Representative modelling of very long HVDC cables

A representative frequency dependent model (FDM) of an HVDC cable is important in ensuring HVDC systems are designed harmoniously. A model of the proposed and very long, 4200 km, AAPowerLink cables is implemented in PSCAD/EMTDC. The suitability of approximations required for efficient simulation are evaluated according to the anticipated cable specifications. In practice, a submarine cable of this length has between 40 to 80 field joints (FJ), which can be onerous to individually express and computationally expensive to model. Frequency domain analysis shows a minimum of 8 FJs is sufficient to represent the behaviour of the core voltage. The sensitivity of the FDM to cable parameters and operating conditions is assessed. The FDM is applied to establishing single ended fault location techniques. For a 4200 km cable these techniques can determine fault location to within 200 km (≈5%). Additional methods are explored to refine fault location estimates.