| With the gradual depletion of traditional fossil energy sources,renewable energy sources are gaining worldwide attention and wind energy,as an important component of renewable energy,is widely used in various countries.However,the random and unstable nature of natural winds leads to limitations in the output efficiency and power quality of wind turbines in operation,limiting the development of new energy industries.In recent years,the application of energy storage technology in wind power generation has played a positive role in improving the efficiency of wind power systems and improving the quality of the system’s power output.For this reason this paper connects three different energy storage batteries to the wind power system and investigates the improvement of each power quality indicator by different energy storage devices.In this paper,off-grid wind power systems are used as the object of study.Steady-state and unsteady-state power quality testing experiments are carried out with the aid of a combination of experiments and simulations,and the experiments are supplemented by analysis using Matlab and Ansys simulation software.Based on the characteristics of the complex physical process corresponding to the source-storage-load system,based on the theory of entropy S=klogw,this paper uses the system loss as the medium to explore the local and global entropy production variation law of the new power system of "wind power +energy storage" and the correlation between entropy production and various evaluation indexes by analyzing key indicators such as total distortion rate of current harmonics,cosφand voltage fluctuation.This paper attempts to propose a power quality evaluation method based on entropy production and directly related to system loss.Firstly,the power quality index test experiment is carried out.: the steady-state experimental platform of the motor instead of the wind wheel is built,and the non-energy storage experimental research is carried out to explore the correlation between each power quality index and the speed and load;three different energy storage batteries were added for experiments,and the power quality indexes were compared and analyzed with no energy storage device.The unsteady power quality test experiment is carried out by using the ’ wind tunnel ’ platform.The wind speed is controlled from 5m / s to 12 m / s,and the external characteristic parameters of the non-energy storage device are tested to explore the correlation between the power quality indicators and the tip speed ratio and load.The energy storage device is added,and the external characteristic parameter test is used as a comparative experiment to improve the power quality evaluation index of the system after adding three different energy storage batteries.Using Matlab simulation software to build a simulation model based on the ’ wind power + energy storage ’ experimental system,the influence of energy storage device on each index is analyzed,and the experiment is supplemented and analyzed.Using Ansys to simulate the temperature and overall loss of each component inside the generator during operation,it provides a basis for exploring the correlation characteristics between power quality indicators and system entropy generation,so as to form a more complete analysis of the correlation characteristics between system entropy generation and power quality indicators.Secondly,according to the mathematical model of entropy generation of wind power system,this paper analyzes the loss of each component of the system during the experiment,and analyzes the correlation between power quality index and entropy generation with the correlation between system loss and power quality and system entropy generation as intermediate parameters.Finally,with the energy storage efficiency of the system as the goal,the load,speed and battery type as the influencing factors,the genetic algorithm is used for multi-objective optimization,and the optimal solution within the constraint conditions is sought to improve the system efficiency and power quality. |
