Research Of Voltage Stability Of Large-scale Wind Farm Groups On The Regional Power Network

With the rapid development of wind power technology, large-scale wind farms andwind power bases have been formed. The integration of large wind farm has changed theoriginal power flow of the grid. Besides, the output power of wind farm fluctuatesconstantly due to the intermittence and randomness of the wind, which will cause severeimpacts to the stability of the grid voltage. In this paper, the influences of large scale windfarm on the stability of the regional area voltage are studied including the followingrespects:First, the problems of wind farm integration and research status of its influences onthe grid voltage stability are elaborated, the structures and operating principles of thesquirrel cage induction wind generator, doubly-fed induction wind generator andpermanent magnet direct drive wind generator are analyzed, the mathematical models ofthe wind speed, wind turbine and different wind generators are built. These works are thebase of establishing different wind farm models.Second, the equivalent models of different wind farms are established using thehomology equivalence method and slip homology equivalence method, and thecomparative analysis are done for the dynamic operating characteristics and transientoperating characteristics of the equivalent model and the detailed modeling model underthe conditions of wind disturbance and three-phase short circuit fault at the wind farmoutput point. The results show that the equivalent model has the same dynamic operatingcharacteristics as the detailed model.Finally, the simulation platform of a regional grid containing wind farms areestablished based on the grid structure of one certain grid in the northeast China, and theequivalents modeling of synchronous generators, wind generators, lines, transformers,reactive power compensation device and the external network are elaborated. Theinfluences of large scale wind farm on the voltage stability of regional grid under differentconditions including sudden increases and dips of wind speed, the use of SVG are given. The results show that the voltage will dip(increase) with the dip(increase) of the windspeed, the nearer the distance to the wind farm is,the clearer the fluctuation is. Besides,SVG has a significant improvement on the grid voltage.