Analysis of HVDC Substation Stray Capacitance Impact on Travelling Waves

High-voltage direct current protection systems utilise transient information from electrical signals following disturbances or short-circuit faults. Stray capacitance and system inductance can induce high-frequency resonances, altering the filtering characteristics of boundary elements in DC protection systems. This paper addresses the need to accurately represent travelling waves (TWs) in protection studies by including stray capacitance in DC substations. In this paper we analyse stray capacitances in air-insulated DC substations and their impact on TWs. The findings reveal that TWs on adjacent lines can traverse boundary elements and cause oscillations, potentially affecting the performance of DC substation protection.