Load application Widely used in smelting and heating of non-ferrous and ferrous metals. Such as cast iron in smelters, general steel, stainless steel plate, alloy steel, copper, aluminum, gold, silver and aluminum alloy, etc. ; Steel and copper parts for diathermy forging, aluminum ingots for extrusion molding, etc. Carry out quenching and tempering treatments such as heat treatment and heat treatment on metal materials. The intermediate frequency furnace heating device is small in size, light in weight, high in efficiency, excellent in thermal processing quality, and favorable to the environment. It is the next generation of metal heating equipment for rapidly eliminating coal-fired furnaces, gas furnaces, oil furnaces, and ordinary resistance furnaces.
Load harmonic characteristics; intermediate frequency melting furnaces are more and more widely used in smelting, casting and other industries. However, when working, the intermediate frequency electric furnace adopts rectification and inverter technology, resulting in a large number of current and voltage harmonics. Harmonic pollution to the power supply system makes precision instruments work in the process of error and increases the loss of power supply equipment. The electrical system of the intermediate frequency induction furnace is a relatively large pulse current source in the power supply system, and there are generally switching power supplies for intermediate frequency induction furnaces and high frequency induction furnaces. Generally, 6 single-pulse intermediate frequency induction furnaces mainly generate characteristic harmonics of 5, 7, 11, and 13 times. For 12 single-pulse converter intermediate frequency induction furnaces, the key harmonics are the 11th, 13th, 23rd and 25th characteristic harmonics. Generally speaking, 6 pulses are used for small converter equipment, 12 pulses are used for large converter equipment, such as Y/△/Y type furnace transformer, or 2 furnace transformers are used for power supply system.
According to the problems encountered in practical activities, the harmonic moisture content of the intermediate frequency furnace is less than 85%, but the system maintenance products are mainly dominated by harmonics, the improvement of harmonics can basically be ignored, and the energy saving effect is not satisfactory. What’s more serious is that the harmonic energy far exceeds the allowable range of energy-saving and environmental protection equipment, and it is easy to be damaged after long-term use, and accidents occur frequently. Therefore, in response to the urgent desire of many end products, the environmental protection and energy saving of intermediate frequency furnaces has become a long-term problem in the industry of energy consumption, which puzzles many industries and enterprises.
1. The intermediate frequency furnace generates a large number of harmonics during use, and the harmonic pollution in the power grid becomes very serious
2. Harmonics will reduce the efficiency of power transmission and utilization, overheat electrical equipment, generate vibration and noise, deteriorate insulation, reduce life, and even malfunction and burn out
3. Harmonics will cause local parallel resonance and series resonance of the power system,
4. Amplify the harmonic content, burn out the capacitance compensation equipment and other equipment;
5. Harmonics cause relay protection and automatic device malfunction;
5. Outside the power system, harmonics seriously interfere with communication equipment and electronic equipment.
6. If the power factor does not meet the regulations of 0.90 of the power supply bureau, the penalty for adjusting the electricity fee will be imposed.
7. The low power factor of the medium frequency induction furnace and the large amount of reactive load provided by the special transformer increase the burden on the transformer.
8. There is also a situation: the power factor of some customers’ intermediate frequency induction furnaces is not low when they are put into operation, and they only need to control the pulse current.
Therefore, improving the power quality of the intermediate frequency furnace has become the key to the response. Solutions to choose from:
plan 1
Centralized management (install harmonic filters in the power distribution room suitable for simultaneous operation of multiple intermediate frequency electric furnaces)
1. Use harmonic control branch (5, 7, 11 filter) + reactive power regulation branch. After the filter compensation device is put into operation, the harmonic control and reactive power compensation of the power supply system meet the requirements.
2. Adopt active filter (remove the order of dynamic harmonics) and harmonic countermeasure branch circuit (5, 7, 11 order filter) # + invalid adjustment branch circuit, and after providing to the filter compensation equipment, put forward Request for invalid compensation of the power supply system.
Scenario 2
On-site management (set up on-site high-order harmonic filtering device next to the power panel of the intermediate frequency furnace)
1. Adopt anti-harmonic bypass (5th, 7th, 11th filter), automatically track the operation of the intermediate frequency furnace, solve the harmonics on site, and do not affect the operation of other equipment during production, and the harmonics do not reach the standard after being put into use.
2. Adopt active filter (bandwidth adjustment unit) and filter bypass circuit (5th, 7th filter), the high-order harmonics after switching on do not reach the benchmark.
Option 3:
Features our advanced repetitive control high power active power filter. Our Hongyan APF power stand-alone has 100A, 200A, 300A, 500A and other specifications, and 6 units can be paralleled. Handles the cooperation of all frequency pairs.
Post time: Apr-13-2023