Energy Storage in the Subway Electric Drives Power Supply System

The article concentrates on building an energy-saving model for the subway power supply system, which, combined with modern adjustable speed induction motor drives, controls current flows between the contact network, the power network and energy storage unit under the contact network (current) load. The energy-saving model provides significant energy savings, line up the power network daily load periods by using the storage unit energy to compensate contact network peak loads. Controlled active rectifiers as part of the energy-saving model ensure (with sufficient accuracy) constant-voltage regulation in the contact network, absence of higher harmonics in the power network and zero shift between the main current harmonic and contact network voltage. The energy storage unit in the supply network is a lithium-ion battery equipped with DC-to-DC converter with battery charge-discharge loop controller. Energy flows are controlled by changing the battery's charge-discharge current within the contact network charging rate and electric current mark using a controller framework. The power supply energy-saving model simulation resulted in drawing oscillograph charts, which confirm the model's efficiency in the main subway rolling stock modes of operation.