Transient Stability Analysis Of Power System Under The Wind Power Output Fluctuation Conditions On TEF Method

Due to the present development of the wind power generation technology,the grid-connected voltage level of wind power and installed capacity of wind turbines have also been greatly improved,the wind power occupies an increasing proportion in the power system,therefore,a series of stability problems caused by wind power access become more and more obvious,the influence of the wind power output fluctuation on power angle transient stability of power system can not be ignored especially.In this paper,the transient energy function of the power system considering wind turbines is established based on the traditional power system energy function method under the structure preservation model,then a transient stability criterion for the power systems with wind power access is proposed by analyzing the effect of the wind power output variation on power angle characteristics of synchronous generators.Finally,the transient energy function and the transient stability criterion are verified by simulation.The transient energy function of the power system is generally established based on the node contraction model,which is reducing the network impedance to the inner node of the generator and establishing the system energy function,this method is relatively simple,but it can not reflect the energy distribution of the system network,especially for power systems considering wind power access,the corresponding energy of the wind turbine output will not be reflected if the energy function under the nodal contraction model is still used.Therefore,for the power systems considering wind power access,it is necessary to establish the energy function under the structure preservation model.The output of wind turbines usually fluctuates actually,but many related studies present only consider the effect of the wind speed's step change on transient stability of power system.However,the actual wind speed has volatility and randomness,this makes it impossible to accurately determine the transient stability of the power system considering the wind turbines connected.Because the greater output of the wind turbines,the transient stability of the system will be worse,the critical energy can be calculated by using the system parameters when the wind power output value is maximum during the continuous fluctuation,and regard it as the transient stability criterion of the system.This method is conservative to some extent,but there will be no case of judging rash advance,it corresponds with the actual requirements.