Adequacy Assessment Of Grid-connected Wind Farms

With the increasing demand of clean energy in the world, wind energy as a renewable clean energy is more and more embraced. Wind power is the most mature and prospects for development of commercial power generation form in new energy resources, and it plays more and more important role in energy supply. However, wind speed has the characteristic of randomness and uncertainty, which cause wind generation realize dispatching power system fully hardly. So it is necessary to evaluate the adequacy of power system with wind farms accurately.The characteristic of wind energy randomness, interacting with WTGs and uncertainty of wind power during system operation are deeply studied in this paper, and the wind farm reliability model is established with considering wind speed randomness, WTG reliability, stochastic wind direction, time delay, wake effect and hilly terrain influence. This paper proposes a sequential Monte Carlo simulation technique to evaluate adequacy of power systems with wind farms, and the effects of those factors on wind farm output and system reliability are analyzed.The main research is as follows: (1) The basic principle and assortment of Monte Carlo simulation technique are studied, the features and the applied scope of analytical technique, sequential and non-sequential Monte Carlo simulations are analyzed and compared. The paper proposes a adequacy assessment procedure of power systems with wind farms based on the sequential Monte Carlo simulation.(2) The basic knowledge of wind farms interconnected with power grid is discoursed, for instance the working principle and basic components of wind turbine. The Weibull probability distribution model according to the randomness and uncertainty of wind speed is built to simulate the hourly wind speed. The different ways are used to estimate Weibull distribution parameters c and k based on actual wind speed data, and a number of major wind energy characteristic indexes are calculated. The results showed that the mean wind speed and standard deviation method of Weibull distribution can better simulate the actual wind speed.(3) The wind farm power output model and reliability model are established with considering wind speed randomness, time delay, wake effect and hilly terrain influence. This paper proposes a coordinate transformation technique and baffle coefficient of upstream and downstream WTGs to establish the reliability model of wind farm considering the stochastic wind direction.(4) Wind farm power outputs for an actual wind farm with considering stochastic wind direction, time delay, wake effect and hilly terrain influence and combining load model are calculated in this paper, on the basis of the wind farm power output model and reliability model, and considering wind speed randomness, WTG reliability, the random failures. The modified IEEE RTS is analyzed to illustrate the effects of those models on system reliability base on the sequential Monte Carlo simulation technique. The results show that, the output of wind farm considering these effects are closer to the practice, and the adequacy assessment of wind farm is more accurate, which provides more significant reference value for power system planning, operation and optimal layout of a wind farm.