Shunt compensation of EHV cables and mixed overhead-cable lines

The paper deals with the shunt compensation of long cable and mixed overhead-cable EHV transmission lines. Attention is focused on "siphon" mixed lines (MLs) including long cable stretches. Shunt compensation requirements of such lines, based on steady-state operational constraints such as voltage jump at the supply node, open-end overvoltages and capacitive rating of line circuit breakers, are evaluated. Alternative locations of shunt reactors (SRs) at the cable stretch terminals or at the ML terminals are discussed and simple calculation procedures are proposed for both configurations. Numerical examples, based on planned or prospective long 400 kV-50 Hz cable applications in Italy, are presented