大型光伏电站经常面临严重的电压波动问题。传统的集中式控制方案采用中央控制器进行无功优化,以确保系统稳定运行。然而,这种方案存在计算负担过重、容易发生单点故障和网络安全问题的弊端。为了解决这些问题,分布式优化方法被提出并...大型光伏电站经常面临严重的电压波动问题。传统的集中式控制方案采用中央控制器进行无功优化,以确保系统稳定运行。然而,这种方案存在计算负担过重、容易发生单点故障和网络安全问题的弊端。为了解决这些问题,分布式优化方法被提出并应用于大型光伏电站。该方法将电站划分为多个子系统,并使用局部控制器分别解决每个子系统的优化问题。相邻子系统之间的信息交流较少,系统信息更加安全,同时也能处理规模更大的光伏电站。基于交替方向乘子法(alternating direction method of multipliers,ADMM),提出一种适用于大型光伏电站的分布式无功优化方案解决电站电压越限问题,并通过案例验证其有效性。此外,通过分析支路潮流模型约束的线性化处理对潮流求解的影响和罚函数系数对ADMM性能的影响,进一步提升优化参数,优化大型光伏电站的运行结果。展开更多
大型光伏电站由于远离负荷中心,长距离输电线路所产生的电网阻抗不可忽略,电网阻抗对于多逆变器相并联的大型光伏电站中某一个光伏发电单元而言将会等效放大数倍,从而造成并网点电压降低导致系统不稳定。光伏电站中的静止无功发生器(sta...大型光伏电站由于远离负荷中心,长距离输电线路所产生的电网阻抗不可忽略,电网阻抗对于多逆变器相并联的大型光伏电站中某一个光伏发电单元而言将会等效放大数倍,从而造成并网点电压降低导致系统不稳定。光伏电站中的静止无功发生器(static var generator,SVG)等无功补偿装置可以用来降低电网阻抗对于并网点电压的影响。然而,研究发现,在补偿容量逐渐增大的情况下,无功补偿装置与逆变器系统之间的相互影响将会使系统出现振荡现象,而在逆变器控制回路内采用串联校正方式可以有效消除这种现象,从而保证系统的稳定运行。仿真结果与实验验证了理论分析的正确性。展开更多
OBJECTIVE:To reach consensus on the diagnostic criteria for Yin deficiency syndrome in hypertension(YDSH)patients by a modified Delphi method.METHODS:Our study was consistent with T/CACM 1032-2017.The methodology of R...OBJECTIVE:To reach consensus on the diagnostic criteria for Yin deficiency syndrome in hypertension(YDSH)patients by a modified Delphi method.METHODS:Our study was consistent with T/CACM 1032-2017.The methodology of RAND/UCLA appropriateness was used to develop consensus guidance statements.A nationwide panel of experienced clinical experts from 19 provinces was constructed.These experts were all prominent in Traditional Chinese Medicine(TCM)of cardiovascular diseases.This consensus process consisted of two rounds of questionnaires and a final round of consultation to analyze the weight score of each item.Moreover,the data extraction process is carried out independently by third-party researchers(LIANG Junya,SUN Yang,and DU Xiaona).When there is disagreement in all three rounds,the expert panel group(odd number)are invited to vote,and the one with more votes wins.In the questionnaires,participants were asked to rate the appropriateness of each syndrome item using a nine-point Likert scale.The consensus was defined as a panel median rating 1-3 or 7-9 without disagreement.And then the diagnostic criteria of YDSH were formed according to the weight score in the final round.RESULTS:Twenty-eight experts(84.8%)participated in the first round,and thirty-one(93.9%)finished the second round.After two rounds,the consensus of YDSH was reached on 11 items(25.6%),including symptoms,signs,and pulse condition.Twenty-one experts(63.6%)completed the final round in which they used a grading system for each item.Red tongue with scanty fur had the highest weighting(22.8%),followed by heat in the palms and soles(20.1%).CONCLUSIONS:The consensus-based diagnostic criteria for YDSH,formed by a modified Delphi method,can be widely incorporated in TCM.A further clinical study will be conducted to analyze the diagnosis value and cut-off score of our YDSH criteria.展开更多
文摘大型光伏电站经常面临严重的电压波动问题。传统的集中式控制方案采用中央控制器进行无功优化,以确保系统稳定运行。然而,这种方案存在计算负担过重、容易发生单点故障和网络安全问题的弊端。为了解决这些问题,分布式优化方法被提出并应用于大型光伏电站。该方法将电站划分为多个子系统,并使用局部控制器分别解决每个子系统的优化问题。相邻子系统之间的信息交流较少,系统信息更加安全,同时也能处理规模更大的光伏电站。基于交替方向乘子法(alternating direction method of multipliers,ADMM),提出一种适用于大型光伏电站的分布式无功优化方案解决电站电压越限问题,并通过案例验证其有效性。此外,通过分析支路潮流模型约束的线性化处理对潮流求解的影响和罚函数系数对ADMM性能的影响,进一步提升优化参数,优化大型光伏电站的运行结果。
文摘大型光伏电站由于远离负荷中心,长距离输电线路所产生的电网阻抗不可忽略,电网阻抗对于多逆变器相并联的大型光伏电站中某一个光伏发电单元而言将会等效放大数倍,从而造成并网点电压降低导致系统不稳定。光伏电站中的静止无功发生器(static var generator,SVG)等无功补偿装置可以用来降低电网阻抗对于并网点电压的影响。然而,研究发现,在补偿容量逐渐增大的情况下,无功补偿装置与逆变器系统之间的相互影响将会使系统出现振荡现象,而在逆变器控制回路内采用串联校正方式可以有效消除这种现象,从而保证系统的稳定运行。仿真结果与实验验证了理论分析的正确性。
基金Supported by National Key R&D Program of China Project:Study on Syndrome Differentiation Standard of Yin deficiency Syndrome in Hypertension(No.2018YFC1704403)National Key R&D Program of China Project:Systematic Study on the Standard of Syndrome Differentiation of Yin Deficiency Syndrome(No.2018YFC1704400)。
文摘OBJECTIVE:To reach consensus on the diagnostic criteria for Yin deficiency syndrome in hypertension(YDSH)patients by a modified Delphi method.METHODS:Our study was consistent with T/CACM 1032-2017.The methodology of RAND/UCLA appropriateness was used to develop consensus guidance statements.A nationwide panel of experienced clinical experts from 19 provinces was constructed.These experts were all prominent in Traditional Chinese Medicine(TCM)of cardiovascular diseases.This consensus process consisted of two rounds of questionnaires and a final round of consultation to analyze the weight score of each item.Moreover,the data extraction process is carried out independently by third-party researchers(LIANG Junya,SUN Yang,and DU Xiaona).When there is disagreement in all three rounds,the expert panel group(odd number)are invited to vote,and the one with more votes wins.In the questionnaires,participants were asked to rate the appropriateness of each syndrome item using a nine-point Likert scale.The consensus was defined as a panel median rating 1-3 or 7-9 without disagreement.And then the diagnostic criteria of YDSH were formed according to the weight score in the final round.RESULTS:Twenty-eight experts(84.8%)participated in the first round,and thirty-one(93.9%)finished the second round.After two rounds,the consensus of YDSH was reached on 11 items(25.6%),including symptoms,signs,and pulse condition.Twenty-one experts(63.6%)completed the final round in which they used a grading system for each item.Red tongue with scanty fur had the highest weighting(22.8%),followed by heat in the palms and soles(20.1%).CONCLUSIONS:The consensus-based diagnostic criteria for YDSH,formed by a modified Delphi method,can be widely incorporated in TCM.A further clinical study will be conducted to analyze the diagnosis value and cut-off score of our YDSH criteria.
