Research On Optimal Dispatch Of Wind Power Integrated System Based On Chance Constrained Goal Programming

Accommodating the wind power in a reliable and efficient way is one of the key researches on the power system dispatching.Because of the inherent uncertainty and fluctuation of wind energy,it is not easy to forecast the wind power and decide the dispatching plan accurately.The effects of wind power on system dispatching are heavily increased,because of the larger wind integration capacity and the higher integrating voltage level.Meanwhile,with the development of smart grid,the battery energy storage system(BESS)is widely applied,which greatly improves the system regulation capability,and complicates the system dispatching at the same time.As a result,the traditional dispatching methods could not meet the requirements of the complicated system with a high penetration level of wind power.In this background,the chance constrained goal programming(CCGP)theory is proposed to address the optimal dispatching of wind power integrated system.Based on the CCGP method,the main researches and innovative achievements obtained are as follows.In order to effectively optimize the dispatching of wind power integrated system,it is necessary to not only decide unit schedules based on the given admissible region of wind power,but also adjust the admissible region considering the unit schedules.In this way,the global optimality of dispatching could be achieved.Firstly,the chance constrained goal programming theory is introduced,and the transformation of its deterministic form is proposed.In addition,considering the stochastic forecasting error of wind power,the CCGP method is applied to the optimal dispatching of wind integrated system.Finally,case studies are carried out,and several conclusions can be obtained as follow.With considerations of the interaction between the given admissible region and unit schedules,the proposed method can optimize unit schedules and adjust the admissible region if necessary,avoiding effects on economic dispatch leading by the confidence level setting.Comparing with the traditional chance constrained programming(CCP),CCGP is more sophisticated and flexible,which is suitable for dispatching problems of wind power integrated system.In order to address the reserve and transmission line constraints,the risk theory is introduced to solve the problem.Considering the accommodation cost and operation risk,unit schedules and admissible region are co-optimized.Firstly,combining with the risk theory,the risk based chance constrained goal programming(RBCCGP)is proposed.After that,RBCCGP method is applied to solve the security constrained unit commitment problem,and the corresponding reserve and transmission constraints are formulated.In addition,case studies are carried out on an IEEE 39-bus system and IEEE 118-bus system.Numerical results from case studies indicate that the wind admissible region is flexibly adjusted and the unit commitment is efficiently optimized with the proposed RBCCGP methodology.More importantly,different transmission lines can be addressed in different priories.Thus,the transmission constraints based on RBCCGP are more flexible and reasonable.A CCGP based rolling dispatch method is proposed to efficiently consider the accuracy change and periodical update of wind forecasting.After analyzing the error distribution changing with the leading time of wind forecasting,the CCGP based static dispatch method is proposed to optimize unit scheduling,with different emphases on cost and risk in different time periods.In addition,by utilizing the periodical update of wind forecasting,the CCGP based rolling dispatch method is proposed to improve the operating economy without increasing the risk.Finally,numerical results from case studies indicate that static dispatch method could effectively combine the error distribution changes and comprehensively consider operation cost and risk.As for the rolling dispatch,the system regulating diffi culty could be reduced and the dispatch plan update could be more foreseeing with the help of the proposed CCGP method.A multi-objective stochastic programming model is proposed,on the basis of CCGP,to optimize system dispatch with the consideration of effects of BESS discharge on the life loss.Firstly,based on the relationship between life loss and depth of discharge(Do D),a non-linear BESS life loss model is established.After that,a CCGP based model is proposed,which co-optimizes the thermal generation/ wind power/ BESS dispatching and considers the BESS life loss.Finally,numerical results from case studies indicate that the proposed non-linear life loss model could well describe the effects caused by Do D,and it is not complicated to solve in t he dispatch problem.Besides,the CCGP based dispatch model could comprehensively consider multi-objectives,including reserve allocation,operation cost and BESS life loss.More importantly,by reasonably dispatching BESS,the BESS life loss could be apparently reduced,with a slight increase on the operation cost.