METHOD FOR POWER OPTIMIZATION IN A VEHICLE/TRAIN HAVING AN EFFICIENCY THAT DEPENDS ON THE OPERATING POINT

PROCEDE D'OPTIMISATION DE LA CONSOMMATION ENERGETIQUE POUR UN VEHICULE/TRAIN A RENDEMENT DEPENDANT DU POINT DE TRAVAIL

English Abstract

The invention relates to a method for optimizing the energy consumption of a
motor vehicle/train that uses time reserves provided for in a schedule. The
aim of the invention is to improve the operating characteristics of said motor
vehicle/train in such a manner that energy is saved by using an optimization
algorithm. To this end, the correlation between the vehicle efficiency or the
dissipated energy and the operating point is taken into consideration.

French Abstract

Procédé d'optimisation énergétique pour un véhicule/train en cas d'utilisation des temps de réserve prévus par un tableau de marche. Pour parvenir à une manière de rouler économisant de l'énergie à l'aide d'un algorithme d'optimisation, on prend en considération la dépendance existant entre le point de travail et le rendement du véhicule ou la dissipation de puissance.

Claims

5
Claims
1. A method for the power-optimal travel mode of a
vehicle/train, the time reserves for unforeseen
events and adverse operating conditions included
when planning schedules being available for saving
power by means of a power-optimal travel mode,
wherein the dependence of the vehicle efficiency,
defined as the quotient of the tractive power
provided - the output power - and the input power
needed for this purpose, on the tractive force
and/or speed and/or temperature is used for the
purpose of optimizing the power with regard to the
time reserves.
2. A method for the power-optimal travel mode of a
vehicle/train, the time reserves for unforeseen
events and adverse operating conditions included
when planning schedules being available for saving
power by means of a power-optimal travel mode,
wherein the dependence of the vehicle power loss,
defined as the difference between the input and
the output power, on the tractive force and/or
speed and/or temperature is used for the purpose
of optimizing the power with regard to the time
reserves.

Description

CA 02379775 2002-O1-28
Method for power optimization in a vehicle/train having
an efficiency that depends on the operating point
Description
The invention relates to a method for power
optimization in a vehicle/train according to the
preamble of claim 1.
During the planning of journeys and the drafting of
schedules for rail traffic, time reserves for
-unforeseen events and adverse operating conditions are
included in the plans. Since, during real journeys, the
operating conditions are typically more favorable than
those assumed during planning, the time reserves
created by this are available for other purposes. A
particularly practical use of the time reserves resides
in the saving of power by means of a suitable travel
mode.
Previously known and used methods for power
minimization are mostly based on the assumption that a
travel mode comprising the constituents maximum
acceleration - travel at constant speed - coasting -
maximum retardation is optimum in power terms. In this
case, the mechanical tractive power which is needed to
accelerate the vehicle is minimized. For verification,
a linear dynamic train model is used, in particular no
account being taken of any term which describes the
quadratic relationship between speed and travel
resistance.
In DD 255 132 Al, this- basic' assumption is expanded by
subdividing a total route into a number of sections, so
that in each section the slope resistance of the route
is constant.

CA 02379775 2002-O1-28
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In EP 0 467 377 B1, the subdivision of the overall
route into a number of sections is introduced in such a
way that in each section the permissible maximum speed
is constant. The travel mode comprising the
constituents maximum acceleration - travel at constant
speed - maximum retardation is repeated in each
section. Coasting is therefore dispensed with.
EP 0 755 840 A1 does not describe a practical method
for power optimization but instead explains a general
system structure with which power optimization can also
be implemented. A cycle comprising acceleration -
travel at constant speed - retardation and braking is
listed as an example.
The invention is based on the object of specifying an
improved method for power optimization with regard to
the time reserves included in the planning of a
schedule of a vehicle/train.
This object is achieved, in conjunction with the
preamble, by the features specified in claim 1.
The advantage which can be achieved by the invention is
in particular that, by taking into account the
dependence of the vehicle efficiency on the operating
point in the optimization algorithm, instead of the
mechanical tractive power, it is the power primarily
used, such as the electrical power in electric rail
vehicles, which is minimized.
An advantageous refinement of the invention is
identified in the subclaim. __
Further advantages of the proposed method emerge from
the following description.

CA 02379775 2002-O1-28
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The invention will be explained in more detail below
using the exemplary embodiments illustrated in the
drawing, in which:
Figs. 1, 2 show characteristic maps of the power
loss of typical electric locomotives,
Fig. 3 shows an exemplary speed plot at an
assumed constant vehicle efficiency and
maximum speed, and
Fig. 4 shows an exemplary optimum speed plot
taking into account the dependence of
the vehicle efficiency on the operating
point, and maximum speed.
The vehicle efficiency is the ratio between the
tractive power provided - the output power - and the
input power needed for this, in particular the electric
power, which is drawn by an electric locomotive via a
pantograph. The difference between the input power and
the output power is the power loss of the vehicle.
The invention provides for the dependence of the
efficiency on the operating point to be included in the
power optimization or for power optimization with
regard to the time reserves included in the planning of
a schedule of a vehicle/train, since a calculation with
an assumed constant efficiency represents only a poor
approximation to the actual optimum. In this case, the
problem of power minimization is formulated as a
mathematical optimization problem and is solved by a
suitable, generally known_optimization algorithm.
Optimization algorithms which are suitable for the
proposed method are known, for example, from
Papageorgiou: Optimierung [Optimization], Chapters 10,
19 and in particular 20, Oldenbourg Verlag, 1996.

CA 02379775 2002-O1-28
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The dependence of the efficiency on the operating point
can be taken into account via a function of the
efficiency or the power loss as a function of important
influencing variables, such as in particular the
tractive force and/or speed and/or temperature. For
this purpose, Figures 1 and 2 show characteristic maps
of the power loss of typical electric locomotives. Such
a three-dimensional characteristic map of the power
loss as a function of the tractive force and the speed
is a typical option for representing the dependence of
the efficiency on the operating point.
Fig. 3 shows, as a traveling diagram, an exemplary
distance/speed plot - see the continuous curve - with
an assumed constant vehicle efficiency and maximum
speed in the individual route sections - see the dashed
curve. The travel mode illustrated is composed of the
known constituents, these being used repeatedly in each
subsection with constant speed limitation. These known
constituents are essentially maximum acceleration,
coasting and braking in the first section, followed by
"travel at constant speed" in the slow-travel section,
followed by maximum acceleration and the change between
coasting and braking to a standstill.
Fig. 4 shows, in comparison with this, as a travel
diagram (and determined in accordance with the
characteristic map according to Fig. 1) an exemplary
optimum speed plot - see continuous curve - taking into
account the dependence of the vehicle efficiency on the
operating point and maximum speed - see the dashed
curve. The optimum. travel._mode illustrated differs
considerably from travel modes which can be determined
with previously known methods (see Fig. 3). In
particular, in the exemplary embodiment illustrated,
use is made of reduced acceleration, which merges
smoothly into the braking.

Representative Drawing