Analysis And Quantification Of Transient Stability Of Power System With Wind Farm Based On Heuristic Energy Function

With the rapid development of wind power generation,the wind power penetration of the wind power-connected power system has gradually increased,which significantly affects the transient stability of the power grid.In the transient stability analysis method,the direct method represented by the transient energy function method can better reflect the physical characteristics of the system,and can quantitatively analyze the transient stability.At present,it still has a high research interest and application prospects,but its application in the emerging field of power system with wind farm integrated is still less.At the same time,the current research on transient stability of wind power systems rarely considers the stochastic disturbance of wind speed,oversimplifies it,so that the research results can not reflect the actual situation well.In view of the above situation,this paper did the following research:1.Constructed a new transient energy function model to describe the transient stability of the power system with wind farm integrated.Compared with previous research,it considers the potential energy absorbed in the inductive element of the double-fed induction generator(DFIG).First,the DQ axis equivalent circuit of DFIG after the coordinate transformation is used to establish a DFIG transient energy function model considering its electromagnetic transient.Then according to the physical characteristics of the synchronous generator,transmission line,load and other components in the power system,combined with the power matching characteristics of the system,the respective transient energy functions of the above components are constructed.Finally,the above transient energy functions are combined to construct the transient energy function of the entire system.Afterwards,through the PEBS method,the transient energy margin,which is an index for quantitative analysis of the transient stability of the system,is defined.The New England 10-machine 39-bus power system built on MATLAB’s Simulink platform is used as the simulation platform in this paper.The simulation results verify the accuracy and effectiveness of the transient energy function model,reveal the influence of different wind power penetration rates on the transient stability of the system,demonstrate the role of transient energy assisted control measures in decision-making,and verify the improvement of system transient stability from the perspective of transient energy margin.2.In order to make the transient energy function model better reflect the actual operation of the power system with wind farm integrated,on the basis of the previous part,this paper introduces the stochasticity of wind speed into the energy function that has been constructed.First,the initial value distribution of wind speed is regarded as the Weibull distribution.Based on this,the stochastic fluctuation of wind speed is modeled as a stochastic differential equation.Furthermore,by linking the stochastic wind speed model,the established transient energy function model includes the information of the stochastic fluctuation of wind speed,which converts the transient energy margin from a fixed value when stochasticity is not considered to a random process,so that it can reflect the actual influence of wind speed disturbance on transient stability.After adopting statistical processing,considering the conservativeness,the transient energy margin is significantly lower than that without considering the stochasticity,which excludes the “false stability” situation under constant wind speed conditions.