Modular Multilevel Converter based STATCOM for Electrical Arc Furnace application

Steel plant - Sremska Mitrovica, Serbia

Metalfer Steel Mill (MSM) is a Serbian steel plant, located in the Northwest of the country, close to the Croatian border. It is owning and operating an EAF-based steel mill manufacturing construction steel products from recycled scrap metal. They are the only rebar producer in Serbia and the leading supplier on the local market, also exporting to the neighboring countries.

MSM is part of Metalfer Group, an industrial group of companies involved in mining, metallurgy, energy, and trading, established in Serbia in 2002.

In November 2021, GE Power Conversion was awarded a contract to provide MSM with a STATCOM system to help stabilize the local grid.


Our customer is operating a mini mill based on an Electric Arc Furnace (EAF) melt shop with a capacity of 400 kT/Y. The EAF is generating high voltage flicker, that the existing SVC system cannot compensate enough, preventing the facility from reaching the standard limit.

The flicker is causing significant power quality issues, to the plant itself but also to the neighborhood. As the Croatian authorities were complaining, MSM has been ordered by the local Transmission System Operator (TSO) to resolve the problem or to shut down the power.


Modular multilevel converter-based STATCOM system installed at Metalfer steel plant in SerbiaTo answer this need for high compensation level, GE Power Conversion proposed a STATCOM system based on its Modular Multilevel Converter (MMC) technology. This advanced transformer less solution, using the MM7 drive, offers high performance with a flicker mitigation ratio up to 6.0 –a strong asset over competition that allowed GE to be selected for this project.

Scope of supply
  • MM7 STATCOM 20 kV/from -49MVar to +121 MVAr
  • 3 phases, each constituted by 5 towers
  • Engineering, delivery, supervision of erection and commissioning

The equipment has been delivered at the end of 2022 and started operating in March 2023. It was then successfully tested in April 2023.

Looking at the future

In a near future, MSM intends to change the plant’s bus voltage from 20 kV to 33 kV – a grid expansion that GE Power Conversion already anticipated and will therefore easily be implemented by adding 2 towers per phase to the MM7, thanks to the high flexibility of the solution.


Despite a relatively low grid quality factor (X/R) and short-circuit level, Power Conversion's solution achieved a flicker reduction above 5, hence meeting the customer's expectations. 

Table of benefits after the performance tests of the STATCOM