Research On Hysteresis SVPWM Fault Tolerant Control For APF In Synchronous Rotating Coordinate System

Active power filter(APF)is one of the most effective methods for harmonic suppression.However,active power filter(APF)works in high temperature,high pressure and high frequency switching for a long time.Therefore,the main circuit switch device is prone to short circuit fault,which leads to the APF in fault state and can not continue to compensate for the harmonic in the system,and when the bridge arm fault occurs in APF,it will become the harmonic source and inject a large number of harmonics into the power system.Therefore,how to ensure that the APF under three-phase four-switch topology will continue to work normally and compensate for the harmonics in the system when the single-phase bridge arm fault occurs in APF,so that the bridge arm of APF fault can be repaired quickly.To win more time and improve the fault tolerance and working stability of APF becomes the focus of three-phase four-switch APF research.In this paper,the fault-tolerant operation of three-phase four-switch APF is studied,and a fault-tolerant control strategy of APF in synchronous rotating coordinate system is proposed.Firstly,the effective space voltage vector is analyzed.There are only four effective voltage vectors in the four-switch system.Then,the coordinate transformation of three-phase power grid current is carried out,which is transformed to the synchronous rotating coordinate system.The sum of the d axis component and the DC side current is taken as the final d axis component.Then,the reference values of the two axes are compared with the reference values of the two axes in the hysteresis comparator,and the error state parameters under the two axes are obtained.Then,according to the two error state parameters and the position of the international voltage vector,we can choose the optimal voltage vector at that time,so that the fault-tolerant operation of APF in the fault state can be realized.And it can improve the fault tolerance and stability of APF.Finally,the simulation model of three-phase four-switch APF is established by using MATLAB,and the hysteresis SVPWM fault-tolerant control algorithm proposed in this paper is simulated in a variety of cases,and then the experimental prototype is built and debugged on the basis of simulation.The simulation results are consistent with the experimental results,which prove the correctness and feasibility of the proposed control strategy.