed and UHV power grid SVC steady characteristics, transient characteristics are analyzed. The simulation results show that under the fault, high pressure station main transformer the power frequency and operating voltage is lower than that of the standard permissible value.Through simulation, the influence of the operating overvoltage and load capacity of the system after SVC is analyzed, and the conditions for the application of the combined SVC in UHV power network are confirmed.