The Theory And Implementation Of The Efficient Method Of The Transmission Lines De-icing And SVC System

The overhead electrical transmission lines icing can cause a serious phenomenon such as lines overloading, galloping etc, which can lead to the accidents such as lines cut off, towers collapsed, the big area power cut, power limited and so on. Such problem may bring serious influence to the national producing, so it is a hard problem which the electrical power system urgently needs to solve. At present some de-icing methods proposed for the overhead electrical transmission lines by domestic and international experts are not effective and some are not actual considering the efficiency and the security. The principle and realization of the double using system which has an extremely good application prospect and can be used as both high effective De-icer and Static Var Compensator have been thoroughly studied in this paper, wishing this system can be used in practice.This paper introduces the present situation of overhead electrical transmission icing, its harm and the de-icing methods. On the basis of analyzing several kinds of de-icing installations which have been recently proposed, a double function installation which can be used as both three-phase full-bridge controlled rectifier de-icer and Static Var Compensator based on HVDC technology is mainly studied, and such installation has a bigger superiority in technology, economy and efficiency. This equipment is mainly composed of three-phase full-bridge controlled rectifier and Static Var Compensator that based on rectifier. The working principle of these two part of electric circuits is analysed thoroughly in this paper and the dq transformation examination method is adopted for the SVC installation, the examining accuraty based on the method can't be influenced by voltage distortion and dissymmetry when examining three-phase electrical network electric current or load current fundamental wave positive sequence component. At the same time, considering this installation can cause serious harmonics, a combined series active filter, which has the characteristics of high controllability and fast response and also can compensate various sub-harmonics is proposed to eliminate the harmonics, producing reactive power which need to be changed, and not influenced by the system parameter. The compensation characteristics are also analyzed based on Matlab, and the results show that the method is effective. For the characteristic of the rectifier phase controlling and the filter pulse width modulation controlling, phase control principle and the pulse width modulation realization method based on FPGA are proposed. The configuration of digital controlled circuit is designed, the control system has the merit of high density, quick speed, nimble programming, good timeliness and redeploys easily. The controlling procedure based on the hardware description language Verilog is compiled, and the simulation based on Modelsim indicates the digitan controlled method is feasible.