Studies On The Impacts Of Large Scale Wind Power Integration On The Security And Stability Of Power Systems

As a lot of wind farms with large capacities are being integrated in high voltage transmission network,more and more impacts will be brought on the security,stability, dispatching,operation and many other aspects of power system in our country and it is emergent to carry out the relevant work of theoretical research and system analysis. Aiming at the problem of analysis of security and stability of power system integrated with large capacity wind farms,the complete mathematical model was established in this dissertation and by large quantities of simulated calculations and theoretical analyses of a real grid,the determination method of acceptable capacity of wind power and the operational control strategies were put forward.The researching work has an important theoretical meaning and pragmatic value for the programming,designing, operation and policy-making of wind power industry.The research work has made the following creative results:1.The internationally matured model of wind speed,model of fixed pitch induction wind turbine generator,model of variable speed constant frequency doubly fed wind turbine generator and modeling method of wind farm were improved and the mathematical model of stability analysis of power system integrated with wind farms suitable to the conditions of our country was established.In the induction wind turbine generator model,a new fitting formula of power coefficient was added to adapt the different characteristics of power conversions,and in doubly fed wind turbine generator model,the power factor control link was added to meet the simulation needs of constant voltage control mode and constant power factor control mode of wind farms.2.The practical mathematical model of large disturbance stability of power system integrated with wind farms was established and through the alternate iterations of differential equations and algebraic equations,the large disturbance stability analysis of power system with wind farms was accomplished.Combining Inner Mongolia power grid,the angle stability and voltage stability of power system with large capacity wind farms were analyzed and a control strategy was put forward through the cooperation of low voltage protection of wind turbine generators and automation equipment installed in the power system.3.The practical mathematical model of small signal stability of power system integrated with wind farms was established.Combining the linearized equations of wind turbine generators with the original linearized equations of power system,the extended state matrix was established.Using the Inverse Iteration/Rayleigh Quotient Iteration algorithm and sparse matrix technology of PSASP,the large scale state matrix was evaluated.Through the calculation of Inner Mongolia power grid,the impacts of wind farms on the oscillation modes and oscillation characteristics of power system were studied and the integrated capacity of wind power and control strategies meeting the small signal stability were put forward.The opinion was put forward that the impacts of wind farms on the damping characteristics of power system will not be greater than that of the synchronous generators with the same capacities.4.The impacts of wind disturbance on voltage regulation and frequency regulation of power system were studied.The opinion that the regulation of power flow on the interconnection lines between the grids restricts the integrated capacity of wind power was put forward.Based on the actual condition of Inner Mongolia power grid,an engineering practical method was put forward to calculate the integrated capacity of wind power under this restriction.The relationship between wind power and spinning reserve and the impacts of other related factors on the capacity of wind power were studied simultaneously.The impact of wind disturbance on voltage stability where the wind farms are located was studied also.