Research On Subtransient Synchronous Oscillation Suppression Of Doubly-fed Wind Farm Based On STATCOM Active Damping Control

As a kind of clean energy,wind energy accounts for an increasing proportion of the grid.Most wind farms in my country are far away from the load center,and wind power needs to be transported over long distances before it can be integrated into the power grid.The series capacitance compensation technology can improve the transmission capacity.Although the series capacitance compensation technology can enhance the stability of the system and increase the transmission capacity of the line,double-fed When a wind farm is connected to the grid via series compensation equipment,it will cause Subsynchronous Oscillation(SSO).When the line has no series compensation capacitor,the short-circuit ratio of the wind farm will be reduced and the system will be weakened when the line is connected to the grid in a weak feed-in connection mode,and the wind turbine may also produce unstable oscillations,which will affect the power quality and grid-connected power.Stability of wind turbines and power grids.Therefore,it is engineering significance to study the subsynchronous oscillation phenomenon of doubly-fed wind farms.This paper first established a mathematical model of grid-connected wind turbines containing doubly-fed wind turbines,including mathematical models of wind turbines,converters,doubly-fed induction generators,and series compensation lines,and analyzed the maximum power tracking control,rotor side and grid-side transformations.The principle of flow control.The necessary system small-signal equations are deduced in detail,and the power network simulation model of the doubly-fed wind farm is built in the PSCAD/EMTDC simulation platform.The subsynchronous oscillation phenomenon of the doubly-fed wind turbine under the weak AC power grid is reproduced,and the frequency and damping characteristics of the subsynchronous oscillation of the doubly-fed wind turbine under different parameters,different short-circuit ratios and different wind speeds are analyzed in detail;the same applies when the line contains series compensation capacitors.At the time,the simulation analyzed the frequency and damping characteristics of the subsynchronous oscillation of the series compensation system with different series compensation degrees,different wind speeds and different controller parameters.Finally,a STATCOM suppression strategy based on an additional active damping controller is given.After the STATCOM is put into use,after a fault occurs,the output power and line current gradually converge and decay.As the simulation time increases,they will eventually tend to the stable level before the disturbance.After increasing the STATCOM proportional coefficient,the convergence trend of fan power is more obvious,and the suppression speed is faster,thus verifying the effectiveness of the suppression strategy.