Analysis And Control Of Frequency Stability In Isolated Microgrid With Varied Distributed Energy Sources

Microgrid is the key to solve the problem of energy shortage and environmental protection in the process of economic development.Due to a large number of distributed power sources in the microgrid,the power time and instability of the microgrid will disturb the frequency of the microgrid system,which is especially obvious when the distributed power island is running.Therefore,modeling the islanding microgrid model and improving the control strategy plays an important role in maintaining the frequency stability of the system.This paper first introduces the research background and significance of the paper,and summarizes the current research status of microgrid.The dynamic frequency response model of microgrid is set up with the micro grid containing diesel generator,photovoltaic cell,wind turbine and energy storage system,and the optimal control parameters are selected to ensure the stability of the system with the root locus method.A microgrid simulation model is established in Matlab/Simulink to verify the effectiveness of the traditional PI control strategy on the islanding frequency control.Secondly,in order to further improve the response speed and the accuracy of frequency control,an active disturbance rejection control strategy based on equivalent input is proposed.According to the state of the system and the state of the observer,the equivalent input disturbance is estimated,and the error between the observed state and the actual state of the system is added to the design of the controller to improve the tracking precision of the state observer to the signal,so that the observation state can be accurately converged to the reference value.At the same time,the low-pass filter is added after the observation state and the actual state error of the system,which reduces the disturbance of the system and improves the control effect of the controller.Finally,the simulation comparison of the system without control strategy,the traditional control strategy and the proposed improved control strategy is carried out.The simulation results verify the superiority of the control strategy to the micronetwork frequency control.Finally,taking an international airport isolated island operation as an example,the feasibility of adopting the improved control strategy is given.According to the location of the airport load and the location of the distributed power in the airport,the single area and dual area operation modes are divided.The frequency control effect ofthe algorithm is studied from two cases in one region and two regions,and the control strategy of the system,the traditional PI control strategy and the active error of the interconnected bus under the three conditions of the improved control strategy are compared under the dual region operation mode,and the proposed control algorithm is verified for the interconnected bus.Active power deviation also has very effective control effect.