Research And Application Of STATCOM In Power Distribution System Based On The Theory Of Active Disturbances Rejection

In recent years,the emergence of a large number of distributed power,nonlinear impact and unbalanced loads has brought more power quality problems,the most prominent problems is the reactive power,unbalance three-phase system and harmonics.Causing loss in the active power and reactive power.Static synchronous compensator(STATCOM),as an important technology of flexible AC transmission system,By regulating the angle between the inveter output voltage and grid-voltage to control the issuse and absorption of reative power,has good control performance and compensation effect.In the control of power flow and quality of electric power system,STATCOM and other FACTS devices have been proven that they can effectively improve the power distribution of the power grid,and can reduce the reactive power over or under the product caused by failure,transmission transmission loss and so on.This paper introduce the research background,significance,status of D-STATCOM and the topology of the main circuit.Through the study of the physical mechanism,the principle of reactive power compensation of D-STATCOM is obtained and established the mathematical model under ABC coordinate system.Through the analysis of the traditional ip-iq current detection method,finding out the source of error detection.Owing to phase locked loop with effect of the time delay,it can not accurately extracting the phase information in the non ideal state.This paper presents a current inspection without PLL measurement in the traditional method of current detection method,by using the average value filtering and optimization the sampling computation process to reduce the detection,accurate extraction of phase information of fundamental positive sequence voltage under non ideal voltage conditions,so as to improve the detection accuracy and the response speed of D-STATCOM.In control mode,D-STATCOM is controled generally by used PID or combination of PID and other control methods.Control principle is based on the error to remove the error.There are coupling between the control amount of D-STATCOM device.A linear auto disturbance rejection controller is proposed in this paper.Using linear ADRC to make the coupling as a disturbance.Based on the D-STATCOM model,a linear active disturbance rejection controller is designed by taking the q axis by transforming abc reference frame to dq0 refrence frame.The stability of the linear active disturbance rejection controller is proved.Through building simulation to verify the theory,D-STATCOM controled linear active disturbance has better robustness and dynamic response which can compensate the reactive current needed by bulk power system in real time,and can achieve the stable value of DC voltage quickly comparing with PID.