Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utili...Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.展开更多
With the growing demand for precise voltage adjustment and reactive regulation,the frequent operation of on-load tap changers(OLTCs)in oil-immersed systems has led to increased erosion of switch contacts by arcs durin...With the growing demand for precise voltage adjustment and reactive regulation,the frequent operation of on-load tap changers(OLTCs)in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching process.This erosion causes significant wear on the contacts,thereby reducing their lifespan.Therefore,the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed OLTCs.To achieve this,a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact pressures.Additionally,finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc energy.The surface morphology of the contacts was observed using an optical microscope.The findings revealed that as the sliding speed increased,the arc energy,arc initiation rate,and contact resistance initially exhibited an upward trend,then decreased,and eventually increased again.The minimum values were observed at a sliding speed of 90 mm/s.Moreover,the arc energy,arc initiation rate,and contact resistance decreased gradually as the contact pressure increased.After reaching a contact pressure of 1.5 N,the variation in the arc energy stabilized.At lower contact pressures,arc erosion dominated the wear on the contact surface.However,at higher contact pressures,the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc erosion.In summary,experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion,contact resistance,and surface damage of OLTC contacts in oil-immersed systems.展开更多
真空有载分接开关(on-load tap changer,OLTC)具有熄弧能力强、无油碳化污染等优点,已被广泛应用于换流变压器有载调压。真空OLTC机械结构复杂,切换开关动作有严格的先后顺序与时间要求,频繁动作时需承受巨大的机械与电流冲击,机械失效...真空有载分接开关(on-load tap changer,OLTC)具有熄弧能力强、无油碳化污染等优点,已被广泛应用于换流变压器有载调压。真空OLTC机械结构复杂,切换开关动作有严格的先后顺序与时间要求,频繁动作时需承受巨大的机械与电流冲击,机械失效的情况时有发生,影响变压器和换流站的安全运行。为深入研究真空OLTC动作时的机械特性,该文以一台三相真空OLTC切换开关为研究对象,介绍真空OLTC切换开关机械结构与动作特性,提出一种真空OLTC切换开关多体动力学的仿真建模方法,计算出真空OLTC切换开关关键部件的动力学特性,结果表明切换开关动作顺序合理,触头切换准确,但是快速机构对部件的冲击力较大。基于此,该文探究配重块和缓冲机构对切换开关动力学特性的影响,并重新设计切换开关的缓冲机构,结果表明新的缓冲机构能够有效降低切换开关切换冲击力。该研究方法可为真空有载分接开关的机械结构设计与优化提供有益参考。展开更多
为提高对真空灭弧式有载分接开关(on-loadtapchanger,OLTC)运行特性的认知水平,掌握真空灭弧式OLTC切换过程中的振动特性,提高其运行可靠性,基于改进密度的含噪声空间聚类(density-based spatial clustering of applications with noise...为提高对真空灭弧式有载分接开关(on-loadtapchanger,OLTC)运行特性的认知水平,掌握真空灭弧式OLTC切换过程中的振动特性,提高其运行可靠性,基于改进密度的含噪声空间聚类(density-based spatial clustering of applications with noise, DBSCAN)算法对比分析了真空与油灭弧式OLTC切换过程中的振动信号。即通过合理设定距离阈值和点数阈值对振动信号进行了DBSCAN聚类,然后根据聚类结果定义了动作点数和离散点数来描述OLTC的振动特性。对SHZV型真空OLTC与M型OLTC切换过程中振动信号的分析表明:改进DBSCAN聚类算法能有效描述OLTC振动信号的脉冲分布特征,相对于油灭弧OLTC,真空灭弧式OLTC切换过程中振动信号的动作点数和离散点数均大于油灭弧式OLTC,反映了真空灭弧式OLTC振动信号多脉冲离散分布的特点。研究结果可为基于振动分析法的真空OLTC机械状态监测技术提供参考。展开更多
有载分接开关(on load tap changer,OLTC)是电力变压器和直流工程换流变压器的核心部件,在稳定电网负荷中心电压、调节无功潮流和直流工程经济灵活运行等方面发挥重要作用。随着真空灭弧技术的快速发展,真空OLTC逐步替代油灭弧OLTC,并...有载分接开关(on load tap changer,OLTC)是电力变压器和直流工程换流变压器的核心部件,在稳定电网负荷中心电压、调节无功潮流和直流工程经济灵活运行等方面发挥重要作用。随着真空灭弧技术的快速发展,真空OLTC逐步替代油灭弧OLTC,并在电网中广泛应用。该文对比分析目前国内外主流真空OLTC的电路拓扑,从机构稳定性、真空管熄弧能力、机构疲劳特性、与油的相容性等方面系统梳理关键因素对真空OLTC可靠性的影响,提出改进和可靠性提升的技术方案。其次,对真空OLTC的运行特性和状态监测技术进行研究,重点分析真空OLTC的产气原因及特性,总结OLTC状态监测和故障防御技术的优缺点。最后,指出真空OLTC未来的发展趋势,为真空OLTC技术升级和可靠运行提供有益参考。展开更多
基金by a project under the scheme entitled“Developing Policies&Adaptation Strategies to Climate Change in the Baltic Sea Region”(ASTRA),Project No.ASTRA6-4(2014-2020.4.01.16-0032).
文摘Decreasing costs and favorable policies have resulted in increased penetration of solar photovoltaic(PV)power generation in distribution networks.As the PV systems penetration is likely to increase in the future,utilizing the reactive power capability of PV inverters to mitigate voltage deviations is being promoted.In recent years,droop control of inverter-based distributed energy resources has emerged as an essential tool for use in this study.The participation of PV systems in voltage regulation and its coordination with existing controllers,such as on-load tap changers,is paramount for controlling the voltage within specified limits.In this work,control strategies are presented that can be coordinated with the existing controls in a distributed manner.The effectiveness of the proposed method was demonstrated through simulation results on a distribution system.
文摘With the growing demand for precise voltage adjustment and reactive regulation,the frequent operation of on-load tap changers(OLTCs)in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching process.This erosion causes significant wear on the contacts,thereby reducing their lifespan.Therefore,the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed OLTCs.To achieve this,a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact pressures.Additionally,finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc energy.The surface morphology of the contacts was observed using an optical microscope.The findings revealed that as the sliding speed increased,the arc energy,arc initiation rate,and contact resistance initially exhibited an upward trend,then decreased,and eventually increased again.The minimum values were observed at a sliding speed of 90 mm/s.Moreover,the arc energy,arc initiation rate,and contact resistance decreased gradually as the contact pressure increased.After reaching a contact pressure of 1.5 N,the variation in the arc energy stabilized.At lower contact pressures,arc erosion dominated the wear on the contact surface.However,at higher contact pressures,the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc erosion.In summary,experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion,contact resistance,and surface damage of OLTC contacts in oil-immersed systems.
文摘真空有载分接开关(on-load tap changer,OLTC)具有熄弧能力强、无油碳化污染等优点,已被广泛应用于换流变压器有载调压。真空OLTC机械结构复杂,切换开关动作有严格的先后顺序与时间要求,频繁动作时需承受巨大的机械与电流冲击,机械失效的情况时有发生,影响变压器和换流站的安全运行。为深入研究真空OLTC动作时的机械特性,该文以一台三相真空OLTC切换开关为研究对象,介绍真空OLTC切换开关机械结构与动作特性,提出一种真空OLTC切换开关多体动力学的仿真建模方法,计算出真空OLTC切换开关关键部件的动力学特性,结果表明切换开关动作顺序合理,触头切换准确,但是快速机构对部件的冲击力较大。基于此,该文探究配重块和缓冲机构对切换开关动力学特性的影响,并重新设计切换开关的缓冲机构,结果表明新的缓冲机构能够有效降低切换开关切换冲击力。该研究方法可为真空有载分接开关的机械结构设计与优化提供有益参考。
文摘为提高对真空灭弧式有载分接开关(on-loadtapchanger,OLTC)运行特性的认知水平,掌握真空灭弧式OLTC切换过程中的振动特性,提高其运行可靠性,基于改进密度的含噪声空间聚类(density-based spatial clustering of applications with noise, DBSCAN)算法对比分析了真空与油灭弧式OLTC切换过程中的振动信号。即通过合理设定距离阈值和点数阈值对振动信号进行了DBSCAN聚类,然后根据聚类结果定义了动作点数和离散点数来描述OLTC的振动特性。对SHZV型真空OLTC与M型OLTC切换过程中振动信号的分析表明:改进DBSCAN聚类算法能有效描述OLTC振动信号的脉冲分布特征,相对于油灭弧OLTC,真空灭弧式OLTC切换过程中振动信号的动作点数和离散点数均大于油灭弧式OLTC,反映了真空灭弧式OLTC振动信号多脉冲离散分布的特点。研究结果可为基于振动分析法的真空OLTC机械状态监测技术提供参考。
文摘有载分接开关(on load tap changer,OLTC)是电力变压器和直流工程换流变压器的核心部件,在稳定电网负荷中心电压、调节无功潮流和直流工程经济灵活运行等方面发挥重要作用。随着真空灭弧技术的快速发展,真空OLTC逐步替代油灭弧OLTC,并在电网中广泛应用。该文对比分析目前国内外主流真空OLTC的电路拓扑,从机构稳定性、真空管熄弧能力、机构疲劳特性、与油的相容性等方面系统梳理关键因素对真空OLTC可靠性的影响,提出改进和可靠性提升的技术方案。其次,对真空OLTC的运行特性和状态监测技术进行研究,重点分析真空OLTC的产气原因及特性,总结OLTC状态监测和故障防御技术的优缺点。最后,指出真空OLTC未来的发展趋势,为真空OLTC技术升级和可靠运行提供有益参考。
