Simple wind-diesel concept with high wind penetration in Cape Verde

Simple wind-diesel conceptwith high wind penetrationin Cape Verde

Per Nørgård, Risø DTU, Denmark, [email protected]ão Fonseca, Electra, Cabo Verde, [email protected]

mailto:[email protected]

mailto:[email protected]

EWEC 2009Per Nørgård2 Risø DTU, Technical University of Denmark

Cabo Verde

•Independent (from Portugal) in 1955•Population: 500 000 at 10 islands•Islands in study:

SantiagoSão VicenteSal(Boa Vista)


Cabo Verde

Risø DTU as Technical Consultant• for InfraCo (international project

developer)• in collaboration with Electra (local

power utility company)

Power generation based on diesel generationExcellent wind conditions

• High average wind speeds most of the year

• Very constant wind• Low extreme wind speed


Growing demand

0

10

20

30

40

50

60

2000 2005 2010 2015 2020

Pow

er (M

W)

Year

Max power load

Santiago São Vicente Sal Boa Vista


IPSYSan energy system simulation tool

Characteristics• Semi-static time series simulation

(minutes time steps)• Includes storage and memory

functionalities• Designed for mixed energy

systems• Performs energy balances and

load flow analysis (power systems)

• Handles advanced and distributed control

• Developed by Risø DTU


Simplified single line diagrams


Operation strategy

1. Minimum continuous diesel load

2. Minimum instantaneous diesel load

3. Minimum spinning reserve diesel capacity

4. Minimum diesel capacity5. Minimum number of diesel

generator units6. Minimum diesel operation

time

• Minimum continuous load of the diesel engines: 30% (optional 50%).

• To prevent the diesel engines from sooting up at low load.

• The wind power generation may be limited to fulfil this condition.


Operation strategy






time

• Minimum instantaneous load of the diesel engines: 10%.

• To prevent for negative load of the diesel generators.


Operation strategy






time

• Minimum spinning reserve diesel capacity connected to the grid:

200% of the observed fluctuation of the diesel load within the last hour andminimum 50% of the actual diesel load (if possible).

• To be prepared for the fluctuations in the wind power and in the load.


Operation strategy






time

• Minimum diesel capacity connected to the grid:

2 times the wind capacity connected to the grid.

• To ensure dynamic stability of the system.

• @ low load + high wind:wind turbines are shut down-> diesel generators shut down


Operation strategy






time

• Minimum number of diesel generator units connected to the grid:

2• Not to rely on a single diesel

generator unit.


Operation strategy






time

• Minimum operation time of a diesel engine:

4 hours.• To limit the number of start / stop

of the diesel engines.


Load profiles(3x3 days)

Load profiles

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

0 1 2 3 4 5 6 7 8 9

Time (days)

Pow

er (M

W)

SantiagoSão VicenteSal


Seasonal variation of wind

5

6

7

8

9

10

11

12

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan

Mon

thly

ave

rage

win

d sp

eed

@ 3

1m (m

/s)

Flamengo

Filipe

Palmeira


IPSYS results (Sao Vicente)


Summary of results

2009 Santiago Sao Vicente SalMin load 16 6 7 MWMax load 32 12 16 MWEnergy consumption 210 70 90 GWh/yDiesel capacity 44 16 20 MWWind capacity 10 6 8 MWPotential wind energy 35 28 33 GWh/yNot utilised wind energy 0 3 3 GWh/yNot utilised wind energy 0% 11% 9%Wind power penetration 17% 36% 33%Avoided diesel fuel 7 5 6 kt/y


Not utilised wind energy

1 p.u.: 20% wind energy penetration

Not utilsed wind power

0%

2%

4%

6%

8%

10%

0.0 1.0 2.0 3.0

Wind power capacity (p.u.)

Not

util

ised

win

d po

wer

(%)

Sal Sao Vicente Santiago


Avoided diesel fuel

1 p.u.: 20% wind energy penetration

100

150

200

250

0.0 0.5 1.0 1.5 2.0 2.5 3.0

Wind power (p.u.)

Rel

ativ

e fu

el c

onsu

mpt

ion

(ton/

MW

h)

-60%

-40%

-20%

0%

Fuel

diff

eren

ce (%

) SantiagoSalSao VicenteSantiagoSalSao Vicente


Minimum diesel load (2012)

Diesel min load Wind power Wind penetration Not utilsed wind% MW % % kt/y

Santiago 30% 8,5 14% 0% -8,34 -14%50% 8,5 14% 0% -8,34 -14%

Sao Vicente 30% 6,0 40% 4% -5,32 -34%50% 6,0 31% 24% -4,07 -26%

Sal 30% 8,3 26% 1% -6,51 -24%50% 8,3 25% 4% -6,29 -23%

Fuel diff


PPA – Power Purchase Agreement

Minimum wind energy level’take & pay’ @ high tariff

• Motivates wind power operatorto maximise production

Additional wind energy@ low tariff

• Motivates diesel operatorto optimise operation


Conclusions

• The most critical operation parameter is the minimum diesel load.

• Even at 40% wind energy penetration, the not utilised wind energy is ’only’ 10%.

• 20% ’overinvestment’ in wind power capacity is proposed

22 MW -> 28 MW -> 0..10% not utilised wind energy.

• This seems economically feasible at 5% reduced generation cost ($/kWh), with the expected demand growth.

Thanks!Seeing you at

Stand 2463 (Hall 2)Per Nørgård

Risø DTU, [email protected]

Hall 2

Simple wind-diesel concept with high wind penetration in Cape Verde

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