Research On Operation Strategy And Capacity Configuration Method Of Energy Storage Combined With Thermal Power Unit In AGC

Owning to merits of fast response,precise control and bi-directional output,electric energy storage has been extensively applied to frequency regulation in power system.Assisting thermal power units with automatic generation control(AGC)has been the primary one mode to commercialize storage,resulting from its non-involve in measurement and independent strategy.However,the full-power charge-discharge strategy adopted by current projects goes ill with sustainability and lacks in optimization aiming at performance.Therefore,it is necessary to conduct research in strategy and capacity configuration of storage that assists with thermal units in AGC.Firstly,this paper makes a comparison between Kp index adopted by North China and performance score(PS)by PJM market,both of which are used to assess regulation resources.For scenario where storage combined with thermal power in AGC,however,that two indexes cannot play a prophetic role in reference output of storage just supported by real-time data.Thus,a new index system used as objective function on how much output storage supply,is established to evaluate the AGC performance.Secondly,in views of index systems,a real-time method is proposed to optimize compensation degree of storage coordinated with thermal power unit in AGC,which operates in specific period,determining output of storage to maximize performance and electricity equilibrium.The practicability gets verified and comparisons between distinctive strategies are presented based on scenarios with two thermal units.Results shows that both regulation performance and storage availability get improved,and a shorter period does better in that.Moreover,time consumption can meet requirement.Finally,storage capacity configuration method under operation strategies in which storage coordinated with thermal power gets proposed.For one strategy that limits the change rate of state of charge(SOC),this paper builds a two-layer model,of which operaton layer is set to minimize both life loss of storage and bias electricity,while economy layer is designed to maximize daily benefit.For compensation strategy and Shijingshan strategy,storage configuration only depends on economy layer.Based on a 1000MW-rated unit,storage configuration gets optimized under three strategies,by which the feasibility of proposed method gets verified.Besides,the performance and benefits have also been compared under different configurations of storage capacity.