Determination of voltage stress in case of operation of a hybrid HVAC/HVDC transmission line

• HVAC/HVDC on the same tower line has been modelled.
• VSC MMC converter has been modelled using PSCAD software.
• Fundamental frequency coupling between HVAC and HVDC line on the same tower has been investigated.
• Design and operational issues require attention in case of converting one circuit of a multiple HVAC line into HVDC.
• Switching overvoltages stress is the most onerous for the electrical design of the hybrid HVAC/HVDC transmission line.

This paper is a study of the proposal to convert one of four 380 kV AC circuits on the same transmission line to a bipolar DC circuit with metallic return, using one of the three phase conductors. This study examines the voltage stresses and line insulation on the DC circuit.