HVDC Transformers

Specifications

Specification

HVDC transformers are key components of HVDC stations. HVDC converter and inverter stations terminate long-distance DC transmission lines or DC sea cables. this type of transformer provides the interface between AC grids and high power rectifiers and are used to control the load flow over the DC transmission lines. these actors adapt the AC grid voltage to an adequate level which is suitable for feeding the valve system of DC converter and inverter.

Feature

Design options
the design concept of HVDC transformers is mainly influenced by the rated voltage, rated power and transportation requirements like dimensions, weight and mode of transportation.
Many large power HVDC converter station are located in rural areas of low infrastructure. Frequently, special geometrical profiles have to be fulfilled in order to move such transformers by railway.
Typically, HVDC transformers are single phase units containing 2 winding limbs. this concept can include either 2 parallel valve windings (two for delta or two for wye system, fig. 5.8-1) or two different valve windings. In order to reduce the total transportation height frequently the core assembly includes 2 return limbs. Due to redundancy requirements in HVDC stations 3 phase units are quite uncommon.