| With the development of power electronics,variable frequency speed control is widely used in industrial and civil field because it has the merits of steady speed,high starting torque,high precision of speed,high efficiency,and energy saving.At the same time,the disadvantages of variable frequency speed regulation include high investment,high harmonic current,extra heating of motor and cable,and axial current will affect motor's service life.This paper is focused on the harmonics generated by the frequency inverter and its suppression.This paper analyzes the frequency inverter mechanism of producing the input side and the output side harmonic and the characteristics of harmonic.This paper also analyzes the long cable phenomenon in the long distance between the frequency inverter and the motor.The harmonic oscillation and the overvoltage of the motor are caused by the high harmonics.Based on the analysis of cable equivalent circuit and transmission theory,the higher frequency pulse transmission and the over-voltage of the transmission and overvoltage are obtained,which brings a big hidden trouble to the normal production of the factory.In this paper,a dual motor driven AC frequency inverter is designed for the process of the 630 square meters blast coiling system of Fuxin steel mill.Due to harmonic interference,it caused the accident in the process of winding system in parking,top equipment relay false operation,affecting the normal feeding of blast furnace.This paper puts forward measures to filter,shield,grounding and isolation.Through the simulation experiments,it verifies the feasibility of measures,solving the problem of harmonic interference of winding frequency converter system and making normal production of the blast furnace,and laying a good foundation on the blast furnace production. |
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