Lightning trip-out risk evaluation of a 220kV transmission line in Shiyan
The lightning trip-out accidents of Shiyan transmission lines occur frequently. The lightning parameters, lightning faults and geography of 220kV shi-xuan transmission line have been collected. The lightning striking simulation model has been built by using electromagnetic transient calculation software ATP-EMTP and multi-wave impedance model. The lightning withstanding level of tower and the lightning trip-out rate have been calculated. The actual operation of the transmission line has been considered in order to evaluate the risk of lightning trip-out. The results can provide guidance for the lightning protection of transmission linewhich locates in mountains.
Influencing Factors of Lightning Outage in Multi-Circuit Transmission Lines on Same Tower in Guangdong Power Grid and Fault Analysis
In recent years the land supply for power construction projects is decreased increasingly and it makes the planner of UHV/EHV transmission line construction inclined to adopt the structure of multi-circuit transmission lines on the same tower,therefore as the result the proportion of simultaneous lightning outage of multi-circuit transmission lines on the same tower evidently raises,thus the secure operation of power grid is affected.The peculiarity of simultaneous lightning outage occurred in multi-circuit transmission lines on the same tower is presented and the influences of key factors on lightning outage are analyzed,besides,the recovery analysis on electromagnetic transient of typical simultaneous lightning outage fault is performed.Results of recovery analysis show that the main reason leading to simultaneous lightning outage of multi-circuit transmission lines on the same tower is the flashback of lightning,however successive shielding failures lead to simultaneous lightning outage of multi-circuit transmission lines as well.It is emphasized that special attentions should be paid to the prevention of simultaneous lightning outage occurred in 110 kV and 220 kV double circuit transmission lines on the same tower,and it is pointed out that the power frequency voltage and the phase sequence arrangement of transmission lines on the same tower greatly influence the lightning outage caused by flashback;the simultaneous lightning outages often occur in the same phase of multi-circuit transmission lines;and the flashover is prone to occur on the upper cross arm insulator that is closer to the struck point.
On the ontology of particle mass and energy in special relativity
Einstein claimed that the fundamental dynamical insight of special relativity was the equivalence of mass and energy. I disagree. Not only are mass and energy not equivalent (whatever exactly that means) but talk of such equivalence obscures the real dynamical insight of special relativity, which concerns the nature of 4-forces and interactions more generally. In this paper I present and defend a new ontology of special relativistic particle dynamics that makes this insight perspicuous and I explain how alleged cases of mass–energy conversion can be accommodated within that ontology.