Loss of synchronization is one of the main issues for a grid-feeding converter in a weak grid after being subjected to a large disturbance.The synchronous transient is highly nonlinear due to phase movement and freque...Loss of synchronization is one of the main issues for a grid-feeding converter in a weak grid after being subjected to a large disturbance.The synchronous transient is highly nonlinear due to phase movement and frequency limiters.However,none of the previous research has considered the anti-windup PI in the phase-locked loop,which is commonly implemented in reality and introduced as an additional nonlinear transient.This work provides a taxonomy to evaluate and compare the effect of different anti-windup PI limiters on synchronization stability,including clamping,back-calculation and combined method.Different anti-windup PI limiters allocate zeros and poles differently and have different impacts on damping and stability enhancement.A case study implemented in Matlab/Simulink serves to compare the trajectory of the converter phase and frequency using different anti-windup PI in the scenario of both with and without equilibrium points during the fault.Simulation results show that anti-windup PI limiters increase damping during the fault and thus improve the synchronization stability margin.展开更多
Construction and demolition waste(CDW)is a low-carbon alternative to natural subgrade aggregates,which can alleviate the pressure of waste accumulation and resource exploitation.This study comprehensively analyzes the...Construction and demolition waste(CDW)is a low-carbon alternative to natural subgrade aggregates,which can alleviate the pressure of waste accumulation and resource exploitation.This study comprehensively analyzes the engineering properties,particle breakage mechanisms,and deformation behavior under environmental-loading effects of CDW as subgrade filler.CDW has both environmental and mechanical potential:it reduces solid waste landfilling and natural aggregate consumption,and its post-construction settlement after compaction is lower than that of traditional fillers.Even under the worst working conditions(brick aggregates with 96%compaction degree),its California bearing ratio(CBR)still reaches 21.6%.However,it has limitations such as a high abrasion value(up to 41%)and strong heterogeneity,requiring optimization through pretreatment(e.g.,ball milling to remove mortar)and gradation control;CDW particle breakage occurs in three modes:fragmentation,abrasion,and grinding.Moderate breakage(controlling the proportion of 5–10 mm particles to 25%–30%)can fill voids and improve shear strength,while excessive breakage leads to strength attenuation.Breakage can be quantified using indices like breakage rate(Bg)and fractal dimension;CDW breakage and deformation are affected by internal and external factors.Among external factors,moisture content exceeding the optimum moisture content(OMC)increases permanent deformation by approximately 20%;each freeze–thaw(FT)cycle reduces the resilient modulus by 15%–25%(the modulus stabilizes after 10 cycles).Deformation of CDW subgrades is controlled by the environment-loading coupling effect,and existing constitutive models cannot fully capture the complex interactive effects of multiple factors.展开更多
基金supported in part by the National Natural Science Foundation of China(U2166601,U2066602)the Science and Technology Department of Xinjiang under Grant No.2021D01C086funded by Sustainable Energy Authority of Ireland(SEAI)by under project FRESLIPS,Grant No.RDD/00681.
文摘Loss of synchronization is one of the main issues for a grid-feeding converter in a weak grid after being subjected to a large disturbance.The synchronous transient is highly nonlinear due to phase movement and frequency limiters.However,none of the previous research has considered the anti-windup PI in the phase-locked loop,which is commonly implemented in reality and introduced as an additional nonlinear transient.This work provides a taxonomy to evaluate and compare the effect of different anti-windup PI limiters on synchronization stability,including clamping,back-calculation and combined method.Different anti-windup PI limiters allocate zeros and poles differently and have different impacts on damping and stability enhancement.A case study implemented in Matlab/Simulink serves to compare the trajectory of the converter phase and frequency using different anti-windup PI in the scenario of both with and without equilibrium points during the fault.Simulation results show that anti-windup PI limiters increase damping during the fault and thus improve the synchronization stability margin.
基金funded by the National Natural Science Foundation of China(grant number 52208426)the Natural Science Foundation of Chongqing(grant number CSTB2024NSCQ-MSX1177)+1 种基金the Science and Technology Research Program of Chongqing Municipal Education Commission(grant number KJQN20230074)the Chongqing Key Special Project for Technological Innovation and Application Development(grant number CSTB2022TIAD-KPX0102).
文摘Construction and demolition waste(CDW)is a low-carbon alternative to natural subgrade aggregates,which can alleviate the pressure of waste accumulation and resource exploitation.This study comprehensively analyzes the engineering properties,particle breakage mechanisms,and deformation behavior under environmental-loading effects of CDW as subgrade filler.CDW has both environmental and mechanical potential:it reduces solid waste landfilling and natural aggregate consumption,and its post-construction settlement after compaction is lower than that of traditional fillers.Even under the worst working conditions(brick aggregates with 96%compaction degree),its California bearing ratio(CBR)still reaches 21.6%.However,it has limitations such as a high abrasion value(up to 41%)and strong heterogeneity,requiring optimization through pretreatment(e.g.,ball milling to remove mortar)and gradation control;CDW particle breakage occurs in three modes:fragmentation,abrasion,and grinding.Moderate breakage(controlling the proportion of 5–10 mm particles to 25%–30%)can fill voids and improve shear strength,while excessive breakage leads to strength attenuation.Breakage can be quantified using indices like breakage rate(Bg)and fractal dimension;CDW breakage and deformation are affected by internal and external factors.Among external factors,moisture content exceeding the optimum moisture content(OMC)increases permanent deformation by approximately 20%;each freeze–thaw(FT)cycle reduces the resilient modulus by 15%–25%(the modulus stabilizes after 10 cycles).Deformation of CDW subgrades is controlled by the environment-loading coupling effect,and existing constitutive models cannot fully capture the complex interactive effects of multiple factors.
