Instrumentation & Measurement Magazine 26-2 - 8

Compared with the
existing works, the comprehensive
models in
this paper can better reflect
the different states of
PCA at the common and
neutral sections. In addition,
the relationships
between the Larc
, d, the
Fig. 7. Transient process of PCA generation at the neutral section.
parameter model when the train passes through the neutral
section. For example, in [22], the author subdivided the
process of PCA generation into four transients, as shown in
Fig. 7. There are four arcing times during the whole process.
Firstly, before the train enters the C-D section, the distance
between the pantograph and the neutral line gradually decreases.
The first arcing occurs when the voltage between the
air gaps increases and breaks through the air. Secondly, when
the train reaches D, the second arcing occurs due to the separation
of the pantograph and the power supply line (phase
A). Thirdly, when the train reaches E after sliding through the
no power area, the pantograph contacts with the power supply
line (phase B), resulting in the third arcing. Finally, the
fourth arcing occurs when the train is separated from the
neutral line after running to F. When the train contacts the
power supply line (phase B), the normal power supply will
be restored.
Therefore, when the distributed parameter model of
the train was established, the arc model (Rarc) was placed at
four different positions in the model in [22]. However, the
Habedank arc model used in the model has not been improved.
Moreover, the model at the common section was
not studied.
Improvement of the Habedank Arc Model: As mentioned, the
Habedank arc model needs to be improved to meet the actual
situation of PCA. The arc voltage (Earc
(Ploss
) and dissipation power
) in the model need to be recalculated. In [23], firstly, the
authors analyzed the switching process of ac high-airflow arc
repeatedly. Then, the Ploss
( P kg L n

loss
arc ) was calculated by
combining the dissipated power factor (β), arc pyroelectric
coefficient (k), and arc length index (n). According to the simplified
circuit for the China high speed rail line, they derived
the relationship between k and the arc current, arc equivalent
resistance, equivalent arc length, and β. Finally, they obtained
the approximate values of β and k to calculate Ploss
by combining
the results of simulation and test system.
However, there are still some shortcomings in improving
the arc model in [23]. Firstly, the different states of PCA at the
common and neutral sections and the influence of the transverse
and longitudinal arc blowing are not considered when
calculating the Earc
and Ploss
Larc
. Secondly, the authors assume that
is equal to d. However, at the neutral section, they are not
equal because of the influence of multiple external forces.
8
train speed, and multiple
external forces are considered
comprehensively to
make the calculation results of parameters in the model more
reasonable.
Analysis of Simulation Results of the
Comprehensive Model
Simulation Results of the Comprehensive Model
In the next analysis, the improved PCA models are put into
the distributed parameter models of the high-speed train (the
position of the Rarc
The characteristic curves of the transient voltage and current
of the EMI when the train passes through this position
at 80 km/h, 150 km/h and 250 km/h are calculated by simulation,
as shown in Fig. 8. Similarly, the characteristic curves
of the transient voltage and current of the EMI when the train
passes through the neutral section at 80 km/h, 150 km/h and
250 km/h are shown in Fig. 9.
Experimental Validation
The PCA Test System is used to measure the electrical characteristics
of PCA. It is composed of a PCA generator and test
system, as shown in Fig. 10, where the variable frequency
motor is used to drive the wheel to rotate to simulate the mutual
movement of the power supply line and the pantograph,
and the arrow direction indicates the moving direction. The
servo motor and roller screw drive are used to simulate the
movement of the pantograph [24]. In addition, the relevant
parameters of the train, PCA, and power supply system
in the test system are set to be consistent with the model (a
typical high-speed electrified rail transit system in China,
27.5 kV/50 Hz).
The maximum transient voltage and current of PCA are
measured by using the PCA Test System. Therefore, the wheel
speed is set to 250 km/h, and the results of measurement
and simulation are listed in Table 4. The error of experiment
and simulation is within 10%, so the simulation results of the
model are reasonable.
Analysis of the EMI Transient Characteristic
◗ The EMI of the high-speed train in the neutral section is
more serious than that in the common section, which is
reflected in the obvious increase of the peak value and
IEEE Instrumentation & Measurement Magazine
April 2023
in Fig. 4 and Fig. 6), respectively, and the
transient voltage and current of the EMI are simulated and
calculated.
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