Research On Power Control Strategy Of Microgrid In Islanded Mode

The situation of energy supply has been severe in recent years,and microgrid power generation technology has attracted much attention.The microgrid can realize the flexible control of distributed generator and provide the required power for the load.The microgrid mainly operates in islanded mode or grid-connected mode.In island mode the droop control strategy is used in microgrid,the difference in impedance of distributed generator transmission lines will cause output voltage,frequency and power sharing deviation.To solve the above mentioned problems the paper with islanded microgrid as the research object,adds distributed secondary control on the basis of droop control to adjust the voltage and frequency of distributed generator ensure system stability and reasonably allocate load power.The main research contents of the paper are as follows:1)Power sharing control strategy of microgrid.Analysis of related factors affecting power sharing in droop control is made based on distributed generator parallel control model.In this paper,the power deviation problem in droop control can be solved by hierarchical control,and the power sharing accuracy can be improved by changing the line impedance and the droop coefficient,taking virtual synchronous generator control technology,and changing the output voltage of the distributed generator.2)Analysis of secondary control methods for microgrid.The segmented compensation secondary control method is proposed as for the communication cost and system stability of hierarchical control of microgrid.The compensation method is selected according to the degree of deviation of the voltage and frequency from the rated value,and achieve plug and play for distributed generator.The segmented compensation control method can improve system response speed and rapidly achieve accurate power sharing in microgrid load fluctuations.3)Communication delay among the distributed generators in microgrid.The distributed control strategy obtains the average global voltage and frequency through the communication in distributed generators.However,the delay leads to slower convergence of the consensus algorithm worse system stability and power sharing accuracy.This paper proposes an optimization consensus algorithm that can improve the response speed of the algorithm and improve the stability of the system within the range of the delay pole.4)Build a simulation model of the microgrid system.The segmented compensation control algorithm and the optimized consistency algorithm are simulated,the results verify that proposed algorithm can achieve the power ratio among distributed generator and the anti-interference ability of the system.