The Research On Harmonic Analysis And Suppression Methed Of Dynamic And Thermal Stability Experiment System

The dynamic thermal stability test system of DC switch equipment is to test whether the DC switch device can withstand the influence of electric stress and thermal effect caused by short circuit current without damaging the short circuit current,so it is of great significance to the research and setting of DC switch device.The experimental system of dynamic thermal stability test system will produce a large amount of harmonics in the operation.These harmonics not only cause harmonic pollution to the power grid,but also affect the normal operation of the daily load of the system under the same grid,and even affect the normal operation of the system,resulting in damage to the test equipment.Therefore,it is necessary to suppress the harmonics generated during the normal operation of the dynamic and thermal stability test system.In this paper,the dynamic thermal stability test system of DC switch is taken as the background of the project:The mathematical model of each component of the dynamic and thermal stability test system is analyzed,and the model of dynamic thermal stability test system is established.The system is simulated and analyzed under normal working conditions to verify the correctness of the system model.Several mature harmonic analysis algorithms are introduced.They are applied to the test system,and their advantages and disadvantages are analyzed by simulation.Then,the harmonic analysis method based on dual tree complex wavelet is introduced,and its performance is simulated under the background of this topic.It is proved that the method can improve the performance of the former algorithm.In the harmonic detection,the composite detection method based on instantaneous reactive power and the lifting wavelet transform detection method are introduced,and the principle and simulation results are compared.Finally,the improved wavelet transform detection algorithm with simple system and high accuracy is selected as the detection algorithm of harmonic suppression in the dynamic thermal stability test system.In harmonic compensation,the parameters and topology of APF are selected firstly.Then,the DC capacitor of APF is controlled by voltage regulation and the tracking control of compensation voltage.In this paper,the double closed loop control method applied to the inverter is introduced into the APF compensation voltage control,and the simulation results show that the double closed-loop control can improve the harmonic suppression performance.