Research On Reactive Power Sharing Control Strategy In Islanding Microgrid

Nowadays,under the pressure of environmental protection and energy demand,more attention has been put into the related technical field of distributed generation(DG),which can improve the utilization efficiency of the traditional energy resources and make full use of all kinds of renewable energy resources.However,with the large number of distributed energy access to the main grid,that takes a negative impact to the safety and stability of the grid and economic operation,so scholars put forward the concept of the microgrid.Microgrid can be stable operation in the grid and islanding mode.Grid mode microgrid performance is controlled current source characteristics,and the main grid provide voltage frequency support.However,in the islanding mode,due to the loss of the main grid voltage frequency support,microgrid performance is controlled voltage source characteristics,due to the difference of feeder impedance between micro-power source and common bus will cause reactive power sharing inaccuracy,yet influences system operation.Therefore,how to improve the reactive power sharing accuracy of microgrid becomes one of the hotspots of microgrid research.So in this paper,it studies the reactive power sharing control strategy in islanding microgird.The paper is divided into the following parts.First of all,the reactive power sharing control strategies of paralleled micro-power source in microgrid are summarized.The application of droop control and virtual synchronous generator control on power sharing in microgrid are analyzed.The consistency of the two control strategies is proved.Summarized power sharing control base of droop method on changing line impendance,changing droop coefficient and changing output voltage,respectively.Then,aiming at the problem in the microgrid when it operates in parallel with the micro-powe source,the feeder line impendance of the micro-power source is different from each other,which leads to the poor precision of the reactive power sharing on conventional droop control.This paper proposes a voltage compensation reactive power sharing to reduce system power circulation and improve the accuracy of reactive power sharing.The simulation model of MATLAB / Simulink is built to verify the effectiveness of the proposed control strategy.At last,aiming at the problem that the traditional double-loop control can cause the power sharing inaccurate and the traditional droop control strategy will cause the voltage frequency to deviate from the rated value when the system power fluctuates.This paper proposed a new method based on voltage-frequency regulation reactive power sharing control strategy.The simulation model of MATLAB / Simulink is built to verify the effectiveness of the proposed control strategy.