Research On Coupling/Decoupling Control Of Power System Integrated With Wind Farm Clusters

At present,that large capacity wind farm clusters access to grid characterizes the development of power system.The significant volatility and intermittent of wind power caused by natural wind speed is seriously threatening the static security of grid.In recent years,several blackouts occurred all over the world show that grid's static security guarantees the stability of power system operation.Under the energy development strategy which says not only energy-saving and emission-reduction but low carbon environmental protection,clean energy based on wind power has a strong development momentum.Traditional method of preventative control decision has some limitations as large capacity of intermittent wind power accessing to grid.It's known line load rate is lower as the penetration capacity of wind power is few.Considering the fact that devices' reactance is greater than the resistance,traditional preventative control based on power decoupling is twofold.One is active preventative control and the other is reactive preventative control.For now the power capacity penetrated by wind farm clusters is large enough to change the power flow distribution in the grid.Excepting for the intermittent of wind power,wind farm clusters will absorb a large amount of reactive power from main network so as to a frequent occurrence of occasion which reactive power on the lines feeding back when the wind power increasing.What worse is that frequency and voltage regulating ability is weaken,while volume equivalent synchronous generators are taking place by wind power penetrated into grid.Additional compensation devices could improve the control capability although that could not guarantee economical index.However,the fact is that the development of both grid and wind power construction is asymmetric.Therefore,this paper first optimizes the traditional preventative control method is order to using the existing adjustable resources,Then proposes a new decision-making method on the basis of coupling influence between active power and reactive voltage.The main works of this paper are summarized as following:Study the impact wind farm integration brought to power flow distribution by fault simulation analysis.Outline the deficiencies traditional preventative control have after the wind power connection to grid.In the aspect of active power correction control,drawing daily output curve of wind farm clusters with different installed capacity by using the index such as fluctuation quantity,fluctuation ratio and variance ratio.In addition,figure out the influence of wind power integration to Gansu grid according the failure analysis of N-1.As for reactive power,drawing voltage-active power output curve of different wind farm clusters,which composed of mainstream generators,located in Gansu jiuquan wind power base.Based on equal and opposite quantities in pairs method and cross-weight factor,a new active power correction control algorithm is proposed.Firstly,derivate the calculation expression of node-branch power sensitivity using first-order Taylor series expansion,and then establish the cross-weight indicator on the basis of sensitivity said before,which is utilized to the selection process for the optimization of reactive power control.Furthermore,propose a active power correction control strategy in order to make full use of existing resources.Propose voltage and reactive power control model based on leveling and districting of power grid.Improve the calculation process of reactive-voltage sensitivity that considering the quasi-steady state first voltage control of grid integrated with wind farm clusters.Then using reactive-voltage sensitivity to figure out the nodes coordinates in var source-space.Take advantage of improved fuzzy c-means method to complete network partitioning for reactive power/voltage control.Ultimately propose the reactive power/voltage control strategy based on leveling and districting of grid integrated with wind farm clusters.Power coupling control method is put forward to solve preventative control problems associated with wind power penetration.Based on the mechanism of active/reactive power located in power sending lines and general lines,propose power coupling control method which is leading by neither active power control or reactive-voltage control.This method could take the coupling influence of active power and node voltage into consideration so as to preventing the normal state variables from out-of-limit during the procedure of correction control.Propose decoupling/coupling control method of grid integrated with wind farm clusters.Figured out the characteristics of state variables in different operation conditions by the basic principle of PQ decoupling algorithm,and then establish pattern recognition method.Using recognition method to determine which kind of strategy should be selected to complete preventative control.To make sure the process going felicitously,this method also establish control priority according with severity degree of out-of-limit...