Analysis of the Electric Locomotives Neutral-section Passing Harmonic Resonance

doi:10.4236/epe.2013.54B104

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Energy and Power Engineering, 2013, 5, 546-551

doi:10.4236/epe.2013.54B104 Published Online July 2013 (http://www.scirp.org/journal/epe)

Analysis of the Electric Locomotives Neutral-section

Passing Harmonic Resonance

Xiaofeng Jiang, Zhengyou He, Haitao Hu, Yangfan Zhang

School of Electrical Engineering, Southwest Jiaotong University, Chengdu, China

Email: [email protected]

Received April, 2013

ABSTRACT

For the further analysis and suppression of the electric locomotives neutral-section passing overvoltage, on the basis of

theoretical analysis of the neutral-section passing harmonic resonance conditions, this paper establishes simplified har-

monic resonance simulation models of the electric locomotives neutral-section passing using MATLAB/Simulink, and

makes the overvoltage simulation analysis of the existing electric locomotives neutral-section passing system in the

event of a harmonic resonance. Results show that when the system harmonic resonance occurs, the operating overvolt-

age of the neutral-section passing is serious intensified by the overvoltage of the harmonic resonance, which will make

the voltage of the pantograph collector head exceeding 100 kV. This amplitude of the overvoltage will breakdown the

air gap, which will be a serious threat to the safety operation of the electric railway. However, this kind of neu-

tral-section passing overvoltage hasn’t cause the attention in the field and theoretical studies, which need more analysis

and verification in the further study.

Keywords: Neutral-section passing; Harmonic Resonance; Overvoltage; Equivalent Modeling; Simulation Analysis

1. Introduction

Recently, the electric railways develop rapidly in China.

With the high-speed, high-capacity and large-scale rail-

way, the electric sectioning device based on the overlap-

ping section with the advantages of hard-spot little and

enterclose-smoothly is widely used in heterogeneous

tractive power supply system. However, it exposes new

problems in electric field at the same time of the applica-

tion and popularization. While the locomotive passed by

the electrical sectioning device, it has strong transient

process such as overvoltage and overcurrent, and it

brings security issues in electric railway.

At present, in view of the electric locomotives neu-

tral-section passing overvoltage research has been com-

prehensive, and it conducts by two fields that the ex-

perimental research and simulation study. In the field of

experimental research, locomotive Department in Lan-

zhou Railway Bureau organizes relevant units which

sponsored Southwest Jiaotong University, China Railway

First Survey and Design Institute and Zhuzhou Electric

Locomotive Research Institute making field tests in the

Lan-Xin Railway Wuwei to Jiayuguan Segment. The

problem of over-voltage when the electric locomotive

passed by the electrical sectioning device based on the

overlapping section has been studied in [1]. In simulation

study, the traction-locomotive system was divided into

four transient processes by the physical process of the

electric locomotives neutral-section passing, to establish

equation of transient process, the voltage of the panto-

graph collector head and the renewed arc in a transient

process have been calculated respectively in [2]. Simula-

tion model of electric locomotive neutral-section passing

has been built with using Pspice in [3], which made si-

mulation analysis of the electric locomotives neutral-

section passing processes when the voltage working un-

der different degrees of saturation and the neutral-section

passing processes of the system which was added the

disincentives.

However, in present studies, few of them take the in-

fluence of harmonic resonance into account, except the

analysis of neutral-section passing overvoltage under the

condition of ferroresonance in [4]. Because of the appli-

cation of the electrical sectioning device based on the

overlapping section, the length of neutral section is about

150-300 m, which increases the likelihood of parameter

matching with resonance. In the case of parameter

matching, resonance and serious harmonic amplification

may occur when the system meets the condition of har-

monic resonance. Because of the voltage distortion

*This work is supported by High-Speed Railway Basic Research Fund

Key Project (U1134205); National Natural Science Foundation o

China (51177139); Science & Technology Research and Development

Key Project of Railway Ministry (2011J023-B).

X. F. JIANG ET AL. 547

which is caused by the resonance and the harmonic cur-

rent increased further, interanimation of the positive

feedback is formed, which results to a resonant over-

voltage and the burning loss of equipment in the process

of the neutral-section passing.

Based on this, according to the careful analysis of neu-

tral-section passing transient process in the condition of

harmonic resonance, the ‘traction network-locomotive’

equivalent model was built. Through the MATLAB/ Si-

mulink, the process of the electric locomotives neutral-

section passing harmonic resonance overvoltage is ana-

lyzed, and we can conclude that the harmonic resonance

has a strong impact on the neutral-section passing over-

voltage, which should be analyzed and considered in the

future research.

2. The Analysis of the Traction Network

Harmonic Transmission Characteristics

Due to the large number of actual traction network wire,

the multi-conductor transmission system was simplified

to an equivalent circuit of the harmonic transmission as

shown in Figure 1 to study the harmonic transmission.

Among which, L1 represents the distance of the section

post and harmonic source, L2 represents the distance of

the traction substation and harmonic source, Ih represents

equivalent current of the harmonic source, If represents

the component which the harmonic source current flows

to section post, Iq represents the component which the

harmonic source current flows to traction substation, Is

represents the traction network current where the dis-

tance from the traction substation is s, Zs represents the

equivalent impedance of traction substation.

Through the steady-state equation and the equivalent

circuit of the power transmission line, the equivalent cir-

cuit with distribution parameters on both sides of the

harmonic source can be shown in Figure 2.

Figure 1. Equivalent circuit of the traction power supply sys-

tem harmonic transmission.

Figure 2. Equivalent circuit of traction network.

It can be concluded from derivation that:

(1)

ZchL

sh LZ

ZchL

hL Z



















(1)

In the equation, t

represents the line characteristic

impedance, /

ZY;

, denote respectively the

equivalent impedance and admittance per unit length of

traction network;



represents line propagation coeffi-

cient,



.

The magnification of the traction network harmonic

current can be gotten as[5]:

2121

()

=() ()

sst

mpx st

IZshsZchschL

ZshLLZchLL







 (2)

As seen in the equation (2) that Amax reaches its maxi-

mum when denominator is set approximately to 0, which

is seen as resonance. The resonance condition can be

deduced that:

12 12

() ()

Zsh LLZch LL0





 (3)

As 1L



, so th LL





, and

/( )





 (4)

Consider that the equivalent impedances of traction

substation mainly consist by the traction transformer in-

ductance Ls , so





(5)

And the resonance frequency can be deduced:

1/(2 )



 (6)

As is seen in the equations (5) and (6) that the farther

the harmonic wave source is away from the traction sub-

station, the larger the current magnification of harmonic

wave is. The transmission characteristics and resonant

frequency of harmonic current in the traction network are

mainly affected by the length of the traction network, the

equivalent impedance of traction substation, the distribu-

tion parameters of traction network, the position of lo-

comotive, and so on. When the harmonic frequency in-

jected from the harmonic source to traction network is

equal to or close to the resonant frequency of traction

network [6], the harmonic wave is enlarged significantly,

and the system resonates.

3. The Equivalent Modeling of

Neutral-section Passing Harmonic

Resonance Overvoltage

The process of electric locomotive’s passing section-

phase is relatively complex, during which the pantograph

has multiple instant contacts and separations with the

X. F. JIANG ET AL.

548

contact wire of catenaries and neutral line at different

positions. At these instant moments, the circuit topology

changes, causing the system’s electromagnetic transient

processes. During these processes [7], the system pa-

rameters may meet the resonance conditions, leading to

the harmonic resonance of neutral-section passing, which

exacerbates overvoltage of neutral-section passing.

As for the overvoltage above, it can be analyzed by the

use of the equivalent harmonic resonance overvoltage

model of neutral-section passing. Equivalent model con-

sists of four parts: catenaries, neutral section, locomo-

tives, and the harmonic source. To establish a simplified

equivalent model with coupling relationship makes a

great significance to the analysis of the neutral-section

passing transient process. The equivalent modeling of

catenaries and the neutral section is similar to the equiva-

lent circuit of the electric wire, which adopts



model

equivalent circuit. The locomotive’s equivalent model is

divided into two parts of normal operation and cutting

the main circuit breaker off the locomotives. When run-

ning normally, locomotive’s equivalent model is replaced

by impedance; otherwise, the locomotive left only inter-

related circuit on the high-pressure side, and thus uses

resistors, inductors and capacitors to represent that on the

high-pressure side.

Based on the field measurement, more serious over-

voltage in neutral-section passing occurred in the tran-

sient process after the main breaker was cut. Thus, the

harmonic source considered in this paper is not provided

by the locomotive itself but by other locomotives through

the traction network, which here equivalent with an ideal

current source. On the basis of the four parts of equiva-

lent circuit above [8], we considered the equivalent

source and equivalent impendence of the traction substa-

tion and the capacitance between catenaries and neutral

section to build the equivalent model of the neu-

tral-section passing harmonic resonance overvoltage as

shown in Figure 3.

Among this, the left and right powered arm in the trac-

tion network are series-connected by traction substation’s

equivalent power (ua, ub) and equivalent impedance (Zsl,

Zsr); the locomotive model is replaced by the locomotive

equivalent impedance (Zm); the harmonic source is

equivalent to an ideal current source(Ih); the traction

network and neutral section line equivalent circuit of left

and right powered arm are formed by two parts of equiv-

alent impedance (Ztl,Zn,Ztr) and capacitance (Ctl,Ctl1,

Cnl,Cnr,Ctr,Ctr1) to ground, taking the capacitance

(Ccnl,Ccnr) between left, right arms and neutral segment of

traction network into consideration at the same time, to

accomplish the equivalent modeling for simulation model

of harmonic resonance overvoltage of section-phase

passing.

4. Simulation Analysis of the Neutral-section

Passing Harmonic Resonance Overvoltage

This paper selects the automatic on-board neutral-section

passing system based on the overlapping section as the

research object, and the neutral-section passing transient

process is divided into five transient processes, based on

the different operating position of the locomotives in the

electrical sectioning device.

4.1. The First Transient Process

The first transient process is the contact of the closure

and the dead section transient process when the electric

locomotives enter the dead section. On the basis of the

previous analysis, after the appropriate circuit simplifica-

tion and equivalent, the establishment of the transient

process simulation model is shown in Figure 4.

The simulation model is built in MATLAB / Simulink

as shown in Figure 4, by controlling the closure of the

circuit breaker and setting the current value of the har-

monic source analog the harmonic resonance overvoltage

analysis, as the contact of the closure and the dead sec-

tion transient process when the electric locomotives enter

the dead section.

4.2. The Second Transient Process

The second transient process is the separate of the clo-

sure and the dead section transient process when the

electric locomotives enter the dead section. On the basis

of the previous analysis, after the appropriate circuit

simplification and equivalent, the establishment of the

transient process simulation model is shown in Figure 5.

Figure 3. The equivalent schematic of the electric locomo-

tives neutral-section passing harmonic resonance overvolt-

age.

Figure 4. Simulation analysis schematic diagram of the first

transient process.

X. F. JIANG ET AL. 549

Figure 5. Simulation analysis schematic diagram of the

second transient process.

The simulation model is built in MATLAB / Simulink

as shown in Figure 5, by controlling the closure of the

circuit breaker and setting the current value of the har-

monic source analog the harmonic resonance overvoltage

analysis, as the separate of the closure and the dead sec-

tion transient process when the electric locomotives enter

the dead section.

4.3. The Third Transient Process

The third transient process is the contact of the closure

and the dead section transient process when the electric

locomotives exit the dead section [9]. On the basis of the

previous analysis, after the appropriate circuit simplifica-

tion and equivalent, the establishment of the transient

process simulation model is shown in Figure 6.

The simulation model is built in MATLAB / Simulink

as shown in Figure 6, by controlling the closure of the

circuit breaker and setting the current value of the har-

monic source analog the harmonic resonance overvoltage

analysis, as the contact of the closure and the dead sec-

tion transient process when the electric locomotives exit

the dead section.

4.4. The Fourth Transient Process

The fourth transient process is the separate of the closure

and the dead section transient process when the electric

locomotives exit the dead section. On the basis of the

previous analysis, after the appropriate circuit simplifica-

tion and equivalent, the establishment of the transient

process simulation model is shown in Figure 7.

The simulation model is built in MATLAB / Simulink

as shown in Figure 7, by controlling the closure of the

circuit breaker and setting the current value of the har-

monic source analog the harmonic resonance overvoltage

analysis, as the separate of the closure and the dead sec-

tion transient process when the electric locomotives exit

the dead section.

4.5. The Fifth Transient Process

The fifth transient process is the closure of the main cir-

cuit breaker transient process when the electric locomo-

tives exit the dead section [10]. On the basis of the pre-

vious analysis, after the appropriate circuit simplification

and equivalent, the establishment of the transient process

simulation model is shown in Figure 8.

The simulation model is built in MATLAB / Simulink

as shown in Figure 8, by controlling the closure of the

circuit breaker and setting the current value of the har-

monic source analog the harmonic resonance overvoltage

analysis [11], as the closure of the main circuit breaker

transient process when the electric locomotives exit the

dead section.

5. Simulation Analysis

Calculating and setting the parameters in the above mod-

els [12], the value of Cm is 1 uF, the value of Lm is 5H,

the value of Rm is 100 MΩ, the value of Ln is 0.001H, the

value of Rn is 0.039 Ω, the values of Cnl and Cnr are 71 nF,

the values of Rsl and Rsr are 0.02 Ω, the values of Lsl and

Lsr are 1.19 mH, the values of Ctl、Ctl1、Ctr、Ctr1 are 40.26

nF, the values of Rtl and Rtr are 2.34 Ω, the values of Ltl

and Ltr are 0.06 H ,the values of Ccnl and Ccnr are 5 uF.

Figure 6. Simulation analysis schematic diagram of the

third transient process.

Figure 7. Simulation analysis schematic diagram of the

fourth transient process.

Figure 8. Simulation analysis schematic diagram of the fifth

transient process.

X. F. JIANG ET AL.

550

(a) The voltage oscillogram of the first transient process

(b) The voltage oscillogram of the second transient process

(d) The voltage oscillogram of the fourth transient process

(e) The voltage oscillogram of the fifth transient process

Figure 9. The voltage oscillograms of the pantograph col-

lector head.

By setting the circuit breaker operation time is 0.20428

s, and the frequency of the ideal current source was taken

to the resonant frequency of the transient process [13].

When the value of is 0 A to simulate that the system does

not occur harmonic resonance overvoltage, and when the

value of is 5A to simulate that the system occurs har-

monic resonance overvoltage. Simulation analysis of the

all five transient processes, Figure 9 shows the wave-

form summary of the voltage of the pantograph collector

head.

The simulation analysis shows that the operating

overvoltage of the neutral-section passing is serious in-

tensified by the overvoltage of harmonic resonance [14],

when the system harmonic resonance occurs, which

made the amplitude of the overvoltage exceed 100kV.

Over time, the overvoltage of the neutral-section passing

tends to smooth. In the first four transient processes, the

harmonic resonance occurred before and after the circuit

breaker operation. This is because that the system pa-

rameters don’t before and after the breaker action, so the

resonant frequency doesn’t change significantly. How-

ever, in the fifth transient process, the system didn’t oc-

cur the harmonic resonance before circuit breaker opera-

tion [15]. This is because that the system parameters

change significantly after the breaker action. The fre-

quency of the harmonic source applied to the system is

the resonance frequency after the circuit breaker opera-

tion.

6. Conclusions

Through modeling the simplified traction power supply

system and electric locomotive, and dividing, modeling,

analyzing and simulating for the electric locomotives

neutral-section passing process, one can know that over-

voltage caused by the harmonic resonance when the sys-

tem meet a condition that harmonic resonance could

taken place can lead to the voltage during

phase-separation process operating seriously intensifica-

X. F. JIANG ET AL.

551

tion [16], which will make the voltage of the pantograph

collector head exceeding 100 kV and penetrating the air

gap and causing serious threats to the electric railway

safety operation. However, this kind of neutral-section

passing overvoltage hasn’t cause the attention in the field

and theoretical studies, which need more analysis and

verification in the further study.

7. Acknowledgements

The authors would like to thank the High-Speed Railway

Basic Research Fund Key Project (U1134205); National

Natural Science Foundation of China (51177139); Sci-

ence & Technology Research and Development Key

Project of Railway Ministry (2011J023-B) for financial

support.

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