Wind Farms Modelling And Generation Extension Planning

Renewable energy has been widely acknowledged because of the reducing of conventional fuel reserves versus the increase of environmental pollution. Among all renewable energies, wind energy has the best exploitation value. So the assessment and analysis of wind energy resources, and the effect of connecting wind energy sources to the electric supply system are taken into account in this paper.The assessment of wind resources in wind farms depends on statistical characteristic of wind, and the frequency distribution of wind is one important form of statistical characteristic of wind. In this paper, the simulation of wind frequency distribution is performed by using the Weibull statistical model, whose parameters are calculated by using Maximum Likelihood Estimation. Some other models and methods are compared with them and several wind energy characteristic indices like average wind speed, average wind energy density, average valid wind energy density, and annual wind energy utilization time etc. are used to check their validity.In addition, a medium and long-term wind speed forecast model based on ARMA time series is presented. The distribution characteristics of future wind speed in wind farms like monthly and daily distribution of wind speed are calculated, and the results show that the impact of ARMA model on wind speed forecast is good.The paper has also emphasized the impact of wind farms on generation extension planning. The research on extension planning of power system including wind farms is done and a model of the optimal extension planning based on improved genetic algorithm is presented. In the model, we can transform the optimization problem with constraints to the optimization problem without constraints through penalty function which would impose the penalty on those dissatisfying constraints cases. Probability method that can truly calculate generation cost is used to treat with the randomicity of wind and the forced outage of wind turbine generators(WTGs) etc. and is applied to stochastic production simulation of generation system including wind farms with analysis about reliability and economy. The results show that, the presented methods are valid and feasible for extension planning of power system.