高速鐵路AT饋電系統對通信線路之電磁干擾

Abstract

未來我國的高速鐵路將採用自耦變壓器(autotransformer, AT)饋電系統，在本研究中，主要探討該系統對鄰近通信線路產生電磁干擾的現象，並提出分析的方法及步驟。吾人首先在鐵軌接地電阻無限大的假設下，計算AT饋電系統之饋電線及鐵軌的對地電壓，藉此初步地分析該系統（單邊或雙邊饋電）在單一列車負載下之電壓分佈。接著建立AT饋電系統（單邊）對通信線路產生電磁干擾的模式，並利用數學模式完整地考慮饋電區間內的互感作用、接地電阻及系統參數，進行鐵軌地電位升、地電流、AT饋電系統基頻磁場與通信線路感應縱電壓之分析。這些電磁干擾分析將在變動下列參數下進行，這些參數包含接地電阻、相鄰AT之距離、列車位置、接地故障與AT匝比。由數值模擬結果發現：當鐵軌接地電阻值增加時，會造成地電位升增加及地電流減少；減少相鄰AT之距離，可同時達到降低地電位升及地電流的效果。當AT饋電系統接地故障時，該系統基頻磁場及通信線路感應縱電壓約為正常饋電的十倍。

In this paper, electromagnetic interference (EMI) of AT-Fed system on telecommunication lines is investigated. The AT-Fed system of the high speed railways will induce interference voltage on neighboring telecoimunication lines. In our study, simple analytical models are sufficient to predict the voltage regulation characteristics of ideal AT-Fed electric railroads with single and double-end fed supply under the operation of a single train. More sophisticated simulation techniques involving comprehensive mathematical modeling of traction and line conditions are necessary for complete operational studies on long track sections. Such simulator can deal with multiple-train operation and involve setting up an electrical circuit of the complete traction power network, which is then solved at discrete values of time. The simulator enables EMI analyses to be made, and sample displays of ground potential rise (GPR), ground current, AT-Fed system power frequency magnetic field, and longitudinal induction voltage under different ground resistance, AT separation, and train location. It is found that a larger value of ground resistance introduces higher GPR and lower ground current, and a smaller distance of AT separation leads to lower GPR and ground current.