why hvdc - r2 - usaid sari/energy integration · why hvdc? page 1 23.08.2011 et ... conventional ac...

Why HVDC? y

23.08.2011 ET-PS Energy Transmission

World Power ScenarioWorld Power Scenario

• World wide electrical power consumption projected to increase by >70% by2030 investments in power generation

• Tendency to a global energy market need of national and internationalgrid interconnectionsgrid interconnections

• Generation and consumption centers separated by long distances Needto transfer power over long distances


Issues concerning Transmission SystemsIssues concerning Transmission SystemsIssues concerning Transmission Systems Issues concerning Transmission Systems

Utilization of existing resources and systems to the maximum extent

Transmission of bulk power over long distances efficiently

Severe Right of Way constraints

Uncertainty in Generation Uncertainty in Generation

Control of flow of power

Stability Stability


Wh t’ d d?Wh t’ d d?What’s needed?What’s needed?

Option of up-gradation / allow implementation in stages

Transfer of allocated power / long-term contractual requirement

Should have margin for transfer of operational surplus in addition to committed powerp

Meet system requirements – active and reactive power following variations in load demand and contingencies

High Availability & Reliability

Low cost to consumers


SMART Transmission – Siemens WaySMART Transmission – Siemens Way

Conventional AC Transmission HVDC Transmission

Siemens InnovationPresent scenario

For Bulk Power transfer over long distances – AC not an efficient solution

• Reliable means of bulk power transfer

• Lower transmission losses 5% 2 000 k

Bhiwadi

RajasthanBalliaMohindergarh

• Degradation of capacity in AC lines with increasing lengths

- 5% over 2,000 km

• Flexibility to enhance the transfer capacity

• Fewer lines with lesser

Talchar

(Orissa)

UP

Mundra

Gujarat

Haryana

• Reactive power management & Losses - a major issue

Right-of-Way

• “SMART GRID” performance features

• More economical

Kolar

Karnataka

Hi h i t f l d & Ri ht f

One of the Worlds largest link

• More economical

2500MW,1400 km-long HVDC link from Talchar to Kolar –Executed by Siemens 3 months ahead of schedule

• Higher requirement of land & Right-of-Way

• Several parallel lines to be used to transfer high power

23.08.2011 ET-PS Energy Transmission 800kV AC

85m

ahead of schedule

Other 2x 2500MW HVDC projects–Under execution by Siemens

Technology OptionsTechnology Options

Use of Compact Lines / Multi-Circuit lines Use of Compact Lines / Multi Circuit lines.

Use of HVDC/multi-terminal HVDC systems to build ysystems in phases.

Use of Voltage Source Converter systems.

Re conductoring of existing lines without outages Re-conductoring of existing lines without outages.


HVDC Applications HVDC is the unique solution to interconnect asynchronous systems, e.g. different

grid frequencies.Solution: HVDC Back-to-Back

HVDC Applications

Up to 1000 MW

Back-to-Back Station

AC AC50 Hz 60 Hz

HVDC represents the most economical solution for distances greater than approx. 600 km / 400milesSolution: HVDC Long Distance

Up to 3000 MW

Long Distance Transmission

AC ACDC line

HVDC is an alternative for submarine transmission. Economical even for shorter distances such as a few 10 km / milesSolution: HVDC Cable


Up to 800 MW

Long Submarine Transmission

AC ACDC cable

Benefits: HVDCBenefits: HVDCBenefits

DC line has lower construction costs than an AC lineFor equivalent transmission capacity

A double HVAC 3-Ø circuit with 6 conductors required to get reliability of a 2-pole DC link

DC losses are less compared to ACFor the same conductor

DC link is asynchronousDC link is asynchronousCan be used to interconnect grids with different frequencies

HVDC systems are more reliableCannot be overloaded by outage of parallel AC linesy g p

Right of way for DC line is 41% lowerCompared to AC Line designed to carry 2,000 MW

C S C


HVDC systems do not add to Short Circuit Power requirements Beneficial, if the installed HV equipments are at / close to their limit Short Circuit capability

Benefits: HVDC (contd )Benefits: HVDC (contd..)

Benefits

DC systems are modularDC systems are modularcan be built in stages if the generation is being added over a longer period

HVDC system along with the existing AC system would enhance grid security and system stabilitysecurity and system stability

Overload and power modulation features of HVDC could be used to cater to grid emergencies in case of outage of AC lines


AC vs. DC: Loss EvaluationAC vs. DC: Loss Evaluation

Line Length – 970 Km Load: 2500 MW Avg. Loading Factor: 90%

AC System: 1 no. 400 kV D/C Quad Moose Configuration + 1 no. 400 kV S/C Quad Moose

ConfigurationDC System: ±500kV HVDC

Resistance of quad moose conductor: 0 056/4 = Resistance of quad bersimis conductor: 0 042/4 =Resistance of quad moose conductor: 0.056/4 0.014 Ω/km at 20°C

Resistance of quad bersimis conductor: 0.042/4 0.011 Ω/km at 20°C

Resistance at 75°C and for line length of 970 Km: 16.57 Ω

Resistance at 75°C and for line length of 970 Km: 10.67 Ω

Power in each circuit: 2250/3= 750 MW Power = 2250 MW

Current per phase: 750/1.732x400x0.9 = 1203 A Current per pole: 2250/2x500 = 2250 A

Losses for AC configuration: 3x3x12032 x16.57=216 MW

Losses for DC line configuration: 2x22502 x10.67=108 MW + Losses at HVDC terminals: 27.4 MW

(from guaranteed loss figure)


Total losses for AC configuration: 216 MW Total losses for DC configuration: 135.4 MW

Saving of 80.6 MW

Right of Way Comparisons

Typical tower structures and rights-of-way. Capacity: 2000 MWTypical tower structures and rights-of-way. Capacity: 2000 MW

Right of Way Comparisons

yp g y p yyp g y p y

± 500 KV DC 800 KV AC 2 X 500 KV AC


50 m 85 m 100 m

Cost comparison of AC and DC transmission

Cost of AC Line

Cost comparison of AC and DC transmission

CostBreak even distance Cost of DC Line

Cost of DC terminal

Cost of AC terminal

Distance in km 500 – 700 km


why hvdc - r2 - usaid sari/energy integration · why hvdc? page 1 23.08.2011 et ... conventional ac...

Documents