The southeast Portland Tacoma substation location will house the first US storage unit that allows for energy created during braking to be stored and then re-used in one of two forms, energy savings or voltage stabilization during peak demand times. TriMet will utilize the system in voltage stabilization mode.
In voltage stabilization mode, the Sitras SES allows the system to avoid problems that have led to disruptions in mass transit operations, Siemens says. If a number of vehicles accelerate simultaneously, system voltage can drop below a critical level and result in instances of undervoltage tripping in vehicles and, consequently, lead to disruptions in passenger service. The Sitras SES ensures the system voltage always remains within the required range and voltage-related disruptions no longer occur.
Siemens is providing additional solutions for the overall 7.3-mile line extension project that will connect the southeast corridor to downtown Portland, and other regions that TriMet MAX serves. Siemens Rail Systems is manufacturing 18 rail vehicles at its Sacramento, Calif., facility for the Portland-Milwaukie extension and Siemens Mobility and Logistics will be implementing its Rail Automation signaling and communication technologies to center control on the line extension.
The first substations will be installed beginning in October 2013. The Portland-Milwaukie Light Rail Transit Project is set to open in 2015 and will expand the MAX system to 60 miles and 97 stations.
The Sitras SES has been successfully installed in Spain and Germany, reducing the energy demand at Cologne Transit Authority substation by 15,000 kWh in one month. The use of just a single energy storage unit could save a maximum of 500,000 kWh per year. In addition to the cost saving, the storage unit can reduce CO2 emissions by 300 tons per year with this reduction in energy generation, Siemens says.