Research On Unbalance Degree And Suppression Measures Of Multiple-circuit Overhead Transmission Lines On Same Tower

With the development of domestic construction,a growing number of regions have established long distance and large capacity transmission lines.However,this will bring about the contradiction between the construction of transmission lines and the use of local land.In order to save floor space and reduce the cost of power system,many regions adopt the transmission scheme of multi-circuit overhead transmission lines on the same tower to save costs and improve transmission efficiency.However,the multi-circuit overhead transmission lines on the same tower will bring about unbalanced operation parameters of the system and affect the stability of the power system.Therefore,it is necessary to study the unbalanced parameters of multi-circuit overhead transmission lines on the same tower,analyze the factors affecting the unbalance,and study the method of suppressing unbalance.It is of great practical significance for system stability.This thesis establishes an overhead transmission line model,introduces the calculation of voltage and current unbalanced degree at home and abroad,analysis of overhead transmission line parameters unbalanced,affecting tower and other factors on the degree of imbalance,propose relevant measures to suppress the reduction of transmission overhead lines imbalance.Through two cases of 110kV double-circuit overhead transmission lines on the same tower with wind farm grid lines and 220kV/110kV four-circuit overhead transmission lines on the same tower with dual voltage,the analysis and calculation of the unbalanced degree of the overhead transmission lines are conducted.The measures for the voltage and current unbalanced degree of the transmission lines are studied.The PSCAD modeling simulation verify the rationality of the above research.