Safe Balance HVDC: Ensuring Insulation Integrity and Operational Safety in Energy Balancing

The Safe Balance HVDC project aims to enhance the reliability of Sweden’s HVDC transmission system in response to new European regulations that demand quicker energy balancing. These regulations significantly increase the frequency of voltage polarity reversals, placing additional stress on Mass-Impregnated (MI) cables. By optimizing voltage reversal intervals and benchmarking Partial Discharge (PD) detection systems, the project seeks to maintain insulation integrity and operational safety, ensuring the long-term resilience of Sweden's electricity infrastructure.

The European Commission's Regulation (EU) 2017/2195 mandates a reduction in energy balancing intervals from 60 to 15 minutes, a change that places increased operational demands on HVDC systems. This regulation affects Sweden’s HVDC network, which relies heavily on Mass-Impregnated (MI) cables for cross-border power transmission. These cables are critical for Sweden’s energy safety, facilitating over 70% of its electricity import and export capacity. However, frequent voltage polarity reversals due to faster energy balancing intervals accelerate the aging of these cables, increasing the risk of failure.

Objectives and Approach

The Safe Balance HVDC project addresses the challenges associated with increased polarity reversals in MI cables. It focuses on three primary goals:

1. Optimize Voltage Reversal Strategies: The project aims to develop operational strategies that minimize the adverse effects of rapid polarity reversals on MI cable insulation. By studying voltage profiles and simulating cable response under various conditions, the project seeks to identify optimal voltage reversal profile that minimizes insulation stress.
   
   
2. Evaluate Insulation Aging: Through controlled laboratory experiments, the project will assess the dielectric properties and aging behavior of MI cable insulation under different stress conditions. Key techniques include DC conductivity measurements and dielectric frequency response analysis, which provide insights into the cable’s lifespan and failure thresholds under high-frequency polarity reversals.
   
   
3. Benchmark Partial Discharge Detection Systems: To ensure reliable PD detection during rapid voltage reversals, the project will compare commercial PD systems against advanced in-house systems developed at Chalmers. This benchmarking process will assess each system’s effectiveness in detecting insulation degradation, contributing to safer HVDC operations.

Involved in the project

Yuriy Serdyuk, Thomas Hammarström, Xiangdong Xu, Björn Sonerud

Partners

Svenska Kraftnät (Sweden's TSO), with additional collaboration from Fingrid and Energinet, Chalmers University of Technology 

Funders

The project is funded by Energimyndigheten, with contributions from Svenska Kraftnät and Chalmers.