Poland Elma Company CMC Steel Plant 31.5kV/100Mvar SVG
Customer Needs
Electric arc furnace (EAF) is a kind of electric furnace that makes use of heat from electric arc to smelting metal. The characteristics of electric arc furnace operating load are no-linear and strong time-varying, which will cause many system power quality problems such as grid voltage flicker and fluctuation, large negative sequence component, more harmonic, low power factor of power grid.
Poland Elma Company CMC Steel Plant uses 31.5kV/105MVA EAF with top charging structure. In the past, fixed capacitor was used for reactive power compensation on site, and there were power quality problems such as low power factor and excessive flicker.
RXPE Solution
According to data analysis and confirmation of technical indicators, the 31.5kV/100Mvar delta-connected SVG device combined with FC fixed compensation equipment is used to compensate reactive power, harmonics, and voltage imbalance and grid voltage fluctuations in the on-site electric arc furnace smelting process, and comprehensive treatment of power quality issues such as flicker.
The 31.5kV/100Mvar delta-connection SVG device used in the project features an outdoor container structure, including 6 power containers and 1 control and water cooling system container. The power valve bank adopts a water-water cooling system, which can provide good heat dissipation conditions for the power valve bank and ensure safer and more stable operation of the equipment.
The performance of flicker suppression and power factor correction
Flicker Suppression
Figure 1 PST for 31.5kV, without STATCOM
Figure 2 PST for 31.5kV, with STATCOM running
The maximum value of power grid voltage PST has been decreased to around 5.0 and PLT is around 3.12. The PLT value of 220kV busline (95% probability value) has been decreased to around 0.649.
Performance criteria
Before SVG put into operation
After SVG put into operation
Suppression ratio
31.5kV PST (maximum value)
19.0
5.0
3.8
31.5kV PLT (maximum value)
10.9
3.12
3.49
220kV PLT (95% probability value)
2.064
0.649
3.18
Power Factor Correction Performance
Figure 3 active power, reactive power and PF
SVG is not operating
Figure 4 active power, reactive power and PF
SVG is operating
Customer Benefits
The 31.5kV/100Mvar containerized water cooling SVG supplied by RXPE effectively mitigated the multiple power quality issues during EAF production in CMC Zawiercie, steel plant in Poland.
The PLT value has been decreased from 2.064 to 0.649 on 220kV PCC point during grid in production, it fully comply with the technical requirement which stated on the technical agreement that the PLT value (95% probability value) not exceeding 0.8. The flicker suppression ratio can reach at 3.18 excluding the power grid background flicker condition.
The power factor on 220kV PCC point is greater than 0.95(tanφ<0.3), it fully comply with the requirement stated on the technical agreement which is tanφ<0.4.
After the SVG put into operation, the harmonics and voltage unbalance on 220kV PCC point fully comply with the requirement of technical agreement.
