This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupli...This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupling model was set up. Based on the calculation result with complex image method, this paper derived the modification factor for induced earth potential from practical measurement, which increased the accuracy of calculation. The modification method is helpful for evaluation on the effect of means used for blocking the dc-bias current in transformer neutral and also useful for the forecast of the DC current distribution when the power grid is in different line connection mode. The DC distribution character in Guangdong power grid is shown and suggestion is proposed that the mitigation of dc-bias should start from those substations whose earth-potential is highest.展开更多
To the Editor:Cardiopulmonary resuscitation(CPR)guidelines,especially the latest 2020 guidelines issued by the American Heart Association(AHA),have emphasized the importance of high-quality CPR.[1]The research on card...To the Editor:Cardiopulmonary resuscitation(CPR)guidelines,especially the latest 2020 guidelines issued by the American Heart Association(AHA),have emphasized the importance of high-quality CPR.[1]The research on cardiac arrest(CA)and CPR has dramatically increased in recent years,and the international recovery guidelines are also being revised and implemented.However,the outcome of in-hospital cardiac arrest(IHCA)remains poor,and the understanding of the prognostic factors for survival outcome after IHCA is lacking,especially in China.Patients with CA are often poorly treated,and the incidence and mortality of CA are increasing yearly.[2]This study analyzed the effects of CPR,and explored the factors that affect survival outcome after IHCA in adults.展开更多
文摘This paper focus on the Modeling and Calculation of DC current distribution in AC power grid induced under HVDC Ground-Return-Mode. Applying complex image method and boundary element method, a new field-circuit coupling model was set up. Based on the calculation result with complex image method, this paper derived the modification factor for induced earth potential from practical measurement, which increased the accuracy of calculation. The modification method is helpful for evaluation on the effect of means used for blocking the dc-bias current in transformer neutral and also useful for the forecast of the DC current distribution when the power grid is in different line connection mode. The DC distribution character in Guangdong power grid is shown and suggestion is proposed that the mitigation of dc-bias should start from those substations whose earth-potential is highest.
基金the National Natural Science Foundation of China(Nos.81871593 and 81701931)the National Natural Science Foundation of Tianjin(No.18JCQNJC10500).
文摘To the Editor:Cardiopulmonary resuscitation(CPR)guidelines,especially the latest 2020 guidelines issued by the American Heart Association(AHA),have emphasized the importance of high-quality CPR.[1]The research on cardiac arrest(CA)and CPR has dramatically increased in recent years,and the international recovery guidelines are also being revised and implemented.However,the outcome of in-hospital cardiac arrest(IHCA)remains poor,and the understanding of the prognostic factors for survival outcome after IHCA is lacking,especially in China.Patients with CA are often poorly treated,and the incidence and mortality of CA are increasing yearly.[2]This study analyzed the effects of CPR,and explored the factors that affect survival outcome after IHCA in adults.
