Research On Improving Transient Stability Of Wind Power Grid Connected System Based On STATCOM-PSS Control

With a large number of fluctuating wind power injected into the grid,the stability of the normal operation of the original system is greatly threatened,which seriously hindered the further development of wind power.Therefore,how to improve the wind power grid stability,reducing the impact on the grid access problem of wind power,has become a hot topic in the field of wind power generation.Based on the current status of wind power in the grid and the agreement on the basis of the double feed type and fixed type two kinds of wind power generator,through its control method and operation characteristics of mathematical modeling and analysis,and discusses on wind power grid stability problems and puts forward the corresponding improvement measures,finally through modeling and simulation verification of the proposed effective method to improve the stability of wind power grid,made a series of research has practical value and innovation.The main contents of this paper are summarized as follows:1.Depth analysis of the principle and the operating characteristics of double-fed and fixed-speed windy power system.Through the establishmen-t of DFIG in the three-phase stationary and two-phase rotating coordinate system,this paper analyzes the commonly used control strategy,and puts forward the control method based on the stator flux directional vector control.At the same time,through the establishment of mathematical model of back-to-back converter and the analysis of control strategy,The method based on grid voltage directional control is proposed for the grid side converter.Finally,the simulation model of double-fed and fixed-speed windy power grid-connected system are established by simulation platform.The simulation results are analyzed under different working conditions,and the validity of the proposed control method and the correctness of the theoretical analysis are verified.2.The principle of static synchronous compensator is analyzed theoretically and simulated.Through the research on the mathematical model and the circuit structure established by STATCOM,theoretically,it can effectively compensate the reactive power shortage of the system.Finally,the simulation model of STATCOM directional current control system is established on the simulation platform.the simulation results verified that the STATCOM has obvious effected in reactive power compensation and the improvement of the power system.3.According to the wind power merge into the power system,the stability might be a problem,put forward a kind of control measure about the input STATCOM device match the power system stabilizer(PSS,Power System Stabilizer),through the analysis of the STATCOM-PSS control applied to wind power generation system and establish the double fed wind power generation system simulation model and constant speed generator wind power system simulation model in the simulation platform,according to the simulation of wind farm operation,there are many different situations under the condition of the simulation experiment,through the comparative analysis of the double fed wind turbine,it has more obvious advantages on fault through ability and alleviate the fluctuation of wind power than the fixed speed wind turbines,that reveal the double fed wind generators in wind farm construction more widely used;At the same time only exist on Simulation of STATCOM,PSS and STATCOM-PSS and without STATCOM-PSS these four cases,that results analyzed and discussed in detail,STATCOM system can provide enough reactive power compensation capacity,have a significant effect on the voltage stability of system fault process,PSS with damping function,and can regulate the system the operation of the power angle stability,ease the system oscillation.When put in STATCOM-PSS control of the two kinds of wind power to improve the stability of the unit grid system effect is more obvious,the breakdown voltage can be quickly recovered at the wind farm,improves the fault ride through capability,stability and improvement the wind power system transient electric energy quality.