Research On The Control Strategy Of Microgrid Inverter With Nolinear Load

With the development of national economy, the power consumption is increasing year by year. The scale of power system is larger than ever. The contradiction between conventional power supply mode and users’needs is gradually emerging. Distributed power generation technology based on renewable energy and microgrid technology is developing rapidly against this background. While the increased penetration of power electronics based distributed generation systems and nonlinear loads may introduce more power quality issues to microgrid. Thus, the performance of interfacing converters is of great significance for ensuring system stable operation.The control strategy of interfacing inverter in mircogrid was studied in this paper. In allusion to the resistance characteristics of the line impedance in microgrid, a P-V and Q-f droop control was adopted to realize the coordinated control among the inverters. A software PLL was adopted to solve the starting pre-synchronization of interfacing inverter, reducing the instantaneous impact current. The reason and impact caused by the different line impedance was analyzed. An improved control strategy by compensating the impedance voltage drops to improve the power sharing is proposed. Traditional current control model to compensate the harmonic current caused by the non-linear loads in microgrid is not suitable. Therefore, a more flexible hybrid control method is proposed. The MATLAB/Simulink software was used to validate the proposed control method.The experimental platform composed of three3kW three-phase inverters controlled by DSP was set up. The experiment of the proposed control strategy was completed based on the platform. The experimental results show that it is practicable to realize the stable operation using the proposed control strategy and improve the power quality of microgrid with nonlinear load.