Traction Energy Storage System with SCiB™
For DC Railway Power Supply Systems
Toshiba developed Traction Energy Storage System (TESS) with SCiB™, a new energy saving solution with Toshiba's own battery technology of high quality.
When a train set is braking, it generates energy which can be used by the adjacent accelerating trains. But in most cases, this regenerative energy is not efficiently utilized by the next train and is wasted as heat through onboard or wayside resistors. Such cases does not only incur energy wastage but also likely to cause abrupt shift from regenerative braking to mechanical braking. This sudden change may further cause passenger ride discomfort and degradation of the brake shoe due to abrasion.
Toshiba's Traction Energy Storage System efficiently stores surplus regenerative energy in the SCiB™ and discharges it to another accelerating train. TESS is installed with Toshiba's patented advance control system which allows flexible control of charge-discharge cycles in accordance to the battery's State-of-Charge (SOC). This allows significant increase in battery lifetime.
Better Regenerative Braking Operation
Regenerative energy can be efficiently charged and discharge to/from the SCiB™ Battery Panels thus reducing abrupt shift from regenerative braking to mechanical braking of cars. This also delays wear and tear of rolling stock brake shoe and contributes to passenger's comfort during train braking.
Field test has demonstrated about 95% charge-discharge efficiency. Such a remarkable charge-discharge characteristic greatly reduces energy wastage and ultimately, promotes power demand peak.
Feeding Voltage Stabilization
Installation of TESS can improve traction power quality through feeding voltage stabilization.
Emergency Power Supply
During power supply failure, TESS can be used as an independent emergency power supply. Stored energy can be utilized to accelerate the trains and safely bring passengers to the nearest station. This function is most applicable when installed in tunnel sections.
Traction Energy Storage System consists of Battery Panel, Converter Panel (DC-DC Chopper Equipment), DC Switchgear and Control Panel which works dynamically together to produce high energy saving effects. Toshiba's TESS is highly flexible to match the customers' needs and produce suitable solutions.
|Converter||1800W x 2380D x 2300H|
|Battery Panel||600W x 650D x 2100H x 8 Panel|
|Control Panel||500W x 600D x 2100H x 2 Panel|
|DC Switchgear||600W x 1700D x 2100H x 2 Panel|
- *Dimensions for 500kW TESS
High Performance SCiB™
TESS utilizes Toshiba's own high performance SCiB™.
This battery has various outstanding characteristics, By using unique oxide materials, SCiB™ holds high resistance against thermal runaway caused by internal short circuiting brought about by physical stresses.
Advanced V-SOC Battery Control
Toshiba also developed a completely new and advanced Charge-Discharge algorithm for the efficient control of TESS.
For conventional energy storage systems, battery is charged and discharged to keep specified SOC (State of Charge). Thus, battery is charged and discharged regardless of the feeding voltage.
There will be instances when the battery will be unnecessarily charged/discharged even at rated line voltage (area between the Charge Start Voltage and Discharge Start Voltage). Thus causing feeding voltage imbalance and shortened battery lifetime.
As for Toshiba's advance V-SOC control method, charge and discharge characteristics automatically shifts depending on SOC. When SOC is high, charge-discharge characteristic will shift to the higher voltage side, hence the battery shall be easily discharged. On the other hand, when SOC is low, charge-discharge characteristic will shift to the lower voltage side thus, battery shall perform more charging.
The lifetime of a battery strongly depends on the charge-discharge times and current. By using this control algorithm, unnecessary charge and discharge can be greatly reduced.
Toshiba's system does not define any certain SOC which means that charge and discharge will be performed dynamically within a wide range of SOC.
- *SOC : State-of-Charge *V-SOC : Voltage-State-of-Charge
Charge/Discharge corresponding with Feeder Voltage
To better tend to customer's needs, Toshiba offers a more customer-oriented engineering which includes a simulation study using Toshiba's advanced traction power simulation software engines. With this, Toshiba can offer a more suitable solution.
Ratings and Specifications
|Item||Rating / Function|
|Rated Power||500kW - 2000kW|
|Rated Capacity||200kWh - 800kWh|
|Rated Feeder Voltage||1500V (950V - 2000V)|
|Rated Battery Voltage||600V (500V - 713V)|
|Load Pattern||1 p.u. (1min) - 0.5 p.u. (4min) 0.5 p.u. - Continuous|
1. V-SOC Mode
2. Emergency Power Supply Mode