Thermal Modeling of a High-Voltage Fault-Tolerant Wind Generator With HTS Bulks

High-voltage fault-tolerant wind generators with high-temperature superconducting (HTS) bulks are being considered for offshore wind farms since they can simplify connections of wind farms and reduce maintenance costs. Due to the low operating temperature of the cross-linked polyethylene (XLPE) insulation used, the key to developing such generators is to accurately predict their thermal performance at the design stage. In this paper, a thermal model based on the lumped parameter thermal network (LPTN) method is established to achieve this goal. The characteristic of this thermal model is that copper loss and iron loss and their temperature dependence are considered simultaneously. These losses are precisely obtained by coupling the electromagnetic field. In particular, the temperature dependence of thermal conductivity is also taken into account. The effectiveness of the thermal model is verified by finite element analysis (FEA). Moreover, a comparison is made with the LPTN model which does not use temperature-dependent thermal conductivity. The established thermal model can be used for the optimization design of generators with similar structures.