With the rise of high voltage DC polymeric cables and accessories, other phenomena have to be considered, that hardly played any role in the design, production and operation of polymeric insulation systems for AC applications. One of the main effects to be considered is the formation and accumulation of space charges within the insulation. These effects become particularly important in the case of multi-layered insulation arrangements, as they occur in cable accessories.
The presence of space charge in a polymeric insulation system can strongly influence the electric field in the insulation. Furthermore, space charges are a potential hazard for the lifetime of the insulation if transient voltages occur. Knowledge of its behaviour and effects are the foundation of any well designed polymeric HVDC insulation. Since possibilities to probe space charges in full-size systems are limited, reliable numerical simulation models based on measurements at model arrangements are required.
The focus of current research is on space charge measurement methods and devices, simulation models, space charge behaviour under operation conditions, qualification of new HVDC-insulation materials and ways to control space charge phenomena, such as nanofillers or other innovative approaches.