Research On Energy Coordination Control Of DC Micro-grid Under Islanding

The rapid development of the global economy in recent decades led to the worsening of the social environment and the increasing depletion of traditional fossil fuels; also making energy and environmental issues more prominent in today’s society. the demand for distributed energy is more urgent in modern society. In this context, a new energy structure emerged, micro-grid system consists of distributed energy generation component was put out, and has been developing rapidly.DC micro-grid has been rapid development as a micro-grid technology, and compared to AC micro-grid, DC micro-grid has its own unique advantages, DC micro-grid has no inverter link, energy conversion efficiency has been greatly improved, and the DC micro-grid has no var power flow, so for the DC micro-grid, stable voltage is considered as the only aim, voltage control problem will become the only control objectives for DC micro-grid, The DC micro-grid lowered difficult to control, facilitate coordination and management between various distributed energy.This paper chooses photovoltaic and wind power generation for distributed energy generation unit and the battery as the energy storage unit and the DC micro-grid coordinated control were studied and analyzed; firstly distributed energy storage unit and modeling analysis, and MATLAB/Simulink model, and power output characteristics of photovoltaic cells and wind turbines are analyzed, we investigated their maximum power point tracking method using an improved perturbation method to achieve PV MPP, using a variable step perturbation method to achieve maximum power tracking of wind power. Also analyzed the principle and the output characteristics of the battery, and laid a foundation for further research.Finally, considering the output characteristics of the distributed power, based on the study of the operation of the DC micro-grid control strategy to stabilize the bus voltage control target, through the establishment of a photovoltaic cell DC/DC controller model, wind power AC/DC controller model and battery bidirectional DC/DC controller model and coordinated controller to ensure the balance of DC micro-grid energy systems, so as to achieve the purpose of stable voltage, and finally to verify the validity of the control strategy by MATLAB/Simulink platform.