Future Electricity Grids 1/2

Mini-Course on Future Electric Grids
Part 1 of 2

Dirk Van Hertem — Dirk.VanHertem@ieee.org

Electric power systems
Electrical engineering department
Royal Institute of Technology, Sweden

February 22, 2010

K.U.Leuven (Belgium) KTH, Stockholm (Sweden)

Dirk Van Hertem (Electric Power Systems, KTH) Mini-course on Future Electric Grids (1/2) 22/02/2010 1 / 29

1 Introduction
Course overview

2 Variable ﬂows in the system
Before liberalization and the rise of renewables
International market environment
More renewable energy generation
Effects on the system
International setting
Common misunderstandings about wind power

3 Investments in the power system
Need for investments
Investments to integrate renewables
Investment technologies to increase transmission capacity


Introduction

1 Introduction
Course overview




Introduction Course overview

Who am I?

Master in engineering from KHK Geel, Belgium
Master of science in engineering from K.U.Leuven, Belgium
PhD in engineering from K.U.Leuven, Belgium
Currently Post-Doc researcher at the Royal Institute of Technology,
Stockholm, Sweden
Active member of both IEEE and Cigré



Course overview and objectives

Overview Part 1
New situation in the power system
1 Liberalization of the market
2 Increased penetration of smaller, variable energy sources
3 No single authority in Europe
4 Lacking investments in the transmission system



Course overview and objectives

Overview Part 2
International coordination in the power system
How this cooperation can benefit and obstruct
Power flow controllers
Coordination and power flow controllers
The future “supergrid”. . .
. . . and the road towards it



What it is about and what not

Not the grid of 2050
Main focus is Europe
Not about smart grids (or not speciﬁcally)
About transmission and not distribution
Mainly from a grid operator point of view


Variable ﬂows in the system

1 Introduction
Course overview




Variable ﬂows in the system Before liberalization and the rise of renewables

The old system

Before liberalization:
Mostly vertically integrated companies
All operational issues were within one company
Both generation and transmission investments were done in one company
and coordinated
Synchronous system to increase security
Limited international trade, and mostly long-term contracts
Before massive introduction of renewable energy sources and
distributed generation:
Centrally planned generation
Centrally controlled
Focus on high availability
Bigger is better (economy of scale)


Variable flows in the system International market environment

Energy is traded

Electric energy is traded on the market in blocks of 1 or more hours
Where different bids can come from different generators
These bids are also from neighboring systems
When a single company offers a block, this is not necessarily from the
same generator
This causes variable flows throughout the grid
Including transnational flows
Physical flows are not equal to contracted flows
A higher reserve margin is needed
The ramping of generators is not immediate


Variable ﬂows in the system More renewable energy generation

Increased penetration of smaller, variable energy sources

Traditional power plants
Bigger is better, more economic
Size is limited by technology (GW power plants)
Generally investments and operation by centrally controlled, big
companies
Renewables, CHP and new generator types emerged
Generation units as small as 1 kW
Not centrally planned or controlled
Further increase to be expected in the future (Electrical cars?)
Uncertain generation pattern. . .
3
Pwind = f (vwind ), no light during the night and clouds,. . .
CHP output is usually dependent on heat process
. . . and consequently uncertain ﬂows
Balancing of wind is a problem for some countries



A strong increase in power from renewable energy

Figure: Share of electricity from renewable energy Figure: The development of wind energy in
to gross electricity consumption. (source: Europe shows an almost exponential increase
Eurostat) (logarithmic scale). (source: Eurostat)



Increased installed wind power in Europe



Installed capacity of wind in Europe

(source EWEA)



Larger part of new generation is from variable sources

(source EWEA)

Variable ﬂows in the system Effects on the system

Unannounced wind power in the north D
scheduled power exchanges
Contracted/scheduled ﬂows
- 980 - 3068

B 798 NL 2169 CENTREL
- 1017 - 2967 PSE
ELIA TENNET D 2150 PSE CEPS

North PL CZ

RWE
1815

SEPS MVM

South +3903
SK H +3126

4669
F +3846 667
RTE - 504
GB
1525 A APG
- 426

118
DC link 752
575
120 +677
CH
646
E +2614 ETRANS

REE +2560

53
3022

3

401
2
17
I ELES
SLO
ELES
P 1704 - 5380 481 - 452
HEP

REN TERNA HR BiH

© K.U.Leuven - ESAT/Electa Ronnie.Belmans@esat.kuleuven.be



scheduled power exchanges vs physical power flows
Physical ﬂows
- 980 - 3068

B 798 NL 2169 CENTREL
- 1017 - 2967 PSE
ELIA D
1485 TENNET 4553 2150 PSE CEPS

North PL CZ

RWE
505
1815

1421 SEPS MVM

South +3903
SK H +3126

4669
F +3846 667
RTE - 504
GB
1525 342
817 A APG

1189
- 426

118
DC link 752
575
120 +677
CH
646
E +2614 ETRANS 28
REE 846 +2560

53
3022

3
2875

401
2
17
I ELES
SLO
ELES
P 1704 - 5380 481 - 452
HEP

REN TERNA HR BiH
1267




difference between physical and programmed flows
Resulting ﬂows

B NL CENTREL
2283 2384
ELIA
TENNET PSE CEPS

729
2320

North PL CZ

D
SEPS MVM

South SK H

RWE PSE
F 4327
150

1307
RTE
A

APG
CH
ETRANS
E 1492 92

REE

147
I ELES
SLO
ELES
P 437
HEP
TERNA
REN HR BiH





Frequency deviations due to hourly changes in generation and limited ramp
rates (source UCTE)



Frequency deviations in Nordel increase in general



Unpredictability of wind power: international context
8000
Actual

6000
Wind generation (MW)

4000

2000

0

−2000
0 5 10 15 20 25 30
Day of the month

Real, estimated and mismatch wind generation in November 2007 in the
E.On-Netz grid (Now transpower, part of TenneT), Day-ahead data for every
15 min



8000
Actual
Expected

6000

4000

2000

0

−2000
0 5 10 15 20 25 30
Day of the month
15 min



8000
Actual
Expected
Difference
6000

4000

2000

0

−2000
0 5 10 15 20 25 30
Day of the month
15 min




+100 MW 2,9 %

16,3 %
-
3,5 %

?
-100 MW
3,9 %

14,2 % 6 6 12,8 %

Wind is predominantly located in the north. . . and is balanced in the south
National problem can have international consequences




Unpredictability of hydro

Runoff variations in the power-generating rivers (source: Swedenergy)


Variable ﬂows in the system International setting

Difﬁcult international setting
Every TSO, generator, regulator,. . . on his own
There is no single European authority: an international patchwork
Each has his own responsibilities and tasks
No common authority and no common goal

European Union Synchronous zones



ETSO TSOs



Third package
3rd package proposes some changes
Full (further) unbundling
Establishment of ENTSO-E (European Network of Transmission System
Operators for Electricity)
ETSO + synchronous zones (UCTE, Nordel, Baltso, UKTSOA, ATSOI)
Establishment of an ACER (Agency of energy regulators) to get ONE
regulatory body with binding decision powers to complement national
regulators
Not a direct successor of ERGEG/CEER
Cross-border cooperation and investments should be promoted
More transparency and solidarity


Steps towards a IEM are being taken: ERI + Third package

Regional coordinated grids ENTSO-E: synchronous zones + ETSO

Variable ﬂows in the system Common misunderstandings about wind power


Wind integration is a hot issue, and much debated
There are both people in favor and against wind
A lot of misconceptions exists
(source: Wind Power Myths Debunked; M. Milligan, K. Porter, E. DeMeo,
P. Denholm, H. Holttinen, B. Kirby, N. Miller, A. Mills, M. O’Malley,
M.Schuerger, L. Söder; Power and Energy Magazine; Nov/Dec 2009)




Power system operation with variable wind?
Variability is something operators can work with, as loads also vary
Variability is lower when more wind generators are grouped, especially
when spread geographically
Forecasting is possible and techniques get better
Answer: yes possible, but higher reserves are needed on the
generators (at a cost + international inﬂuence)

Capacity credit?
Capacity credit: sufﬁcient installed capacity to cover load
Planning takes normally a reserve margin for generation (outages etc)
But can we count on wind?
Answer: yes, but not at full capacity. Capacity margin should be
calculated through LOLE (loss of load expectancy)




What are the chances on no wind at all?
. . . or simultaneous shut down at too high wind speeds
Aggregation again lessens the problems
Current forecasts are good enough to start up alternative energy
generation in due time

Difﬁcult to predict wind?
Amplitude and shift
Long time horizons are more difﬁcult to predict than short
Updating of forecasts and scheduling is needed
Forecast errors need to be integrated in predictions




Expensive to integrate wind?
Integration costs money
But these costs can be integrated
Also here balancing over large areas helps

New transmission needed?
Any generation needs transmission
Distributed wind might initially reduce the need for grids
Remote locations need to be connected (e.g. new offshore always
needs new lines)
Similar as connection of hydro in 60’s and 70’s
Balancing/variability requires more grid than traditional generation for
the same amount of energy delivered



Wind power and backup generation: burning fossil fuels?
Backup (reserves) are needed
In practice this is done through existing generation not working at 100 %
capacity or controllable generation (mostly hydro)
→ No dedicated backup
System-wide, CO2 is saved and fossil fuel consumption decreased
(although single machine efﬁciency might be lower)

Storage is needed?
The grid itself works as a storage device by balancing different variable
energy sources
Storage might be interesting from an economical point of view,
especially at very high levels of penetration
Storage must compete with wind curtailment, new transmission lines
and generation dispatch
Limited availability of useful storage technologies
Hydro (pumped or controlled ﬂow) best storage



Does wind generation measure up taking capacity factor into
account?
This is a purely economic consideration: e/kWh

Is there a limit to the accommodation of wind?
There is an economic limit (linked to willingness to pay for a “greener”,
CO2 -free society or a more reliable energy supply)
Dependent on the grid
Technically there is no clear limit as both active (through curtailment)
and reactive power can be controlled
Control of the wind generators and the system as a whole needs to be
adapted in order to accommodate a high penetration of wind


Investments in the power system

1 Introduction
Course overview




Investments in the power system Need for investments

Lacking investments in the power system
In the vertically integrated system, investments were “easy”
Centrally controlled with government support
Security above everything else: overinvesting is ok
Generation investments and transmission investments were planned
within one organization
Now investments in transmission lines are subject to regulatory approval
Regulator is usually focussed on reducing transmission tariffs
Regulators consider mainly issues within their member state
Policy and regulations (environmental, building permits,. . . ) have
become more stringent, complex and especially time consuming
Difﬁcult investment climate due to uncertain investments in generation
and uncertain politics/regulations
Heavy public opposition against any new investment (environmental,
public, political, health,. . . )
NIMBY, NIMTO, BANANA, CAVE,. . .
According to ETSO: . . . in some countries, not a single overhead power
line exceeding ﬁve kilometres has been built in the last 10 years”



Lacking investments in the power system
In the vertically integrated system, investments were “easy”
Centrally controlled with government support
Security above everything else: overinvesting is ok
Generation investments and transmission investments were planned
within one organization
Now investments in transmission lines are subject to regulatory approval
Regulator is usually focussed on reducing transmission tariffs
Regulators consider mainly issues within their member state
Policy and regulations (environmental, building permits,. . . ) have
become more stringent, complex and especially time consuming
Difficult investment climate due to uncertain investments in generation
and uncertain politics/regulations
Heavy public opposition against any new investment (environmental,
public, political, health,. . . )
NIMBY (not in my backyard), NIMTO (not in my term of office), BANANA
(Built absolutely nothing anywhere near anything), CAVE (citizens against
virtually everything),. . .
According to ETSO: . . . in some countries, not a single overhead power
line exceeding five kilometres has been built in the last 10 years”


Investments over the last decades
DSO data

The grid was built about 40 years ago

sources: resp. RWE, PBPower/IBM and KEMA



Cross border investments

Why cross-border investments are especially problematic
Cross-border connections are traditionally weak: previously only
needed for synchronization and in emergencies
Price differences between zones speciﬁcally show themselves as
congestion on borders
Uncertainty about what is happening abroad (limited knowledge of the
outside grid development)
Different policies and requirements across borders
Paradox of investing in transmission lines for other beneﬁciaries



Paradox of investing in cross-border lines

Paradox of investing to relieve congestion

A B
A is congested because of
north-south ﬂow in B





A B
A B
Investing in A is ‘bad’ solution for
A is congested because of
A: local investment for foreign
north-south ﬂow in B
problem





A B
Investing in B would be best, but
no reason for B (or the regulator
of B) because no local problem





A B
A B
Investing in B would be best, but
no reason for B (or the regulator PFC can help
of B) because no local problem



Result: Bottlenecks in the system

Figure: Electricity Projects of European Interest (source: PIP:
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=COM:
2006:0846:REV1:EN:PDF)



Obstables for PIP projects according to TEN-E
PIP= Priority Interconnection Plan

Obstacle # Projects
1 Electromagnetic fields (EMF) 11
2 Environmental issues 9
3 Visual impact 7
4 Densely populated/Urban/Rural areas 7
5 Grid issues 9
6 Dependency on other project(s) 2
7 Authorization procedure and legal framework 12
8 Identification of cross-border points 3
9 Commercial Problem 3
10 Difficult terrain and weather 4
11 No perception of supra-national or European perspective 2

Table: Obstacles according to the priority interconnection plan of TEN-E


Investments in the power system Investments to integrate renewables

Investing to accommodate renewables

Any generation needs transmission
Renewables often located at remote locations
This is certainly the case for wind (NIMBY)
. . . and evident for offshore
Variability of wind makes that on average more grid is needed for the
same load


Investments in the power system Investments to integrate renewables

Power from the sea: Belgian example

Concessions:
C-power: 216-300 MW, 27 km
Belwind: 330 MW, 42 km
Eldepasco: 180-252 MW,
38 KM
More coming/being processed


Future Electricity Grids 1/2

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