Research On Control Strategy Of Three-level Active Power Filter

With the development of society and technology,electricity demand has been increasing and the power industry has been developing rapidly.The quality of electrical energy in industry or in life is getting higher and higher,therefore higher requirements on the performance of filter compensation effect are put forward.In the existing filtering harmonic and reactive power equipment,active filters have been developed rapidly because of better harmonic elimination and reactive power compared to passive filter.The two level active power filter cannot be applied to high voltage large capacity due to the constant improvement of the voltage level and the limitation of the capacity of the switching tube.While the three level active power filter can be applied to low voltage switching devices in high voltage and large capacity applications,which has low switching frequency,low voltage and low switching loss compared to two level active power filter in the same requirements.In this paper the diode clamped three level active power filter based on extraction was studied and some new control algorithms were put forward.The research results of this paper have a great improvement on the compensation effect and performance of three level active power filter.In order to overcome the switching frequency of the active filter volatile and current tracking performance issues,a method for tracking the current dual-loop space vector control was proposed in this paper,which can apply to the three-level active filter.The method aims to simultaneously reduce the switching frequency and current tracking error,it is controlled on the complex plane directly.By determining magnitude of the error current amplitude and the use of dual-loop control scheme optimized for the switching frequency,it can effectively reduce the switching frequency at the output of the current error to meet requirements of the premise.Using pulse width modulation technology,it can be able to accurately track the current instruction.The results show that the program is high real—time,robust,which has good harmonic compensation performance.Considering the efficiency,cost,load and other factors,diode clamped three level structure was used as the main circuit structure of three level active power filter.The system design and working principle of three level active power filter were studied.Analysis of mathematical model of three level active power filter was completed.In this paper,simulation and verification of three level active power filter algorithm were completed.The feasibility of the proposed algorithm was proved,and the hardware and software design of the system were completed.