Research On The Inductive Filtering Technology And Circulating Current Issue Of The12-Pulse Common Core Rectifier Transformer

Large-power rectifier system provides a new way for the electric powerutilization by the AC/DC convention, and it has become an important part of thenational industry. The nonlinear devices in large-power rectifier devices produce largeamounts of harmonic in operation, leading to serious distortion of the voltage andcurrent waveforms of AC power grid，damaging to the power grid. Therefore，harmonic suppression problem of the large-power rectifier system is urgent. As a newtype of harmonic suppression technology, the inductive filtering technology arises atthis historic moment, the new technology does the harmonic governance and reducesthe loss of the system. In order to save cost, common core rectifier transformer wasusually adopted in the large-power rectifier system, voltage unbalance of transformersecondary windings causes a circulating current. This circulating current causes therectifier bridge bearing current unbalanced, shortening the service life of the device,this problem can not be ignored. Around these problems, specific research work inthis paper is as follows:First of all, two kinds of structure characteristics of the rectifier transformer inthe12-pulse rectifier unit and the problems in the scheme selection needed attentionhas been summarized, the working principle of rectifier circuit and the commonrectifier transformer are analyzed,the new type energy-efficient filtering rectifiertransformer was researched, then the author researches the advantage of a newlarge-power rectiifer systems based on this technology.Secondly, combined with the previous research work，this paper usesMatlab/Simulink simulation software to establish simulation model of both traditional12-pulse rectifier system and a new type of rectifier system based on inductivefiltering technology.lt also simulates two types of working condition for filter,analyzing its network side harmonic current and the power factor. Network voltage,current, harmonic distortion rate and the power factor of rectifier unit are analyzedaccording to the measured waveforms, the results show that the new type of rectifiertransformer and its filtering system can suppress harmonic current very well on valveside and has good harmonic suppression function, which proved that the new type ofrectifier transformer based on inductive filtering technology and this new12-pulserectifier system have a good engineering application value. Finally, according to the circulating current problems in chemical electrolyticrectifier power system at present, this paper analyzes the circulation in equivalent12-pulse rectifying power supply and common core12-pulse rectifier systemrespectively, builts a model on the Mat lab/S imulink platform, gets the factors ofcirculation influence, and puts forward the measures to restrain circulation, which canbe can extend the service life of the device, reduce economic investment very welland has the good economic efficiency.