The Harmonic Control Of The Thyristor Rectification System For Pingguo Aluminum Electrolyzers

In recent years, with the rapid development of the power electronic technology, it is wildly used in rectification of power system ,metallurgy and other industries. Harmonic has produced serious adverse effects in the equipment of power generators and distribution, the equipment of their control and protection , users and communication fields. So the pollution of harmonic control has already been the imminent task in the power supply and distribution system!This topic using of the actually measured data, through mathematical analysis and necessary simulation means finds out the harmonic generation, harmonic magnified, resonant of the rectification system in the PingGuo Aluminum Electrolysis. Reorganization the parameters of harmonic filters and transforming the thyristor rectifier in technology, solve the problem of the harmonic magnified and the harmonic resonance.The main reason of the harmonic generation of thyristor rectification system for PingGuo Aluminum Electrolysis is:Thyristor, step-down transformer, Rectifying transformer are the nonlinear components; Using the analogical triggering signal which produce big error, cause the asymmetric trigger; The components of the thyristor rectifier can not reach the level of equalizing voltage and equalizing current; the anode effect cause the angle of the thyristor rectifier inconsistently.The main rules of the harmonic generation in the thyristor rectification system for PingGuo Aluminum Electrolysis is:The third harmonic has been seriously amplified. When the parameter drift, the parallel resonance is caused ; even harmonic was produced in the system , especially the sixth harmonic was seriously amplified by the harmonic filters and the power system; The characteristic harmonic was filtered by the harmonic filter basically ,but the non-characteristic harmonic , especially the third, the fourth, the sixth, the ninth harmonics was severely amplified in the twelfth harmonic filter.The interrelation of the harmonic of thyristor rectifying system for aluminum electrolysis and electrolysis positive electrode effect is:Positive electrode effect was occured in aluminium electrolysis, If it was not been extinguished at the appropriate time , the optimization produces of the electrobath will be affected and the harmonic increased rapidly, especially the non-characteristic harmonic . In the side of power network, if the filter are not configured appropriately, a part of the non-characteristic harmonic will be amplified, especially using the LC filter, the parallel resonance is caused easily, leading to the electric energy quality declined gravely. When the operation way of power network is changed at the same time, the consequence is especially grave, and the operating state of the power network is very disadvantageous. So optimizing the parameters of aluminium electrobath (especially the voltage of electrobath), equally optimizing the parameters of outside part of power network, play an important facilitating role in improving the electric energy quality.Finally, according to mathematical analysis and simulation results of harmonic filters, the parameters of harmonic filters have been restructured and the thyristor rectifier have been transformed in technology .Through many actually measured data proved that the project has already achieved the purpose of the harmonic control. It provide a safe, economical and stable operation for the rectifying equipments in the PingGuo aluminium electrolysis, and also supply the valuable experience to the same industry and even the same equipment.