Application Of Hybrid Active Power Filter In Harmonic Suppression And Reactive Power Compensation In Casting And Forging Enterprises

With the progress of science and technology,industrial development and the wide application of various types of power electronic devices,the application of electric power in various fields has become increasingly prominent.Especially in the large-scale casting and forging enterprises,almost every link cannot be separated from the participation of electricity,which is the most widely used non-linear equipment,because the use of such equipment,resulting in increased harmonic content in the power grid,power factor Low,voltage and current waveform distortion,etc.,a serious threat to the normal operation of the grid and electrical equipment.Therefore,it is very important to solve the problem of reactive power compensation and harmonic control in the power system of the cast and forged enterprises to ensure the power quality and safe operation of the power system,reduce the loss and improve the efficiency of the electricity equipment.This paper first introduces the causes and hazards of harmonics in power system,and the history and current situation of mixed active power filter research both at home and abroad.And the working process of the common three-phase 6-pulse and 12-pulse Medium frequency induction heating furnace is analyzed.The results show that the 12-pulse rectifier circuit produces harmonic content and amplitude far below the 6-pulse rectifier circuit.Based on the selection of 12-pulse rectifier circuit,the various measures of reactive power and harmonic compensation of medium frequency induction heating furnace are studied,and the characteristics of various measures are analyzed and compared,and the hybrid active power filter Is the ideal harmonic control and reactive power compensation device so far.Then,according to the existing methods of harmonic and reactive current detection,the characteristics and the method of using them are analyzed,and the method of current detection based on instantaneous power theory(also called p-q method)is introduced.In order to avoid the deviation of the detection accuracy caused by the harmonic components such as reverse voltage and current in the system,the virtual unit positive sequence voltage vector is introduced,and the traditional p-q method is found in the traditional p-q method.Unit negative sequence voltage vector Fu1 and Fu2,through the calculation,simulation of the improved algorithm is more simple than the traditional way of calculation,detection accuracy is higher.According to the principle of active filter control,select the structure is relatively simple,cost-effective,lower loss of voltage-type PWM converter as the active circuit of the main components of the filter.By comparing the application of various kinds of tracking instruction signal change control method,it is found that the hysteresis comparison control method is simpler in the control process of the PWM converter,the switching loss is smaller and the corresponding speed is faster,which satisfies the needs of the engineering design.On the basis of the above analysis,the main circuit of the parallel hybrid active filter and the circuit parameters corresponding to the engineering practice are designed.Finally,the results of this paper are applied to the practical engineering.By analyzing the results before and after the new device is put into operation,it can be seen that for the system current waveform with serious distortion,when the parallel active power filter is put into parallel,the harmonic current content and amplitude of the system are obviously reduced,the harmonic current Distortion rate has also been significantly improved,and reactive power compensation effect is also better,power quality in line with national grid-related standards.