HVDC Cable System Testing

This paper reviews the existing testing techniques for high voltage direct current (HVDC) cable systems, following as abackbone the structure of CIGRE Technical Brochure (TB) 852:2021 ‘Recommendations for testing DC extruded cable systemsfor power transmission at a rated voltage up to 800 kV’ because it has a fairly similar structure to CIGRE TB 853:2021 forlapped DC cables, and especially because of the impressive spread of HVDC extruded cables experienced worldwide in the last25 years. The review considers development tests, pre‐qualification tests, extension of qualification test, type tests (with hints atIEEE 1732‐2017 for space charge measurements in the qualification of HVDC extruded cables), routine tests (with hints atIEEE 2862‐2020 for routine tests of HVDC extruded cable system joints), sample tests and after installation tests. The reviewalso analyses CIGRE TB 853 for lapped HVDC cable systems, as these cables remain unbeaten for submarine applications at thehighest sea depths. The main novelties of CIGRE TB 852 and 853 with respect to previous standards for HVDC cable systems(mainly CIGRE TB 496 and IEC 62895 for extruded cables and CIGRE Electra 189:2000 for lapped cables) are put under thespotlight—with focus on the so‐called temporary over‐voltage tests—together with the limits and gaps of CIGRE TB 852. Themain HVDC cable system testing equipment that is usually employed for electro‐thermal tests is also treated. Emphasis is givento CIGRE TB 490 to treat the peculiarities of submarine cable systems, as well as to mechanical tests, having CIGRE TB 623 asa reference, with particular focus on the special sea trial tests. An example of an innovative sea trial testing procedure is shown,which is the outcome of a fruitful partnership between a cable manufacturer and the national Transmission System Operator inItaly