| As the representative of the new energy, wind power achieved rapid development over the world in the background of increasingly serious environmental pollution problems and gradual depletion of traditional fossil energy sourcesWith the gradually increasing penetration of wind power, the influence sphere of wind power output to the power grid will also increase accordingly. In a power grid with large penetration of wind power, wind power will change the power flow and the power on the transmission line. On account of the special nature of wind power, the original power system voltage stability will be changed. The voltage stability influenced by wind power in the power systems is studied in this thesis, and the main contents are as follows.Firstly, this thesis analyzes the mathematical model of wind, wind turbine, transmission system, DFIG and its converters with control system. Based on vector control technology, control strategies for rotor-side converter and grid-side converter are established.Secondly, mechanism of static voltage stability for the power system connected with wind power is discussed. The voltage-var sensitivity and curves of P-V and V-Q are used in analysis of static voltage stability. Since the traditional P-V curves do not reflect the volatility of wind power, the safe operation region made of three-dimension P-V surface is established, and the limit of wind power connected to a certain power system can be determined. By means of sensitivity analysis, the effect of different wind power penetration on static voltage stability is analyzed considering different operating modes.Lastly, the relation between terminal voltage of DFIG and system voltage is inferred, and the impact of DFIG on transient voltage stability is analyzed and testified in the single machine infinite bus system. Then taking the real power system for an example, the effect of different wind power penetration on transient voltage stability is analyzed by simulation. |
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