Reasons for implementing low voltage reactive power compensation in submerged arc furnace


Reactive power compensation of power supply network can improve power factor, reduce reactive power loss of power supply network and improve power supply quality, which has great economic benefits. At present, there are 35kV, 10kV and 110kV submerged arc furnaces for reactive power compensation. The power factor of submerged arc furnace operation is increased above the specified index to avoid the adverse impact caused by low power factor. However, when this compensation method is applied to the reactive power compensation of submerged arc furnace, it can only improve the power factor of electric metering point of submerged arc furnace, and has no obvious effect on increasing the output of submerged arc furnace and reducing energy consumption. There are still some defects in the benefits and performance of reactive power compensation.

For submerged arc furnace, the reactive power of the system is mainly caused by arc and short network, and the high current characteristics of short network determine that the consumption of reactive power will be mostly reflected in the short network in the form of reactive current, and the voltage drop generated by another short network reaching the electrode must be different. Smelting has what we usually call strong and weak phases. During smelting, the furnace core is formed, and the thermal center and power center are staggered, which not only increases the difficulty of process operation, but also causes the inconsistency of the three centers. In addition, since the high-voltage or medium voltage compensation only compensates the reactive power loss of the power supply line in front of the transformer, it is conducive to improve the power supply on the high-voltage side and improve the operating power factor, and the effect is also obvious. However, due to the reasons of its access point, high-voltage or medium voltage compensation can not reduce a large amount of reactive power loss in the short network at the low-voltage side, nor can it do anything to improve the three-phase instability caused by the three-phase short network layout.


Based on the instability of the short network layout of submerged arc furnace, a large amount of reactive power loss on the short network, and the limitations of reactive power compensation on the high voltage side or medium voltage side of furnace transformer, we can draw the following two inferences:


Selecting the compensation access point close to the connection between the short network and the electrode to compensate the reactive power of the low-voltage short network has great energy-saving potential.


Due to the unbalanced layout of the short network, the current situation of strong and weak phases can be changed after the phase separation compensation of the short network at the low voltage side, and the three-phase power is basically balanced.


Key words: submerged arc furnace DC submerged arc furnace DC electric arc furnace