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Customer Success Story
Reference Degefors

Improved productivity and economy of EAF process by means of SVC

In 1985, an Hitachi Energy SVC (Static Var Compensator) came on line in Avesta Sheffield‘s steel plant in Degerfors, Sweden, to operate with a 40 MVA electric arc furnace (EAF) used for steel scrap melting and refining.

The SVC, rated at 10 Mvar inductive to 50 Mvar capacitive, serves the purpose of stabilizing the arc furnace bus voltage at a high value chiefly during the melting phase, thereby achieving a number of important benefits for the user of the EAF:

− An increase in available melting power which gives shorter melt down time and thereby higher productivity

− A decrease of specific electrode consumption due to more stable arcs

− A decrease of specific energy consumption due to lower radiation losses per melt

− A decrease of plant losses due to the decreased flow of reactive power

− Lower specific power billing due to a higher power factor at the point of common coupling.

The decreased specific electrode as well as energy consumption together with the more favourable power billing have effected a considerable reduction of the specific operating costs for the EAF process. From a purely technical point of view, the SVC improves the EAF operation as well:

− A decrease of voltage fluctuations in own as well as neighbouring facilities

− An improved power handling capability

− Suppression of harmonic distortion in own as well as neighbouring facilities

− Suppression of negative phase sequence voltage in own as well as neighbouring facilities

− An improved power factor

Main data
System TCR/FC (Thyristor-controlled reactor plus harmonic filter banks)
Commissioning year 1985
Controlled voltage 20 kV
Dynamic range 10 Mvar (inductive) to 50 Mvar (capacitive)
Harmonic filtering 15 Mvar/2nd harmonic
10 Mvar/3rd harmonic
25 Mvar/4th harmonic 
Power factor correction From 0.8 (uncompensated) to >0.99 (compensated)
Control system Individual phase control by means of fast-acting open loop reactive power control
Thyristor valve 3-phase water-cooled thyristor valve with magnetic firing