Research On The Capacity Configuration Of 300 MW Double-fed Wind Farm STATCOM Devices

Due to the planning and construction of the large-scale wind power generation system,the grid connection of wind farm has exerted more and more influences on the grid,which includes the voltage stability of wind farm grid connection point.In the practical engineering construction,the configuration of the capacity of the double-fed wind farm reactive power compensation devices should meet the following demands.It is extremely necessary to satisfy the demands of the grid connection of double-fed wind farm as well as its economics.This essay chooses static synchronous compensator(STATCOM)and doubly-fed induction generator(DFIG)as the research subjects,and the author has analyzed and researched elaborately on their operation principle,mathematical models and control policy.Under the MATLAB and Simulink simulation environment,and according to the mathematical model,this essay has built the following models:double-fed wind farm model with STATCOM devices,the control model of rotor side converter which was controlled by stator-flux oriented vector,pitch angle control model,control model of line side converter which is controlled by voltage orientation vector,the STATCOM controller model including voltage control and reactive power control.On this basis,the author has conducted simulation analysis of grid connection on DFIG and STATCOM respectively,and through which process,the correctness of the model has been proved.This essay has proposed one method to determine the configuration of STATCOM devices.Firstly,the reactive power loss should be estimated.And then,the equivalent modeling should be built according to the parameters of double-fed wind farm.And we should conduct simplified flow calculation on the steady state operation data.Finally,the capacity of the STATCOM devices can be determined.On this basis,this essay has further probed into other elements which will influence the capacity configuration of double-fed wind farm STATCOM devices.These elements include the output of wind farm,the grid voltage sag,length of transmission line and the change of reactive power output with different configuration.The result shows that with the increase of the output of the wind farm and demand of reactive power.To some extent,the grid voltage sag and reactive power needed to maintain voltage stability of PCC has the linear relationship.The reactive demand will increase with the increase of the length of transmission line,and this process will be slower gradually.With fixed electricity,the reactive power output will be almost saturated with the increase of the capacity configuration of STATCOM devices.This essay has proposed one method to determine the capacity of STATCOM devices,and has made comparison with practical capacity configuration of 300 MW double-fed wind farm.The correctness of this method has been proven.This essay has further probed into other elements which will influence the capacity configuration of double-fed wind farm STATCOM devices,which has provided the evidence of the capacity configuration of reactive power compensation.And it has also provided guidance for improving the economics of double-fed wind farm reactive power compensation devices.