Research On Optimal Dispatch For Pumped Storage And HVDC Tie-line With Wind Power Integrated Systems

In recent years,with the rapid development of wind power technology,Wind power installed capacity is rising in electrical power system,even if the wind power generation has many advantages,such as cleanliness without any pollution,low cost,renewability and so on,but wind power accommodation problems remain to be solved.On the one hand,wind speed has properties of randomness and volatilit y under natural conditions,which leads to low prediction precision,and more reserve capacity will be set aside to calm wind power prediction error.Thus,the cost of reserve capacity is increased,and the ability of in depth peak load cycling is reduced in thermal power units.In serious cases,wind abandoning measures need to be adopted to ensure the normal operation of the system.on the other hand,wind resource has the characteristics of regional distribution in our country,and reverse peak shaving between wind power and load is more pronounced in wind power enrichment area.Therefore,wind power elimination on the spot is difficult,and thermal power units need to further reduce output or even stop to assimilate wind power,which is not conducive to economic and stable operation of the system.In order to explore the various influence produced by wind power composing into power grid and the measures to improve the utilization rate of wind power,wind power system optimization scheduling problem is studied by means of mathematical modeling and solving.This paper is divided into the following specific :1)Probabilistic analysis was carried out on the wind power forecast error,and confidence interval of prediction error is estimated under a certain confidence level.Thus,the minimum reserve capacity is calculated.Based on this,the confidence interval estimation method is put forward,namely BP neural network algorithm,compared with the traditional Mont Carlo,the method has higher calculation precision and better robustness.2)The running mechanism of pumped storage is analyzed,and the method of stochastic programming is adopted to create wind power-thermal power-pumped storage multi-source coordinate joint economic scheduling model.In order to improve the efficiency of the solution method for model,thoughts of determining sectional integer variables is proposed to reduce the non-convexity of the model.By solving the model multi-indexes contain unit commitment results,the operation of pumped storage and the economic efficiency of the system and so on are analyzed under different confidence level.Results show that the higher confidence level is,the more reliable unit commitment results are.However,it increases the burden of the system operation under high confidence level,for example,the operation of the pumped storage time,quantity of peaking units and economic cost of system will rise significantly.3)Three modes of HVDC tie-line namely fixation operation,freedom operation and discretization operation in turn are put forward taking mutual aid system between two areas as example.The corresponding mathematical model is established to study wind power scheduling problems between regionals.Meanwhile,the linearization methods of objective function and constraint conditions are put forward.After solving the model by CLPEX,results show that the effect of discretization operation mode is close to freedom operation.Discretization operation makes full use of the mutual aid system between two areas,and at the same time,it takes advantages of reducing regulating time of HVDC tie-line effectively,which will guarantees the system stability.