In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave th...In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.展开更多
针对江西省浔湖Ⅰ-Ⅱ双回线路存在严重的三相电流不平衡问题,提出采用电容器补偿措施减小三相电流不平衡度。由于对称分量法对不换位的输电线路误差较大,利用模分量法推导出三相不平衡度表达式;并根据GB/T 15543—2008《电能质量三相电...针对江西省浔湖Ⅰ-Ⅱ双回线路存在严重的三相电流不平衡问题,提出采用电容器补偿措施减小三相电流不平衡度。由于对称分量法对不换位的输电线路误差较大,利用模分量法推导出三相不平衡度表达式;并根据GB/T 15543—2008《电能质量三相电压不平衡》中电网正常运行时负序不平衡度不超过2%的要求,理论计算补偿电容的大小。以江西220 k V浔湖双回线路为例,利用电磁暂态程序ATP/EMTP建立电容器补偿的同塔双回输电线路模型。理论与仿真结果表明:采取合理配置补偿电容可以减小线路三相不平衡度。展开更多
为准确获得淮南—上海1 000 k V同塔双回交流输电线路的工频序参数,采用基于全球定位系统的异频双端同步测量方法测量试验中各相导线首、末端电压与电流;提出了将所测电压与电流代入长线方程来求解异频下的工频序参数的计算方法,并与单...为准确获得淮南—上海1 000 k V同塔双回交流输电线路的工频序参数,采用基于全球定位系统的异频双端同步测量方法测量试验中各相导线首、末端电压与电流;提出了将所测电压与电流代入长线方程来求解异频下的工频序参数的计算方法,并与单端测量所得结果进行比较。结果表明,采用所提出的双端测量计算法能够获得准确的工频序参数,与采用分布参数模型的单端测量计算结果相比,其差异百分比≤1.52%;而与采用常规集中参数算法的单端测量法相比相差较大,其中零序电阻差异百分比可达16.48%,这是因为单端测量法不适用于长距离线路的参数计算。将上述双端测量计算法用于测量特高压同塔双回交流输电线路淮芜Ⅰ线与Ⅱ线的工频序参数,获得了准确的结果,为继电保护及短路电流计算等提供了数据基础。展开更多
文摘In recent years,several failures of double circuit transmission line on the same tower due to lightning were happened in Beijing power grid.Although it can be reclosed successful,the lightning strike caused a grave threat to the power grid security.The cause of the accident and the accident process were studied for the sake of further understanding of the impact of lightning on power grid.As an example,110 kV double circuit transmission line(Xilong-line) was analyzed.At first,the system topology was given.Through the analysis on relay protection actions and the fault recorder data,over voltage on the insulator strings was calculated.Based on the analysis and the calculation,accident cause and the process were presented respectively.Secondly,it comes to the conclusion that the lightning failure was caused by counterattack.The wave of the lightning over voltage would spread to the not grounded neutral point of the transformers,and make the neutral protective gap breakdown,then cause freewheeling with the frequency of 50 Hz.As results of the relay protection,the double circuit transmission line all tripped out.Finally,the causes of the accident were proposed that included terrain features,large corner towers,strong thunderstorm weather and poor grounded contact of the tower.
文摘针对江西省浔湖Ⅰ-Ⅱ双回线路存在严重的三相电流不平衡问题,提出采用电容器补偿措施减小三相电流不平衡度。由于对称分量法对不换位的输电线路误差较大,利用模分量法推导出三相不平衡度表达式;并根据GB/T 15543—2008《电能质量三相电压不平衡》中电网正常运行时负序不平衡度不超过2%的要求,理论计算补偿电容的大小。以江西220 k V浔湖双回线路为例,利用电磁暂态程序ATP/EMTP建立电容器补偿的同塔双回输电线路模型。理论与仿真结果表明:采取合理配置补偿电容可以减小线路三相不平衡度。
文摘为准确获得淮南—上海1 000 k V同塔双回交流输电线路的工频序参数,采用基于全球定位系统的异频双端同步测量方法测量试验中各相导线首、末端电压与电流;提出了将所测电压与电流代入长线方程来求解异频下的工频序参数的计算方法,并与单端测量所得结果进行比较。结果表明,采用所提出的双端测量计算法能够获得准确的工频序参数,与采用分布参数模型的单端测量计算结果相比,其差异百分比≤1.52%;而与采用常规集中参数算法的单端测量法相比相差较大,其中零序电阻差异百分比可达16.48%,这是因为单端测量法不适用于长距离线路的参数计算。将上述双端测量计算法用于测量特高压同塔双回交流输电线路淮芜Ⅰ线与Ⅱ线的工频序参数,获得了准确的结果,为继电保护及短路电流计算等提供了数据基础。
