The characteristic of the DC side harmonics produced by the converter in ±1 100 kV HVDC project is analyzed in this article.The DC side harmonic voltage is calculated according to the available project parameters.The calculation result and ±800 kV HVDC project are compared.The equivalent disturbing currents in DC pole lines and DC electrode lines are calculated.After many times filtering performance result for different DC filter schemes are calculated

finally one DC filter solution

which satisfies the performance limits and low-cost

is proposed.The maximum equivalent disturbing currents in DC pole lines and DC electrode lines is calculated.The maximum equivalent disturbing current: bipolar mode 2 728 mA;unipolar mode 5 882 mA.The result of this study is helpful in determining the final project DC filter solution.