Electrical transmission networks are becoming increasingly interconnected, on continental scales, toward secure and cost-effective supplies of electrical energy met by growing adoption of low-carbon generation. High voltage direct current transmission links employ power electronics to enable this interconnection, of which conventional designs require highfrequency distortion to be filtered by dedicated assets including resistors, reactors, and capacitor banks. These assets are tuned to select for characteristic harmonic frequencies, but operating conditions (firing angle and commutation overlap) also influence high frequency signal composition. This paper presents simulations of these filtering assets to illustrate high frequency signal attenuation, considering the effects of varied operating conditions, filter bank switching, and component degradation.