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Abstract-This paper describes the results of experimental testing using a high-speed permanent magnet synchronous machine and its motor drive designed to recover potential energy in mobile gantry crane applications. Rubber-Tired Gantry (RTG) cranes are commonly used in shipping ports around the world to move containers massing up to 40 metric tons. These cranes are mobile and derive their electrical power requirements for the hoist motor from a diesel engine and generator set rather than from the utility system. Because these cranes are independent of the utility system, energy regenerated via the hoist motor as a container is lowered to the ground is typically wasted as heat in dissipator resistors. This paper details the operation and experimental results of a novel long-life flywheel motor and its drive system which can capture the regenerated energy and provide it for subsequent container lifts. Such a flywheel system has proven to significantly reduce fuel usage and diesel engine emissions.

The Los Angeles County Metropolitan Transportation Authority (LA Metro) Red Line (MRL) provides heavy rail subway service with six-car trains at up to 65 mph, connecting downtown to the San Fernando Valley with weekday headways down to five minutes. MRL trains have either DC chopper propulsion or AC propulsion. Revenue service measurements at the busy Westlake/MacArthur Park station show that natural regeneration from braking trains to accelerating trains recoups 34% of the energy provided by nearby braking trains. The remaining 66% of the braking train energy is a candidate for capture and reuse. To capture and reuse this energy, Metro contracted with VYCON Inc. to design, supply, and integrate a flywheel Wayside Energy Storage Substation (WESS). WESS will capture and reuse train braking energy at the MRL Westlake traction power substation, located at the Westlake/MacArthur Park station. The project, funded by a grant from the Federal Transit Administration through its Transit Investments for Greenhouse Gas and Energy Reduction (TIGGER) Program under the American Recovery and Reinvestment Act (ARRA), is being cooperatively performed by Metro and VYCON. The initial WESS deployment is of a 2 MW rated system with a 15 s charge / discharge time, and an 8.33 kWh energy capacity. The WESS design allows easy expansion to a 6 MW rating. This paper presents results from initial MRL tests to measure regenerative energy savings which occur during revenue service operations, before installing the WESS.

The Los Angeles County Metropolitan Transportation Authority (LA METRO) subway provides service with up to six-car trains at up to 65 mph at five minute headways on weekdays. To reduce energy usage, LA METRO implemented a flywheel-based Wayside Energy Storage Substation (WESS), which reduces energy usage by capturing and reusing braking energy generated by trains when they decelerate and brake approaching the passenger station. The LA METRO WESS has a 2 MW, 15 second capacity, or 8.33 kWh, and can charge and discharge with a 1.5 minute cycle rate. WESS has been in daily full operation since August 2014. WESS has saved 10 to 18% of the traction power energy at the Westlake TPSS, every day.

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