Generator step-up transformers (GSU)
Generator step-up transformers (GSU)
Generator step-up transformers (GSU) are the critical link between the power station and the transmission network, often operated day and night at full load. They must be built to withstand extreme thermal loading without ageing prematurely. ABB have successfully passed the world’s first and highest voltage short circuit test, on a 315 mega volt ampere (MVA), 765 kilovolt (kV) generator step up transformer (GSU).
GSU take the voltage from the generator voltage level up to the suitable transmission voltage level.
These transformers are located in a power station and are built as single-phase or three-phase units.
There are two (2) basic technologies for designing and manufacturing: core and shell. With shell-formed transformers, the primary and secondary are on one leg and surrounded by the core. With a core-formed transformer, cylindrical legs windings cover the core legs.
HVDC Converter Transformers
HVDC converter transformers
HVDC (high-voltage direct current) is a highly efficient alternative for transmitting large amounts of electricity over long distances and for special purpose applications. As a key enabler in the future energy system based on renewables, HVDC is truly shaping the grid of the future.
ABB pioneered HVDC transmission technology in the 1950s and continuously develops the HVDC technology to meet the demands of economic and sustainable transmission and integration of different electricity generation types.
The ultra-high voltage (UHV) technology is an advancement of HVDC, transmitting large amount of power with minimum losses and integrating renewables often located at a great distance from centers of the demand. ABB successfully developed and tested 1,100 kV converter transformer technology breaking the record for the highest DC voltage levels ever.
Shell Specialty Transformers
Polytransformers, multispare and high voltage mobile transformers
ABB offers a full range of transformers to address any generation or transmission contingency a customer might have. These include multi-functional units such as the polytransformer, universal generator and mobile transformers.
System Intertie Transformers
System intertie transformers
Substation transformers transfer the incoming high voltage to the next lower voltage level. As an example, incoming high voltage of 400 kV would be transferred down to 220 kV.
In general substation transformers are equipped with on-load-tap changers (OLTC). Incoming transmission lines are connected to the transformers through bushings and cables through cable boxes and cable sealing ends. These transformers are built in core form with auto connected windings, ie common main winding and a separate low voltage winding.