Dielectric Strength of XLPE Plate Samples Under Transient Overvoltages Based on CIGRE TB 852

The ongoing energy transition and its challenges will lead to efficient transmission and distribution systems in future. Therefore, DC systems will be implemented into the existing grid as HVDC and as MVDC systems. By considering MVDC, the interest lies in the usability of MVAC cable systems for MVDC to realise an environmentally friendly and cost-efficient solution for challenges regarding transmission systems. The dielectric strength of the insulation of MVDC cable systems is an important parameter as DC cable systems are exposed to various voltage stresses in addition to DC stress, e.g. a slow front temporary overvoltage (SFTOV) can occur when the converter topology is using symmetric monopoles. Therefore, this contribution presents the dielectric strength of XLPE at different voltage waveforms. In addition to dielectric strength at AC and DC, dielectric strength is investigated under TOV such as zero crossing damped temporary overvoltage (ZCDTOV) and SFTOV. In this regard, the impact of superimposed DC voltages and the time parameters of SFTOV on the dielectric strength of XLPE is discussed in detail.