A. Koronides, S. Efstathiou G. Koutzoukos, N. Boulaxis

11

Interconnection of the Cycladic Interconnection of the Cycladic islands of Syros, Tinos, Mykonos, islands of Syros, Tinos, Mykonos, Paros and Naxos to the Mainland Paros and Naxos to the Mainland

System via submarine cablesSystem via submarine cables

A. Koronides, S. Efstathiou G. Koutzoukos, N. Boulaxis

22

The Interconnection of the Northern Cycladic Islands has been considered as early as the early 90‘s because of: Rapid growth of their consumption

(development due to tourism) Building new Generating Capacity was always

very difficult very difficult due to environmental constraints (all existing in proximity to the main towns)

High operating cost using diesel and heavy fuel

BackgroundBackground

33

Area of ConcernArea of Concern

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[M

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Paros-Naxos Mykonos Syros Andros-Tinos Total

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erg

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GW

h]

Paros-Naxos Mykonos Syros Andros-Tinos Total

Evolution of DemandEvolution of Demand

Evolution of Energy demand (1980-2004)

Evolution of Peak load (1980-2004)

Year of connection of Andros-Tinos to the Mainland

2005

55

Load ForecastLoad Forecast

Forecasted Energy demand (2005-2025)

Forecasted Peaks (2005-2025)

0

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11002

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Year

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erg

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GW

h]

Paros Naxos Mykonos Syros Andros Tinos Total

020406080

100120140160180200220240260280300

2006

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Year

Pe

ak

Lo

ad

[M

W]

Paros Naxos Mykonos Syros Andros Tinos Total

66

0

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Local GenerationLocal Generation

12.324

34

548

6

11

15

20 (30)

Andros Syros Mykonos Paros

Current capacity Planned Expansion Possible additional capacity

[MW]

77

Introduced in the late 80’s to be implemented in early 90’s :

weak interconnection to the Mainland by single cable

OHL on the islands and submarine cables between them (shortest distances)

development of new geothermal power plant in Milos

Foreseen implementation in two phases:

Phase A: interconnection of Andros,Tinos, Mykonos and Syros to the Mainland

Phase B: expansion of the connection to Milos (reaching the Geothermal Field) and installation of Geothermal Power Plant in Milos

Initial Interconnection PlanInitial Interconnection Plan

88

Initial Plan (made in1989)Initial Plan (made in1989)

New 150kV OHL

New 150kV submarine cable

New 66kV OHL


Existing 150kV substation

New 150kV substation

New 66kV substation

Existing PS

New PS (geothermal)

PHASEPHASE Α Α

PHASEPHASE Β Β

99

By the end of the 90´ were installed the cables (mid 90’s ) :

• Main System – Andros

• Andros – Tinos

• Tinos – Syros

• Tinos – Mykonos the OHL over Andros (late 90’s)

What has been done (1/2)What has been done (1/2)

1010

In the meantime :

Local Reaction against construction of OHL (150kV, 66kV) on the islands has escalated

also

Local Reaction against Geothermal plant in Milos started

However, a new interconnection plan was prepared

What has been done (2/2) What has been done (2/2)

1111

Revision of Initial Plan (2001)Revision of Initial Plan (2001)

Existing 150kV OHL

New 150kV OHL

Existing 150kV submarine cable


New 66kV OHL

Existing




New 66kV substation

Existing PS

New PS (Diesel)

1212

Expansion of the Interconnection to Paros and Naxos

Revised plan for installation of new “big scale”“big scale” thermal station in Naxos

Expectations to overcome local reactions

Sitting of thermal station in Naxos considered possible

Revision of Initial Plan (2001)Revision of Initial Plan (2001)

1313

Local Reactions Escalated State Council Decision was issued againstagainst

construction of new High Voltage Lines on the Islands

Sitting of new thermal stations almost impossible

Nevertheless in 2003 the construction of an AIS in Andros was completed

Court Decisions Court Decisions (2001-2004)(2001-2004)

1414

Facing said facts, a more “pragmatic” design was done

No new OHL over the islands

No new thermal stations on the islands

Use of existing thermal plants only as cold reserve - No thermal Production on the islands

Possibility to exploit significant wind capacity (installation of W/F)

New Design New Design (2004 - 2005)(2004 - 2005)

1515

Final Plan (2005)Final Plan (2005)

Existing 150kV OHL

New 150kV OHL

Existing 150kV submarine cable


Existing 66kV cable



Existing PS

1616

ProsPros Secure power supply of the Islands (from the mainland interconnected grid) Long-term solution – no new local generation every 2-3 years Substitution of power (Diesel) from existing local PS (gradual

decommissioning) with power from the Interconnected System Economic and Environmental benefits

Increase of wind power penetration on the interconnected islands Possible future extension of the Interconnection to the Southern Cycladic

Island (further exploitation of considerable wind and geothermal potential of the islands)

More economical than feeding the islands by diesel stations in the long run ConsCons

Considerable initial investment cost:• submarine cables• advanced interconnection technology (DC with VSC, GIS substations,)

Long amortization period Use of new innovative, but not sufficiently proven technologies (long

XLPE* submarine cables, DC control in abnormal situations e.t.c).

* XLPE cables have low MVAR/km than OIC (1,5 vs 2,5)

Pros and Cons Pros and Cons of the Interconnectionof the Interconnection

1717

Technical DescriptionTechnical Description 4 new GIS Substations 150/20kV in Syros, Mykonos, Paros and

Naxos Submarine Interconnection of above substations

(cables 1×3phase / AC / XLPE / 150kV / 200MVΑ): Syros - Mykonos 36km Syros - Paros 50km Paros - Naxos 16km Naxos - Mykonos 40km Syros - Andros 32kmReactive compensation (reactors) of the cables is required

Submarine Interconnection of Syros to the Mainland (Lavrion EHV Substation). Two alternative technologies:

D.C. Interconnection: Submarine D.C. interconnection Lavrion - Syros ~100km 250ΜW

(2+1 cables) An AC/DC converter station at each end of the interconnection

(-50/+150ΜVA) A.C. Interconnection:

Submarine A.C. interconnection Lavrion - Syros ~110km 250ΜW (2×3phase / AC / XLPE / 150kV / 200MVΑ).One stop at Kythnos for junction and reactive compensation with SVC in Syros ~ +/- 150 MVAR

1818

Basic Economic and Basic Economic and Technical assumptionsTechnical assumptions

Πηγή: ΔΕΗ/ΔΣΠ

* Price in 2006 570€/lt

Basic economic assumptions (in 2005 prices)

Inflation 3%

Rate of fuel price variation above Inflation 2%

Cost of FuelDiesel 410 €/t*

Heavy oil 190 €/t

Cost of Energy from Interconnected System 54 €/MWh

Cost of Energy from local PS 80 €/ΜWh

O&M cost of old local PS 96.03 €/KW&year

O&M cost of expansion of existing local PS 38.41 €/KW&year

Investment Cost (after taxes) 7%-9%

Basic technical assumptions (in 2004 prices)

CO2 emissions 8-20 €/ton CO2

Efficiency of new PS (diesel) 42%

Investment Cost (new PS) 1100 €/KW&year

Cost of Expansion of old PS 825 €/KW&year

1919

Comparative Cost AnalysisComparative Cost Analysis(estimates with 2005 prices(estimates with 2005 prices

in MEuros)in MEuros)

* new OHL over the islands, submarine cables between the islands, connection with new cables and lines to the north

** New prices increase 40%

Cost Component [MW]Final

SolutionExpansion of existing PS

No further interconnectionLeast Cost Approach*

Investment Cost 170 ~230 133.03 101.26

Cost of Fuel (Diesel)** 0 472.74 0

Cost of Energy from Interconnected System

380 61.62 380.72

CO2 emissions 0 11.86 0

Fixed O&M Costs 10 ~ 75 49.53 48.62

Total Cost 560-685 728.77* 530.6

new oil prices

2020

ΑΝDROS 150kV

Lavrion EHV400kV

150kV XLPE AC 1×3 200MVA40km

~

150kV XLPE AC1×3 200MVA36km



~


DC (2+1 cables)250MW100km

1×16MVAr1×9MVAr

1×16MVAr1×9MVAr 1×9MVAr

1×16MVAr 1×16MVAr

1×9MVAr

1×18MVAr

1×18MVAr

1×16MVAr

~

1×18MVAr

1×19MVAr

1×16MVAr

1×16MVAr

1×16MVAr

D.C. SolutionD.C. Solution

AC/DC Converter station-50/+150MVAr

AC/DC Converter station-50/+150MVAr

MYKONOS 150kV

NAXOS 150kV

SYROS 150kV

PAROS 150kV

2121

PAROS150kV

MYKONOS150kV

SYROS150kV


~




~


150kV XLPE AC2×3ph/280MVA110km

1×16MVAr1×9MVAr

1×16MVAr1×9MVAr 1×9MVAr

1×9MVAr1×18MVAr

1×9MVAr2×18MVAr

(junction at Kythnos)

1×18MVAr

1×16MVAr 1×16MVAr

1×9MVAr

1×18MVAr

1×18MVAr

1×16MVAr

~

1×18MVAr

1×18MVAr

1×16MVAr

1×18MVAr

1×16MVAr

SVC-50/+150MVAr

Transformer 400/150kV

150kV

ANDROS 150kV

1×18MVAr

A.C. SolutionA.C. SolutionLavrion EHV400kV

Junction point in the island of Kythnos

2222

Expansion of the Network (Overhead Lines) Faces huge local Reaction

Generalized use of Cables is not realistic:

Huge Cost

Technical Problems (reactive capacitance)

Use of Cables in the mainland is restricted to very specific cases involving heavily populated areas

Conclusions 1/5Conclusions 1/5

2323

The Cycladic Islands are the closest islands of the Aegean Archipelago to the mainland.

They represent a significant load with high rate of increase.

Development of local generating units is associated with high operational cost and practical difficulties to find new locations.

A submarine “cable” connection to the mainland is the only “pragmatic” solution.


2424

The least cost solution, would involve several overhead HV lines on islands and new ~70km in the mainland in Evia

New OHL on the Islands would “insult” dramatically the aesthetically sensitive landscape of the islands and was denied by the State Council

Licensing of new long OHL in Evia considered impossible


2525

Solution Chosen :

Long Submarine Connection of the central island of Syros to the Lavrio production center in the mainland and,

DC converters and cables or

AC XLPE Cables and junction in island in about half distance plus SVC in Syros

Connection to other Islands by AC XLPE cables


2626

Solution Chosen

Has high initial investment cost

But is economically feasible in the long run

Is environmentally friendly, therefore is pragmatic

Allows installation of Wind Power up to about the peak load of the islands (otherwise very limited)

Is acceptable by the local communities


2727

Other interesting cases experienced by HTSO Other interesting cases experienced by HTSO (1/4)(1/4)

Corfu

South Evia

2828


In the Island of Corfu a second 150 kV submarine cable was planned to satisfy the reliability needs for the island (N-1 criterion )

Total length ~ 17 km submarine

To ease the local reaction the 3 km OHL line on the island was designed as underground cable

Nevertheless the project faces big delays since reaction appeared requesting transferring of the local Substation (existing for many decades) to a new location and use of GIS technology.

2929


A new Connection of Evia to the mainland was designed to support Wind Energy

Initially least distance submarine cable solution was chosen (~17 km OHL and ~8 km submarine cable)

It was rejected and replaced by a solution with

~ 20 km submarine cable and 2 km underground cable through a small town

Recently, local reaction appeared against the underground cable through the town.

3030


Lesson Learned :

Use of cables,

Although is expected to be acceptable by the local societies

might bring new reaction and

further requests.

Documents

A. Koronides, S. Efstathiou G. Koutzoukos, N. Boulaxis