Towards an Impedance-Based Criterion for Efficient Analysis of Resonant Overvoltages in the Swedish Transmission System

Time domain simulations can be used to study complex problems such as resonant overvoltages following transformer saturation. However, it is often too time consuming to use time domain tools to assess the risk. Therefore, this work develops an impedance-based criterion for efficient analysis of resonant overvoltages in the Swedish transmission system. To develop the impedance-based criterion, two study cases are considered: a heavily cablified urban network, and future connection of offshore wind in a weaker part of the network. The overvoltage stress is evaluated considering thermal and dielectric sensitivities of the various components. The selected impedance limits were found to be in line with those used by other transmission network operators.