The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM(Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finit...The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM(Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finite element code DEFORM 3D.According to the effective plastic strain,the mean stress and the mean plastic strain distribution of the radial forging,the forging penetration efficiency(FPE) was studied throughout each operation.The results show that the effective plastic strain in the center of the forging is always greater than zero for the desirable larger axial drawing velocity.The mean stress in the center of the workpiece is proposed to describe hydrostatic pressure in this paper.There is compressive strain layer beneath the surface of the workpiece to be found,while there is tensile strain core in the center of the workpiece.These results could be a valuable reference for designing the similar forging operations.展开更多
This study analyzes the stability and reactive characteristics of the hybrid offshore wind farm that includes gridforming(GFM)and grid-following(GFL)wind turbines(WTs)integrated with a diode rectifier unit(DRU)based h...This study analyzes the stability and reactive characteristics of the hybrid offshore wind farm that includes gridforming(GFM)and grid-following(GFL)wind turbines(WTs)integrated with a diode rectifier unit(DRU)based high-voltage direct current(HVDC)system.The determination method for the proportion of GFM WTs is proposed while considering system stability and optimal offshore reactive power constraints.First,the small-signal stability is studied based on the developed linear model,and crucial factors that affect the stability are captured by eigenvalue analysis.The reactive power-frequency compensation control of GFM WTs is then proposed to improve the reactive power and frequency dynamics.Second,the relationship between offshore reactive power imbalance and the effectiveness of GFM capability is analyzed.Offshore reactive power optimization methods are next proposed to diminish offshore reactive load.These methods include the optimal design for the reactive capacity of the AC filter and the reactive power compensation control of GFL WTs.Third,in terms of stability and optimal offshore reactive power constraints,the principle and calculation method for determining the proportion of GFM WTs are proposed,and the critical proportion of GFM WTs is determined over the full active power range.Finally,case studies using a detailed model are conducted by timedomain simulations in PSCAD/EMTDC.The simulations verify the theoretical analysis results and the effectiveness of the proposed determination method for the proportion of GFM WTs and reactive power optimization methods.展开更多
Grid-forming(GFM)control is a key technique for power systems with high penetration of converter-interfaced generation.However,its application to photovoltaic(PV)systems faces challenges related to DC voltage transien...Grid-forming(GFM)control is a key technique for power systems with high penetration of converter-interfaced generation.However,its application to photovoltaic(PV)systems faces challenges related to DC voltage transient stability.This paper investigates a common countermeasure involving a PI-based DC voltage controller for GFM-PV systems,revealing that their small-signal stability is sensitive to parameter tuning.The study develops a generalized DC voltage-dominated 2nd-order GFM model and successfully conducts complex torque analysis,showing that this approach can be effectively extended to other dynamics governed by DC voltage-dominated GFM systems.Subsequently,the paper establishes a stability criterion for GFM-PV systems and proposes a parameter tuning method for DC voltage controllers that incorporates damping margin considerations.The performance of the tuned single-machine-infinite-bus GFM-PV system is validated on the RT-LAB real-time simulation platform under scenarios involving solar irradiance fluctuations and grid frequency disturbances.The proposed method proves effective in ensuring the stability of the GFM-PV system,with robust theoretical support.展开更多
随着“双碳”目标建设和大型城市旧城改造的推进,传统发电设施逐渐迁移,导致“电源空心化”问题凸显,系统惯量下降,电网安全稳定运行面临挑战。以成都电网为例,其作为四川电网的负荷中心,受电主要依赖外部通道,南部重负荷片区暂态电压...随着“双碳”目标建设和大型城市旧城改造的推进,传统发电设施逐渐迁移,导致“电源空心化”问题凸显,系统惯量下降,电网安全稳定运行面临挑战。以成都电网为例,其作为四川电网的负荷中心,受电主要依赖外部通道,南部重负荷片区暂态电压支撑不足,因此有必要开展新型动态无功补偿技术的研究。首先分析了成都电网的动态无功需求,研究了跟网型静止无功发生器(static var generator,SVG)、调相机、构网型SVG等动态无功补偿装置的技术特点。通过比选,提出并研发了单体具备稳态无功60Mvar、暂态无功450Mvar能力的构网型SVG成套设备。该设备通过500kV人工短路试验验证了其大电流、快响应的暂态性能,有效解决了成都电网的动态无功不足问题,实现了德宝直流提升100万kW送电能力。相关研究为治理新型电力系统电网电压稳定问题提供了典型案例示范,为构网型产品成套设计和工程应用提供了理论依据。展开更多
文摘The numerical thermal mechanical simulation of radial forging process of steel H13 stepped shaft with GFM(Gesellschaft fur Fertigungstechnik und Maschinenbau) forging machine was carried out by three-dimensional finite element code DEFORM 3D.According to the effective plastic strain,the mean stress and the mean plastic strain distribution of the radial forging,the forging penetration efficiency(FPE) was studied throughout each operation.The results show that the effective plastic strain in the center of the forging is always greater than zero for the desirable larger axial drawing velocity.The mean stress in the center of the workpiece is proposed to describe hydrostatic pressure in this paper.There is compressive strain layer beneath the surface of the workpiece to be found,while there is tensile strain core in the center of the workpiece.These results could be a valuable reference for designing the similar forging operations.
基金supported by the Research Project of China Southern Power Grid Co.,Ltd.(No.030400KK52220008(GDKJXM20220327))。
文摘This study analyzes the stability and reactive characteristics of the hybrid offshore wind farm that includes gridforming(GFM)and grid-following(GFL)wind turbines(WTs)integrated with a diode rectifier unit(DRU)based high-voltage direct current(HVDC)system.The determination method for the proportion of GFM WTs is proposed while considering system stability and optimal offshore reactive power constraints.First,the small-signal stability is studied based on the developed linear model,and crucial factors that affect the stability are captured by eigenvalue analysis.The reactive power-frequency compensation control of GFM WTs is then proposed to improve the reactive power and frequency dynamics.Second,the relationship between offshore reactive power imbalance and the effectiveness of GFM capability is analyzed.Offshore reactive power optimization methods are next proposed to diminish offshore reactive load.These methods include the optimal design for the reactive capacity of the AC filter and the reactive power compensation control of GFL WTs.Third,in terms of stability and optimal offshore reactive power constraints,the principle and calculation method for determining the proportion of GFM WTs are proposed,and the critical proportion of GFM WTs is determined over the full active power range.Finally,case studies using a detailed model are conducted by timedomain simulations in PSCAD/EMTDC.The simulations verify the theoretical analysis results and the effectiveness of the proposed determination method for the proportion of GFM WTs and reactive power optimization methods.
基金supported in part by Northeast Branch of State Grid Corporation of China(52992624000W).
文摘Grid-forming(GFM)control is a key technique for power systems with high penetration of converter-interfaced generation.However,its application to photovoltaic(PV)systems faces challenges related to DC voltage transient stability.This paper investigates a common countermeasure involving a PI-based DC voltage controller for GFM-PV systems,revealing that their small-signal stability is sensitive to parameter tuning.The study develops a generalized DC voltage-dominated 2nd-order GFM model and successfully conducts complex torque analysis,showing that this approach can be effectively extended to other dynamics governed by DC voltage-dominated GFM systems.Subsequently,the paper establishes a stability criterion for GFM-PV systems and proposes a parameter tuning method for DC voltage controllers that incorporates damping margin considerations.The performance of the tuned single-machine-infinite-bus GFM-PV system is validated on the RT-LAB real-time simulation platform under scenarios involving solar irradiance fluctuations and grid frequency disturbances.The proposed method proves effective in ensuring the stability of the GFM-PV system,with robust theoretical support.
文摘随着“双碳”目标建设和大型城市旧城改造的推进,传统发电设施逐渐迁移,导致“电源空心化”问题凸显,系统惯量下降,电网安全稳定运行面临挑战。以成都电网为例,其作为四川电网的负荷中心,受电主要依赖外部通道,南部重负荷片区暂态电压支撑不足,因此有必要开展新型动态无功补偿技术的研究。首先分析了成都电网的动态无功需求,研究了跟网型静止无功发生器(static var generator,SVG)、调相机、构网型SVG等动态无功补偿装置的技术特点。通过比选,提出并研发了单体具备稳态无功60Mvar、暂态无功450Mvar能力的构网型SVG成套设备。该设备通过500kV人工短路试验验证了其大电流、快响应的暂态性能,有效解决了成都电网的动态无功不足问题,实现了德宝直流提升100万kW送电能力。相关研究为治理新型电力系统电网电压稳定问题提供了典型案例示范,为构网型产品成套设计和工程应用提供了理论依据。
