Optimal Power Dispatching Strategy For Wind Farm Considering Wind Turbines Fatigue

With the constant change of the world energy system,new energy has developed rapidly and will play an increasingly significant part in the coming year.Wind power,as one of the earliest and fastest new energy sources,has attracted extensive attention from scholars.At present,the biggest problem facing wind power generation is that the cost of wind power is higher than that of traditional energy.Besides,wind power is dependent on the new energy subsidy policy of the country.Once the relevant policies expire or cancel in the future,the competitiveness of wind power will be greatly weakened.In order to improve the competitiveness of wind power,the optimal power dispatching strategies of the widely used doubly fed induction generator(DFIG)wind farm is studied in this paper.And then put forward the optimal power dispatching strategies of wind farm under the limited operating mode and the maximum operating mode to realize the improvement of considering operating indexes(fatigue indexs,electric quantity indexes,economic index)of wind farm.Specific work is carried out as follows:Under the limited operating mode,an optimization strategy is proposed which aims at minimizing the maximum value of wind turbines fatigue coefficients and minimizing the error rate of the real on-grid electricity for wind farm.This strategy proposes a new fatigue optimization objective in the rationed operating mode.On the one hand,the target considers the requirement of the power system for the error rate of the real on-grid electricity of the wind farm under the mode of limited operating.On the other hand,the optimization requirements of fatigue distribution of wind turbines are considered.In order to verify the effectiveness of the proposed strategy,a simulation model of the wind farm is built in this paper.The wind speed,wind direction and initial fatigue state are taken as variables for short-term simulation respectively.Besides,the medium-and-long-term simulation of wind speed,wind direction and turbulence coefficient changing under the two initial fatigue states are respectively carried out.The final simulation results show that the proposed strategy is more effective than the traditional equivalent allocation strategy in improving the fatigue distribution of wind farm and discounting the error rate of on-grid electricity.Under maximum operating mode,an optimization strategy aiming at maximizing net present value per unit is proposed.This strategy not only takes the profit reduction of the wind farm caused by the traditional power loss into account,but also takes the operating cost of the wind farm caused by the fatigue growth into account.The net present value(NPV),which is used to measure the long-term profitability of wind farms,is treated in the short term and the concept of NPV per unit is put forward.The NPV per unit is taken as a new optimization objective to improve the economic benefits of wind farms.Similarly,in order to verify the effectiveness of the proposed strategy,this paper takes wind speed,wind direction and initial fatigue state as variables to conduct short-term simulation.On this basis,the medium-and-long-term simulation of wind speed,wind direction and turbulence coefficient changing under two initial fatigue states is carried out.The final simulation results show that the proposed strategy is more effective than the traditional maximum power point tracking(MPPT)strategy in increasing economic benefits and improving fatigue distribution.To sum up,aiming at improving the competitiveness of wind farms,this paper systematically studies the operation principle and mathematical models of wind farms.And then,a wind farm power optimization strategy considering wind turbines fatigue under the two operating modes is put forward respectively.The two strategies consider the optimization of the error rate of the on-grid power under the limited operating mode and the optimization of the operating cost caused by the increase of the wind turbines fatigue coefficient under the maximum operating mode.And the Simulation results show that the proposed strategy is effective in improving fatigue distribution and increasing economic benefits of wind farms.This study provides new ideas and methods for wind farm optimization operation.