Research On Microgrid Operation Control And Power Quality Improvement Based On Master-slave Structure

Because of its characteristic of environmental protection and adequate reserves, the microgrid becomes more and more popular in the world. But at the same time its power quality problem becomes more and more prominent too. In order to improve the power quality in the microgrid, this paper makes researches on control method and power quality of the master-slave structure microgrid.Firstly, the research status of mircogrid power quality problem is summarized in the paper. Then its mathematical model is established in both of three phase static abc frame and dq synchronization reference frame. And the structures of the PQ control and the V/f control are inferred in this paper. Then the LCL filter is used as the output filter of the grid-connected inverter to reduce harmonic current. The LCL filter's parameters and its performance are also discussed in detail. Then simulation models are built in the PSCAD. The simulation results show that the master-slave structure microgrid can work stably and the LCL filter can improve the microgrid power quality effectively.Based on the former researches on the microgrid power quality, this paper presents a new composite control method of grid-connected inverters and derives its working principle. Depending on controlling the output current of the grid-connected inverter to follow the composite command current, which is consist of the grid harmonic current signal and the PQ control signal, the inverter can generate electricity for the system, and compensate reactive power and harmonic current of the microgrid. And then the current harmonic detection method and the SVPWM control method are analyzed in detail. Then the simulation model of the composite control is built in the PSCAD. The simulation results show that the composite control method is an effective method to improve the microgrid power quality.Finally, the TMS320F28335 is used as the maincontrol chip in the experiment platform. And the system program is designed. At last, the experiment is completed. The experiment results show that the theoretical analysis and simulation performance of the composite control are correct.