Simulation and analysis of resonance characteristics of MIDC systems based on ETAP

Shanghai power grid is a multi-infeed AC/DC hybrid power systems with four inverter stations. Due to monitoring harmonics magnifying phenomenon about 11th order characteristic harmonic of HVDC (high voltage direct current) transmission system in Shanghai power grid , the resonance characteristics of Shanghai power grid is studied in this paper. Based on the parameters of 500kV and 220kV Shanghai power grid and equivalent loads of 220 kV lower voltage grades , the simulation model is built on the power system analysis software ETAP developed by OTI company in America. Scan the impedance-frequency characteristics of the Shanghai grid 500kV buses in different switching combination ways of AC filters. Frequency scan result shows series parallel resonance points of 500kV buses in Shanghai power grid and the influence of different switching combination ways on resonance points. At last, the measures to improve resonance characteristics of Shanghai power grid are proposed.