HVDC Transmission System for KMUTNB

HVDC Transmission SystemElectrical Engineering Seminar

September 2, 2008 14.00-16.00 Hrs. Faculty of Engineering

King Mongkut’s University of Technology North Bangkok

Presented byNitus Voraphonpiput, Ph.D.

Engineer Level 8 Technical Analysis – Foreign Power Purchase Agreement Branch

Power Purchase Agreement DivisionElectricity Generating Authority of Thailand

2

Aims To introduce basic concept of the High Voltage Direct Current (HVDC)

transmission systems. To present applications and

technologies of the High Voltage Direct Current (HVDC) transmission

systems.

3

Content Introduction Why uses HVDC? Applications of HVDC Future Trends Conclusion

Introduction

5

Power transmission was started in the early 1880s using direct current (DC).

With the development of transformers, induction motors and synchronous generators, the DC transmission systems were replaced by AC

Transmission system.

Nowadays, due to successful development of HV converters (rectifiers and inverters) based on

Silicon Controlled Rectifiers (SCR), the High Voltage Direct Current (HVDC) transmission systems become an economic and attractive

technology.

Introduction

6

HVDC is the abbreviation of High Voltage Direct Current.

Beginning of HVDC Transmission System Marcel Deprez put his experiment (1881) to

practice in 1882. a 1.5 kW at 2 kV over a distance of 35 miles was operated.

In 1889, R. Thury continued the D. Marcel work, he used DC generators connected in series to generate high voltage and sent 20 MW at 125

kV over a distance of 230 km (Moutiers-Lyon) in France.

7

Part I: Mercury Arc Valve

The first commercial HVDC in Europe was Gotland in Sweden (1954).

Cross Channel -1961; 160 MW, 64 km cable between England and France (ASEA)

Volgorod – Donbass - 1965; 720 MW, 470 km in Russia Sardinia; 1967; 200 MW, 413 km between Sardinia and Italian

mainland (GEC England) New Zealand – 1965; 600 MW between the south and north

islands (ASEA) Konti-Scan I – 1965; 250 MW, 180 km between Sweden and

Denmark (ASEA) Sakuma - 1965; 300 MW frequency converter in Japan (ASEA)

Vancouver I - 1968; 312 MW, 69 km between BC and Vancouver island (ASEA)

Pacific HVDC Inter-tie – 1970; 1440 WM, 1362 km overhead line between Oregon and Los Angeles (JV between ASEA and GE)

8

Part II: Thyristor Valve

Gotland Extension – 1970; Adding 50kV and 10 MW to the Gotland scheme using thyristors (ASEA)

Eel River – 1972; 320MW first all thyristor asynchronous link in Canada (GE)

……………………..(more than ten projects)…………. Haenam-Cheju – 1993; +/- 180 kV, 300 MW, south Korea

(English Electric) Baltic Cable Project – 1994; 450 kV and 600 MW (Sweden

Germany) Kontek HVDC Interconnection - 1995; 400 kV, 600 MW,

Denmark Scotland-N.Ireland – 1996; 250 kV and 250 MW

Leyte-Luzum -1997; 400 kV; 1600 MW; 440 km, Philippines. Chandrapur-Padghe – 1997; +/- 500 kV; 1500 MW; 900 km, India

Greece-Italy – 1997; 500 kV EGAT-TNB – 2001; 300kV and 300 MW, 110 km thyristors

(Siemens) ………

9

Main components of a HVDC transmission

Cooling system

10


Converter stations connected to the AC bus via transformers.

Two-winding or three-winding transformers, in which a 30 degrees phase shift is required between the

converter units because of the 12-pulse connection selection of vector groups.

The on-load tap changer of the transformer Filters and capacitor banks.

Converter bridges, usually two six-pulse bridges in series, equipped with controls of their own enables

independent operation Cooling system

11


Firing pulses of the thyristors are usually passed via optical fibers.

Control system. Smoothing inductors (act as filters harmonics in DC

and limits the rate of current change.) DC Filters (on overhead lines).

A cable or an overhead line as a transmission path for the current passing through sea or earth, also

electrodes are required.

12

6-pulse Bridge Circuit

Thyristor valveComponents of the thyristor m

odules

13

A Thyristor valve

Thyristor Module

2x 6-bridge

Symbol

Thyristor valves

EGAT-TNB HVDC 300 MW 300 kV

14

YY

Converter Transformers

Transformer


Converter Transformers

15

Switchyard, Capacitor Banks and AC Filters DC Tower and DC Line


16

Smooth Inductor

(smoothing reactor)DC Active Filter


17

HVDC Transmission System (electrical system)

18

Electric Power Transmission

R

UUP dd 2

21

12

HVAC HVDC

jX RES ER Ud1 Ud2

RSRSS

RSRS

X

EEEQ

X

EEP

cos

sin

2

12

12

19

IUP

IUPR

UUI

d

d

dd

.

.

22

11

21

Rectifier Inverter

+ UR -

AC system

AC system

Electric Power Transmission using HVDC

20

MWAkVP

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I

2901000.290

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Electric Power Transmission using HVDC

21

Converter Operation

Voltage and current waveform of HVDC converters

22

30

VI.cos

I

I.sin

30

866.02

)2515cos(15cos

2

)cos(coscos

Rectifier Operation of the 6-pulse bridge converter

Assume = 15 and = 25

The converter operates in rectifier mode. It transmits active power while consumes reactive power.

Converter Operation

23

145

VI.cos

II.sin

145

823.02

)25135cos(135cos

2

)cos(coscos

Inverter operation of the 6-pulse bridge converter

Assume = 135 and = 25

The converter operates in inverter mode. It receives active power while

consumes reactive power.

Converter Operation

24

Alternatives for the implementation of a HVDC transmission system

i) Mono-polar Configuration

ii) Bipolar Configurationa) Earth Return

b) Metallic Return

iii) Homo-polar Configuration

25

Alternatives for the implementation of a HVDC transmission system (continued)

26

This configuration can be found as early as 1954, there was no interest in its commercial use until the 1990s because the control and protection equirements were considered to be exce

ssively complex.

The first commercial application, taken into full service in June 2000, is a 1100 MW asynchronous back-to-back link betwee

n Argentina and Brazil

Source: Alstom

Capacitor Commutated Converter HVDC (CCC-HVDC)

Why uses HVDC?

28

Why uses HVDC?The reasons that HVDC have been used

are:1. An overhead DC transmission line with its towers can be designed to be less costly per

unit of length.2. It is not practical to consider AC cable systems exceeding 50 km (due to capacitive

current charging of the cable).3. Some AC electric power systems are not synchronized to neighboring networks even though their physical distances between

them is quite small. (Interconnection problem)

29

Less cost/unit length

Source: Siemens and Jos Arrillaga’s book (1998)

30 300 km 300 km 300 km

900 km

HVDC

HVAC


31 Source: ABB


32

System Modeling for Line Loadability

Line model

Source: EPRI

Limitation of AC transmission line

33

Typical values of SILfor overhead transmission lines

Rated voltage

[kV]

Thermal Limit [MW]

SIL

[MW]

230 400 135-145

345 1,200 325-425

500 2,600 850-1075

765 5,400 2,200-2,300

1100 24,000 5,200

Note: No series or shunt compensation

Constant line voltage drop 5%

Steady state stability limit (30% margin)

Source: EPRI

Thermal Limit

HVDC can utilize line up to thermal limit.

Limitation of AC transmission line

34

Limitation of AC cableGeneral AC Cable Technologies Pipe-type

Coated and protected steel pipe houses the cable and dielectric fluid

Dielectric fluid is maintained under pressure Insulation material is Kraft paper or laminated

paper-polypropylene Self-contained, fluid-filled (SCFF)

Insulation impregnate is a low viscosity liquid which must be maintained under pressure internally

Conductor has central fluid duct Extruded cross-linked polyethylene (XLPE)

Solid dielectric insulation, no fluid, no pressurizing plant

Limited applications above 230 kV to dateSource: ABB

35

1.SCFF for AC or DC 2.MI for DC

3.Single-core XLPE for AC 4.Three-core XLPE for

5.Extruded HVDC Light for DC 6.Extruded HVDC Light for DC

Source: ABB

36 Source: ABB

Limitation of AC cables

37 Source: ABB

HVDC can utilize cable up to thermal limit.

Limitation of AC cables

38

Limitation of AC Interconnection

It is impossible to connect two (or more) different system frequencies via HVAC.

Without control center to take care off whole system frequency, it is impossible to connect two (or more) systems through HVAC event

their system frequencies are equal.

Difficult to control power flow between areas without special equipment such as phase

shifting transformer.

But HVDC can overcome these problems.

Applications of HVDC

40

Applications of HVDC

41

Emergency Frequency ControlWhen a large generator is

tripped, the system frequency falls down over an acceptable level.

HVDC can rapidly increase or reverse power flow direction to

compensate unbalance active power to recover system frequency.

42

Automatic Frequency ControlWhen you require to improve frequency deviation in normal

operation and after large disturbances, application of Automatic Frequency Control (AFC) function is recommended.

Source TMT&D, Japan

43

Power Swing Damping Control

The modulation control of the DC power improves power swing stability and effectively dampes power oscillations. (this function is not limited for HVDC–HVAC line in parallel, but also applies to

HVDC linked between two AC networks.)

Source TMT&D, Japan

44

Starting Up the Generator

When an HVDC system is connected to the isolated generator at the sending end, the system has to be started up in coordination with the governor action of the generator. The bipoler operation is available, overall transmitted power can be built up smoothly from zero to the rated value by having two poles transmit power in opposite dire

ctions.

Source TMT&D, Japan

45

Usage of HVDC in USA (same frequency)

46

Usage of HVDC in Japan (two different system frequencies)

Source: Toshiba

47 Usage of HVDC in India.

48

Usage of HVDC in China

49

Itaipu, Brazil

Brazil decided to build a HVDC transmission system from Itaipuhydro power plant to SãoPaulo to meet the rapidly growing

power demand in 1978. A 3150+3150 MW ±600 kV HVDC power link between Itaipu and SãoPaulo brings power generated at 50 Hz (in

Itaipuhydropower plant) to the 60 Hz network in SãoPaulo. This project was commissioned in 1984-1987.

50

Québec -New England, Canada -US

This project was commissioned in 1990-1992. It is a 2000 MW ±450 kV multi-terminal HVDC power link.

The HVDC multi-terminal system brings power from La Grande II hydro power station to loads in Montreal, Québec, Canada

and to Boston, Massachusetts, USA

51

Baltic Cable, Sweden -Germany

A 600 MW 450 kV HVDC sea cable system links between Germany and Sweden to enable further integrate power systems of the Baltic Sea region. This project was commissioned in 1997 and it

is an economic exchange between a thermal power system and a hydro/nuclear power system

52

Brazil -Argentina Interconnection

This project links Argentina (50 Hz) and Brazil (60 Hz) to utilize their electricity resources more efficiently and cost effectively.

It providers import and export power to take advantage of peaks demand between Brazil’s and Argentina’s asynchronous

networks. It is a CCC-HVDC (2200 MW 140 kV (±70 kV) back-to-back system).

53

HVDC has been integrated. Because of long transmission lines, the AC system experiences severe power oscillations after systems faults, close to the stability limits. In first case, HVDC is transmitting power in constant power mode (curve a). ,the power oscillations occur.

With daming control of HVDC, the oscillations are damped very effectively (curve b). Without HVDC, e.g. with a fully synchronous interconnection, such a large power system would be unstable in case of faul

t contingencies, thus leading to blackout.

HVDC GuiGuang, China

54

Hokkaido-Honsyu HVDC (Japan)

Source: Toshiba

55

EGAT-TNB HVDC, Thailand

In 2003, a mono-polar 300 MW 300 kV HVDC transmission system was installed between Thailand and Malaysia. This HVDC offers an

important option in economic operation of the Thailand power system. It transfers economical energy between two countries. This HVDC provides

four enhanced stability functions for AC system. One of these is Power Swing Damping (PSD) function. This function was designed to damp inter-

area oscillation on the tie transmission line linking Central system and Southern system.

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January 13, 2005, TNB experienced the separated system event between the Northern part and the Southern part. It resulted in over-frequency

in the Northern part and low frequency in the Southern part due to over generation (in north) and lower generation (in south) respectively. Frequency Limit Control (FLC) function of the HVDC increased power into EGAT system

from 300 MW to 406 MW to stabilize frequency in TNB system.

TNB frequency

DC Power to EGAT

K u a h

M e la k a

S e re m b a n

G e o rg e to w n

K o ta B h a ru

K u ala T e re n g g a n u

Ip o h

K u an ta n

S h a h A la m

A lo r S e ta r

K a n g a r

J O H O R

P A H A N G

M E L A K A

N E G E R I S E M B IL A N

S E L A N G O R

P E R A K

K E D A H

P U L A U P IN A N G

K E L A N T A N

T E R E N G G A N U

P E R L IS

W IL A Y A HP E R S E K U T U A N

L A N G K A W I

M E L A K A

B E R S IA

K E N E R IN G

T E M E N G O R

K E N Y IR

S G P IA H U P P E R

S G P IA H L O W E R

J O R

W O H

O D A K

C H E N D E R O H

P E R G A U

MAIN GRID INPENINSULAR MALAYSIA

N

L e g e n d

H y d ro P o w e r S ta t io n

T h e rm a l P o w e r S ta t io n

S ta te C a p ita l

E x is t in g P la n n e d

5 0 0 k V O v e rh ea d L in e

2 7 5 k V O v e rh ea d L in e

2 7 5 k V C ab le

J o h o r B a h ru

P R A I

G E L U G O R

S E G A R I

C O N N A U G H T B R ID G E

S E R D A N G

K A P A R

P O W E R T E K

P D P O W E R

G E N T IN G S A N Y E N

P O R T D IC K S O N

Y T L

P A S IR G U D A N G

P A K A

Y T L

A y e r T a w a r

B a tu G a ja hP ap a n

K u a la K a n g s a r

B u k it T a m b u nJ u n ju n g

B u k it T en g a h

G u ru n

B e d o n g

K o ta S et ar

C h u p in g

B u k i t T ar ek

K L (N )K L (E )

H ic o m G

K L (S )

S a la k T in g g i

M ela k a

K g A w a h

S c u d a i

T elo k K a lo n g

T an a h M e ra h

J A N A M A N J U N G

M a jo r T N B S u b s ta t io n

Y A N

Y o n g P e n g (N )

B u k it B a tu

S ed il i

L e n g g e n g

Y o n g P e n g (E )

3 0 0 k V H V D C L in e

EGAT-TNB HVDC, Malaysia

Future Trends

58 Source: ABB

59

Voltage-sourced converter based HVDC systems are called HVDC Light (ABB) or

HVDC Plus (Siemens) become new trend of HVDC due to

Converters do not require reactive power. Suitable both for submarine and land cable connecti

ons. Advanced system features.

Small footprint (e.g. 550 MW): 120 x 50 x 11 meters. Black Start Capability Short delivery time.

60

Voltage-sourced converters (VSC) operate with a smooth dc voltage provided by a

storage capacitor. The fast switching capability of the IGBT allows to create a

pulse width modulated (PWM) AC voltage.

The converter can operate in 4 quadrants of the active power and reactive power plane.

The commutation does not depend on the ac network voltage. Thus it can connect to very weak

power systems. The ac output voltage of the converter can be

changed extremely quickly.

61

However, the voltage and power ratings of IGBTs are as yet far below those of

thyristors and so applications with voltage-sourced converters are limited to low and

medium power. The first commercial project was once more

commissioned on Gotland and taken into service in November 1999. A power of 50 MW is transferred

through two underground cables of 70 km length at a voltage level of ±80 kV from the south of the

island to the north. A similar installation (3X60 MW, ±80 kV) was

commissioned and brought into operation in 2000 to connect the grids of Queensland and New South

Wales, Australia.

62

Power rating of Switching devices

Source: ABB

63 Source: ABB

64 Source: ABB

65 Source: Siemens

Conclusion

67

Advantages of HVDC DC lines can be loaded up to

the thermal limit. Power flow control.

Does not increase the short-circuit currents in the AC

network. No capacitive charging

current on DC lines. Ground or sea can be used

as a return conductor. Fast control of power and

stabilizing of AC system. N-1 criteria may not be

required. Economic for long

transmission line and bulk energy.

Interconnection between two AC systems is possible.

Disadvantages of HVDCElectric Field can cause a

problem to human.Converter stations are

expensive and complex arrangements when

compared with the stations in an AC system.

Conventional Converters (rectifier and inverter)

require reactive power. Converters produce

harmonics both in the AC network and the DC side.In mono-polar links, the return current passing through ground causes

corrosion in metal objects.Sensitive to fault in AC network near converter.

68

Long distance over land

Long distance over sea

Inter-connection

asynchronous network

Wind Turbine

connection to network

Feed

a small isolated

loads

HVDC

+ OH line HVDC

+ Cable CCC

B2B CCC

+OH line CCC

+ Cable VSC

B2B VSC

+ Cable

69

In emerging countries, power systems will grow (very) fast. Because of reliability and economic reasons. HVDC will play a signific

ant role in the future (such as China and Indian).

Conventional HVDC still uses in power system. It is a proven technology.

In future, VSC-HVDC and polyethylene DC cables will made Economic at lower power levels (down to 200 MW) Economic at short distance (60 km).

70

Thank you

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Questions and discussions are very welcome.

Documents

HVDC Transmission System for KMUTNB