Capacitance Effect Based Ice-cover Detection Method

The frozen ice of transmission lines has been a serious threat to the safe operation of the power system,causing serious impact on social and economic development and people’s life,so the detection of the ice state of transmission lines is very important.After years of efforts by researchers,the methods currently applied to transmission lines can be divided into manual measurement methods,video image methods,mechanical properties methods,theoretical model calculation methods,etc.However,the above methods have problems such as cumbersome operation,poor equipment stability and insufficient measurement accuracy,therefore,the development and research of new transmission line ice detection methods have been the focus of domestic and foreign research.In this paper,a capacitance effect-based over-ice detection method is proposed,relying on the multifunctional artificial climate chamber of Chongqing University and the Xue Feng Mountain Energy Equipment Safety National Field Scientific Observation and Research Station,the over-ice experiments after the addition of pole plates on the conductor,the capacitance change characteristics of the conductor over-ice growth under the influence of different conditions are obtained,the main research content of this paper is as follows.(1)this paper uses a broadband dielectric spectrometer,the formation of different over ice water conductivity of the over ice electrical characteristics parameters experiments,found that at low frequencies,the over ice water conductivity on the relative relative dielectric constant of ice is relatively large,this effect decreases with the increase in frequency,at 10~7Hz,the relative dielectric constant of the over ice formed by different over ice water conductivity tends to stabilize at a value of 3.8,the difference is very small;low frequency,the Ice dielectric loss angle tangent is larger,and with the increase of ice water conductivity and become larger,with the increase of frequency,ice dielectric loss angle tangent rapid decline in 10~7Hz are tending to 0,at this time the ice can be regarded as a pure capacitor;ice volume impedance rate also with the increase of ice water conductivity and decrease,with the increase of frequency and decrease.That is,the electrical parameters of ice are very stable at high frequencies.(2)The traditional parallel plate capacitor is not suitable for transmission line ice detection,because its geometric structure will block the process of wire icing capture over cooling water droplets,which has an impact on the amount of ice coverage between the poles,this paper uses curved veneer electrodes as capacitive poles,and its rationality is verified by calculation and experiment respectively.The relationship between the capacitance and ice thickness of the ice-covering growth of the conductor presents a power function relationship,with an obvious nonlinear relationship;the influence of different ice-covering water conductivity on the capacitance of ice-covering is small,while the type of ice-covering and ice-covering form has a greater impact on the capacitance of ice-covering,under the same conditions and ice-covering thickness,the capacitance of freezing rain ice is the largest,followed by mixed drift,and the smallest hard fog;also under the same conditions and thickness,the capacitance of cylindrical ice-covering is greater than that of wing-shaped The capacitance of cylindrical ice cover is larger than that of wing-shaped ice cover under the same conditions and thickness,and the difference in capacitance becomes larger with the increase of ice cover thickness.In the case of the same type and form of ice cover,the capacitance of natural ice cover of equal thickness is greater than that of artificial climate chamber ice cover,and the ice cover formed under natural conditions is found to be denser than that of artificial climate chamber ice cover.The calculated values of capacitance for freezing rain,mixed drift and hard fog with water film are on average 1.77,1.97 and 2.02 times higher than those without water film,respectively.