Study On Icing Grades Classiifcation And DC De-icing Scheme For Power Grid

The ice covering on the power lines always makes them broken or galloped, andleads to the power towers broken or deformed. As a result, these accidents for severeicing usually make the power grid paralyzed, and then influence on reliable operationand normal power supply for citizens. They always cause large economic losses. As theglobal climate becomes more and more abominable, ice disaster frequency is also moreand more high, and the power grid will face more and more severe challenge. Currently,there are many achievements for the research on power grid icing theory, and anti-icingand de-icing technology for icing lines both at home and abroad. But their depth andbreadth are still limited for solving icing problem. Therefore, this thesis mainly studiedthe micro topography and the climate factors which influence on icing condition ofpower lines in China, icing grades for power lines, and DC de-icing devices’optimalallocation for the easily icing power grid and so on.Firstly, the thesis analyzed meteorological elements distribution by consideringhistorical meteorological data, and studied power grid icing distribution by conductor’sicing condition in China. Then this showed that the power lines in the southernprovinces and cities, such as Gui Zhou, Hu Nan, Hu Bei, Guang Xi, Guang Dong, SiChuan and Chong Qing, are easily iced.In order to solve the icing problems for the icing lines in the easily icing areas, thisthesis secondly studied the icing influence of micro topographies on such lines,classified the icing grades for them and proposed a novel method for discriminating thepower lines’icing grade, then developed a discriminating software based on VB 6.0,which could determine a power line’s icing grade and calculate the icing contrast ratiowhich is more accurate to describe a line’s icing condition.By using the discriminating method, it is easy to obtain a connected power gridwhich is composed of many lines whose icing grade is more serious than serious icinggrade. Thirdly, the thesis further studied the optimal allocation theory and method ofDC de-icing devices for the icing power grid, which could make the number of devicesthat installed in substations most reasonably. This will make sure that the cost is lowest,and each device can de-ice the lines which are related with it and whose icing grade is more serious than the serious icing grade.Finally, the thesis analyzed the DC de-icing for icing power transmission line indetail, deduced the needed de-icing current, de-icing time, and de-icing capacity forthe icing line. Then an icing line was given as an example to be analyzed in detail, itscorresponding standard de-icing current was calculated, and the corresponding devicewas obtained by the current. The simulation process with MATLAB/SIMULINKshowed that the DC de-icing technology can reliably and efficiently de-ice the icecovering on the power line in short time.The study results have important guiding significance for power workers to doanti-icing and de-icing job well, and provide an available scheme for solving the icingproblem of power grid.