The reactive power compensation devices currently in operation are usually divided into the following two ways based on the access point of the compensation device:

1. The compensation device is connected to the high voltage side of the ore furnace transformer, which is called high voltage compensation;

2. The compensation device is connected to the low voltage side of the ore furnace transformer, which is called low voltage compensation;

2、 Reactive power compensation device

1. High voltage compensation

The high voltage side voltage of the ore furnace transformer is generally 10KV, 35KV, or 110KV. There are two types of high-voltage compensation: one is to directly connect the compensation device to the high-voltage side; Another way is to connect it to the high voltage side through a compensating transformer. Compensation devices with corresponding voltage levels (including power capacitors, switches, reactors, lightning arresters, protection equipment, etc., the same below) can be directly connected to the high voltage side of the submerged arc furnace transformer (the compensation device is connected to the input end of the submerged arc furnace transformer), or directly compensated separately or centrally in the substation. Its characteristics are:

1) Simple equipment and low investment;

2) When the compensation device malfunctions, the current does not pass through the ore furnace transformer;

3) The compensation device is not affected by changes in the wiring of the ore furnace transformer or other aspects of the ore furnace.

2. Low voltage compensation

2.1 Principle

Low voltage compensation is a reactive power compensation device that uses modern control technology and short network technology to connect large capacity and high current ultra-low voltage power capacitors to the secondary side of a submerged arc furnace. This device not only embodies the principle of reactive power compensation, but also enables the power factor of the ore blast furnace to operate at a higher value, reducing the reactive power consumption of the short network and primary side, and eliminating the 3rd, 5th, and 7th harmonics. Leveling the three-phase power and improving the output capacity of the transformer. The focus of control is to reduce the imbalance of three-phase power and achieve equal three-phase power. Expand the crucible, concentrate heat, increase the furnace surface temperature, accelerate the reaction, and achieve the goal of improving product quality, reducing consumption, and increasing production.

This technology belongs to the application of mature on-site compensation technology to the secondary low voltage side of the submerged arc furnace. The reactive power generated by capacitors is absorbed by the system through a short line, partially through the submerged arc furnace transformer, and partially compensates for the reactive power loss of the submerged arc furnace transformer, short network, and electrodes, increasing the active power input to the submerged arc furnace. At the same time, phase separation compensation is adopted to make the active power on the three-phase electrodes in the ore blast furnace equal, achieving the effect of improving power factor, reducing three-phase power imbalance, and improving production indicators. Advantages of using low-voltage on-site compensation/filtering technology:

1. Low voltage compensation can improve the utilization rate of transformers and high current lines, increase the effective input of smelting,

2. Improve three-phase imbalance.

3. Reduce high-order harmonic values.

4. Reducing transformer and network additional losses can eliminate power regulation electricity costs and save energy and reduce consumption.

5. Improve the active power output of the ore smelting furnace transformer, thereby increasing production and economic benefits.