矿热炉在使用中产生大量的谐波,导致电网中的谐波污染非常严重。矿热炉一般由可控硅整流装置提供直流电源。可控硅整流装置会在交流侧产生很大的无功功率和谐波电流,导致电压、电流波形严重畸变,功率因数低,造成进线电流大,变压器利用率降低,能耗增加。谐波还会干扰拉晶控制系统,造成错位、断晶、跳闸,严重影响正常生产。 矿热炉是一种高能耗的电冶炼炉,具有电阻电弧炉的特性。其功率因数是由炉内电弧及电阻R和电源回路中(包括变压器、短网、集电环及电极)的电阻R和电抗X值的大小来决定。 COSΦ=(R+R)/ 电阻R电抗X值在矿热炉运行时,一般不变动,它们取决于短网和电极布置的设计和安装。电阻R与运行时短网上各载流部件的电流密度有关,变化较小,但电阻R却是矿热炉运行时决定矿热炉功率因数的主要因数。 由于矿热炉比其它电冶炼炉的电阻弱,故其功率因数相应地也降低些。除了一般小型矿热炉的自然功率因数能达到0.9以上,而容量在10000KVA以上的中、大型矿热炉的自然功率因数都在0.9以下,矿热炉容量越大,功率因数越低。这是由于大容量矿热炉的变压器感性负载越大,短网越长,电极[敏感词]炉料较深增加了短网的电抗,因而降低了矿热炉的功率因数。 为了减少电网的损耗,提高供电质量,供电局要求用电企业的功率因数要在0.9以上,否则要对用电企业处以高额罚款。同时功率因数偏低,也会降低矿热炉的进线电压,影响电石的冶炼。故目前国内外大容量矿热炉都要加装无功补偿装置,以提高矿热炉的功率因数。
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.
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.