计入保护线影响的AT牵引网等值电路推导

Derivation of AT Traction Network Equivalent Circuit with Protective Wire’s Effect Reckoned

为了方便分析AT牵引网的电气特性,通常采用等值电路的分析方法。目前采用的AT牵引网等值电路忽略了保护线对牵引网电气特性的影响,势必带来较大的误差。本文通过比较AT牵引网中保护线与钢轨辅助连接不同间隔距离的牵引网阻抗特性,发现当该间隔为1.5km甚至更小时,进行牵引网阻抗计算可以近似把保护线和钢轨等效成一条线路。对等效后的AT牵引网电路根据戴维宁等效定理消去AT,并应用AT牵引网中的各电流关系立电流方程组,采用比较系数法消去互感,最后推导得出计入保护线影响的AT牵引网等值电路。采用Matlab/Simulink按照原电路分析的假设条件建立仿真模型,通过仿真实验值与理论计算值对比,验证了公式推导的正确性。

The method of equivalent circuit is usually adopted to analyze electrical specification of AT（Autotransformer） traction network. The equivalent circuit of AT traction network currently used ignored protective wire＇s effect, which leaded to biggish errors. When connective protective wire（CPW） interval in the AT traction network changed, traction network impedance specification also changed. If CPW interval is 1.5 km or less, protective wire and rail could be equivalent to a single line approximatively in traction network impedance calculation. On the basis of Thevenin＇s theorem, AT could be eliminated in the traction network circuit. Complied with the current relations in the circuit, systems of current equations could be listed. Coefficient of comparison could be used to eliminated the mutual inductances. AT traction network equivalent circuit with protective wire＇s effect reckoned could be derived at last. Simulation model was built by Matlab/Simulink according to assumed condition in primary circuit. The simulation experiment fitted close to the theoretical arithmetic, so the theoretical derivation accuracy was validated.