Research On Droop Control Strategy For Low-Voltage Microgrid Inverter

With the energy crisis and environmental problems is becoming increasingly prominent, micro grid technology to its energy saving, safe and reliable, flexible operation mode, etc., is favored by the experts of energy and electric power. Micro grid is composed of renewable energy,load, energy storage device and inverter control device. The micro source in the micro grid needs to be connected to the AC grid through the inverter, and the inverter is the basic power electronic interface unit in the micro grid. It will be of important significance to the inverter control device’s study in Micro grid.In this paper, the basic principle and characteristics of the droop control strategy used in the distributed generation unit are analyzed in detail. In the case of distributed generation units in parallel operation, the problem of the reliability and stability of the system is severely damaged due to the inconsistency of the line impedance. On the basis of this, the traditional droop control strategy is introduced, and the accuracy of the output voltage is analyzed in detail. An improved droop control method based on the closed-loop control of virtual impedance is proposed. The proposed method is introduced in the same time, the voltage droop characteristic of inverter output port is closed loop control. At last, the simulation model of the parallel system with two inverters and the control method of active port voltage(P-V), the MATLAB/simulink control method, the TMS320F28335 DSP control method,and the experimental results are presented. The simulation and experimental results show that the improved droop control strategy has good control effect on the power sharing and output voltage precision control.Prove the correctness and feasibility of the strategy.