Components Of Hvdc 12191n

SPECIAL COMPONENTS OF TALCHER – KOLAR BIPOLAR HVDC Lecture by P.RANGA RAO Chief Manager / Kolar

HVDC EQUIPMENTS

What are the Special Components of HVDC?

MAIN COMPONENTS OF HVDC 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.

Converter Transformer Valve Hall AC Harmonic Filters Shunt Capacitors DC Harmonic Filters Smoothing Reactors DC Current / Voltage measuring devices Valve Cooling / Ventilation System Valve Timing PT VESDA Electrode Station Repeater Station

Basic Components of HVDC Terminal Converter Xmers AC Harmonic 400 kV filters

DC Line

Smoothing Reactor

DC D CFilter F ilt e r

D C F ilt e r

Electrode station

D C F ilt e r

D C F ilt e r

A C FShunt ilte r AC

A C F ilt e r

Capacitors

Valve Hall -Thyristors

Valve Cooling / Ventilation system

-Control & Protection -Telecommunication

CONVERTER TRANSFORMER

400KV SIDE BUSHING

STAR BUSHINGS

DELTA BUSHING

Converter Transformer

CONVERTER TRANSFORMERS

 Three

Singe Phase Transformers for each Pole  Each Transformer is of Three Windings  



Winding -1 connected to 400KV side in Star Winding -2 connected to one six pulse bridge in Star Winding -3 connected to second six pulse bridge in Delta

 Easy

transportation

FEATURES OF CONVERTER TRANSFORMERS

Automatic onload tap changer control with appropriate make and break capacity  Extra insulation due to DC currents  Proper conductors and magnetic shunts to take care of the extra losses due to harmonic currents  Very rugged and reliable OLTC as tap-changing is a integral means of conversion process and control. 

Converter Transformer Ratings   •Type of converter transformer : Single phase three windings •Rated power of line / star / delta winding (MVA) : 397/198.5/198.5 •Rated current of line / star / delta winding (A): 1719/1635/944 •Rated Voltage of Line/star/delta winding (Noload): 400/√3/210.3/√3/210.3 •Tap changer (voltage range) to +20 % •Tap changer steps -4 (21 steps) •Tap changer current capacity

: -5 % : 16 to : 2X2000A

Converter Transformer Ratings  No

load losses – 192KW  Load losses - 760KW @75°C  Oil type – Napthanic, Shell Diala  Bushings     

Line side – oil filled Valve side – Y – SF6 filled Valve side – D – RIP condenser Total weight – 461 Ton Oil weight – 118.7 Ton

Converter Transformer Connection Valve Hall

1-ph 3 winding Converter Transformer

D Y

R

D Y

Y

D Y

B Outdoor

Converter Transformer Cooling control  

       

Automatic daily changeover of cooling pumps and fans 5 groups of fans and pumps  Each group – One oil circulating pump & 3 cooling fans 4 groups will be in service with 2 fans each One redundant group – changeovers every day Extra fans will switch ON when winding temperature > 75ºC Redundant group will switch ON when winding temperature >85ºC WTI Alarm - 115ºC WTI Trip - 130ºC OTI Alarm - 85ºC OTI Trip - 95ºC

Converter Transformer internal connection

HVDC VALVE HALL LAYOUT

Multiple Valve Unit • Indoor type • Air insulation • Direct water cooling of all components in the valve producing losses • Application of single thyristors with a high current carrying and voltage blocking capability (no parallel connection of thyristors) • Optoelectronic firing and monitoring system from the ground to thyristor potential and vice versa without intermediate electronics • Monitoring of the status of all thyristor levels during operation • Protective firing of the thyristors as back up firing for self protection of the valves against high over voltages in forward direction • Direct parallel connected surge arresters to each valve

Valve Hall Layout Cross Section

Converter Valves

Converter Transformer Smoothing Rector

DC Bushing

Valve Hall

MULTIPLE VALVE UNIT G rd Q u a d r u p le v a lv e

V a lv e A rre s te r

A C

Multiple Valve Unit

D Y

Y

A C

D C

Circuit Diagram of the Converters for Pole 1

Valve Tower side view

1. AC Terminal 2. DC Terminal 3. Cooling Water Inlet 4. Cooling Water Outlet 5. Fiber Optic Cables Tubes

6. Thyristor Module 7. Insulator 8. Arrester 9. Screen

• Max. length of fibre optic cables in quadruple valve L max = 17.5m • Weight of quadruple valve without arresters: approx. 19300 kg • All dimensions in mm

Valve Tower top view / 3D view

• Max. length of fibre optic cables in quadruple valve L max = 17.5m • Weight of quadruple valve without arresters: approx. 19300 kg • All dimensions 1. AC Terminal in mm 6. Thyristor Module 2. DC Terminal 7. Insulator 3. Cooling Water Inlet 8. Arrester 4. Cooling Water Outlet 9. Screen 5. Fibre Optic Cables Tubes

Valve Structure Valve Section / tier

Single Valve

Quadra Valve

Hierarchy of valve structure Each Thyristor level consists •Thyristor •Snubber circuit – to prevent high dv/dt •Snubber Capacitor •Snubber Resistor •Valve Reactor – to prevent high di/dt •Grading Resistor – to equilize the potential across all the levels in a valve – static equalizing •Grading capacitor – dynamic equalizing

Components in one valve Component

Population Population at Talcher at Kolar

Thyristor Snubber Capacitor Snubber Resistor Valve Reactor Grading Capacitor Grading Resistor Valve arrester TE card

84 84 84 24 6 84 1 84

78 78 78 24 6 78 1 78

Components in one Pole Component

Population at Talcher

Population at Kolar

Thyristor Snubber Capacitor Snubber Resistor Valve Reactor Grading Capacitor Grading Resistor Valve arrester TE card

1008 1008 1008 288 72 1008 144 1008

936 936 936 288 72 936 144 936

Thyristor Module GRADING CAPACITOR

SNUBBER CAPACITOR SNUBBER RESISTOR

COOLING PIPE-PEX

THYRISTOR

TE CARD

FIBRE OPTICS

Thyristor Modular Unit top view

Thyristor Modular Unit Detailed View of Thyristor Stack

Eastern Terminal (Talcher)

Southern Terminal (Kolar)

14 Thyristors

13 Thyristors

Thyristor Modular Unit Schematical Cooling Circuit

Eastern Terminal (Talcher) 14 Thyristors Z = Cooling Water Inlet A = Cooling Water Outlet

Southern Terminal (Kolar) 13 Thyristors

Composition of an HVDC Valve T h y r is to r le v e l TL

=

+

G a te u n it

H eat s in k s

+

+

1< k< n W h e re k= n = +

V a lv e s e c t io n

N o te V S

TL

=

V S

+

1 TL k V a lv e

V S =1

+ V S

n

k

F ib re o p t ic s yste m

+

N o. in a N o. in a

o f t h y r is t o r le v e l s v a lv e s e c t io n o f th y r is to r l e v e ls v a lv e

is t h e s m a ll e s t r e p e a ta b le e le c t ric a l u n it o f a v a lv e , m e c h a n ic a l s u b - u n it s m a y c o n t a in m u l t i p l e o r s u b -d e v id e d v a lv e s e c tio n s

C o o la n t d is t rib .

+

In s u la tin g s tru c tu re

Block Diagram of Thyristor Electronic

1 Light Receiver 2 Light Transmitter 3 Thyristor Voltage Detection 4 Logic

5 Gate Pusle Amplifier 6 Back Up Trigger Circuit (BTC) 7 Energy Supply

Multi-Arm Fibre Optic Cable Used for Monitoring Receiver Side

Emitter Side

1 Protective sleeves in red colour 2 7 continuous single fibre cables

3 Labelling with markers 4 Designation on shrinking tube

Multi-Arm Fibre Optic Cable with Signal Mixing Used for Triggering Emitter Side

Receiver Side

1 Protective sleeves in blue colour 2 Fibre cables statistically mixed

3,5 Labelling with markers 4 Designation on shrinking tube

Thyristor T1501 N75 T - S34 (1) Features: • High-power thyristor for phase control • Ceramic insulation • s copper, nickel plated • Anode, Cathode and gate pressure ed • Inter digitised amplifying gate

Applications: • HVDC-Transmissions • Synchro- drivers • Reactive-power compensation • Controlled Rectifiers

Internal Structure of Thyristor

Thyristor T1501 N75 T - S34 (2) - Electrical Maximum Ratings • Repetitive peak off-state voltage

VDRM = 7.5 kV at TVJ = +5°C...120°C

• Repetitive peak reverse voltage

VRRM = 7.5 kV at TVJ = +5°C...120°C

• Non-repetitive peak off-state voltage

VDSM = 8.0 kV at TVJ = +5°C...120°C

• Non-repetitive peak reverse voltage

VRSM = 8.3 kV at TVJ = +5°C...120°C

• Surge-on state current

ITSM = 22 kA at TVJ = +90°C, 50 Hz Sinus, VR

=0V

• Critical non-rep. rate of rise of on-state current

di/dtcr = 160 A/µs at TVJ = +90°C, VD = VDRM

• Critical rate of rise of on-state voltage

dV/dtcr = 8600 V/µs at TVJ = +90°C

Thyristor T1501 N75 T - S34 (3) - Electrical Characteristic Ratings • Off-state current

ID = 500 mA at TVJ = +90°C, VD = VDRM

• Reverse current

IR = 500 mA at TVJ = +90°C, VR = VRRM

• On-state voltage

VT = 2.7 kV at TVJ = +90°C, ITM = 4000 A (stat. 50%/90% value)

• Circuit-commuted recovery time

tq = max. 800 µs at TVJ = +90°C, ITM = 4000 A di/dt = -4 A/µs, VR = 100 V dV/dt = 100 V/µs, VD = 5000 V

• Gate trigger current

IGT = 400 mA at TVJ = +25°C, VD = 12 V

• Gate trigger voltage

VGT = 3 V at TVJ = +25°C, VD = 12 V

Thyristor T1501 N75 T - S34 (4) - Thermal and Mechanical Ratings • Operating junction temp. range

TVJ = +5°C...+120°C

• Storage temp. range

Tstg = -50°C...+60°C

• Thermal resistance

Rth JC = 0.0064 K/W

• Mounting force

fm = 63 kN...91 kN

• Weight

m = 3.9 kg

• Creepage distance

dcreep = 49 mm

• Air distance

dair = 20 mm

Valve Reactor - Electrical and Mechanical Ratings • Voltage-time area

 = 80mVs ±10%

• Saturated part of main inductance

LH = 0.55 mH ±10%

• Reactor current

ID max = 1270 A

Current and Voltage Characteristic of the Valve Reactor

Valve Reactor - Dimensional Drawing

Grading Capacitor - Electrical and Mechanical Ratings • Capacity

C = 2.4 µF ±3%

• Nominal voltage

UN = 58 kV

• Periodical max. voltage

Umax = 88 kV

• Short time max. impulse voltage

Us = 8700 V

• Nominal effective current

IN = 1 A

• Periodical max. current

Imax = 100 A

• Operating frequency

f = 50/60 Hz

• Cooling type

self-cooling

• Weight

approx. 25 kg

• Impregnation

SF6 gas

Grading Capacitor - Dimensional Drawing

Snubber Circuit Resistor

Resistance R

45 

Tolerance

± 3%

Cooling

Water

Snubber Circuit Capacitor X View X

Capacitance

1.6 µFd

Tolerance

+/-5%

Insulation

SF6

DC Smoothing Reactors

Smoothing Reactor - Purpose   

 

Connected in series in each converter with each pole Decreases harmonic voltages and currents in the DC line Smooth the ripple in the DC current and prevents the current from becoming discontinuous at light loads Limits crest current (di/dt) in the rectifier due to a short circuit on DC line Limits current in the by valve firing due to the discharge of the shunt capacitances of the dc line

DC Smoothing Reactor ratings •Two Smoothing Reactors per pole •Inductance - 125mH •Nominal DC Voltage – 500KV •Max DC Voltage – 515KV •BIL – 950/1425KV

DC Smoothing Reactor ratings

•Continuous current - 2000A •Continuous Over load current - 2200A •Type – Air Cored Dry type •Natural Air Cooled reactors •Location : Outdoor •Total mass – 30 Ton •Temperature Class - F

HARMONIC FILTERS  

Conversion process generates – Harmonics AC side Harmonics- Current harmonics    



Generated harmonics – (12n ± 1) harmonics n = 1,2,3…. Predominant harmonics – 11,13,23,25,35,37 Additionally 3rd harmonics

DC side Harmonics- Voltage harmonics   

Generated harmonics – (12n) harmonics n = 1,2,3…. Predominant harmonics – 12,24,36

Disadvantages of Harmonics  Over

heating and extra losses in generators  Over heating and extra losses in motors  Instability in the converter control  Interference with telecommunication systems  Over voltages due to resonance

AC Filters - Kolar ITEM

A

B

C

Filter sub bank

DT 12/24

DT 3/36

Shunt C

Rating (3 ph., 400 kV)

MVAr 120

97

138

No.of 3 phase Banks

-

6

3

5

HV-Capacitor C1

μF

2.374

1.85

2.744

HV-Reactor L1

mH

16.208

5.444

1.602

HV-Resistor R1

ohms

420

300

-

LV-Capacitor C2

μF

4.503

3.759

-

LV-Reactor L2

mH

7.751

204.2

-

LV-Resistor R2

ohms

-

1500

-

12/24 Double Tuned Filter – 120 MVAr

C1=2.374µF

L1=16.208mH

R1=420Ω

C2=4.503 µF

L2=7.751mH

11

13

23

Impedance Graph

25

12/24 Double Tuned Filter – Sectional view

Capacitor Stack

CT Resistor Reactor

Reactor

3/36 Double Tuned Filter – 97 MVAr

C1=1.85µF

L1=15.444 mH

R1=300Ω

C=23.759µF

L2=204.2mH

R2=1500 Ω

3

35

37

Impedance Graph

3/36 Double Tuned Filter – Sectional view

Capacitor stack

CT

Resistor

Reactor

Reactor

C=23.759µF

Shunt Capacitor – 138 MVAr •No harmonic filtering C1=2.744 µF

L1=1.602 mH

•Supplies MVAr to the grid •Switched into the circuit for voltage control purpose •Capacity – 138 MVAr

Shunt Capacitors-Voltage Improvement

Ratings of Capacitors C1 & C2 of 12/24 filter Type

96 TILP

8 TILR

Make

NOKIAN

NOKIAN

Capacitance ( per ph )

2.37 F

4.50 F

Capacitor Bank 1 phase output

67.4 Mvar

0.94 Mvar

Capacitor Bank Voltages

301 kV

25.5 kV

Capacitor bank currents ( 1 ph )

290 A

404 A

System Frequency

50 Hz

50 Hz

No. of units in series (s)

32

4

No of units in parallel

2+1

2

Total Units (1 ph )

96

8

Unit Capacitance

25.3 F

8.99 F

Capacitor Unit rated output

703 Kvar

115 Kvar

Capacitor unit rated voltage

9406 Volts

6380 Volts

Capacitor Unit rated current

74.7 A

18 A

Capacitor Bank Rating

Electrical connections:

Capacitor Units

Ratings of Resistor of 12/24 filter              

Type : EKE/ KLK Resistor DT 12/24 R1 Make : KLK Electro Materials, Spain Resistor material : Stainless Steel Ni-Cr 40 Cooling : Natural Air Temperature Coefficient of resistance : C = 0,00054u / OC Resistance (at nominal current) : 420 ohm MCOV -HV to Ground : 35 kV BIL/ SIL : 325/250 kV Total Losses : 678 kW/356 kW Max. temperature rise for the resistor element: t = 170 °C Inductance : L < 10320 H Thermal Time constant : 400 s Fundamental frequency : 50 Hz Weight : 450 kg

Ratings of Reactors L1 & L2 of 12/24 filter Type

Dry, Air core

Dry, Air core

Make

Trench Limited, Canada

Trench Limited, Canada

Nominal Inductance

mH

16.208

7.751

Tolerance on Inductance

%

+/-0.5

+/-1.0

Nominal Frequency

Hz

50

50

Amps Amps Amps

180 151.7 ( 11th ) 223

180 241.3 ( 11th ) 366

Amps

287

408

kV kV kV

325/250 325/250 150/150

150/150 150/150 95/95

Continuous Current rating Fundamental Major harmonic Geometric sum of Harmonic Current Total Current Stress BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

Ratings of Capacitors C1 & C2 of 3/36 filter Type

90 TILP

4TILR

Make

NOKIAN

NOKIAN

Capacitance (ph)

1.85 F

2.85 F

Capacitor Bank 1 phase output

48.2 Mvar

0.74 Mvar

Capacitor Bank Voltages

288 kV

25 kV

Capacitor bank currents ( 1 ph )

180 A

75 A

System Frequency

50 Hz

50 Hz

No. of units in series (s)

30

4

No of units in parallel

2+1

1

Total Units (1 ph )

90

4

Unit Capacitance

18.5 F

11.4 F

Capacitor Unit rated output

536 KVAr

151 KVAr

Capacitor unit rated voltage

9600 Volts

6500 Volts

Capacitor Unit rated current

55.8 A

23.3 A

Capacitor Bank Rating

Electrical connections:

Capacitor Units

Ratings of Resistor of 3/36 filter Type : EKE/ KLK Resistor (DT 3/36 R1 ) Make : KLK Electro Materials, (Spain) Resistor material : Stainless Steel Ni-Cr 40 Cooling : Natural Air Temperature Coefficient of resistance : C = 0,00054u / OC Resistance (at nominal current) : 420 ohm MCOV -HV to Ground : 35 kV BIL/ SIL : 325/250 kV Total Losses : 678 kW/356 kW Max. Temperature rise for the resistor element: t = 170 °C Impulse energy at warm resistor : 230 kJ Inductance : L < 10320 H Thermal Time constant : 400 s Fundamental frequency : 50 Hz Weight : 450 kg

Ratings of Reactors L1 & L2 of 3/36 filter Type

Dry, Air core

Dry, Air core

Make

Trench Limited, Canada

Trench Limited, Canada

Nominal Inductance

mH

5.444

204.2

Tolerance on Inductance

%

+/-0.5

+/-1.0

Nominal Frequency

Hz

50

50

Amps Amps Amps

167 43.2 ( 13th ) 66

181 23.3 (13th ) 24

Amps

180

183

kV kV kV

325/250 325/250 250/250

250/250 250/250 95/95

Continuous Current rating Fundamental Major harmonic Geometric sum of Harmonic Current Total Current Stress BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

Ratings of Capacitors in Shunt C Type

96 TILP (138 Mvar)

Make

BHEL

Capacitor Bank Rating Capacitance ( ph )

2.744 F (+/- 1%)

Capacitor Bank 1 phase output

63.8 Mvar

Capacitor Bank Voltages

272kV

Capacitor bank currents ( 1 ph )

234.4 A

System Frequency

50 Hz

Electrical connections: No. of units in series (s)

38

No of units in parallel

4

Total Units (1 ph )

152

Capacitor Units Unit Capacitance

26.07 F

Capacitor Unit rated output

419.6 Kvar

Capacitor unit rated voltage

7.16 kV

Capacitor Unit rated current

58.6 A

Ratings of Reactors in Shunt C Type

Dry, Air core

Make

Trench Limited, Canada

Nominal Inductance

mH

1.602

Tolerance on Inductance

%

+/-1.5

Nominal Frequency

Hz

50

Continuous Current rating Fundamental Major harmonic Geometric sum of Harmonic Current Total Current Stress

Amps Amps Amps Amps

232 49.6 13th ) 78 245

BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

kV kV kV

325/250 325/250 95/95

DC Filter 12/24 TYPE

C1=1800 nF

L1=14.71 mH

R1=400 Ω

C1=5700 nF

L2=8.19 mH

Ratings of Capacitors C1 & C2 of 12/24 filter Make

ABB

ABB

Nominal Capacitance

nF

1800

5700

Tolerance of Nominal Capacitance

%

+/- 0.5

+/-1.0

Maximum DC Voltage kV Arithmetic sum of Harmonic Voltage kV Total Voltage Stress kV

538 59 621

5.3 7.5

Geometric sum of Harmonic Current A

63

70

BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

1300/1175 1425/1300 450/350

150/150 250/250 150/150

kV kV kV

Ratings of Resistors of 12/24 & 12/36 filter

Make

KLK Electro Materials, Spain

Type

KLK DT 12/24

Resistance at nominal current

Ω

400

Tolerance %

%

+/-5

Total losses

kW

160

Rated frequency

Hz

50

BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

kV kV kV

325/250 325/250 95/95

Ratings of Reactors of 12/24 filter Make

Trench Limited, Canada

Type

Dry, Air core

Dry, Air core

Nominal Inductance

mH

14.71

8.19

Tolerance on Inductance

%

+/-1

+/-1

Continuous Current rating DC Current Major harmonic Geometric sum of Harmonic Current Total Current Stress

Amps Amps Amps Amps

0 43 (12th ) 60 60

0 110 (12th ) 120 120

BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

kV kV kV

250/250 450/250 250/250

150/150 250/250 150/150

Minimum Creepage Distance

mm

800

400

DC Filter 12/36 TYPE C1=1800 nF

L1=7.21 mH

R1=400 Ω

C1=3300 nF

L2=12.68mH

Ratings of Capacitors C1 & C2 of 12/36 filter Make

ABB

ABB

Nominal capacitance

nF

1800

3300

Tolerance of Nominal Capacitance

%

+/- 0.5

+/-1.0

Maximum DC Voltage Arithmetic sum of Harmonic Voltage Total Voltage Stress

kV kV kV

538 61 624

9.2 13

Geometric sum of Harmonic Current

A

65

76

BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

kV kV kV

1425/1050 1425/1050 325/250

1425/1050 1425/1050 325/250

Internal

Internal

Type of Fusing

Ratings of Reactors of 12/36 filter Make

Trench Limited, Canada

Type

Dry, Air core

Dry, Air core

Nominal Inductance

mH

7.21

12.68

Tolerance on Inductance

%

+/-1

+/-1

Continuous Current rating DC Current Major harmonic Geometric sum of Harmonic Current Total Current Stress

Amps Amps Amps Amps

0 44 (12th ) 65 65

0 116 (12th ) 123 123

BIL/ SIL (HV to LV) BIL/ SIL (HV to Ground) BIL/ SIL (LV to Ground)

kV kV kV

250/250 450/250 250/250

150/150 250/250 150/150

Minimum Creepage Distance

mm

1050

400

DC MEASURING DEVICES   

Measurement on DC side for control, monitoring and Protection AC CTs cannot be used on DC side – saturation DC current measuring devices – OPTODYNE    



DC shunt – low value resistor mV drop from the shunt will be taken for determining the current To solve insulation problems – electrical signals are converted to optical at the shunt and at control system converted to electrical Supply for the conversion process is obtained from the control s in the form of optical power

DC voltage divider   

Capacitive & resistor divider circuit Drop across the resistor scaled for determining the voltage Optical conversion process is same as the current measuring device Details follows……

DC Current Measuring Device (OPTODYN) Lay out at HVDC Kolar 6 UdL

6 IdH

4 IdL

Line 1

Pole1 4 UdN 2 IdN

4 IdE

IdN

IdE

2

4

8 Idee1 Idee2 UdN 4

Idee3 8

8 Current Measuring Devices 11Nos (4 HV+7 LV) Voltage Dividers 04 Nos ( 2 HV+2 LV)

Pole2

IdH 6

Electrode lines

Line 2

IdL UdL 6

4

Example for the Use of the Hybrid Optical Sensor Ir o n C o r e In d u c tiv e C T

OPTODYN

Shunt

R o g o w s k i A ir C o r e C T

H V /E H V - L in e

TM

G ro u n d L e v e l

C a p a c itiv e R e s is ta n c e In d u c t iv e V o lta g e V o lta g e D iv id e r V o lta g e D iv id e r T ra n s fo rm e r

Functional Concept Shunt Analog/ Digital

Optical Digital/ Optical

Id

Electrical Energy

Signal fibre

Power fibre

Optical Energy

Digital

Optical Energy Electrical Energy Control/ Protection system at ground level

Sensor Head at high voltage level Fibre optical cable

Digital control/ protection system SIMADYN D

Power supply

Power Supply of Sensor Head I s o la t io n o f S y n c h r o n is in g s ig n a l f r o m p o w e r s u p p ly v o lta g e le v e l ( c a r r ie r )

LO W PO W ER E le c t r o n i c s a t t h e Sensor

P o w e r S u p p ly O u tp u t f o r P r e c o n d itio n in g a n d T r a n s m it te r E le c t r o n ic s

V o lt a g e R e g u la t o r

P h o t o c e ll- A r r a y (P o w e r C o n v e rte r)

O p tic a l F ib e r

LASER

L A S E R D r iv e r

D io d e A r r a y

a n d P r o te c tio n

5 V D C c a . 2 5 W fo r u p to 9 c h a n n e ls f r o m S IM A D Y N D S y s te m P o w e r S u p p ly

O p t ic a l In t e r f a c e , O p t ic a l P o w e r - M o d u le ( a s p a r t o f t h e O p t ic a l I n t e r f a c e C a r d )

Optical Data Transfer

BURDENR E S IS T O R ( a t C T o n ly )

Fast T r a n s ie n ts + R F I- P r o t.

BUFFER

A N T IA L IA S IN G F IL T E R

1 2 B it A /D C o n v e rte r

O p t ic a l F ib e r

O P T IC A L R E C E IV E R

O p tic a l In te r fa c e

BUFFER

D ig it a l D a ta f o r p r o c e s s in g in C o n tr o l a n d P r o t e c t io n S y s t e m s

O P T IC A L TRANSM IT T E R

Components 1

8

1 Ohmic Shunt at High DC Voltage Level for Direct Current Measuring

11 6

7

2

3

2 Voltage to Light Telegram Conversion 3 Fibre Optic Transmission to Ground Level 4 Composite Insulator

10 5 Control or Protection System 6 Light Pulses for Power Supply 4

7 Power Supply for Sensor Head 8 Rogowski Coil for Harmonic Current Measuring 9 Control of Active DC Filter

9

5

10 Hybrid Direct Current Measuring System with Fibre Optic Transmission 11 Sensor Head

Current measuring device – components

Redundancy Concept complete redundancy from sensor head via FO cable to control/ protection equipment  only one Analog/ Digital conversion per signal path  direct digital signal processing 

Shunt

Sensor Head

Pole control System 1

Sensor Head

Pole control System 2

Sensor Head

Protection System 1

Sensor Head

Protection System 2

Id

high voltage level; switchyard

common composite insulator and fibre optic cable

ground level; control building

DC Measuring Scheme: Conventional DC Transducer C o n v e n t io n a l D C M e a s u r in g S c h e m e : T o t a l A c c u r a c y < + - 0 , 8 %

ty p ic a l + - 0 ,1 %

ty p ic a l + - 0 , 2 %

C o n v e n tio n a l D C T r a n s d u c e r : A c c u r a c y < + - 0 ,5 %

D ig ita l C o n tr o l S y s t e m 0

0

D ig ita l S ig n a l S ig n a l

Is o la tio n

A m p lifie r

A m p lif ie r

P ro c e s s o r

0 to re d u n d a n t c o n tro l s y s te m o r Is o la tio n A m p lif ie r

p ro te c tio n s y s te m

DC Measuring Scheme: HybridOptical DC Measuring System H y b r id - O p t ic a l D C M e a s u r in g S y s t e m : T o t a l A c c u r a c y < + - 0 , 7 5 %

C u rre n t S e n s o r: ty p ic a l + - 0 ,2 %

t y p ic a l + - 0 , 5 %

0 ,0 %

O PTO DYN

D ig ita l C o n tr o l S y s te m

E le c t r o n ic S e n s o r H e a d 0

D ig it a l S ig n a l P ro c e s s o r

Comparision to Conventional Solution Comparison between Hybrid-Optical  Conventional DC Measuring System The weight of the new measuring device is



reduced from 4,000 kg to 100 kg No additional Post Insulators No electromagnetic interference (EMI) due to fibre optic links Full redundancy up to the measuring location Excellent dynamic performance 

Picture 2

Hybrid-Optical Measuring Device

Measuring Shunt

Sensor Head Box

Composite Insulator incl. Fiber Optics

Connection Box

Sensor Head Box with Sensors

Assembly of Shunt

OPTODYN

Sensor

Analoge Input Signal from Shunt

Optical Data Link

Optical Power Supply Link

Summary  Measures DC current quantities up to the range of 18,000 A  High voltage insulation level up to 500 kV rated DC voltage  Current measuring by a high precision shunt  Light construction  High insulation capability also under extreme environmental conditions  Less pollution due to less electrostatic potential of silicon surface  Hydrophobic silicon material reduces risk of leakage currents  No electromagnetic interference by use of fibre optic cables

Summary  Optical powered electronics at high voltage level  Optical signal transmission  Optical receivers directly placed in the control or protection system  Separate channels for control and protection including their redundant subsystems  Excellent dynamic Performance  Bandwidth 0 - 7 kHz (depending on application)  Overall system accuracy  0.75 %  Signal delay  160 µs  Temperature operating range -40 C to +50 C

DC Voltage Measurement

DC Voltage Measurement

System Description



The Valve Cooling System is a single closed loop deionised water system. Heat transfer to the ambient is provided by dry coolers. The Valve Cooling System is for one pole and works independent of other cooling and air conditioning systems.



Spray water will be used if the water temperature rises above controller set point value.

Design Basis Kolar Station

Talcher Station

Maximum Dry Bulb One Hour Average

450C

500C

Minimum Dry Bulb One Hour Average

20C

00C

Total Cooling Capacity

4340kW

4053kW

Water flow

4140 ltr./min

4350 ltr./min

Water Inlet Temperature MAX

500C

500C

Water Outlet Temperature Average

620C

620C

Water Conductivity

<0.5μS/cm

<0.5μS/cm

Redundant Circulating Pumps

One of two

One of two

Spray Water Storage for

24hrs

24hrs

Flow Diagram

VALVE COOLING MAIN PUMP    



Two centrifugal circulating pumps One pump - operating Other pump - standby Periodical automatic pump changeover. Changeover to the stand by pump takes place in case of failure of the operating pump Capacity of  

Motor – 45KW Pump – 265Cu.m/Hr

VALVE COOLING - MAIN FILTER 



In the main water line to the thyristor valves locates a 50 micron filter The filter is used for start up and cleaning and later on for safety, that no particle greater than 50 micron can enter the thyristor valves

VALVE COOLING - MAIN FILTER 



Main filter consists of group of filter cartridges as shown in the figure If the filter gets chocked for any reason, differential pressure will be sensed and this warns for maintenance

VALVE COOLING – MAKE UP WATER TANK 





A storage tank with a pressure pump is placed on the pump skid for the first filling with deionised water and for compensation of evaporated water during operation The make up water system works automatically and keep the expansion tank water level constant The make up water flows from the storage tank through a 50 μm filter, then the make up water the ion exchanger and flows finally into the main water circuit

VALVE COOLING – ION EXCHANGERS 







Two ion exchanger chambers are installed on the pump skid The ion exchanger is hydraulically switched in by to the main water line A mixture of 50% anion and 50% cation (H+/OH-) is used for the resin Water flows from top to the bottom through the ion exchanger

VALVE COOLING SYSTEM – COOLING TOWERS









Six cooling towers are installed to cool down the fine hot water coming out from the valves One tower consist of two cooling coils with stainless steel tubes and seawater resistance aluminium fins. Two axial type fans are mounted on the top flow. The fans work on the suction side in parallel to the cooling coil surface without baffle sheets. Because there is no baffle sheet, the working fan will cover the whole cooling coil surface, therefore the lost cooling capacity will be less then 50% of the tower.

Each

fan is provided with Variable frequency Drive (VFD). This regulates the speed of the fan depending on the water temperature If one fan fails, the speed of the remaining fans will be increased automatically.

•A spray water distribution pipe with nozzles locates on the top of each cooling coil •Water will be sprayed over the coil if the water inlet temperature exceeds specified limit

Water Treatment plant  

 



To avoid scaling on the cooling coil fins, the spraying water will be treated by a reverse osmosis* unit. The incoming water from the station supply will be filtered, softened by the reverse osmosis unit and stored in the spray water storage tank. The same water is used to make up the loss in the main water circuit High pressure pumps each of 100% capacity are used for the spray water lines. *slow change in concentration: the flow of a solvent by diffusion through a semi permeable membrane from a more concentrated solution to a less concentrated one, until the concentrations are equalized. It is a major factor in regulating the movement of water into and out of tissues in living organisms.

VALVE COOLING SYSTEM-CONTROL    









Controlled by two redundant SIMATIC S95U programmable controller. The PLC working independent of each other. The PLC generates the necessary status, alarm and trip signals for the station control. The inlet water temperature to the Thyristor valve modules is maintained at constant value for every load and ambient conditions. A digital process controller SIPART DR22 is used for the temperature control The controller output signal is used for the set point of the cooling fan speed. Start and stop signal for the fans is given by the PLC. 80 KVA UPS is provided as backup power supply. Since the outage of main pump generates immediate trip to the pole.

Expansion Tank 







The expansion tank is place on the highest point of the cooling system. The tank size is big enough to store the expanded fine water volume. The expansion tank is an open type expansion tank, the construction of the tank allows the air to come in with the water, but dust can not enter the tank. Thyristor valve manufacturer requires a oxygen saturated water, therefore the need of an open system. The tank is connected to the suction side of the main water line, the connection to the discharge main water line will be used for circulation and for venting.

Valve Hall Ventilation system Flow Diagram

AIR INLET 5m ABOVE GROUND LEVEL

Valve Hall Ventilation system          

Consists of the primary circuit (Air Ventilation Circuit) and Control System Open loop system – supply air will taken in and left out through the exhaust dampers One ventilation system is in operation while the other one is in stand by mode. The outdoor air will be entering the unit by a concrete block duct in a level of 5 m to avoid the dust concentration at the floor level. The supply air will filtered in two stages – pre filter and fine filter The supply air will be distributed into the valve hall by high speed air nozzles. The exhaust air flows via dampers and weather guard louvers into the atmosphere. A by damper and a heater enables the circulation of air from the valve hall back to the unit in case of no load or during start up. Through out the process, positive pressure will be maintained in the valve hall to prevent dust to enter the valve hall. Positive pressure is maintained with the automatic control of exhaust dampers

Valve Hall Ventilation system-components 

One single ventilation unit consist of 

One axial type fan speed regulated



One electrical heater



One air filter bag type as a pre filter



One air filter bag type as a high efficiency filter



One Supply air damper with DC drive



One Return air damper with DC drive



One By or re-circulating damper with DC drive



The two exhaust dampers with DC drives combined with a weather guard louver, as well as the air inlet weather guard louver working together with the two ventilation units. In case of failure of the operating unit, a switchover to the stand by unit takes place.



A periodically automatic switchover is also provided by a programmable timer. The timer can operate in automatic or manual mode.

Ventilation system - Control 









The ventilation system will be controlled by two SIMATIC S95U programmable controller. The PLC‘s are working independent from each other; a switch off of one PLC for repair, replacement or service will not disturb the ventilation system operation. The input signals from the single sensor will be wired parallel on the two PLC. The output signal from the PLC working on the same relay coupled by a diode. The PLC generates also the necessary status, alarm and trip signals for the station control.

KOLAR SINGLE LINE DIAGRAM

AC PLC (Noise) Filter

AC PLC FILTER Equipment Designation

Kolar

Talcher

=20C08.C C1/TD, C2/TD =10C03.C C1/TD, C2/TD =20C10.C C1/TD, C2/TD =10C05.C C1/TD, C2/TD

Number of single phase units

6

6

Rated Capacitance

40 nF

80 nF

Nominal voltage

400 kV

400 kV

Short -time current (1s)

40 kA

40 kA

Basic Insulation level (BIL)

1425 kV

1425 kV

Switching Insulation level (SIL)

1050 kV

1050 kV

10500 mm

10500 mm

Min creepage distance

VALVE TIMING PT •Inductive Voltage Transformer - Connected to converter transformer 400 KV side •Pole control gets the zero crossings of the Voltage on line side and uses this as the reference for generating firing signals for the valves •This PT is used only for firing signal generation – not used for nay protection task

VALVE TIMING PT

•It is inductive voltage transformer •Oil filled – Oil type Shell Diala D •Make – Trench. •Primary/secondary voltage ratio – 400√3/110 √3

VESDA SYSTEM

VESDA – VERY EARLY SMOKE DETECTION & ANALYSER SYSTEM   



 

   

Air sampling based detection system for early detection of incipient smoke / fire in Valve Hall. Installed in each Valve Hall. Sufficient points are well distributed over each multiple valve structure & inside the ventilation air duct for faster response of hazard. The VESDA detectors are located such that there is no condensation due to temperature differences between the sampled air & the outside temperature. Air is sampled by PVC (red) pipes - no risk of flashover or corona inside the valve hall. The detection system has VESDA laser scanner & laser compact. This gets the signal from the sampling pipes which are of PVC make & are ed at regular interval of 1.5 m. For more sensitivity & easy detection,the sampling area is divided into 4 zones.The detector has 4 alarms namely . Alert Action / Prealarm Fire 1 Fire 2

VLC – VESDA LASER COMPACT VLS – VESDA LASER SCANNER

VESDA - LAYOUT PVC conduit

Vent diameter – 4 mm

End cap – 4 mm VALVE - HALL VESDA laser compact

VESDA - LAYOUT

AIR SAMPLING PVC

VLC

Each detector has separate settings of alarm Level DETECTOR

ALERT

ACTION

FIRE 1

FIRE 2

SCANNER

0.075 %

0.13 %

0.19 %

0.25 %

COMPACT

0.15 %

0.3 %

-----

0.5 %

0.075 %

0.16 %

-----

0.25 %

[ SUPPLY AIR ]

COMPACT [ RETURN AIR ]

NOTE : All values have the unit obscuration / m or Ob / m

In the event of detection of smoke in valve hall 

  



Ventilation system shall be tripped automatically. The exhaust dampers shall be opened. The valve-hall shall be de-energized. The smoke management system shall indicate “smoke evacuation mode”. The audible fire alarm system in the station shall also be activated.

VESDA LASER SCANNER - SPECIFICATIONS

    

Voltage – 18 to 30 V DC. Power – 5.8 to 9.6 W. Current – 240 to 400 mA. Sensitivity – 0.005 to 20 % Ob/m Operating temperature   

   

Detector ambient : 0 to 39oC Sampled air : 20 to 60oC Humidity : 10-95%RH.

Maximum area of coverage – 2000 m2. Up to 18000 events can be stored on a FIFO basis. Four levels of fault warning – Alert,Action,Fire1,Fire2. Relays – 12 relays rated at 2A @ 30 V DC.

VESDA LASER SCANNER - SPECIFICATIONS

    

Voltage – 18 to 30 V DC Power – 4 W Current – 170 mA Sensitivity – 0.005 to 20 % Ob/m Operating temperature  

   

Detector ambient : 0 to 39oC Sampled air : 20 to 60oC

Maximum area of coverage – 500 m2 Up to 12000 events can be stored on a FIFO basis Smoke level, alarms & faults with time & date stamp Relays – 3 relays 2A @ 30 V DC

ELECTRODE STATION  



Converter requires reference ground for insulation coordination, control & protection DC currents cause corrosion in metallic structures, hence generally the grounding is done at a safe distance away from HVDC stations (30 to 35 Km) Reliability of HVDC System  



Eliminates the requirement of a separate line as return path 

 

When one line is faulty then by using earth as return path 50% of rated Bipole power can be transmitted. When one pole trips other pole continues in ground return with over load capacity of that pole thus providing transient stabilty / sudden loss of power During balance bipolar operation no current flows through the ground however it provides a return path

Located at Sidalagatta about 32 km from Kolar Station. Similar station exits at Talcher.

Electrode station - Layout

EARTH ELECTRODE         



Conductor type ACSR “Bersimis” Double bundle - 2 x 725.2 Sq.mm Length – 32 Kms DC resistance at 20°C – (0.0421 / 2 ) ohms / km Electrode resistance < 0.3 ohms Electrode – Double ring of diameter 450/320m Each ring consist of a buried coke bed at approx. 2.5 m depth. The outer ring is divided into six sections and the inner ring into two sections Current is distributed by an overhead system to the feeding cables of each electrode section. The cables are connected to the buried electrode. The electrodes are equipped with detecting wells for monitoring the temperature and humidity development of the soil

PLCC SCHEMATIC Pole 1 DC Line

PLCC S

PLCC S

PLCC S

BT PLCC S

BT

BT BT PLCC S

PLCC S

Pole 2 DC Line KOLAR

BT= BALANCING TRANSFORMER

REPEATER

TALCHER

REPEATER STATION •Repeater station is required due to the long distance of the line - 1400Km (approx.) •Located at Jungareddygudem (Rajahmundry) almost at a distance of 630 km from Kolar •Conventional AC stations don’t require repeater station in between the line •Modulated signals consisting of Data, protection and speech are sent to repeater station from one end over the DC lines •Signals are demodulated, amplified and again modulated and sent to the other end from repeater station – thus working as a signal amplifier •ABB PLCC s ETL 580 model are used which works on advanced DSP technology

REPEATER STATIONOther Equipment •PLCC signals are injected to the line through the PLC coupling capacitors •For maintenance works on the PLC equipment, earth switches are provided •PLCC s requires 48V DC supply - provided from batteries •Auxiliary supply is be provided from local SEB supply •DG set is provided as backup to the SEB supply