Scrigroup - Documente si articole

Username / Parola inexistente      

Home Documente Upload Resurse Alte limbi doc  

 
CATEGORII DOCUMENTE






BulgaraCeha slovacaCroataEnglezaEstonaFinlandezaFranceza
GermanaItalianaLetonaLituanianaMaghiaraOlandezaPoloneza
SarbaSlovenaSpaniolaSuedezaTurcaUcraineana

AdministrationAnimalsArtBiologyBooksBotanicsBusinessCars
ChemistryComputersComunicationsConstructionEcologyEconomyEducationElectronics
EngineeringEntertainmentFinancialFishingGamesGeographyGrammarHealth
HistoryHuman-resourcesLegislationLiteratureManagementsManualsMarketingMathematic
MedicinesMovieMusicNutritionPersonalitiesPhysicPoliticalPsychology
RecipesSociologySoftwareSportsTechnicalTourismVarious

Harmonic Generation and System Response Characteristic in Electrified Railway - Focused on Measurement and Analysis -

electronics

+ Font mai mare | - Font mai mic



DOCUMENTE SIMILARE

Trimite pe Messenger
CONTROL STRATEGIES FOR A MULTIPLE DEGREE OF FREEDOM PROSTHETIC HAND
INSULATED GATE BIPOLAR TRANSISTORS BASED REVERSIBLE PWM CONVERTER FOR D.C. MOTORS
Automated Lighting System with Sound Activation
Optical Disc Technology
Designing your own power supply
Harmonic Generation and System Response Characteristic in Electrified Railway - Focused on Measurement and Analysis -
Aliasing Applications
AMV Convert Tool
Circuit Components
Development of a Parallel Structured Cycler System for Large Capacity Battery


Harmonic Generation and System Response Characteristic in Electrified Railway

- Focused on Measurement and Analysis -

Han-Min Lee

Korea Railroad

Research Institute

Email: hanmin@krri.re.kr

 



Abstract Harmonic current originating from electric locomotives can be magnified due to the impedance characteristics of power supply circuit and bring about various problems. That is, electromagnetic interference with communication lines, operational trouble in signaling, overheat and/or vibration in power capacitor, malfunction in protection relay and so on. Therefore, the exact assessment of the harmonic current flow must be undertaken at designing and planning stage for the electric traction systems.

For these reasons, we proposed a new approach to model and to analyze traction power feeding system focused on system response to current and voltage harmonic. Moreover, harmonic characteristics in electric train depend on its operational modes. Therefore, Measurements of harmonics are performed on the real railway power supply systems under normal operation. The spectrum and distortion analyses in measurement data are variously described in this study.

Keyword: Electrified Railway System, Harmonic Generation,  Harmonic Analysis

I.                     INTRODUCTION

The harmonic current happened in the electric train is resonated at the specific frequency by the impedance characteristic of the power supply system. The resonance causes the amplification phenomenon of the harmonic current and various problems.

The harmonic current make interference in the adjacent lines of communications and the railway signaling system. Furthermore, in case it flows on the side of power system, overheating and vibration at the power capacitors are caused. Also, abnormal operation at the protective devices can occur.

Therefore, we need to evaluate harmonic problems accurately in planning step to construct new electric railway system

In reference to this study, we showed how the system respond to the harmonics originated from electric train. That is, the system response to the harmonics was derived by computational algorithm with numerical formulas in theoretical aspects. However, the real catenary system has complex configuration of conductors. it is an important point that we can consider the circuit element of catenary conductors as uniformly a distributed RLC element. Moreover, harmonic characteristics of electric train depend on its operational modes [1].

From this point of view, measurements of harmonics are performed on the real railway power supply systems under the various operational modes. The spectrum and distortion analyses in measurement data are variously described in this study.

II.                   Measurements and analyses of harmonics

We analyzed the measurement data of the harmonic current on the test track of the high-speed railway system for the field test. The field test was performed in the KTX(Korea Train Express

) and in the substation (Shinchungju)

2.1 Characteristic of power consumption of KTX

The characteristics of the power consumption of the KTX and the characteristics of the harmonic occurrence are tested in the KTX. The voltage is the potential difference between the pantograph and the rail. The current is measured through the CT of the circuit that supply the current to 3 Motor Blocks. In case operating whole 6 Motor Blocks, we regard double of measured current value as the whole current of the KTX.

The detailed results of the power consumption by the speed of the KTX are shown in Fig 1.

Fig. 1 Characteristic of power consumption of KTX

The power consumption of the KTX is locally peaked at about 100km/h in Fig 1. And the whole peak power consumption is max at 200km/h. The special characteristics of the curves appear at about 100km/h. The phenomenon is due to the additional injection of the PFC(Power Factor Compensator).

2.2 Harmonic characteristic of KTX

(1) Test condition

The power car of the KTX was put in the end section to measure the harmonics occurred from the KTX. We operated whole 6 Motor Blocks and recorded the characteristics of the harmonics. The KTX was isolated from the adjacent power system. We dontt have to consider line impedances and capacitances of the catenary system. Therefore, the whole circuit is as following.

Power utility - transmission line - main transformer - auto transformer - KTX.

The test condition is shown in Table 1. B1, B2, B3 and B4 are the combination of the size of Motor Block and the state of injecting the PFC.

(2) Result

The measured waveform of the voltage and the current is illustrated in Fig 2~5 under the test condition of B1~B4. In case the PFC is off, Fig 4 shows that the current includes especially much harmonics at the low frequency.

Table 1. Test condition for measuring harmonic characteristic of KTX

No.

Test condition

B1

6MB  PFC:On  (2/MB)

B2

6MB  PFC:On  (2/MB)

B3

6MB  PFC:Off 



B4

3MB  PFC:On  (2/MB)

Fig 2. Waveform of voltage(up) and current(down)-B1

Fig 3. Waveform of voltage(up) and current(down)-B2

III.                 Measurement and analysis of system response characteristic

We define the amplification of the harmonic current. The harmonic current is amplified by the parallel resonance. The parallel resonance is occurred by the capacitive reactance of the catenary system and the inductive reactance of the substation. That is, the amplification of the harmonic current, m(k), is calculated as the ratio of the current injected into the substation over the current occurred from the electric train [2].

m(k) = ISS(k)/ Ipanto(k)

where,

m(k) : the amplification of harmonic current at k frequency

ISS(k) : k frequency current injected into the substation [A]

Ipanto(k) : k frequency current occurred from the electric train [A]

The location of the substation is at 129km from the specific point. The end of the catenary is at 108km from the specific point. So, the substation feeds the power from 129km to 108km.

The test conditions are as follows.

- The KTX is located at two spots, which are 129km and 108km.

- The system feeding the power to the catenary is on/off.

-The size of the Motor Block is changed.

Fig 4. Waveform of voltage(up) and current(down)-B3

Fig 5. Waveform of voltage(up) and current(down)-B4

 Fig 6. Amplification of harmonic current

(129km, 6MB, Power-Off)

Fig 8. Amplification of harmonic current

(129km, 3MB, Power-On)

The amplification of the harmonic current is shown in Fig 6~9.

In case the system feeding the power to the catenary is off, the phenomenon of the amplification of the harmonic current is not so obvious(Fig 6).

In case the system feeding the power to the catenary is on, the harmonic resonance is appeared at 25th harmonic order. When the KTX is located at 129km, the amplification of the harmonic current is about 4 or 5 times higher than it that the KTX is located at 108km.

IV.                Measurement and analysis of THD depend on KTXts operational modes

We execute the running test of the one KTX to investigate the THD(Total Harmonic Distortion) limited at PCC(Common Coupling Point) and measured harmonics at the 154kV bus of the substation.

According to the running patterns of the KTX, which are 3 modes of acceleration, maximum speed and regenerative breaking.

Fig 7. Amplification of harmonic current

(129km, 6MB, Power-On)

 Fig 9. Amplification of harmonic current

(108km, 6MB, Power-On)

The spectrum of the harmonic voltage and the harmonic current are illustrated in Fig 10~12.

Also, the THD in time domain is shown in Fig 13. The THDs in 3 modes of the running pattern are different.

In Fig 10~12, while the harmonics of 3rd ~ 5th, 15th ~19th are high remarkably in the acceleration mode. The harmonics of 3rd ~21st are high in the regeneration mode.

Also, the harmonics of the acceleration mode and the regeneration mode are higher than those of the maximum speed mode.

For this reason, Fig 13 shows the results that the THDs of the acceleration mode and the regeneration mode are higher than those of the maximum speed mode.

V.                  CONCLUSION

In the real electric railway system, the results of the measurement of the system response characteristic and the harmonics are as follows.

(1) In case the system feeding the power to the catenary is off, the phenomenon of the amplification of the harmonic current is not so obvious(Fig 6).

In case the system feeding the power to the catenary is on, the harmonic resonance is appeared at 25th harmonic order. When the KTX is located at 129km, the amplification of the harmonic current is about 4 or 5 times higher than it that the KTX is located at 108km.

(2) In spite of the condition that the running KTX is one, the measured maximum THD is 1.8%. The THD exceeds the limitation of 1.5% at the PCC.

(3) The THDs of the acceleration mode and the regeneration mode are higher than those of the maximum speed mode.

References

[1]     Korea Railroad Research Institute, tEvaluation of Power Quality In Seoul-DaeGu High-speed Railway(),t 2002.

[2]     Yoshifumi Mochinaga, tHigher Harmonics Resonance on AT Feeding Circuit and Countermeasures to Suppress it,t T.IEE Japan, Vol. 114-D, No. 10, 1994


Fig. 13 THD in 3 running patterns of KTX

DISTRIBUIE DOCUMENTUL

Comentarii


Vizualizari: 1099
Importanta: rank

Comenteaza documentul:

Te rugam sa te autentifici sau sa iti faci cont pentru a putea comenta

Creaza cont nou

Distribuie URL

Adauga cod HTML in site

Termeni si conditii de utilizare | Contact
© SCRIGROUP 2022. All rights reserved