| With the rapid development of China’s economy and society,there is a huge demand for electric energy.The construction of power grid leads to more transmission lines passing through the icing-prone areas.Line icing and ice-shedding will lead to insufficient inter phase clearance,which will cause flashover,tripping and other faults,affecting the safety and stablility of power grid.There are some researches on the ice-shedding problem of icecovered conductor at home and abroad,but there is still a lack of sufficient understanding on the determination of interphase clearance and the ice-shedding suppression effect under some scenarios.Therefore,based on the numerical simulation model of transmission line,this paper studies the effect of ice-shedding jump on phase-to-phase clearance and the iceshedding suppression scheme based on phase-to-phase spacer.The main contents are as follows:(1)The numerical simulation of transmission line ice-shedding process is realized by ANSYS.The elaborate finite element model of each component of transmission line is established.The initial configuration of conductor is obtained based on catenary equation,and the form-finding is carried out through iterative calculation.The icing and de-icing of conductor are simulated by controlling the density of conductor element.The accuracy of form-finding is verified by theoretical calculation of sag,and the accuracy of numerical model is verified by previous test.(2)The simplified formula of ice-shedding jumping height is obtained by regression.The effects of eight parameters on jump height are studied including: number of spans,span length,elevation difference,type of cables,ice thickness,ice-shedding rate,material and configuration of insulator strings.The regression analysis and diagnosis are carried out by MATLAB,and the regression formula is improved.(3)The calculation method of the minimum phase-to-phase clearance for the vertical arrangement of phase conductors is proposed.Based on this,the phase-to-phase clearance of a case in the state of static icing and dynamic ice-shedding is checked.The applicability of the simplified formula for calculating the ice-shedding jumping height is modified.According to the formula,an early warning model of phase-to-phase distance based on ice thickness and span length is developed.(4)The arrangement scheme and installation mode of phase to phase spacer under different ice-shedding scenarios are optimized.Five kinds of spacer arrangement schemes are compared and the optimal arrangement scheme is determined.Focusing on the compression failure of the spacer during the ice-shedding of bottom phase,the axial force of the spacer is checked and the critical service conditions are determined;the triangular installation mode is proposed,which can reduce the axial force by about 50% compared with the traditional vertical installation mode.The dynamic response of conductors and suppression schemes using phase-to-phase spacers during mechanical de-icing are studied,it shows that the dynamic response of lines can be effectively reduced by setting the start point of de-icing at end of the span with controlling de-icing speed below 10m/s.The installation of spacers makes definite improvements on suppressing the jump height of cables,especially installed at middle of the span. |
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