Effects of wind power variability and intermittency on power flow

The variability and intermittency of wind generation have brought new challenges to the planning and operation of interconnected power systems with high penetration of grid-connected wind farms. In this paper, the probability theory and fuzzy sets theory are employed to carry out systematic and thorough studies on power system fuzzy power flow calculation incorporating uncertainties of wind power from different types of wind turbines. The Weibull distribution which can reflect the variability and intermittency of wind power well is used as wind speed probability density model. With the possibility/ probability consistency principle(PPCP), it is transformed to the wind speed possibility distribution. In accordance with the simplified power-speed curve of wind turbine, the fuzzy modeling for power outputs of SCIG and DFIG is then presented. The proposed fuzzy model is linearized further for simplicity. The sensitivity analysis based method is employed to solve the possibility distributions of fuzzy power flow solutions. Numerical results based on a modified IEEE 14-bus system demonstrate the validity and effectiveness of the proposed models and methods.