Ultra-supercritical double-reheat boilers employ multiple temperature-regulating methods during flexible peak shaving.This exposes the boiler to significant tube-wall temperature deviations and overtemperatures.In thi...Ultra-supercritical double-reheat boilers employ multiple temperature-regulating methods during flexible peak shaving.This exposes the boiler to significant tube-wall temperature deviations and overtemperatures.In this study,a compartment model was developed to subdivide the overlapping high-temperature heating surfaces of a 660-MW double-reheat boiler into smaller compartments.The model was verified using field experimental data and was applied to calculate the enthalpy and tube-wall temperature distributions under different loads.In addition,the effects of three temperature-regulating methods(swinging burners,regulating dampers,and flue gas recirculation)on the variation tendency and deviations of the tube-wall temperature were analysed.The results indicated that overtemperatures occurred in the high-temperature superheater under a low load.The regulating damper method caused the high-temperature secondary reheater to exceed the permissible temperature by 21.4℃.The tube-wall temperature exhibited a bimodal distribution along the width.At 0%flue gas recirculation,the maximum tube-wall temperature deviation attained 13.39℃,exceeding a reasonable value by 3.39℃.The swinging burner method was the least likely to cause tube-wall temperature deviations and overtemperatures.The reasonable regulation ranges for swinging burners,regulating dampers,and flue gas recirculation were-20°to 7°,45%to 60%,and 8%to 24%,respectively.Based on different flexible peak shaving constraints,an appropriate temperature-regulating method was selected,and the regulation rangewas specified.展开更多
To maximize conversion efficiency,photovoltaic(PV)systems generally operate in the maximum power point tracking(MPPT)mode.However,due to the increasing penetra tion level of PV systems,there is a need for more develop...To maximize conversion efficiency,photovoltaic(PV)systems generally operate in the maximum power point tracking(MPPT)mode.However,due to the increasing penetra tion level of PV systems,there is a need for more developed control functions in terms of frequency support services and voltage control to maintain the reliability and stability of the power grid.Therefore,flexible active power control is a manda tory task for grid-connected PV systems to meet part of the grid requirements.Hence,a significant number of flexible pow er point tracking(FPPT)algorithms have been introduced in the existing literature.The purpose of such algorithms is to real ize a cost-effective method to provide grid support functional ities while minimizing the reliance on energy storage systems.This paper provides a comprehensive overview of grid support functionalities that can be obtained with the FPPT control of PV systems such as frequency support and volt-var control.Each of these grid support functionalities necessitates PV sys tems to operate under one of the three control strategies,which can be provided with FPPT algorithms.The three control strate gies are classified as:①constant power generation control(CP GC),②power reserve control(PRC),and③power ramp rate control(PRRC).A detailed discussion on available FPPT algo rithms for each control strategy is also provided.This paper can serve as a comprehensive review of the state-of-the-art FPPT algorithms that can equip PV systems with various grid support functionalities.展开更多
基金funded by the Shanghai 2020“Science and Technology Innovation Plan”Social Development Science and Technology Research Project(Grant No.20dz1205202).
文摘Ultra-supercritical double-reheat boilers employ multiple temperature-regulating methods during flexible peak shaving.This exposes the boiler to significant tube-wall temperature deviations and overtemperatures.In this study,a compartment model was developed to subdivide the overlapping high-temperature heating surfaces of a 660-MW double-reheat boiler into smaller compartments.The model was verified using field experimental data and was applied to calculate the enthalpy and tube-wall temperature distributions under different loads.In addition,the effects of three temperature-regulating methods(swinging burners,regulating dampers,and flue gas recirculation)on the variation tendency and deviations of the tube-wall temperature were analysed.The results indicated that overtemperatures occurred in the high-temperature superheater under a low load.The regulating damper method caused the high-temperature secondary reheater to exceed the permissible temperature by 21.4℃.The tube-wall temperature exhibited a bimodal distribution along the width.At 0%flue gas recirculation,the maximum tube-wall temperature deviation attained 13.39℃,exceeding a reasonable value by 3.39℃.The swinging burner method was the least likely to cause tube-wall temperature deviations and overtemperatures.The reasonable regulation ranges for swinging burners,regulating dampers,and flue gas recirculation were-20°to 7°,45%to 60%,and 8%to 24%,respectively.Based on different flexible peak shaving constraints,an appropriate temperature-regulating method was selected,and the regulation rangewas specified.
基金supported in part by the Future Battery Industries Cooperative Research Center(www.fbicrc.com.au)as part of the Australian Government’s CRC Program(www.business.gov.au),which supports industry-led collaborations between industry,researchers and the community.
文摘To maximize conversion efficiency,photovoltaic(PV)systems generally operate in the maximum power point tracking(MPPT)mode.However,due to the increasing penetra tion level of PV systems,there is a need for more developed control functions in terms of frequency support services and voltage control to maintain the reliability and stability of the power grid.Therefore,flexible active power control is a manda tory task for grid-connected PV systems to meet part of the grid requirements.Hence,a significant number of flexible pow er point tracking(FPPT)algorithms have been introduced in the existing literature.The purpose of such algorithms is to real ize a cost-effective method to provide grid support functional ities while minimizing the reliance on energy storage systems.This paper provides a comprehensive overview of grid support functionalities that can be obtained with the FPPT control of PV systems such as frequency support and volt-var control.Each of these grid support functionalities necessitates PV sys tems to operate under one of the three control strategies,which can be provided with FPPT algorithms.The three control strate gies are classified as:①constant power generation control(CP GC),②power reserve control(PRC),and③power ramp rate control(PRRC).A detailed discussion on available FPPT algo rithms for each control strategy is also provided.This paper can serve as a comprehensive review of the state-of-the-art FPPT algorithms that can equip PV systems with various grid support functionalities.
