Research On Power Quality Control Of Active Power Distribution Network Supply Terminal Based On Energy Storage System

In recent years,with the rapid development of distributed energy represented by wind energy and solar energy,distributed generation technology has been paid more attention to in the world.The distributed generation plays an important role in meeting energy demand,improving energy structure,reducing environmental pollution,protecting ecological environment and promoting economic and social development.However,the distributed power generation is characterized by randomness,volatility and intermittent,which results in that the fluctuation power will affect the power quality of the distributed power supply to the distribution network and bring stability to the grid.The energy storage system can quickly adjust the power of active / reactive power.It can be applied to the distributed grid connected power generation,which can smooth power,cut peak and fill valley.It is of great theoretical and practical significance to investigate the power quality control of active power distribution network with distributed generation.The power quality problems of the distribution network connected with wind power generation are studied in this paper.Firstly,the structural characteristics and load characteristics of active distribution network and the influence of wind power integration on power quality of active power distribution network are analyzed in detail,and the reasons of power quality problems caused by wind power integration are obtained.Then,the existing methods of power quality control are compared.Secondly,The power quality control method based on fuzzy logic idea and super capacitor energy storage for distribution network system connected with wind power is proposed,and the simulation and analysis of the proposed power quality control method in Matlab/Simulink environment is carried out.It is verified that the method can realize the low voltage ride-through of wind power grid-connected short circuit fault,and thus the system is stabilized consequently.In addition,the doubly fed variable speed wind generator can ensure the voltage stability by increasing the reactive power output when the short circuit occurs in the bus.Thirdly,because of the similar structure between the energy storage converter and other power quality control devices,active power quality control can be realized.For this reason,a kind of power quality controller based on super capacitor energy storage interface dual four leg converter is put forward in this paper,accessing to active distribution network by series parallel connection.Then,on the basis of the series parallel connection mode of energy storage power quality controller,its limitationsare analyzed,and therefore a control strategy for voltage coordination compensation of active power distribution network based on super capacitor residual capacity is presented in this paper.The above-mentioned methods can effectively improve the power quality of the active distribution network connected with wind power and enhance the stability of the active distribution network.