Active Earth Fault Compensation and Railway Application · PDF fileActive Earth Fault...

Active Earth Fault Compensation and Railway Application of Medium Voltage Converters

Dr. Jörg Janning

May 2004May 2004

APCG / / 4JAN003_(IEEE_BAUM_RSK-Borken)_00EN.PPT

05.2004 2APCG / 4JAN003_(IEEE_BAUM_RSK-Borken)_00EN.PPT / Dr.J.JANNING / Be


Content

� Medium Voltage 3-Level GTO Phase Module� Active Earth Fault Compensation (RCC)

(Residual Current Compensation)– Motivation and Operation Principle– RCC Converter for DB Energie– Measurement Results

� Standardized Static Frequency Converters (SFC)– Concept and Assembly– 120 MW Substation

� Conclusion


0V V

-–12

ud–12

ud

1 ~2 16 Hz2

3

3 x 4QC

50 Hz3 ~

3 6 8

4 x 4QC

1 ~2 16 Hz2

3

3 x PM

50 Hz3 ~

3 3

3 x 4QC 3 x 4QC

3 x PM

Typical Applications of the 3-Level Phase Module (ALSPA VDM7000)

50 Hz3 ~

3 3 3 M 4

3-Level Phase Module(PM)

Three-Level Voltage Source Converter Drive[18 MVA]

Back-to-Back Converter[18 MVA]

Back-to-Back Converter[9 MVA]

Three-Level Voltage Source Converter Drive[9 MVA]

6 modules

12 modules

7 modules

14 modules

4 x PM 3 x PM

3 x 4QC

50 Hz3 ~

3 6 6 M

3 x 4QC



principle schematic

Medium Voltage 3-Level GTO Phase Module


Traces of the output potentials of two phase modules of the 4QC and the resulting output voltage uAB = vA - vB

vA

vB

uAB

ud

- ud

0

0- – ud

12

– ud12

0- – ud

12

– ud12

βA1

βA2αA1

αA2

αA3 αA4 αA5 αA6

αAi

βA3 βA4 βA5 βA6

π 2π

2ππ

αBi

δB6 δB5 δB4 δB3

δB2

δB1

2ππi(α)

αAi/

αBi/

αAi:=βAi−π/

αBi:=2π−γBi/

αBi:=π−δBi

α

α

α

γB1

γB4 γB3

γB2

γB6 γB5

Phase Module(ALSPA VDM7000)

Pulse frequency of the GTO: 150 Hz (up to 250 Hz with derating)� 3 pulses per fundamental harmonic for the 50 Hz converter � 6 switching angles available for pulse pattern optimization

0V

ud1

-ud2

V



Classical approach for power transmission grids

� Resonant grounded systems with arc-suppression coils (Petersen coil) � self extinguishing arcs in case of line to ground faults� power transmission not affected by earth faults

Problems

� Cable faults, harmonics, large grids with high damping� high currents at the fault location: danger to life, danger of fire

Solution

� Active compensation of residual currents with VSI feeding the neutral system of the transmission grid

Motivation of the Residual Current Compensation



d + j ⋅ v

- k

U

UNE =

B10+B20+B30

G10+G20+G30+G0d =Damping factor:

Tuning factor:

Symmetry factor:

Neutral voltage:

Neutral

Line 1

U30URCC

Y10

Y0

Earth

Line 2

Line 3

a²U

U10

RCC

I0

Y F

IF

IRCC

UNE

~

~

~aU

U

U20~Y20 Y30

B10+B20+B30

B10+B20+B30+B0v =

k =B10+B20+B30

Y10+a2⋅Y20+a⋅Y30

Principle of the Residual Current Compensation

Target of RCC: IF = 0� RCC needs to move potential of line 1 to earth potential ( URCC = UNE = U )� current of the RCC: IRCC = U × k - U × (d + j ν)


Residual Current Compensation for DB Energie (Borken)


� 18.500 km of 110 kV lines, 2AC 16.7 Hz (DB and ÖBB)

� Active power of 5.5 MW according to the damping of the grid

� Compensation of 3rd, 5th, 7th Harmonic and 50 Hz components

� ALSPA VDM7000 medium voltage 3-level converter



400 V50 Hz

50 Hz11 kV

16.7 Hz

2

1

Residual Current Compensation for DB Energie

resistor with DC-chopper

rectifier

50 Hz transformer

Four-quadrant converter (4QS) � 2 phase modules DC link capacitors, 33.3 Hz and 66.6 Hz filter circuits

16.7 Hz transformer



Test conditionsIsland grid fed by two 55 MVA Generators:500 km of overhead lines + simulation of 1400 km overhead lines by capacitors

Simulated faults� Earth fault with low impedance

– short circuit of 110 kV busbar to ground� Earth fault with high impedance

– tree contact– breaking of an overhead line

� Cable fault

Residual Current Compensation for DB EnergieField Tests



~~

~

VSI

Line 1

Line 2

U12

U20 U10

Generator(55 MVA)

IF

UNE

Residual Current Compensation for DB EnergieTest Conditions



Tree contact Fault detection 1.5 s

1)

2)

3)

4)

5)

IF

U12

U10

UNE

U20

RCC - Measurement of High Impedance Fault (caused by tree)

RCCoff

RCCon

RCCoff

RCCon

RCCoff

RCCon

RCCon



BeforeFault

RCCoff690ms

RCCon

2,75s

RCCoff 6.3 s

RCCon

1)

2)

3)

4)

5)

IF

U12

U10

U20

UNE

RCC - Measurement of Cable Fault



intermitting arc

current measurement

RCC - Field Tests



RCC - Compensation of Cable Fault



� Proven method in medium voltage applications� First high voltage application has passed realistic field tests and is

ready for full operation � Higher safety due to self-extinguishing arcs and low voltages at the

fault location� Increased availability of power supply due to fault clearing without

power interruption� Compensation of fault currents even in case of cable faults, high

harmonics and a high damping in the grid� Detection and location of faults

Residual Current Compensation - Highlights


30 MW60 MW

Concept of the standardized Static Frequency Converter (SFC)

ALSPA VDM70003 level GTO converter

for high power applications(9...18 MVA)

I C E

110 kV; 16.7 Hz

110 kV; 50 Hz

15 kV; 16.7 Hz

20 kV; 50 Hz

1~

3~

1~

3~

1~

3~

1~

3~SM

ASMASM

SM SM

ASM

SM

ASM

1~

3~

1~

3~

about 50...100 km

Application of the 3 level GTO converter ALSPA VDM7000



V

20.5 kVbzw.30 kV50 Hz

Block diagram of standardized SFC type BAUM

400 V50 Hz

Four-quadrant converter (4QS) � 2 phase modules

15 kVresp.110 kV16.7 Hz

Rated power at the single phase end:18.5 MVAresp.15 MW (cos ϕ = 0.81) Precharge and

earthing system

DC link capacitors33.3 Hz filter circuits

Single phase transformerincluding filter circuit

Resistor with DC-chopper


UU

W

2

U1

3

4


50 Hz transformer

16.7 Hz transformer

16.7 Hz transformer

50 Hz transfromer

1066

cm

640

cm

2100 cm

Ground plan

Side view

Resistors of DC chopper

air conditioning system

phase modules

control cubicle

transformeroil pits

capacitors of 33.3 Hz filter circuits

50Hz transformer including 2 reactors of 33.3 Hz filter circuits

Arrangement of the components in the modular container concept

(all components aredesigned for thetransportation via rail and standard road haulage)

heat exchanger(air / glycol water)

20 kV cable

110 kV line

heat exchanger(air / glycol water)




Assembly of prefabricated modules of the back-to-back converter (BAUM) for railway applications within 4 days

1th.day prefabricated foundation of building and transformers with ready-made oil collecting pits.

2nd.day Erection of 16.7Hz transformer and 1. Container halve of converter room

3rd. and 4th. day Total view after assembling of SFC pilot type BAUM

16.7 Hz-Trafo

16.7 Hz-Trafo50 Hz-Trafo

Power part


Pilot of Standard Converter Type BAUM




120 MW SFC Converter Substation for Berlin - ThyrowHighlights� standardized units� pre-tested, portable� compliance with local line

requirements� adjustable power factor� high efficiency

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