Design of medium frequency electric furnaceless edge filtering equipment

The steel mill is a metallurgical enterprise mainly engaged in medium frequency furnace steelmaking. There are two main transformers in the 35kV inlet line of 12.5MVA and 35kV/10kV respectively. There are mainly 3 12t intermediate frequency furnaces on the 10kV bus. Variable capacity 8000kVA, dual-winding 12-pulse rectification. Because the system is being built, it is impossible to conduct related tests. When SSE designs passive filter equipment, it mainly depends on the following aspects.

1) According to the operating characteristics of the 12-pulse rectification mode IF power supply, it is assumed that the main typical harmonics should be 11 or 13 times together with 5 or 7 times, and the uniform value can reach 5% to 10% of the fundamental component; "GB/T 14549-93" harmonic current superposition formula, calculate the large harmonic current generated by the three intermediate frequency furnaces working together on the 10kV side is 5 times 60.36A, 7 times 30.64A, 11 times 68.46A, 13 times 57.68A. The normal operating cycle of a single intermediate frequency furnace is 1.5h. There are two main operating conditions: heating and thermal insulation. The average natural power factor is 0.90 for normal operation and the compensation capacity is 3000kvar for increasing the power factor to 0.95.

2) Confirm 3 filter branches according to the characteristics of harmonic current. The tuning frequency and filter type of each branch are 5 single-tuned structures, 7th and 11th second-order high-pass structures; confirm according to system conditions and filtering requirements. The fundamental wave compensation capacities of the three branches are 800kvar, the tuning frequency and filter type of the road are 5 single-tuned structures, and the 7th and 11th second-order high-pass structures; 3 branch fundamental compensations are confirmed according to system conditions and filtering requirements. The capacities are 800kvar, 800kvar and 1400kvar respectively. Run one intermediate frequency furnace on its own for 5 times and 7 branches; run two and three intermediate frequency furnaces, all three branches are put into operation to ensure better filtering compensation.

For more information about the intermediate frequency electric furnace, diathermy furnace and induction furnace of Kunshan Wantai Electric Furnace Co., Ltd., please contact Xiaobian.

Medium frequency electric furnace, diathermic furnace, induction furnace,