Research on Active Support Scheme for Grid-connected Distributed Photovoltaic Based on Fuzzy Control
When the photovoltaic inverter is running in the maximum power tracking mode,it may cause the voltage and frequency of the photovoltaic grid connection point to fluctuate.In severe cases,the bus voltage may deviate from the standard seriously,and the photovoltaic grid will be disconnected in a large area,which hinders the application of photovoltaic power generation technology.In response to this problem,this paper combines the active power control and reactive voltage droop control of photovoltaics,and explores an active support control scheme for photovoltaic inverters.In order to solve the problems of large power fluctuations and slow stabilization speed in the active power reduction control based on the improved perturbation and observation method under the fixed step size,an auto-tuning step-length based on fuzzy control is used to improve the speed and stability of the active power reduction control strategy.Aiming at the slow speed and large fluctuation of photovoltaic power tracking when the Boost circuit adopts the PI controller with constant parameters,a fuzzy control-based PI parameter self-tuning scheme is used in voltage loop to improve the speed and stability of photovoltaic power tracking.Finally,the active support control strategy is simulated and verified by establishing the active support simulation model of the photovoltaic inverter in MATLAB/SIMULINK.And the proposed self-tuning method of step size is tested by building the grid-connected photovoltaic power experimental platform.The results show that the proposed method can improve the active support ability of the photovoltaic inverter to the grid-connected point voltage,improve the speed and stability of power tracking under the control of photovoltaic active support,and then improve the stability of the distribution network.
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