Research On Stability Control Of Photovoltaic And Energy-storage Hybrid Microgrid

With the rapid development of the world economy,the demand for electric energy is increasing day by day.The fossil energy crisis and environmental pollution caused by the traditional power generation method also make the electric power industry in the world face great challenges.The structure is mostly centralized single power supply system,making the power grid on the power supply of large-scale power quality,safety,reliability requirements are getting higher and higher.Microgrid with its flexible and efficient power generation and economic and reliable power supply method and distribution network to form a perfect complement to effectively improve the power quality and power supply reliability.However,due to the randomness and intermittency of distributed power generation,the stability of micro-grid is very important because of the increasing permeability of microgrid,which shows the influence of grid-connected operation on the stability of power system.In this paper,based on the microgrid,the mathematical model is built and the output characteristics of the photovoltaic cell are built according to the working principle of the photovoltaic cell.As the photovoltaic cells affected by natural factors can not output stable power for load use,this paper puts forward the maximum power point tracking method combining a fixed voltage method and incremental conductance method,which compared with a simulation example verify that the tracking performance of the proposed MPPT method is better.And then take a study on a hybrid system composed of lithium-ion battery and supercapacitor.Based on the working principle of lithium-ion battery and supercapacitor,an equivalent mathematical model is established and a power factor-based charge and discharge control strategy to better compensate for the power fluctuations within the micro-grid suppression.Then study on the distributed power inverter,three common control methods(PQ control,Droop control and V/f control)for distributed power inverters in microgrid are studied in this paper.,according to the working principle of their control and the mathematical model is established,and the parameters were designed to ensure that each control method has better dynamic performance and stability by the frequency domain analysis,the paper presents a stable control method based on the above three kinds of control methods,not only to ensure stable operation of the micro-grid under steady-state conditions,but also through the phase-locked loop and the voltage amplitude and frequency of the PI regulator to ensure that the transient case of voltage phase,amplitude and frequency of the seamless convergence.Finally,the smooth switching of the network and the normal steady operation of the load provide the control theory support for the stable operation of the microgrid.At last,the structure of optical microgrid is put forward and the simulation model is built in Matlab/Simulink platform.Under the condition of stable control,the input and output load of the microgrid and the switching power supply and the different control The simulation results show that the stable control not only ensures stable operation under steady-state conditions,but also achieves smooth switching of the microgrid state,and no distortion and flicker of voltage and current occur during the switching process.Load in the normal state between the stable operation of the switch to achieve the final realization of the micro-grid stability control.