Analysis And Treatment Of Voltage Sag In Distribution Network With Distributed Generation

Voltage sags seriously affect the normal operation of voltage sensitive loads,and even bring huge losses to industrial production.The large-scale and large-scale access of distributed generation to distribution network has greatly changed the structure and power flow of traditional distribution network.The impact on voltage sag of distribution network can not be ignored,and how to manage it also needs to be discussed.The main contents of this paper are as followsFirstly,the basic theory of voltage sag is analyzed,and the main causes of voltage sag are summarized;three basic characteristics and detection methods of voltage sag are studied,as well as sag area,critical distance and Voltage Sag Sensitivity of electrical equipment,which are the basis of subsequent design and simulation;Secondly,distributed generation(DG)is divided into three types:synchronous type,asynchronous type and inverter type,and its basic principle is introduced.On this basis,the typical inverter type DG photovoltaic power generation system is emphatically analyzed and modeled.The impact of DG access on distribution network voltage sag is divided into the adverse impact of DG on distribution network voltage sag and the active regulation of DG access on distribution network voltage sag This paper analyzes the function of DG,points out the problems of DG participating in voltage sag regulation,and concludes that the inverter type distributed generation must cooperate with the active power quality control device for joint compensation.Finally,the dynamic voltage restorer(DVR)is analyzed and studied.Based on the existing literature,a dynamic voltage restorer system based on battery supercapacitor hybrid energy storage is designed.A DVR topology which can meet the requirements of large capacity and long life operation is constructed.According to the advantages of similar topology between the designed DVR device and the inverter type DG,when the grid voltage is normal or voltage sag occurs,the micro power droop control strategy and composite control compensation strategy are proposed respectively for DVR,so as to improve the voltage quality of the system and avoid the failure of the whole set of equipment in the compensation function The machine is idle.In addition,in the case of grid voltage interruption,DVR can also play the role of uninterruptible power system(UPS)to supply power to the load.Finally,the DVR system is simulated to verify its effectiveness.The voltage sag of distribution network with distributed generation can be effectively controlled by DG self-regulation and DVR coordination compensation.