Study On Integration Modeling Of Large-scale Wind Farmsand Transient Voltage Stability

With the continuous development of wind power technology, the numberof wind farms and the capacity of single wind turbine increase significantly, theinfluence of wind farm on the grid voltage is becoming more and more, whichis mainly manifested in the lack of reactive power regulation means, the poortransient voltage stability of wind farm and wind farm integration. And nowmany countries are improving their own wind farm integration standards, sothat wind power can be better integrated into grid. Therefore, the study oftransient voltage stability of wind power integration has important practicalsignificance. The main work of this paper is as follows:(1) The most widely used doubly fed induction generator system isconsidered as the research object, analysis deeply the mathematical model andvector control strategy of doubly-fed induction generator, which also includesthe wind speed model, the wind turbine model and the shaft model ofmechanical transmission part.(2) Research the control strategies and corresponding mathematical modelof the grid side converter and analyze the reactive power regulation capabilityin the fault period. The proposed reactive control model can realize variablepower factor operation of the grid side converter, supply reactive power for thegrid as soon as possible, improve the transient voltage stability of wind powerintegration system and verify the proposed model in the software ofDIgSILENT/Power Factory.(3) Put forward the reactive coordinated control strategy of DFIG statorside, grid side converter and the reactive power compensation equipmentSTATCOM, and set up the reactive coordinated control model in the softwareof DIgSILENT/Power Factory. Compared with the traditional unity power factor control of wind farm, the proposed reactive coordinated control modelcan play a good supporting role in transient voltage stability of wind powerintegration, reduce the installed capacity of STATCOM and save the investmentcost of wind farm.(4) Analyze the influence factors of transient voltage stability of windpower integration from the three aspects of double-fed induction generator,additional reactive compensation equipment and load characteristic. Theinfluence of different load models on system stability is focused, constantpower load, large industrial motors and air-conditioned motor pose the greatestthreat to the transient voltage stability of system. According to the aboveanalysis, Put forward a comprehensive load model, so that the load model candescript the true load characteristics more accurate, and finally verify thecorrectness of the reactive coordinated control strategy once again.