Study On Harmonic Suppression And Reactive Compensation Strategy Of Mine Power System

In the power supply system of mines,a large number of power electronic devices and other nonlinear power electronic devices are used,which makes the harm of reactive power and harmonic pollution are becoming more and more serious.What's worse,the quality of power supply and stability of the power system are reduced,the harmonic content is high,low power factor the safety of equipment the staff are hard to be guaranteed.Therefore,in view of the characteristics of the mine power supply system,a suitable scheme for harmonic suppression and reactive power compensation is designed to improve the operating conditions of the power grid and improve the power supply quality of the system.First of all,the paper analyzes the causes of harmonics and reactive power in the coal mine system of Jixi Rong coal mine.With the research results of harmonic suppression and reactive compensation at home and abroad combined,and the common reactive power compensation scheme contrasted,a scheme selecting a static var compensator(SVG)as a compensating device is applied.Secondly,according to the basic principle,working characteristic and main circuit of SVG.This paper introduces two control methods,direct control and indirect control,and applies the direct control method to the SVG compensation system.In order to effectively compensate the reactive power and harmonics in the system,the harmonic current and reactive current ought to be detected quickly and accurately.In this paper,several different methods of reactive current detection are introduced,compared and analyzed,and their characteristics and applicability are obtained.The advantages,disadvantages and limitations of the traditional p-q and ip-iq methods are analyzed.Under the condition of three-phase voltage distortion and asymmetry,it is impossible for ip-iq method to detect the accurate fundamental positive sequence active and reactive currents.According to this,an improved method is put forward to add A phase fundamental positive sequence voltage extraction unit,coordinate detection method based on power supply voltage rotation vector for improved ip-iq method.In this three parts,the first two are used to extract fundamental sequence positive sequence voltage of A phase,at the same time,phase locked loop can be omitted,and the delay problem can be greatly improved.The latter one can get the expression of trigonometric function and omit the trigonometric transformation.The two different methods of harmonic and reactive current detection are simulated in the Simulink module of MATLAB software.Comparing the obtained waveform,choosing a better detection scheme and comparing the waveform with the traditional ip-iq method,the test results of the improved current detection method are better than the traditional ip-iq method.Then,the and software of the SVG compensation system are designed,the general principle block diagram of the SVG compensation system is drew out,DSP2812 chip is taken as the main control chip.The hardware design module includes the voltage over 0 detection circuit,the driving circuit and so on,software design module includes the compensation system main program,the PWM output and so on.Finally,on the basis of theoretical research,the paper uses the Simulink module of MATLAB software to simulate and verify the ip-iq harmonic current detection method and the improved ip-iq method in the whole compensation system simulation.The simulation results show that the improved ip-iq method is effective for harmonic suppression and reactive compensation in mine power supply system.