Dielectric losses in HVDC cables

In HVAC cables, dielectric losses are due to conduction phenomena and dipole polarization hysteresis. In this case, the latter phenomenon is preponderant over the former.In HVDC cables, dielectric losses are mainly due to the leakage current through the insulation. Due to the interdependence, in dielectric materials, between electrical conductivity and dielectric losses, the leakage current can be roughly calculated through complex conductivity or bipolar charge transport models.

A cable manufacturer created and validated a simplified procedure for the calculation of dielectric losses in the insulation of HVDC cables. With this purpose, an analytic model for the calculation of dielectric losses was developed under simplifying assumptions. This approach leads to obtaining an integral function for the calculation of dielectric losses which can be treated by numerical methods. The outputs of this approach were compared with the results of simulations carried out using FEM software for various case studies. From the comparison between the results, it was deduced that the proposed method provides reliable results within a certain range of temperature and dielectric properties of the insulating material.

The method is proprietary and patent pending.

Symbol

$W_{d,DC}$

Unit

W/m

Formulae

$\lambda_{i} \int\limits_{r=r_{isc}}^{r_{osc}} \left[ \Delta w_{d} r \right] dr$

Related

$\Delta w_d$

Increment of volumetric density of dielectric losses in HVDC cables [W/m$^3$]

$\lambda_i$

Parameter $\lambda$ for linear density of dielectric losses