Intermediate Frequency Furnace Harmonic Suppression

With the rapid development of electronic power industry, the popularization ofnonlinear devices has been greatly promoted in the industrial application, whichcontributes to the widely use of the intermediate frequency furnace. Nowadays, theapplication of intermediate frequency furnace has been extensively applied to thefield of electricity high-consumption industry in China, such as smelting and steelrolling. Some devices of the intermediate frequency furnace have not been optimized,such as the existence of nonlinear devices--rectifying device etc. Therefore, theharmonic it generates can bring severe impair to the power quality. The problem ofharmonic has gained increasingly attention in recent years, so lots of companies hadmade corresponding measures aiming at the management of the harmonic. This paperaims to restrain the problem of harmonic by using the Injection Hybrid Active PowerFilter (IHAPF), based on the intermediate frequency furnace’s characteristics of highelectricity consumption, massive harmonic, and low reactive power factor. Under thecondition of meeting the filter’s capacity, the filter manages the harmonic intensivelyon the high pressure side. During this process, the management and reactivecompensation of the specific harmonic take place in the Passive Filter (PF), and thedynamic compensation of the harmonic in the Active Power Filter.The filter’s property depends to a high degree on the accuracy of the electricity’scontrol. Owning to the restriction of the hardware’s property in the IHAPF, there issome certain unavoidable delay when testing the electricity. This delay has an effecton the restrain of harmonic. In order to solve this problem, this paper analyzes severalmethods on how to control and test the electricity. This paper also makes progress onthe research of these methods through the study of the mechanism of how the delaygenerates, and the low pass filter design and simulation based on the transient reactivepoweri p-iqtest method. By predicting and analyzing of the delay, correspondingcompensational angle is added to make up the phase deviation that caused by thedelay. At the same time, this paper analyzes the voltage control on the direct currentside by simulation to ensure that the filter can output stable compensation current andto further verify the improved harmonic test. After modeling and simulating thefilter’s effect on the MATLAB before and after being improved, it can be concludethat the test current’s delay, the harmonic compensation performance of the whole system, the dynamic tracking ability and the detection accuracy all have greatlyimproved.Based on the analysis of structure and operating principle of intermediatefrequency furnace, this paper aims to optimize and improve the parameters of thefilter devices. To begin with, the optimization of the parameters of the passive part inthe single-tuned filter makes the single-tuned filter conform to the powercharacteristics of the intermediate frequency furnace and avoid too much reactivecompensation. Second, Optimize the injection branch parameter Settings, to seek theoptimal parameters, improve the ability of harmonic injection. Third, while theinverter in the active part generates the compensational harmonic, it also generateshigh frequency switching harmonic. The frequently-used LC output filter’s restraintowards high frequency harmonic has wave band that can have syntony with thepower grid. Meanwhile, it will amplify the certain higher harmonic. After adding theresistance to the LC to form the LCR output filter, the revised output filter comes intobeing by means of the MATLAB simulation. Through analysis, such kind of revisedoutput filter can avoid the syntony with the power grid and the amplification of thecertain higher harmonic. Meanwhile, it can restrain the higher harmonic withoutinfluencing the compensation of low harmonic. Finally, modeling and simulating thefilter’s unit on the MATLAB after being improved.