Research On The De-icing & Anti-icing Method By Transferred Current Of Bundled Conductor And The Smart Unit Of The Method

Atmospheric icing affects the outdoor equipment of power system in many countries. The accidents such as flashover of insulators, tower collapse and conductor break caused by the ice accretion on the transmission lines of bundled conductor are more serious than that of single conductor. Ice melting used AC or DC is applied widely and effective. However, this method has certain drawbacks, such as interruption of the normal power supply during ice melting, expensive and cumbersome additional equipment, and long operation time, and the ice-melting with the short-circuit current on the bundled conductor transmission lines with a long distance needs a remarkable high capacity of the ice-melting power. The paper proposes a real-time and on-load anti-icing & de-icing method, which can be implemented intelligently through the transferred current of bundled conductor. The implementation approach and load demand of the method are discussed and analyzed. The smart module to implement the method is designed, trial-manufactured and tested in this research.The rationale and the work procedure of the anti-icing & de-icing method by the transferred current of bundled conductor are analyzed and discussed. On this basis, the main parts of the smart module as well as their functions and relationships are determined, and the preliminary design of the smart module for the method is completed. The surface temperature of the sub-conductors in the anti-icing procedure by the transferred current is calculated, and value range of the conducting time ?t of sub-conductors is obtained. The conducting number m of sub-conductors can be obtained from the restrictive conditions of the anti-icing initial temperature T0. The launch condition of the anti-icing method by transferred current is the consistent decreasing of the sub-conductor surface temperature to T0. The equivalent ice thickness of the iced conductor can be used to calculate the critical ice-melting current according to the analysis on the critical ice-melting state. The value range of m and the de-icing critical load current of the lines can be obtained from the restriction of the maximum ice-melting time tp on ?t.The load flow calculation of 500 kV and 220 k V transmission lines in Hunan power network is performed in the operation mode of small load in winter. The load demand of the anti-icing & de-icing method by the transferred current is analysed according to the results of load flow calculation and the anti-icing & de-icing strategy. In the extreme of small load in winter, the load current of the most 500 kV transmission lines of Hunan power gird can satisfy the load demands of the method by transferred current, and only a few 220 kV transmission lines can satisfy the corresponding load demand. The anti-icing & de-icing method by the transferred current of bundled conductor has more advantages on the transmission lines of four bundled conductors or even more.The switch module of the smart anti-icing & de-icing equipment is designed and manufactured, and its permanent magnetic actuator operates with the cooperation of the bi-stable state and closing spring, which improves fundamentally the closing reliability of the smart module. The dimensions of the components of the permanent magnetic actuator and its static and dynamic characteristics are optimized through the static and dynamic simulations of the actuator. With the guarantee of the current capacity and breaking capacity of the switch module, the prototype of the actuator is designed with the relatively smaller volume, weight and energy consumption. The module for energy induced from the lines is designed and manufactured with a high power, which can satisfy the power demand of the permanent magnetic actuator and ensure the steady operation of the control module as well as the sensors at the same time.The control module of the smart equipment is designed and manufactured, and its two operating modes are discussed. An ice accretion monitor of the transmission lines based on a rotatable reference conductor is designed and manufactured, which is tested in the multifunction atmospheric chamber. The measured values of the force sensor of the monitor can represent the equivalent ice thickness of the iced conductor, and the ice-melting system of the monitor has a good cooperation with de-icing method by the transferred current.The first prototype of the smart module was tested in the natural disaster experimental station of Xiaosha river: the temperature of each observation point is kept steady with a total current of 2000 A, and the current of the sub-conductor is transferred successfully with a total current of 1000 A and 1600 A. The second prototype of the smart module was tested in the natural icing experimental station of Xuefeng mountain: within the calculated time, a four bundled conductor is de-iced successfully by the transferred current through the prototype with the power induced the lines. On the basis of the aforementioned modules and tests, the specific design of the third prototype is completed, and its production process and performance are further improved.