Research On Power Quality Control Strategy Of Low Voltage Microgrid Based On Photovoltaic Power Generation

Energy Internet is an important part of the industrial revolution,photovoltaic micro-grids,which are at the heart of the energy Internet,also play an important role.The large amount of research and development of photovoltaic micro-grids has greatly improved the reliability and flexibility of power supply,and at the same time environmental problems have been greatly improved.In recent years,the development of photovoltaic micro-grid has been widely valued by scholars at home and abroad.But the distance between the micro grid and the user side is short,which belongs to the distribution network,and the voltage level is low and the installed capacity is also small.The disturbance of system and load will bring great influence to the stable operation of micro-grid.Therefore,a reasonable control strategy is adopted to regulate the operation of inverter to achieve the goal of stable operation of micro-grid,and ultimately provide users with high quality power.The effective utilization of new energy requires highly precise control strategy.In order to achieve optimal economic dispatch of photovoltaic micro-grid,we must ensure excellent power quality.Therefore,deep research on power quality control strategies applied in PV micro-grids is of great significance.In this paper,we study the basic control strategy of micro-grid and propose the power quality control strategy of the improved droop control algorithm.The PQ control strategy is suitable for power control in grid connected operation of micro-grid.V/f control is suitable for power control in islanding operation of microgrid,but these two control methods only have good control effect in single case,and can not be applied to any case.The actual status of grid-connected microgrid operation can not be predicted,and the quality of power supply will be affected by many factors.Since conventional droop control is highly dependent on line resistance ratio,this paper adds a drag coefficient ratio on the basis of conventional droop control algorithm,and proposes an improved droop control algorithm for power quality control strategy.Secondly,through the study of the proportional integral(PI)control algorithm in the traditional voltage and current double closed loop,it is found that the PI control algorithm can only control the zero steady-state error of the direct current.In other words,the gain of PI control output at DC frequency is infinite.However,it is not possible to achieve zero-steady-state error control of the amount of communication,that is to say,the gain at ?can not reach infinity.Therefore,this paper proposes a voltage and current double closed loop control strategy based on proportional complex integral(PCI)control algorithm,which shows good control effect and can achieve zero steady-state error control for AC and DC quantities simultaneously.Finally,using Matlab/Simulink as experimental platform,two inverter models are built The simulation and analysis of the power quality control strategy based on the combination of the PCI control algorithm and the improved droop control algorithm based on Matlab/Simulink.The feasibility of the control algorithm proposed in this paper is verified.