Research On The Improvement Of Power Quality Of Micro Grid Based On Harmonic Suppression

In order to deal with the continuous consumption of traditional energy and environmental pollution problems,the development of distributed generation based on renewable energy sources is a good solution.Distributed generation can make the power grid more flexible and reliable,and it is a favorable supplement to the large power grid.But the distributed generation system has its own problems.Distributed generation is influenced by the natural environment,and the output power is very random and volatile,which can cause the fluctuation of voltage and reactive power of the power system.The power quality problems caused by the distributed power supply system will affect the safety of the users.In order to solve these problems,micro grid is proposed.At present,the domestic and foreign research on micro grid.In this paper,the analysis and research on the control of the micro grid operation and harmonic suppression.Firstly,the two operation modes of micro grid island and grid connected operation are analyzed.When the micro grid is in the isolated island operation,the control strategy has the master-slave control and the peer to peer control strategy.Analysis and comparison of these two control strategies.For the grid connected inverter type micro power supply,analyzes the PQ control of constant power,constant voltage constant frequency V/f control and Droop control.Analysis principle,control target.The structure diagram of the controller is given,and the simulation model is established.Then it points out the problems of the harmonic wave in the micro grid.The source,characteristics,harm and improvement of micro grid harmonics are analyzed.An active power filter is proposed to suppress the harmonic of micro grid.Analysis of active power filter classification,system structure,working principle.After comparing several detection methods,APF based on instantaneous reactive power of the harmonic detection algorithm.In the control of harmonic current,the method of one cycle control is adopted.In the DC side voltage control link,using PI regulation to maintain the stability of the DC side voltage of APF.Finally,the simulation model of micro grid system is established.Verify the feasibility of the control strategy and method in the grid connected operation and isolated island operation mode.The simulation results show that the micro grid has a lot of harmonics and the harmonics are effectively suppressed after adding APF to compensate harmonics.The feasibility and effectiveness of the APF method is used to suppress the harmonic method.