Research On Fault Ride Through And Stability Of Microgrid System

With the increasingly prominent environmental and energy issues and the rapid development of power electronics technology,microgrid technology has become an unstoppable development trend.However,there are still many key issues in microgrid technology to be studied,such as fault ride-through of microgrid systems,the stability of microgrid systems,and so on.Fast and accurate fault ride-through is an important indicator of microgrid systems,and the stability of microgrid systems is the most basic problem in the operation of micro-grid systems.It is necessary to study them.The main work and innovations of this paper are as follows:(1)Analyzed the main problems that may exist in the micro-grid system to achieve fault crossing,revealing the VSG control output imbalance during the fault,the power angle between the inverter voltage and the common bus voltage and the inverter output voltage out of control.After the fault is removed,the current impact is large,the system recovery is very slow and so on,and verified by simulation and experiment.(2)In view of the problems existing in the traditional VSG control algorithm for fault ride-through,two improved strategies for different control objectives are proposed.One is to maximize the output of active power during the fault,and the other is to maintain the power angle between before and after the fault.Consistently,both solutions can quickly achieve fault ride-through of the microgrid system.The low-voltage ride-through simulation experiments of single-machine and multi-machine were carried out for the two strategies.The multi-machine high-voltage traversal simulation experiment was also carried out.The experiment verified that the improved strategy can well realize the fault traversal function of the micro-network system.(3)Simplify the model of microgrid system with rational hypothesis.The relationship between active power and output frequency and the relationship between reactive power and output voltage are modeled,and the system identifiability is analyzed.(4)Analyzed the recognition accuracy of the system identification algorithm,and proposed an improved method to verify the effectiveness of the improved method.(5)Based on the experimental platform constructed by the actual prototype of 100 kW microgrid inverter of East,the identification experiment was carried out and the stability analysis was carried out.