In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in th...In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in this paper.Firstly,the 3-terminal synchronous fundamental positive sequence voltage and current phasors are extracted and substituted into the fault branch distance function to realize the selection of fault branch when the fault occurs;Secondly,use the condition of the fundamental positive sequence voltage phasor at the fault point is equal to calculate all roots(including real root and virtual roots);Finally,the phase-angle jump check function is used for checking calculation,and then the only real root can be determined as the actual fault distance,thereby achieving the purpose of high-precision fault location.MATLAB simulation results show that the proposed new algorithm is feasible and effective with high fault location accuracy and good versatility.展开更多
在电子电路板制造行业,部分非标异性元件需要人工完成供料工序,再对接快速贴片机(Surface Mount Technology,SMT)完成整个生产工序,效率低下,无法满足电子产品组装行业的发展需求。为此设计了一种基于单片机控制的散料异形件供料器,包括...在电子电路板制造行业,部分非标异性元件需要人工完成供料工序,再对接快速贴片机(Surface Mount Technology,SMT)完成整个生产工序,效率低下,无法满足电子产品组装行业的发展需求。为此设计了一种基于单片机控制的散料异形件供料器,包括2套振动装置和直线导轨,振动装置呈螺旋形上升与直线轨道连接,2个直线导轨并行工作,直线振动器可使导轨部件振动使导槽内的散料移动,当散料移动至导槽的末端时,插件机吸夹嘴定点取料从而进行自动贴插件。与传统的手工贴插件相比,散料经本装置供料后,自动贴装品质更加得到保证。实践结果表明,该装置兼容现有的SMT设备及插件机设备,实现了供料器的全自动工作,提高了生产效率;所需员工从5人减少至1人,生产节拍从5 s/件降低至1 s/件,次品率从3‰大幅度下降至1‰。展开更多
随着高压直流输电工程的不断投产,以及风电项目的增多,越来越多的风电场出现在电网换相换流器高压直流输电(line-commutated-converter based high voltage direct current,LCC-HVDC)受端换流站近区,两者构成的系统存在振荡风险。为此,...随着高压直流输电工程的不断投产,以及风电项目的增多,越来越多的风电场出现在电网换相换流器高压直流输电(line-commutated-converter based high voltage direct current,LCC-HVDC)受端换流站近区,两者构成的系统存在振荡风险。为此,该文针对直流受端馈入站与近区风电场系统的振荡特性展开研究。首先,建立并验证系统的状态空间模型,基于该模型计算出系统特征值,确定LCC-HVDC与风电场共同参与的振荡主导模式并进行参与因子分析。进一步地,通过对比是否接入LCC-HVDC的主导模式,得到LCC-HVDC的接入会削弱系统阻尼的结论。最后,从系统额定容量、交流系统短路比、风电场并网线路长度等方面探究系统稳定性的影响因素,并分析系统的不同短路比、潮流比对风机网侧换流器(grid-side converter,GSC)外环控制和换流站定电流控制器性能的影响。展开更多
基金supported by National Nature Science Foundation of China(51507031).
文摘In order to effectively solve the dead-zone and low-precision of T-shaped transmission line fault location,a new T-shaped transmission line fault location algorithm based on phase-angle jump checking is proposed in this paper.Firstly,the 3-terminal synchronous fundamental positive sequence voltage and current phasors are extracted and substituted into the fault branch distance function to realize the selection of fault branch when the fault occurs;Secondly,use the condition of the fundamental positive sequence voltage phasor at the fault point is equal to calculate all roots(including real root and virtual roots);Finally,the phase-angle jump check function is used for checking calculation,and then the only real root can be determined as the actual fault distance,thereby achieving the purpose of high-precision fault location.MATLAB simulation results show that the proposed new algorithm is feasible and effective with high fault location accuracy and good versatility.
文摘在电子电路板制造行业,部分非标异性元件需要人工完成供料工序,再对接快速贴片机(Surface Mount Technology,SMT)完成整个生产工序,效率低下,无法满足电子产品组装行业的发展需求。为此设计了一种基于单片机控制的散料异形件供料器,包括2套振动装置和直线导轨,振动装置呈螺旋形上升与直线轨道连接,2个直线导轨并行工作,直线振动器可使导轨部件振动使导槽内的散料移动,当散料移动至导槽的末端时,插件机吸夹嘴定点取料从而进行自动贴插件。与传统的手工贴插件相比,散料经本装置供料后,自动贴装品质更加得到保证。实践结果表明,该装置兼容现有的SMT设备及插件机设备,实现了供料器的全自动工作,提高了生产效率;所需员工从5人减少至1人,生产节拍从5 s/件降低至1 s/件,次品率从3‰大幅度下降至1‰。
文摘随着高压直流输电工程的不断投产,以及风电项目的增多,越来越多的风电场出现在电网换相换流器高压直流输电(line-commutated-converter based high voltage direct current,LCC-HVDC)受端换流站近区,两者构成的系统存在振荡风险。为此,该文针对直流受端馈入站与近区风电场系统的振荡特性展开研究。首先,建立并验证系统的状态空间模型,基于该模型计算出系统特征值,确定LCC-HVDC与风电场共同参与的振荡主导模式并进行参与因子分析。进一步地,通过对比是否接入LCC-HVDC的主导模式,得到LCC-HVDC的接入会削弱系统阻尼的结论。最后,从系统额定容量、交流系统短路比、风电场并网线路长度等方面探究系统稳定性的影响因素,并分析系统的不同短路比、潮流比对风机网侧换流器(grid-side converter,GSC)外环控制和换流站定电流控制器性能的影响。
