Research On Grid Connected Inverter With Harmonic Suppression Function

At present,we are facing the energy shortage and environmental pollution problems :traditional fossil fuel is consumed in a nonrenewable way, and emits lots of harmful gases harmful gases,which is causing environmental pollution.In order to solve above problems,Distributed Generation System is even more becoming focused and favorable due to its unique advantages of using pollution-free green new energy such as wind energy, solar energy and so on.Distributed generation system not only makes the zero emissions of pollutants possible,but also can be convenient to take electricity or heat nearby,which greatly improves the efficiency of energy.The energy transfer and exchange between the distributed generation system and the large electric power grid is realized by the grid connected inverter.Therefore, the grid connected inverter directly affects the quality of the grid connected electric power.In addition,due to the development of high and new technology,lots of power electronic and non-linear electrification devices are put into use,which causes serious distortion of power grid waveform and pollution of electrical environment.Owing to above aspects,it became one of research hot spots that how to control grid connected inverter, make the network security and achieve harmonic suppression function at the same time.Aimed at enabling the three-phase grid connected inverter to have harmonic suppression function and based on traditional current and voltage double closed loop control,this paper added synthesis harmonic impedance into the voltage loop to achieve effective harmonic suppression function for both current and voltage.Based on the above approach,two strategies have been proposed,which are power decoupling control strategy in combination of synthetic main harmonic impedance and power calculation control strategy in combination of synthetic harmonic impedance with SOGI model.In order to verify the rationality and feasibility of the two control strategies,the system simulation model of the two control methods has been established on the MATLAB/SIMULINK simulation platform in this paper,including harmonic extraction model,power control model,synthetic harmonic impedance model,PR controller model,coordinate conversion model and so on,and the SPWM has been used to control the inverter operation.Simulation results in this paper show that the double closed control strategy with harmonic impedance can effectively reduce the current and voltage harmonics of the power grid and improve power network quality,which verified the feasibility and effectiveness of the proposed control strategy,realized the design goal of this paper,and laid a certain theoretical basis for the actual project.