Lithium battery energy storage system in the analysis of application of urban rail transit

Source: 2020 - 04 - 11 18:49 hits: lithium-ion battery energy storage system in urban rail transit at present, the application of urban rail transit can adopt main storage form of lithium ion battery energy storage, super capacitor energy storage and flywheel energy storage. Among them, the lithium ion battery as developing rapidly in recent years, energy storage component, its capacity and power level can meet the requirements of regenerative braking energy absorption and release. In addition, compared with the super capacitor and lead-acid batteries, lithium ion batteries have the advantages of high energy density, can realize miniaturization and lightweight components. Lithium battery charge and discharge fast, long service life, therefore, can satisfy the requirement of electrified rail transit. Figure 1 lithium battery energy storage system for city rail transit lithium battery energy storage system, mainly composed of the bidirectional DC/DC converter, controller, lithium battery and other parts. Among them, the lithium battery monomer by setting way of series-parallel connection, form a lithium-ion battery pack. Described in the lithium battery by bi-directional DC/DC converter on both ends of the traction network connection. Controller of traction power network state monitoring signal processing and lithium-ion battery pack sensors energy flow between the electric traction power grid and the control of lithium battery by controlling IGBT1 conductance and IGBT2 bi-directional DC/DC converter, and realize the automatic control of the charging and discharging lithium battery pack. Energy storage device can be installed on the vehicle, known as vehicle energy storage devices; Also can be installed in the ground or the special room of the tunnel, is called the ground type. In this experiment USES the ground type. Energy storage device of the rated voltage of the DC 1400 ~ 1800 V, rated capacity of 160 ah, rated power of 240 kw, traction network of the rated voltage of 1500 V DC. Lithium battery energy storage system control strategy in the process of vehicle running, there are three types of traction start, idle, and braking, cause traction network voltage reduction, constant pressure and dynamic change of rising respectively corresponding to the energy storage system of three ways: electrical energy release, spare and energy absorption. Therefore, the selection of traction network voltage value f as control variables. In the process of vehicle acceleration starting, traction motor, electrical energy through the VVVF inverter to obtain from the traction network. When the energy storage system detect Ut setting of threshold voltage is less than the controller. When off the bi-directional DC/DC converter IGBT1, IGBT2 open ( Single guide of lithium batteries for traction network) , lithium-ion battery energy is converted to the required voltage range of the traction network and the traction network as an auxiliary power supply maintenance of traction network voltage threshold voltage value of the above. In the process of vehicle idling, no energy exchange between vehicle and traction network, traction network voltage constant, energy storage system has not started, in the standby state. In the process of regenerative braking, the motor vehicle in the working state of the generator, the vehicle's kinetic energy into electricity, after VVVF rectifier feedback to traction network. When the energy storage system to detect U is greater than the limit set by the voltage controller, bi-directional DC/DC converter is IGBT1 and IGBT2 closed ( Single direction traction network of connections between and lithium battery) , and traction network of electric energy into the range of voltage and current lithium battery rechargeable lithium batteries. The absorption of renewable energy, energy storage system to maintain traction network voltage is lower than the value of voltage.