Using an Energy Storage System Based on Supercapacitors for Smoothing the Peak Loads in a Variable-Frequency Tram Electric Drive

In the paper the problem of smoothing peak loads in a frequency-controlled tram electric drive is considered. The article shows that during the starting operation modes of urban transport in weak DC contact power supply, a significant voltage drops can occur, which can negatively affect on the operation of other consumers. The authors propose to supplement the system of frequency-controlled electric drive with an additional power source. The additional power source includes a block of supercapacitors and a bidirectional DC/DC converter with its own automatic control system. The article discusses several options of control algorithms for solving the problem of limiting the peak power, consumed from the contact power supply during the starting modes of urban transport electric drive. After the analysis, a variant of the energy storage system was proposed, which limits the energy consumption of the electric drive from the contact line at a given level, while providing the necessary technological operation modes of tram electric drive. Block diagrams and control algorithms are given. In conclusion, the simulation results of the frequency-controlled tram electric drive with energy storage system are presented, which show the effectiveness of the developed control algorithms.