Researchon Control Strategy Of Microgrid With Photovoltaic And Energy Storage

With the depletion of non renewable energy,the deterioration of the ecological environment,the shortage of primary energy and the contradiction of the quality of storage,renewable and pollution-free energy has been favored by human beings.The research of distributed generationsupply has become a hot spot,at the same time,it is the coordination between the grid and the distributed generation supply.In order to better integrate and apply large-scale distributed generation,microgrid is proposed as a system that can make good use of the potential of distributed generation.In this paper,a microgrid structure with photovoltaic and energy storage is proposed for the low utilization of renewable energy and the intermittency of distributed generation supply.This structure has the characteristics of making full use of renewable energy and ensuring the stability of the output of the system.On this basis,the control strategies for various operation modes of the microgrid are studied.In order to maximize the use of solar energy,the maximum power point tracking algorithm of the photovoltaic power generation system in the microgrid system is analyzed.According to the basic principle of the photovoltaic cell,a variable step size maximum power point tracking algorithm is proposed,and the response time and the recovery time of the traditional algorithm in the maximum power rate point tracking process are also restored.The complex time and the system efficiency are compared.In order to make up the intermittence of photovoltaic power in the microgrid,the energy storage unit is added to the microgrid system.Based on the analysis of the basic principles and characteristics of various energy storage devices,a hybrid energy storage system is composed of battery and supercapacitor,and the structure of the hybrid energy storage system and the double closed loop control strategy are studied.According to the research on the design of micro power supply and its control strategy in the microgrid system,this paper focuses on the control strategy of the two mode switching of the micro grid based on the photovoltaic andenergy storage in the grid-connected to the isolated island and the island to grid-connected.When the microgrid is run by the grid-connected island,the energy storage system serves as the main control unit for the system,which ensures the stability of thedirect current voltage,and presynchronous control of the microgrid before the island is converted to the grid,so that the impact current is reduced.The simulation results show that the microgrid can operate stably under various operating conditions and achieve smooth switching.The feasibility of the proposed control strategy is verified.