Hysteresis Control Research Based On Space Vector For Tri-level APF

With the continuous development of coal mine production technology and the unceasing enhancements of energy saving and emission reduction requirements,the use of various types of nonlinear loads in coal mine power supply system is increasing rapidly.This type of load will produce a large number of harmonics in the runtime,which not only affect the other electric equipment to normal power supply,but also cause serious electromagnetic interference on communication system,protection system and monitoring system,etc.A large number of harmonics brings great risks to the s safety production in the coal mine.Therefore,it is urgent to take effective measures to restrain the harmonic pollution in coal mine power system.Active power filter(APF)has the advantages of the good compensation effect,the fast response times and the board adaptability.It is an effective device to restrain harmonics.In this dissertation the T-shaped tri-level shunt APF had been taken as the research object,focusing on the three-level hysteresis control optimization.In the traditional three-level hysteresis control,the power switch device has redundant switching action because of the independent control of each phase.So in this dissertation hysteresis control and space vector pulse width modulation are combined organically,and three-level hysteresis control strategy based on space vector is proposed.Compared with the traditional hysteresis control,it can achieve better filtering effect with lower switching losses.In the aspect of blance control of neutral point potential in DC side,the dissertation through the real-time detection of neutral point potential bias and neutral point current direction to adjust the the different switch combination,and then achieve neutral point potential balance control.In the end,based on the Matlab simulation platform and the dSPACE experimental platform,and the test is carried out.Specific contents and the achievements are as follow.1)This dissertation expounds the causes and terrible effects of the harmonic current in the coal mine power grid,and introduces the development of the filter.Then the different filters are analyzed,explained and compared,and the research contents of this paper are puts forward.2)The T-shaped tri-level shunt APF had been taken as the research object.Operating principles,harmonic current detection and current tracking control are introduced in this paper.The paper puts forward the technical ideas of APF.3)The problems of hysteresis control are analyzed.And then hysteresis control and space vector pulse width modulation are combined to achieve hysteresis control strategy based on space vector.On this basis,the simulation model of hysteresis control based on space vector is constructed.The simulation results show the rationality and effectiveness of the proposed control algorithm.4)The reason for tri-level APF neutral point potential unbalance is analyzed.This dissertation puts forward a method by real-time detection of neutral point potential bias and neutral point current direction to adjust the the different switch combination.On this basis,the simulation model of neutral point potential control is constructed.The simulation results show that the neutral point potential balance control can be realized better.5)The dSPACE experimental platform was built to conduct experiments.The results show that the proposed hysteresis control strategy based on space vector and neutral point potential control method are correct and effective.