The International Electrotechnical Commission (IEC) has published IEC TR 62001-4:2016, a technical report on "High-voltage direct current (HVDC) systems - Guidance to the specification and design evaluation of AC filters - Part 4: Equipment." The first edition is now available on the IEC webstore.
A new edition of IEC 62501 has been published by the International Electrotechnical Commission. IEC 62501 ed1.1 Consol. with am1 applies to “Voltage sourced converter (VSC) valves for high-voltage direct current (HVDC) power transmission - Electrical testing.” The new edition is available for purchase on the IEC website.