Tomographic Analysis of High-Voltage Insulation Systems
The reliable supply of electrical energy is a fundamental prerequisite for modern societies and plays a key role in the energy transition. A central part of this infrastructure are high-voltage transmission lines and components such as power cables or joints. Their reliability is crucial for grid stability – particularly in light of the increasing use of high-voltage direct current (HVDC) technologies. A frequently underestimated risk for such systems is the presence of space charges: accumulations of electrical charge carriers within the insulating materials. Over time, these charges can significantly alter the internal electric field, accelerating ageing processes and – in extreme cases – leading to dielectric breakdown and total failure of the component. A single fault in an HVDC system may require weeks of repair and cause substantial costs, potentially resulting in large-scale power outages. To detect such risks early and mitigate them effectively, precise measurement and analysis of space charges within insulating materials is essential. This is the objective of TAHIS: to develop novel methods for determining space charge distributions that go beyond the current limitations of existing techniques. The widely used pulsed electroacoustic method (PEA) has proven to be fundamentally suitable, but faces significant challenges when applied to complex systems. In particular, signal evaluation is susceptible to disturbances, often provides limited spatial resolution, and is highly sensitive to measurement noise. Moreover, many existing interpretation methods rely on heuristic or simplified models, which limits their physical validity. TAHIS takes an innovative approach by formulating the problem of space charge detection as an inverse problem – a methodology well established in fields such as medical imaging, geophysics, and engineering. Physical models of the measurement process are combined with modern statistical data analysis techniques. This enables the incorporation of uncertainty and prior knowledge, leading to more robust and informative results. A central aspect of the project is the detailed modelling of the entire measurement process – from the interaction of charge carriers with the insulating material to the detection of the resulting electrical signal. These models are validated through targeted experiments and provide the foundation for new reconstruction algorithms that aim to significantly improve the accuracy and robustness of space charge measurements. In parallel, a new amplifier system is being developed, tailored specifically to the requirements of the enhanced data processing methods. By advancing both the measurement techniques and the associated signal analysis, TAHIS contributes to the development of more durable and reliable high-voltage insulation systems. This is particularly relevant for the evaluation of innovative, environmentally friendly insulation materials, whose electrical behaviour is not yet fully understood. In the long term, the project aims to support safer and more efficient expansion of power grids and lays the groundwork for future research in areas such as real-time diagnostics and digital twins for high-voltage infrastructure.
