Superimposed Impulse Voltage Tests on HVDC Cables Using Coupling Capacitor

Population rise, the advancement of the digital economy, and the shift toward electric vehicles are collectively propelling an escalating need for electricity, a surge anticipated in the near future. Notably, the International Energy Agency projects an increase of over 25% in overall energy requisites by 2040, primarily instigated by countries like India and other rapidly developing economies. Despite significant converter-station costs, HVDC is techno-economically preferred in general applications for: long-distance, large-scale power transfer; subsea and long-distance cable-power transmission; interconnecting asynchronous AC systems or systems with different frequencies; controllable power transfer between different nodes in an electricity market or markets; AC grid-stability support and connecting isolated systems like offshore wind farms or oil platforms [1].
Besides traditionally used HVAC overhead power lines and cables, more and more underground and subsea HVDC cables are installed with increasing length. The choice between overhead line or cable is influenced by environmental constraints as well as an overall optimization that considers total capital cost, performance, losses and transmission system reliability.
To verify the performance of HVDC cable systems it is common to start with type tests to verify the integrity and continue with pre-qualification tests to evaluate reliability. Additional requirements include withstand to non-standard dynamic voltage stresses such as polarity reversal and transient overvoltages (TOVs) [3].
One electrical test that is characteristic for HVDC cables is superimposed impulse voltage tests. Different test circuits that are used to perform this test impose technical challenges and are discussed in this paper.