Long HVDC lines as bearers of combined MV and fibre based telecommunication services

The paper evaluates the viability of the combined usage of an insulated shield wire and insulated OPGW scheme or a SWER scheme on long HVDC lines for MV distribution services. This could be a cost-effective method of supplying electrical power to remote communities in developing countries located along the route of such HVDC lines and fibre optic repeater stations for telecommunication services required for the control and protection of HVDC systems. The paper focuses on investigating the possibility of installing multiple loads along the line, whereby the technical limitations of volt-drop, stability, capacitive coupling between the HVDC and MV systems, harmonic induction and briefly lightning performance are accommodated. As a result of these technical considerations it is shown that from the volt-drop point of view both schemes are feasible. Harmonic filtering on either the MV line or in the LV supplies to the repeaters could be needed, while resonance between the 50 Hz source, coupled capacitance and HVDC line reactance could be a problem.