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National Railroad Passenger Corp. (Amtrak)

Acela and HHP Locomotives Regenerative Braking Support

LTK assisted Amtrak in the design, development and commissioning of the Acela High Speed Train sets and HHP locomotives between 1993 and 2002. This project also included the North End Electrification Project, a major design and construction effort with new 25 kV, 60 Hz catenary between New Haven, CT and Boston, MA.

EC1-AmtrakLTK served as the lead engineering firm for this project from start to finish with tasks of specification writing, evaluation of product offerings, design reviews, vehicle testing at TTCI in Pueblo, CO and on Amtrak’s Northeast Corridor (NEC) between Washington, DC and Boston.

LTK participated in every aspect of the design including propulsion, auxiliary power, HVAC, the dynamic tilting system, friction brakes, lighting, on-board diagnostics, the nine-aspect cab signal package, the Advanced Civil Speed Enforcement System (ACSES) and communications.

These vehicles are equipped with GTO inverter drives and regenerative braking to return the kinetic energy of the train back to the traction power system, where it can be used by other trains or returned to the utility grid. The “front end” has four quadrant PWM rectifiers to maintain near unity power factor under all modes of operation.  Between Washington and the Hell Gate Bridge in Queens, NY, the NEC catenary supply is 11.5 kV, 25 Hz.  The power is supplied by rotary converters, solid state converters and two waterwheel generators. This territory is highly receptive to regenerated power because of the density of electric train traffic and traction power system operation that normally does not open section breaks between Washington and the Hell Gate Bridge.

Between New Haven and Boston, the 25 kV, 60 Hz catenary is supplied by transformers from several utility companies and is capable of accepting regenerated power from the vehicles and supplying it back into the power grid. This section is also very receptive to regenerated power. The section between New Rochelle, NY and New Haven is owned and operated by Metro-North Railroad and is 12.5 kV, 60 Hz. The substations can accept regenerated power back to the utility grid.

Amtrak owns and operates a short 12.5 kV 60 Hz traction power system between the Hell Gate Phase Break in Queens, NY and Metro-North in New Rochelle.

During the early stages of the project, the electric power utility companies were reluctant to accept the regenerated power and feared poor power quality from the train. LTK worked with Amtrak to demonstrate through a series of tests that the power from the train had lower harmonic content than the existing power grid. The power companies then agreed to accept the regenerated power, yielding significant operating cost reductions.

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Metro-North Railroad

M-7 Electric Multiple Units Performance Optimization

When MTA Metro-North Railroad (MNR) received the first of their new M‑7 third-rail multiple unit cars from Bombardier in 2004, there was concern that the heavier M‑7s would be unable to maintain schedules that had been handled for years by the lighter M‑1a and M‑3a multiple units.  The M‑7s could certainly deliver the required schedule performance, but whether they could do it without tripping substation breakers was a separate question. 

EC2-MNRMNR's DC power distribution system had been optimized over the prior three decades for the older cars, with substation breaker settings known to provide both reliable service and reliable protection. MNR wanted to avoid – or minimize – any changes to the protective relaying of the DC power distribution system.  A key decision was whether the AC-drive M‑7s should be programmed for constant-rate performance mimicking the older DC-drive cars – resulting in a relatively slow take-off, with line current steadily rising across most of the speed range – or for full-capability initial acceleration, with current-limited (constant-power) operation taking over thereafter. 

LTK performed detailed simulations of MNR's power system for various M‑7 train lengths and programming options.  As a result, the full-initial-rate, current-limit solution was adopted.  Existing MNR schedules could be met, while ample margins against substation breaker tripping were preserved.  An interesting sidelight is that for the longest M‑7 trains – ten cars or more, deployed only on certain rush hour schedules – a whole-train current limit (already provided in the design) also had to be utilized.  The slight performance reduction that results is not significant on the specific express schedules to which these longer trains are assigned.

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New York Power Authority

Traction Power System Study and Energy System Storage Analysis

on New York City Transit System

EC3-NYPALTK was selected by the New York Power Authority and New York City Transit to identify, evaluate, and quantify potential benefits of aluminum contact rail and energy storage systems, such as batteries, supercapacitors, and flywheels.  In order to accomplish this, traction power simulations were performed on a set of typical system configurations.  The simulations were performed using specially developed software capable of representing train operation along an alignment and predicting the effects of regeneration and generic energy storage systems on maximum power demand requirements, energy consumption, and voltage improvement.

The study confirmed that power demand and energy savings are possible by implementing the aluminum contact rail, the energy storage system, or both.  Further, both technologies improve the voltage profile along the alignment as experienced by train operations.

In order to determine whether any one or more energy storage systems and the aluminum contact rail are economically viable, comprehensive financial analyses evaluating costs and benefits of the various options were performed.  The project costs included capital investment costs and annually recurring costs, such as the operation and maintenance (O & M) costs.  The project benefits included power demand and energy savings, as well as improvement in voltage profile along the system.  LTK computed the benefits of the projects using three different financial models – the Payback Period Method, the Return on Investment Method and the Net Present Value of Life-Cycle Costs/Benefits Method.

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Southeastern Pennsylvania Transportation Authority (SEPTA)

Market Frankford Subway/Elevated M4 Rapid Transit Vehicle

EC4-SEPTAFor nearly a decade, LTK has served as SEPTA’s consultant for rail vehicles, providing support for vehicle engineering and line operations staff on a task-order basis. Among the projects undertaken for SEPTA was the procurement of 220 M4 rapid transit cars now serving the Market-Frankford Subway/Elevated line. The first cars entered revenue service in 1997 with the final portions of the ABB Daimler Benz fleet commissioned by 1999.

The M4 cars are an engineered-to-order design incorporating microprocessor controls, on-board diagnostics, solid state GTO-based AC drive propulsion and solid state IGBT-based battery voltage supply. Included in the design is a system of wayside video cameras, communications and in-cab monitors to facilitate one-person train operation with enhanced door-monitoring features.

The car design provides higher performance, regenerative braking energy recovery, and air conditioning, all within the infrastructure weight limits of the prior, simpler car fleet.  Regenerative braking energy is used to supply the cars’ auxiliary power demands, such as lighting, heating, air conditioning and other carborne systems.  Regenerative braking energy is also returned to the traction power system, where it can be used productively by other nearby trains.  When no train or other demand source is nearby, the voltage at the cars’ third rail shoe rises as the regenerative energy is returned to the system.  To protect carborne and wayside equipment, the regenerative energy is, instead, diverted to on-board energy dissipation devices during times when the system has limited or no regenerative braking receptivity.

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Washington Metropolitan Area Transit Authority (WMATA)

Rail Cars - 30 Years of Procurement and Rehabilitation Support

LTK has provided railcar engineering and program management services for three decades to WMATA for the procurement of high performance rapid transit cars as well as several vehicle rehabilitation projects for service on the highly successful Washington subway system. The firm’s involvement with WMATA began in the late 1960s during initial procurement of 300 R1000 series cars built by Rohr. The initial Rohr fleet, built in Winder, Georgia, featured aluminum carbodies, padded seats and carpeting throughout the entire passenger area. The carpeting contributed to the warmth and quietness of the interior while contributing to public acceptance of the vehicles.

EC5-WMATAAs the WMATA system continued to grow and expansion was needed, LTK again joined with the Authority for the procurement of 466 series B2000, 3000 and 4000 Breda cars in a program that began in 1978.  The Breda cars featured aluminum carbodies and incorporated microprocessor-controlled propulsion, braking and ATC systems. The initial Breda contract provided 76 cam control cars similar to the Rohr fleet propulsion system and 18 solid-state chopper control cars for evaluation. The chopper system featured regenerative braking which returned braking power to the third rail system, thereby reducing energy costs and heat build-up under the car. Due to the success of the chopper cars, the remaining 372 Breda cars were all chopper control vehicles, supporting regenerative braking.

Following the completion of the Breda car procurement program in the mid-1990s, the original Rohr fleet was overhauled to convert to a solid-state propulsion control system, and the DC traction motors were replaced with AC traction motors. This brings the same energy-saving regenerative braking benefits to the entire WMATA rapid transit fleet.

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