| The development of human society puts forward new requirements for the energy supply,energy structure and energy use model.Especially in the new century,fossil energy shortage,serious environmental pollution and global climate change and other issues have become increasingly prominent,making a reasonable and effective large-scale use of clean energy increasingly strong.At the same time,power transmission,energy supply and demand wide area balance needs continue to deepen.The new energy situation promotes the revolution in energy technology,which drives the way of transmission changes.In the use of clean energy power generation,wind power is a very promising development of sustainable development of green energy,and the most effective way of the development and utilization of wind power is through large-scale wind farm and network operation.But wind power has many characteristics that are different from other energy sources.With the wind energy is intermittent and uncontrollable,wind power is a kind of fluctuating random power.After wind power is connected to the power grid,the safety and stable operation of power grid and the impact of power quality are affected.Therefore,it is of great practical significance and value to study the wind power grid operation technology and to stabilize the wind power fluctuation to improve the grid power quality.In this paper,the wind farm is put forward by the flexible DC transmission and the grid model,and the DC bus is mixed with the energy storage device in order to achieve the purpose of stabilizing the wind power fluctuation and improving the power quality of the wind power.The main contents include:1.First,the battery and super capacitor equivalent circuit model is established respectively,and we discuss the main structure of hybrid energy storage system,then determine the mixed storage system circuit structure and its connection,and build a DC side through the two-way DC / DC control of the hybrid energy storage system in the MATLAB simulation software.It is verified that the hybrid energy storage system composed of super capacitor and battery has the characteristics of high power density,high energy density and long service life.2.This paper introduces the structure of flexible DC transmission technology.According to the principle of flexible DC transmission,the mathematical model of flexible DC transmission is established,and the mathematical model of VSC-HVDC in synchronous rotating coordinate system is deduced by dq0 transformation.According to the control theory,Inverter station controller,and build a simulation model.3.Combined with the advantages of hybrid energy storage and flexible DC transmission,the wind power grid is established and designed by flexible DC transmission and connected to the DC bus,and the wind power grid is modeled in the parallel bus.Simulation shows that the V400-HVDC DC transmission line on the parallel energy storage device,by controlling the energy storage device charging and discharging power can stabilize the wind farm input power to the grid to improve the stability of the wind farm operation. |
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