Cold spells are extreme weather events characterized by the invasion of cold air from high latitudes into the middle and low latitudes,resulting in significant cooling.Cold spells have various adverse health effects,i...Cold spells are extreme weather events characterized by the invasion of cold air from high latitudes into the middle and low latitudes,resulting in significant cooling.Cold spells have various adverse health effects,including epidermal damage,respiratory tract spasms,respiratory immune abnormalities,acute cardiopulmonary diseases,and exacerbation of urinary and endocrine disorders.In response to the frequent cold spells in recent years.展开更多
To address the challenges in fault location in distribution networks,the distribution of magnetic field under overhead line and its relationship with three-phase currents are explored in this paper.At the same time,co...To address the challenges in fault location in distribution networks,the distribution of magnetic field under overhead line and its relationship with three-phase currents are explored in this paper.At the same time,considering the influ-ence of sensor installation position,line sag and galloping on magnetic field,a grounding fault location method of an overhead line based on dual-axis magnetic field trajectory is proposed.The analytical expressions of the magnetic field on the x-axis and y-axis under the overhead line are obtained by least squares fitting.The Lissajous figure synthe-sized by dual-axis is then compared with the general equation of an ellipse,and the characteristic quantity expression characterizing the magnetic field trajectory structure is obtained.Finally,a fault location criterion is constructed using the difference of the characteristic quantities of the ellipses synthesized by x-axis and y-axis magnetic fields upstream and downstream of the fault point,i.e.,the difference of the length of the major axis and the minor axis,and the sign for the ratio of the cosine value of the inclination angle.Compared with other location methods based on electrical quantity,the principle of this method is simpler and it can locate faults more quickly and accurately.A large number of simulation results show that the proposed method is suitable for different types of fault conditions.展开更多
文摘Cold spells are extreme weather events characterized by the invasion of cold air from high latitudes into the middle and low latitudes,resulting in significant cooling.Cold spells have various adverse health effects,including epidermal damage,respiratory tract spasms,respiratory immune abnormalities,acute cardiopulmonary diseases,and exacerbation of urinary and endocrine disorders.In response to the frequent cold spells in recent years.
基金supported in part by the National Natural Science Foundation of China(52177114,61403127)Jiangxi Electric Power Co.,Ltd of State Grid(521820210005,521820220016).
文摘To address the challenges in fault location in distribution networks,the distribution of magnetic field under overhead line and its relationship with three-phase currents are explored in this paper.At the same time,considering the influ-ence of sensor installation position,line sag and galloping on magnetic field,a grounding fault location method of an overhead line based on dual-axis magnetic field trajectory is proposed.The analytical expressions of the magnetic field on the x-axis and y-axis under the overhead line are obtained by least squares fitting.The Lissajous figure synthe-sized by dual-axis is then compared with the general equation of an ellipse,and the characteristic quantity expression characterizing the magnetic field trajectory structure is obtained.Finally,a fault location criterion is constructed using the difference of the characteristic quantities of the ellipses synthesized by x-axis and y-axis magnetic fields upstream and downstream of the fault point,i.e.,the difference of the length of the major axis and the minor axis,and the sign for the ratio of the cosine value of the inclination angle.Compared with other location methods based on electrical quantity,the principle of this method is simpler and it can locate faults more quickly and accurately.A large number of simulation results show that the proposed method is suitable for different types of fault conditions.
