Research On Fault-tolerant Technology Of Cascaded Active Power Filters

APF as the current control of the vital power of the harmonic equipment,combined with high-power converter can work in the high-voltage power applications,to achieve APF applications from low to high-voltage field.However,the number of power switching devices used in high-power converters has increased exponentially with the increase in voltage in the application field.Compared with the APF applications in the low-voltage field,the possibility of failure in the operation of the high-power converter is greatly Increase,reliability greatly reduced.This major defect greatly limits the rapid development of high-power converters,so to solve the reliability of high-power converter has become an urgent issue of important issues.For the common open circuit fault of cascade APF switching device IGBT,this paper uses the fault detection method based on the current voltage flow to determine the specific position of the fault switch.Cascade APF series H-bridge number and more features,and further proposed low cost,easy to achieve single-phase single-sensor multi-level fault detection principle for H bridge fault detection.Based on the actual number of connected H bridges,the 3N+1 or 3N+n fault-tolerant control strategy is proposed to improve the reliability of cascaded APF and reduce the redundancy cost.The multi-level control principle is studied,and CPS-PWM is selected as the control method of cascade APF.DC-side capacitance voltage phase-to-phase balance control method based on ip-iq harmonic detection method,the method is relatively simple and easy to implement.The cascade APF system is simulated and the prototype is designed and built.The simulation results show that the open circuit fault diagnosis,the single-phase singlesensor multi-level fault detection scheme and the corresponding 3N+1 fault-tolerant strategy are correct and reasonable.The design of the harmonic detection algorithm,cascaded multi-level inverter topology and its control algorithm used in power system harmonic compensation,has a certain reality and engineering significance.