Control of Voltage Level in Railway Contact Network Using IGBT Booster Transformers

Controlling the voltage level in the contact network of railways is an important task, since it ensures the throughput capacity of the section and reduces power losses. However, the use of voltage regulation devices can lead to the deterioration in the electric power quality. For example, the use of booster transformers leads to the deterioration in the coefficient of voltage asymmetry in the negative sequence. To overcome this drawback, the authors proposed a traction power supply circuit with a booster transformer, which implies the presence of a switch and a voltage sensor at the sectioning post. A detailed description of the operation of this circuit is given. The role of each element in controlling the voltage level in the contact network is described. The switch switches the supply winding of the IGBT booster transformer to different phases of the step-down transformer depending on the value of the traction load. In this case, the amount of voltage boost is calculated taking into account the readings of the voltage sensor at the sectioning post. Due to this, the required voltage level in the contact network is ensured and the coefficient of voltage asymmetry in the negative sequence is improved. The article provides an example that proves the improvement of power quality indicators using the proposed voltage level control scheme in the contact network.