Research On Reactive Power And Voltage Comprehensive Optimization Strategy Of Large-scale Wind Power Integration Grid

The areas with abundant wind energy resources in China are not consistent with the areas with concentrated electrical load,this characteristic causes the development and utilization of wind power in China to adopt the mode of concentrated development in large-scale and long-distance transmission.The wind power clusters are connected from the end of the grid,and the electrical connection with the main system is weak.Due to the influence of poor anti-disturbance ability of new energy,insufficient reactive power support,low power grid strength and other factors,the voltage quality problems occur frequently in points of connection of collection stations and wind farms,which seriously restricts the consumption of wind power.In order to improve the voltage quality of large-scale wind power integration grid and enhance the safe,efficient and stable operation level of the system,this paper carries out the following research work from the perspective of reactive power and voltage optimization:Firstly,the reactive power limit of doubly fed induction generator and permanent magnet synchronous generator is analyzed.The compensation principle and characteristic of common centralized reactive power compensation equipments are introduced.The reactive power loss of collector lines and transformers is analyzed.The reactive power regulation range of wind farm is derived,which lays a theoretical foundation for the subsequent research on reactive power and voltage optimization strategy.Secondly,a reactive power and voltage comprehensive optimization strategy for large-scale wind power integration grid under the condition of voltage balance is proposed.In this strategy,the reactive power demand of collection stations is estimated according to the voltage control requirement of the pilot nodes,the wind farms involved in reactive power regulation are selected according to the voltage-reactive power sensitivity and loss-reactive power sensitivity.In order to reduce the voltage control error of the pilot nodes,improve the voltage quality of the points of connection of wind farms and improve the economy of the system operation,a reactive power voltage optimization model is established considering the voltage deviation of the wind power integration grid and the active power loss,the particle swarm optimization is used to solve the optimization model.The effectiveness of the proposed strategy and its advantages compared with the traditional proportional control strategy are verified by an example analysis.Finally,a reactive power and voltage comprehensive optimization strategy for large-scale wind power integration grid under the condition of voltage unbalance is proposed.A phase-divided power flow optimization model is established with the control objectives of suppressing voltage unbalance,reducing voltage control error of pilot nodes,improving voltage quality of points of connection of wind farms and increasing reactive power reserve capacity of the system The multi-objective particle swarm optimization is improved to improve the optimization performance.For the obtained quasi-optimal compensation schemes,order relation analysis is combined with the technique for order preference by similarity to an ideal solution method to select the optimal compensation scheme.The effectiveness of the proposed strategy and the advantages of the improved optimization algorithm are verified by an example analysis.