Study On Improved Droop Control And Harmonic Suppression Method Of Microgrid

In this paper,the operation quality control strategy of island microgrid is studied.By introducing virtual impedance,an improved traditional droop control strategy is designed,and the harmonic suppression method of this kind of system is further studied.By effectively coordinating the management and control of distributed power supply,the efficient utilization of distributed renewable energy can be realized.Compared with the current centralized power grid,microgrid is easier to connect distributed generation to large power grid.However,because the microgrid system itself is thin,it is easy to be affected by the micro-power supply and load during the operation,which leads to the uneven distribution of power and stability,and so on.A large number of power electronic devices will also cause a large number of harmonics in the system,which will affect the power quality.Therefore,the design of effective control strategy and harmonic suppression method is the core and key to ensure the stable operation of microgrid.Especially when the microgrid is in isolated island mode,the inverters must cooperate to ensure the voltage and frequency stability of the microgrid system,and can share the load power according to their own capacity,so as to achieve the equal distribution of power.Therefore,the control method of isolated microgrid is designed and analyzed in this paper.Considering the problem of power quality,the harmonic suppression method of this kind of system is further studied.The simulation model of voltage and current double loop module,power module and droop controller is built,and the problems of traditional droop control in microgrid operation and power balance are analyzed.In this paper,the control principle of improving power distribution accuracy in microgrid is studied,and an improved droop control strategy with virtual impedance is proposed.The output characteristics of the system after the introduction of virtual impedance are analyzed by frequency domain analysis,and the stability of the droop control model based on virtual impedance is analyzed according to the closed-loop transfer function of the system.The simulation results of the traditional droop control strategy and the improved droop control strategy with virtual impedance are compared.The results show that the improved droop control strategy has better control performance than the traditional droop control strategy.The shortcomings of traditional droop control applied in microgrid are solved,and the stable operation and equal power distribution of microgrid system are realized.Finally,the harmonic suppression method of microgrid based on virtual impedance is studied,and the harmonic suppression effect of microgrid in isolated island mode is analyzed.The simulation results show that the method can suppress harmonic distortion of microgrid voltage.Meet the grid-connected standard of distributed power generation.Therefore,the improved droop control strategy based on virtual impedance in this paper can make the voltage stability of the connection point between the microgrid and the large power grid,so as to ensure the stable operation of the whole microgrid system.When the load changes,the power can be automatically distributed without communication and the effect of equal distribution can be achieved.The harmonic suppression method based on virtual impedance can effectively suppress harmonics and improve power quality.