Research On Control Strategy Of AC/DC Hybrid Microgrid

With the development of the global economy,the massive consumption of fossil energy will bring great harm to the environment.Renewable energy represented by wind and photovoltaics is gradually replacing fossil energy,but its randomness and intermittentness hinder their further development.Microgrid enables intermittent and decentralized renewable energy sources to be connected to the grid with minimal impact.The AC/DC hybrid microgrid takes into account the output characteristics of distributed power sources and the power supply requirements of the load.It can realize the reliability,economy and diversity of the power supply system,and improve the utilization of renewable energy.It is a microgrid with the most potential for development.Form,this article takes the AC/DC hybrid microgrid as the object,and launches research on its control technology.First of all,a micro-source mathematical model with different output characteristics such as wind turbines,photovoltaics and battery energy storage is established,and the control strategies under different operating modes are studied,and the correctness of the models and control strategies is verified through simulation.Secondly,the mathematical model of the two-way interconnected converter in the stationary and rotating coordinate systems is established,and the filter parameters of the two-way interconnected converter are designed.During grid-connected operation,a constant DC bus voltage control strategy is studied to maintain the stability of the DC-side bus voltage.When off-grid operation,a comprehensive droop control strategy is studied to maintain AC-side frequency,DC-side voltage and sub-network power.Balanced,designed the switching threshold range of two-way interconnected converters to reduce device losses and improve system efficiency.Simulations have verified the effectiveness and feasibility of the AC/DC hybrid microgrid control strategy in the off-grid operation mode.Finally,set up an experimental platform,design the parameters of the experimental platform,and conduct experimental research on the constant DC bus voltage control strategy and the comprehensive droop control strategy in the parallel/off-grid mode,verifying the correctness of the researched control strategy.