Transient Performance and Operational Insights of Hybrid 380 kV AC Transmission Systems

The primary objective of this paper is to identify potential interactions and operational challenges associated with the underground cable sections within 380 kV hybrid transmission systems. Understanding these interactions is essential for ensuring reliable system performance and guiding future planning and design decisions.

The paper focuses on the transient behavior and response of these transmission systems under various operating conditions. These include lightning strikes, single phase to earth faults, switching operations directly on the system and in the close vicinity, and normal steady-state operation. Transient simulations are conducted to evaluate the systems’ responses to these scenarios, with particular attention to the resulting local overvoltage’s and voltage distribution

(profile)along the transmission routes.

The simulation models represent real 380 kV transmission line systems in Germany and include detailed modelling of the different overhead line and cable sections, as well as the transition stations with or without shunt reactors and cross-bonding joints in the cable sections. The simulation results were compared and discussed in detail with measurement data obtained from the actual operation of the modelled transmission lines, also under fault conditions. This validation process enhances the credibility of the simulation models and provides deeper insights into the systems’ transient behavior under real-world conditions. The findings contribute to a better understanding of hybrid EHV transmission systems and support the development of robust design and protection strategies for future grid infrastructure.