Mitsubishi Heavy Industries Technical Review Vol. 47 No. 2 (June 2010)
1Integrated APM/LRT Simulator for Energy Evaluation
YASUYUKI SUZUKI*1

KYOTARO ONISHI*1

HIROSHI YAMASHITA*2

KATSUAKI MORITA*3NORITAKA YANAI*3

MASAYA MITAKE*4

In response to the growing interest in environmentally friendly energy-efficienttransportation systems, Mitsubishi Heavy Industries, Ltd. (MHI) has developed a simulation systemfor evaluating the operational aspects and energy efficiency of guided transportation systems. The
simulator can be used to analyze not only conventional systems that use a contact line to supply
electricity to trains, but also energy-smart transportation systems that use a battery. Improvements
in system design efficiency and optimal system planning are now possible because the simulator
enables the comprehensive evaluation and energy analysis of complete transportation systems aswell as single trains. This article provides an overview of the simulator.

|1. Introduction
Environmentally-friendly transportation systems are attracting greater attention asenvironmental issues become a global concern. MHI provides safe and comfortable groundtransportation systems around the world, including an automated people mover (APM), a newsystem equipped with rubber tires, and steel-wheeled light-rail transit (LRT) systems. At the sametime, MHI is actively pursuing the development of high-performance batteries with greater energy
and output densities. Aimed at use in guided transportation systems, and hybrid and electricvehicles, battery performance is improving rapidly. The need for energy-efficient transportation
systems is expected to grow. System conditions such as gradient, operational conditions, number ofcars, and requirements for battery systems vary greatly depending on the client’s routespecifications. The use of simulation techniques for overall system evaluation is crucial to be able
to respond swiftly to each client’s specific needs, and to offer a system that enables transportationof the required capacity with optimal energy efficiency.
MHI’s transportation system simulator allows the company to improve system design
efficiency and to offer optimal client-specific system solutions. The program also features
animation capabilities that provide users better visual and intuitive understanding of train
performance characteristics.

|2. Simulator overview
As shown in Figure 1, the simulator recreates the overall behavior of a transportation system
by linking models of components, such as the power, trains, operation control system, andsignaling system, with a separate ground model.
The ground model controls the network structure of the tracks, track circuit, and gradientdata. While the train model performs runs between stations based on departure commands from theoperation control system model, it also requires gradient information from the ground model andeffective thrust force from the power model for accurate kinetic calculations. The travel distancedata from the kinetic calculations are sent to the ground model, which returns data on thepost-travel vehicle position and gradient, as well as speed signals for automatic train operation. Thesignaling system model performs speed signal setting and turnout control for the track circuit basedon route requests from the operation control system model, train positions, and turnout status.
*1

Manager, Transportation Systems and Advanced Technology Division*2

Manager, Hiroshima Research and Development Center, Technical Headquarters*3

Hiroshima Research and Development Center, Technical Headquarters*4

Nagoya Research & Development Center, Technical Headquarters

Mitsubishi Heavy Industries Technical Review Vol. 47 No. 2 (June 2010)
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Incorporation of the automatic operation system and the signaling system model in thesimulator enables not only evaluation of the energy efficiency but also analysis of a wide range offunctions, such as master system planning and block system design. Sections 2.1 to 2.4 provide anoverview of the key components of the simulator.

Figure 1 Simulator overview

The simulator links models of the power, trains, operation control system, and signaling system with a separate
ground model to simulate the overall behavior of a transportation system.

2.1Train model

Based on detailed logic modeling of on board controller, the train model accurately replicatesthe control of speed for optimal ride comfort, gradient correction, fixed-position stopping, and train
behavior when a particular speed profile is exceeded (Figure 2). The train model consists of thefollowing components.

Figure 2

Run curve

Train positions are indicated on the horizontal axis while speed signals, train speed, elapsed time, and gradientdata are shown on the vertical axis. The train model accurately replicates the motor characteristics, gradienteffects, and speed control required to achieve a comfortable ride.

(1) Automatic train operation (ATO)
The use of automatic operational logic equivalent to that used in MHI’s autonomous
APMs allows detailed simulation of ride comfort by controlling jerking and fixed-position
stopping, thus enabling high-precision calculations of time required for traveling. As anenergy-saving feature, ATO also features a function for trams that predicts the timing of traffic
signal changes and adjusts the speed to avoid sitting at stoplights (Figure 3). The function
improves the energy efficiency by limiting unnecessary acceleration and deceleration of thetrain.

Mitsubishi Heavy Industries Technical Review Vol. 47 No. 2 (June 2010)
3Figure 3

Run curve comparison of normal and energy-saving operations

The speed of the train is kept low when nearing traffic lights to avoid deceleration and saveenergy based on prediction of the traffic signal changes. The acceleration/deceleration
frequency is thus reduced without changing the overall running time.

(2) Automatic train protection (ATP)The simulator features an automatic train control system for a preliminary study of theminimum headway, a key requirement for guided transportation systems. The simulator also
includes automatic train protection (ATP) to prevent collisions and derailments. This feature
decelerates the train when approaching too close to the train in front or when a turnout has beenswitched. The ATP system is equivalent to the automatic train control system (ATC) commonlyused in Japan, and operates in concert with the wayside signaling system model described
below.
(3) Kinetic calculations
Kinetic calculations of the train motion are performed by applying the motor’s effective
thrust, gradient, and travel resistance based on a notch command supplied by the ATP/ATOsystems. The effect of insufficient power due to voltage drops can also be simulated because
effective thrust is determined by a circuit network calculation in the power model.

2.2

Power model

In the power model, devices such as the contact line-powered systems, substations, batterysystems, and charger systems can be positioned at any point along a route. The power rails caneither be set over the full length of the route (common practice), partially set, or not set at all. The
train type can be selected as either standard contact line-powered or battery-powered, with theoption of placing multiple trains on the route.
The model’s capacity for dynamic simulation allows flexible output of the state of charge
required for evaluation of current/voltage behaviors and batteries at multiple points during train
operation (Figure 4). The resulting data can be used for analysis of voltage drops on the contact
line, and substation and battery capacities to determine the specifications of each device. The
model also provides data for overall system power consumption in addition to individual data foreach train and facility.

2.3

Signaling system model

The signaling system model consists of the interlocks and the ATP required to conduct
accurate simulation of complex train operations such as re-entering a main line.
(1) Interlock
The interlock controls turnouts, the signal aspect based on the track circuit status, theturnout status, and the route requests received from the operation control system.
(2) ATPThe ATP sends speed signals to the track circuit appropriate to the number of open
sections on the route. The ATO and ATP described in Section 2.1 permit automated train
operation based on these speed signals. Inclusion of this signaling system model allows anoverlapping display of accurately simulated train behavior and block-by-block speed data(Figure 5), which can be used for preliminary evaluation of the signaling system.

Mitsubishi Heavy Industries Technical Review Vol. 47 No. 2 (June 2010)
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Figure 4

Power simulation

The model’s dynamic simulation capability allows flexible output of the state of charge required for evaluationof current/voltage behaviors and batteries during train operation.

Figure 5

Train operation simulation

Train behaviors and block-by-block speeds overlapping on the diagram withtime on the x-axis and train position on the y-axis are used for preliminary
evaluation of the signaling system.

2.4

Operation control system model

The operation control system model monitors the entire system, sending run commands totrains based on train diagrams and route requests to the signaling system model.

|3. Visualization capability
The simulator is equipped with visualization capability to display the simulation results in athree-dimensional animation (Figure 6) and allow users who are not train specialists to understandtrain behaviors intuitively.Mitsubishi Heavy Industries Technical Review Vol. 47 No. 2 (June 2010)
5(1) The train in theforeground isalready on the main
track and is now
passing the turnout.
(2) The train in theforeground has
passed the turnout;
the turnout is now
being switched over.
(3) The switch iscomplete; the routefor the second train
is now clear.
(4) The second train
enters the turnout.

Figure 6

Three-dimensional animated display showing an example of a turnout area

|4. Evaluation sample
After the simulator was developed, its accuracy was verified using performance dataobtained from MHI’s test track and actual train routes. Examples of evaluations using the simulator
include a comparison of power consumption with various operational scenarios and power facility
configurations for the LRT system having streetlights on its route (Figure 7). The results below
show Case 1 (standard operation mode), Case 2 (energy-efficient operation mode) and Case 3 (useof battery systems in addition to the energy-efficient operation mode).
Although the power consumption in Case 2 was less than in Case 1 due to less-frequent
acceleration/deceleration, a power loss due to regenerative resistance still occurred in Case 2 (thered lines in the graph). Such a loss takes place when the regenerative power is not being used byother trains, thus causing a voltage increase in the contact line. In Case 3, however, the power
consumption was further reduced as the regenerative power was collected using battery systems, tobe used later (the green line on the graph).
Energy-efficient operation modeUse of battery devices

Figure 7

Not applicableNot applicable

ApplicableNot applicable

Applicable
Applicable

Power consumption comparison

In Cases 2 and 3, the energy-efficient operation modes, trains accelerate and decelerate less than in Case 1.
The power consumption in Case 3 is reduced even further due to regenerative battery.

|5. Conclusion
In response to the growing interest in environmentally friendly transportation systems, MHI
has developed a simulator that enables the evaluation and analysis of systems that use anenergy-efficient operation mode and battery, as well as conventional contact line-powered systems.
This simulator permits comparison of the power consumption of contact line-poweredsystems with that of energy-efficient systems, thus enabling verification of the energy efficiency.
This will allow MHI to contribute more fully to the wider use of energy-efficient guided
transportation systems by offering clients improved system design efficiency and optimal systemsolutions.