| Energy is the important material basis of human survival and development, withthe development and progress of human society, the consumption of energycontinues is in the growing, at the same time, the energy structure is also changing.The development and utilization of renewable energy is paid more and moreattention, the wind power generation is one of the cheapest and the most promisinggreen energy resources. Wind power makes up a growth percentage in the electricenergy resources, the impact of wind power generation system on grid can’t beignored. There are a lot of wind resources in our country, so the wind is a potentialand enormous renewable energy.At the early stage of the wind turbine was handled by constant speed constantfrequency wind power generation, with the development up to now has been handledby the megawatt of variable speed constant frequency wind power generation. Thedoubly-fed motor variable speed constant frequency wind power generator (DFIG)has become a mainstream model of the wind power generation due to its variousadvantages. The wind power generation system which adopts doubly-fed motor havesome advantages, such as variable speed operation, improving power quality, andsmall converter capacity, which are widely used in wind power generation. The basicstructure，operation principle and energy now of DFIG are analyzed and themathematical model of DFIG is established based on which the control system ofrotor—side and grid—side converters are set up. On the basis of structure build therotor side and network side control system. The rotor side converter can realizedecoupling control of active and reactive power, network side converter can realizethe stability of the dc bus voltage and control of unit power factor.Based on power system simulation software Matlab/Simulink as a platform, thisarticle builds up a simulation model for the entire wind power control system. Andaccording to the analysis of the situation that when grid symmetrical fault occurs, find out the major reason results from the influence on the doubly-fed inductionmotor rotor current and the torque of the main causes of volatility when grid voltageinstantaneous drop. And then put forward the corresponding improved controlstrategy. According to the simulation analysis, this paper proposes a improvedcontrol strategy can achieve the goal of low voltage ride through. |
