Research On Wind Power Penetration Limit Based On Static Voltage Stability And Transient Stability

As a kind of renewable energy,wind power has alleviated the current energy crisis to a certain extent.it has been continuously inst alled on a large scale in recent years.However,excessive access to wind power will threaten the stable operation of the system.On the one hand,when a large-scale wind farm transmits electric energy to the grid through the transmission line,the reactive p ower loss on the step-up transformer and the line will reduce the static voltage stability of the system;On the other hand,the grid connection of wind farms will change the original power flow distribution and inertia of the system,and affect the transient stability of the system.Therefore,in the planning and construction of wind farms,it is of great significance to analyze and study its penetration limit.Based on static voltage stability and transient stability,combined with mathematical optimizat ion model and dynamic simulation method,a calculation method of wind power penetration limit is proposed.The specific research content is as follows:(1)A continuous power flow model containing wind power systems is established.Based on formula derivation,the influence of wind farms connected to the grid via transmission lines on the static voltage stability of the system is analyzed.Considering the regional imbalance and randomness of the load growth direction during the calculation of the load margin,the load growt h coefficient is defined to lay the foundation for the subsequent solution of the wind power penetration limit based on static voltage stability.(2)Taking into account the static voltage stability of the system,and considering the randomness of wind speed and load growth direction,a multi-objective chance-constrained optimization model for wind power penetration limit is proposed,in which the maximum wind farm installed capacity,the maximum expected load margin and the maximum reciprocal value of the load margi n standard deviation are taken as the objective function.A hybrid intelligent algorithm composed of an extreme learning machine and a multi-objective backbone particle swarm algorithm is used to solve the Pareto solution set of the model.And then verify and analyze the above models and algorithms in the improved IEEE30-node system,the relationship between the objective functions according to the optimization results is analyzed,And according to the lower limit of the load margin,the wind power penetration limit based on static voltage stability when the wind farm is connected to a given node and the grid-connected line impedance is different is determined.(3)Use PSD-BPA software to study the transient stability of a benchmark system which includes 3 generators and 9 bus and doubly-fed wind farms.the wind farm installed capacity and fault location changes on the transient stability of the system is analyzed.The simulation results can provide ideas and basis for the subsequent formulation of the transient stability-based wind power penetration limit solution process,and also show the necessity of transient stability verification when calculating the wind power penetration limit,and then,the maximum installed capacity of a wind farm based on static voltage stability is used a s the reference value of the grid-connected capacity of the wind farm,and the transient stability of the improved IEEE30-node wind farm grid-connected system under this capacity is samulated.Finally,the wind power penetration limit under the constraints of transient stability is determined,which is also the wind power penetration limit based on static voltage stability and transient stability.