Research On The Voltage Stability Of Power System Connected With Wind Power

With the increasing seriousness of environmental pollution and the gradual depletionof traditional fossil energy, the technology of power grid integrated with new energydominated by wind power develops rapidly in all countries of the world. As the penetrationrate of wind power increases, the range of influence caused by the wind power output inpower grid has extended. In a power grid with large penetration of wind power, the loadflow is changed, and so the power transmitted on the line. On account of special nature ofwind power, the original voltage stability of power system is changed by the characteristicsof wind turbines.The voltage stability influenced by wind power in the power systems is studied in thispaper, and the main contents are as follows:Firstly, this paper analyzes the mathematical model of wind, wind turbine,transmission system, DFIG and its converters with control system. Based on vector controltechnology, control strategies for rotor-side converter and grid-side converter areestablished.Secondly, mechanism of static voltage stability for the power system connected withwind power is discussed. The voltage-var sensitivity and curves of P~V and V~Q are usedin analysis of static voltage stability. Since the traditional P~V curves do not reflect thevolatility of wind power, the safe operation region made of three-dimension P~V surface isestablished, and the limit of wind power connected to a certain power system can bedetermined. By means of sensitivity analysis, both in strong and weak systems, the effectof different wind power penetration on static voltage stability is analyzed consideringdifferent 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 take the real power system for a example, the effect ofdifferent wind power penetration on transient voltage stability is analyzed by simulation.