分布式光伏(distributed photovoltaic,DPV)的大规模无序接入为山区配电网带来了过电压、功率倒送等问题,影响配电网的稳定运行。如何准确计算山区配电网DPV承载能力已成为目前亟待研究和解决的重要问题。针对这一问题,以山区配电网所...分布式光伏(distributed photovoltaic,DPV)的大规模无序接入为山区配电网带来了过电压、功率倒送等问题,影响配电网的稳定运行。如何准确计算山区配电网DPV承载能力已成为目前亟待研究和解决的重要问题。针对这一问题,以山区配电网所能接入的DPV最大容量为目标函数,构建考虑储能系统(energy storage system,ESS)容量健康退化和含有ESS的智能软开关(soft open point integrated with energy storage,E-SOP)的确定性模型。其次,分析DPV出力曲线,并在确定性模型的基础上构建山区柔性配电网DPV承载能力双层鲁棒模型。然后,根据KKT条件将模型转化为混合整数线性规划问题,并采用Gurobi求解器求得模型评估结果。最后,通过改进的IEEE33节点山区柔性配电网进行算例分析,研究ESS容量健康退化和DPV出力不确定性对DPV承载能力的影响。算例分析表明所提模型使DPV承载能力提高了8.43%,验证了该模型的可行性和有效性。展开更多
In this note, we define approximating minimal Q processes, whose paths can be constructed by approximating Markov chains in Ref. (3)By approximating minimal Q processes, we have constructed paths for a class of nonsti...In this note, we define approximating minimal Q processes, whose paths can be constructed by approximating Markov chains in Ref. (3)By approximating minimal Q processes, we have constructed paths for a class of nonsticky Q processes which contain the well-known Doob’s processes as a special case.展开更多
Northwest China serves as a critical ecological barrier region for maintaining national water,energy,and food security,as well as transboundary ecological governance.However,under the dual pressures of climate change ...Northwest China serves as a critical ecological barrier region for maintaining national water,energy,and food security,as well as transboundary ecological governance.However,under the dual pressures of climate change and human activities,ecosystem services(ESs)are facing severe challenges in this region.Based on multi-source remote sensing and statistical data during 2000–2020,this study investigated the spatiotemporal evolution characteristics of four key ESs(water yield,habitat quality,carbon storage,and food provisioning)in Northwest China using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.Integrating morphological spatial pattern analysis(MSPA)and circuit theory,we identified ecological sources,corridors,pinch points,and barriers,and further designed three optimization scenarios(bottleneck optimization,high-resistance corridor buffering,and barrier removal optimization)to enhance landscape connectivity.The results revealed that ES supply and demand exhibited marked spatial heterogeneity,with high-supply areas concentrated in the southeastern sectors.Ecological sources primarily distributed in the southeastern and northern sectors,and ecological resistance surfaces continuously intensified.Water yield and habitat quality demands were increasing,food provisioning demand was decreasing,and carbon storage demand was surging.A total of 61 ecological sources(8%of the study area),142 ecological corridors(24,957 km in total length),237 ecological pinch points,and 89 barrier zones were identified.Among the three optimization scenarios,barrier removal achieved optimal connectivity improvement across all distance thresholds,with the probability of connectivity index improvement reaching up to 4%.This study provides scientific foundations and spatial decision support for ecological network optimization and sustainable governance in arid and semi-arid areas.展开更多
Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact ...Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.展开更多
文摘分布式光伏(distributed photovoltaic,DPV)的大规模无序接入为山区配电网带来了过电压、功率倒送等问题,影响配电网的稳定运行。如何准确计算山区配电网DPV承载能力已成为目前亟待研究和解决的重要问题。针对这一问题,以山区配电网所能接入的DPV最大容量为目标函数,构建考虑储能系统(energy storage system,ESS)容量健康退化和含有ESS的智能软开关(soft open point integrated with energy storage,E-SOP)的确定性模型。其次,分析DPV出力曲线,并在确定性模型的基础上构建山区柔性配电网DPV承载能力双层鲁棒模型。然后,根据KKT条件将模型转化为混合整数线性规划问题,并采用Gurobi求解器求得模型评估结果。最后,通过改进的IEEE33节点山区柔性配电网进行算例分析,研究ESS容量健康退化和DPV出力不确定性对DPV承载能力的影响。算例分析表明所提模型使DPV承载能力提高了8.43%,验证了该模型的可行性和有效性。
文摘In this note, we define approximating minimal Q processes, whose paths can be constructed by approximating Markov chains in Ref. (3)By approximating minimal Q processes, we have constructed paths for a class of nonsticky Q processes which contain the well-known Doob’s processes as a special case.
基金supported by the Tianchi Talent Introduction Program of Xinjiang Uygur Autonomous Region(2024000104)the National Key Research and Development Program of China(2023YFF0805603).
文摘Northwest China serves as a critical ecological barrier region for maintaining national water,energy,and food security,as well as transboundary ecological governance.However,under the dual pressures of climate change and human activities,ecosystem services(ESs)are facing severe challenges in this region.Based on multi-source remote sensing and statistical data during 2000–2020,this study investigated the spatiotemporal evolution characteristics of four key ESs(water yield,habitat quality,carbon storage,and food provisioning)in Northwest China using the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.Integrating morphological spatial pattern analysis(MSPA)and circuit theory,we identified ecological sources,corridors,pinch points,and barriers,and further designed three optimization scenarios(bottleneck optimization,high-resistance corridor buffering,and barrier removal optimization)to enhance landscape connectivity.The results revealed that ES supply and demand exhibited marked spatial heterogeneity,with high-supply areas concentrated in the southeastern sectors.Ecological sources primarily distributed in the southeastern and northern sectors,and ecological resistance surfaces continuously intensified.Water yield and habitat quality demands were increasing,food provisioning demand was decreasing,and carbon storage demand was surging.A total of 61 ecological sources(8%of the study area),142 ecological corridors(24,957 km in total length),237 ecological pinch points,and 89 barrier zones were identified.Among the three optimization scenarios,barrier removal achieved optimal connectivity improvement across all distance thresholds,with the probability of connectivity index improvement reaching up to 4%.This study provides scientific foundations and spatial decision support for ecological network optimization and sustainable governance in arid and semi-arid areas.
文摘Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.
