Simulation and Harmonic Analysis on Ultra High Voltage AC Transmission System

Against the background of 1000 kV AC Pilot Project from Jindongnan to Jingmen via Nanyang which has been completed in January 2009, based on accurate modeling of the nonlinear equipments such as autotransformer and shunt reactor in 1000 kV system, the harmonic characteristics of 1000 kV system are calculated and analyzed in PSCAD/EMTDC. Simulation results show that for the 1000 kV system, the total harmonic distortion of voltage (THDu) is higher, in which 3rd and 5th harmonics are the main components and change with the variation of places. The reason why the THDu of 1000 kV system is higher is mainly that the permeation of harmonic voltage in 500 kV system into 1000 kV system is stronger, and the particularity of harmonic impedance and transmission characteristic of 1000 kV system will amplify certain order harmonic voltages or currents, which further raises the harmonic level of 1000 kV system.