Because the electric arc furnace will produce a lot of reactive power impact when it works, it will cause a large reactive power fluctuation on the public busbar of the power grid, and it will produce irregular low order harmonics, which will have a greater impact on the hydropower plant equipment close to this load. When the electric arc furnace is working, the active power fluctuation of the hydroelectric generating unit can reach 6MW ~ 7MW. The rapid fluctuation of the active power may cause the vibration of the unit, which has great harm to the long-term stable operation of the unit.

RXPE solution

In order to solve the existing power quality problems on site, RXPE installed a set of 10kV cascade dynamic reactive power compensation and harmonic filtering device (SVG + FC type) with compensation capacity of not less than 14Mvar at the outgoing line of 10kV switch cabinet, totally one set. The device includes a set of SVG not less than ± 7 Mvar and a set of FC with fundamental compensation capacity not less than 7 Mvar. The device can realize continuous and rapid reactive power regulation in the range of not less than 0 Mvar inductive to 14 Mvar capacitive, and filtering each harmonic current generated by electric arc furnace.

Main wiring diagram of dynamic reactive power compensation and harmonic filtering device

Site photos of dynamic reactive power compensation and harmonic filtering device①

Site photos of dynamic reactive power compensation and harmonic filtering device②

User benefits

After the operation of SVG, the grid voltage is stable, the power factor is higher than 0.95, and the power quality problems such as harmonics, negative sequence and voltage flicker are obviously improved.
在并網點電能質量明顯提升的同時，用戶水力發(fā)電機組運行狀況也得以改善，電弧爐工作時，水力發(fā)電機組的有功功率波動小于1MW。While the power quality of the grid is improved obviously, the operation condition of the user's hydropower units is also improved. When the electric arc furnace is working, the fluctuation of the active power of the hydropower units is less than 1MW.

Comparison of harmonic current before and after compensation

Comparison of instantaneous flicker before and after compensation