NBS-M017
2013
CLIMATE CHANGE GOVERNANCE AND
COMPLIANCE
Regulation in Electricity Supply
The changing face of the Electricity Market in the UK
Изменяющееся лицо рынка электроэнергии в Британии
N. Keith Tovey, M.A. PhD, C.Eng MICE
Н.К.Тови М.А., д-р технических наук
Energy Science Director
Low Carbon Innovation Centre
University of East Anglia, Norwich
Руководитель по энергетическим исследованиям
Центр экологических инноваций
Университет Восточной Англии, Норвич
1
Course WEB Page http://www2.env.uea.ac.uk/energy/energy.htm
or http://www.uea.ac.uk/~e680/energy/energy.htm
2
The changing face of the Electricity Market in the UK
Изменяющееся лицо рынка электроэнергии в Британии
• A brief review of the UK Electricity Industry prior to 1990
under State Ownership.
– differences in approach between England / Wales and
Scotland.
• Fuels used for generation
•
•
•
•
Fuel Diversity – The Shannon-Wiener Index
The Electricity Markets in the 1990s after Privatisation
The New Electricity Trading Arrangements NETA (2001)
The British Electricity Trading and Transmission
Arrangements (BETTA).
• The Supply of Electricity since 1990
• Conclusions
3
The Generation and Distribution of Electricity has always been different in
Scotland compared to England and Wales
(Шотландия всегда отличалась от Англии и Уэльса в плане производства и
распределения э/э )
Scotland (Шотландия):
Scotland
Шотландия
Northern
Ireland
Северная
Ирландия
England and
Wales
Англия и
Уэльс
Two vertically integrated
companies supplying discrete
areas (Две вертикально
интегрированных компании,
снабжающие отдельные
территории)
England and Wales
(Англия и Уэльс):
One Generating Company
(CEGB) and 12 Regional
Electricity Suppliers
(Одна генерирующая
компания (CEGB) и 12
региональных поставщиков).
2000 MW
EdF
Electricité de France
EDF
4
Scotland
Шотландия
Scottish Hydro
Structure of Electricity Supply in
early 1990s
Структура
системы энергоснабжения
в начале 1990 г.г.
Scotland Шотландия
Scottish
Power
Northern
England &
Wales
NORWEB
Yorkshire
Англия
и
Уэльс
East Midlands
MANWEB
Midlands
SWALEC
SWEB
•
two companies
две компании
England and Wales
Англия и Уэльс
12 Regional Supply Companies
12 региональных компаний
Eastern
London
Southern
Vertical Integration
Вертикальная интеграция
SEEBOARD
also Distributed Network
Operators
а также распределяющие
сетевые операторы
5
Electricity Generation in the UK
Производство электроэнергии в Великобритании
Coal + Oil
Nuclear
Gas (CCGT)
Renewables
Until 2006, growth averaged 1.8% over previous 20 years
In recent years gas has overtaken coal as dominant fuel and nuclear has
6
Implications of daily/weekly/monthly variations in fuel use
for Electricity Generation
The carbon factor for electricity generation in UK is ~ 540g/kWh
Varies from
• Hour to hour
• Day to day
• Week to week
• Month to month
• See
www.bmreports.com
Current accounting only uses Grid annual average. In future
accounting may relate to emissions associated with time of use
Thus a heavy industry with high electricity demand in day time
could significantly reduce its carbon emissions by operating
overnight rather than during day.
7
Daily fuel mix in electricity Generation
11th January 2010
70000
France
Hydro
Pumped Storage
Wind
Coal
CCGT
Nuclear
60000
Data for 11th
January 2010
Demand (MW)
50000
40000
30000
20000
10000
0
0
2
4
6
8
10
12
14
16
18
20
22
24
Weekly fuel mix in electricity Generation
11 - 17th January 2010
70000
France
Wind
Nuclear
60000
Hydro
Coal
Pumped Storage
CCGT
Demand (MW)
50000
40000
30000
20000
10000
0
1
Mon
Tues
Wed
Thurs
Fri
Sat
Sun
Notice higher proportion of coal used during day time hence a higher
carbon emission factor.
Shannon – Wiener Index of Fuel Mix Diversity
• The Shannon-Weiner Index (H) is defined as:
H = -  pI ln pI
where pi is the proportion of the ith fuel.
The index value increases with number of items and also the
relative proportions of items
1.2
100%
1
80%
0.8
60%
0.6
40%
nuclear
0.4
gas
20%
With three fuels, the
maximum value reaches
1.09 when all the fuels
are in equal proportions.
Index
120%
In Norway where Hydro
provides 99.5%, the index
for the three fuels used is
just 0.035.
0.2
coal
0%
0
10
Shannon – Wiener Index of Fuel Mix Diversity
• Shannon – Wiener Index is a measure of diversity originally developed as a
measure of biodiversity.
• Higher index values occur with higher diversity.
• But there is no absolute upper limit.
• There is a maximum diversity index for a given number of fuels (e.g.
species, fuels) when all items are in same proportion, but index will be
higher for a greater number items.
• Index is low if one item dominates
Variation in maximum value of
Index with number of items.
The situation occurs when all
items have equal proportion.
2.5
Index
2
1.5
1
0.5
0
0
1
2
3
4
5 6
Items
7
8
9
10
e.g. with 6 fuel types the
maximum value of index
would be 1.8.
11
Shannon – Wiener Index of Fuel Mix Diversity Exercise
Selected link for EXCEL Spreadsheet Template
12
Transmission Network in the UK
Scotland
Шотландия
Transmission throughout England, Wales and
Scotland became unified on April 1st 2005
400 kV
England
and Wales
Англия и
Уэльс
275 kV
132 kV
Historically transmission networks
have been different in England and
Wales compared to Scotland
Исторически, сети передачи
э/энергии в Англии и Уэльсе
отличались от сетей Шотландии
13
Most Generating Capacity is in the North - most demand is in South
MW
Interconnector
to Scotland
+1643
Generating Capacity
Surplus/Deficit
+7525
on February 12th 18:00
+418
+ve: generating capacity
-4709
exceeding demand
-ve: demand exceeding
generating capacity
-1963
Interconnector
to France
14
Electricity Generation - pre 1990
• Decision on how electricity was to be generated was done on a
generating set basis
• Generating Sets to run were selected on Merit Order.
• Based on Marginal Costs
• (i.e. the fuel costs - цены на нефть)
Some generating sets were run OUT of MERIT ORDER where
system constraints were an issue.
• Generators sold electricity to Regional Electricity Boards
• Electricity Boards sold to consumers in their Area only
• Prices to consumers varied between regions
15
Privatisation of Electricity Supply Industry 1990
Central Electricity Generating Board
Центральное
•Coal (Угольные) Fired Power
Stations
National Power
PowerGen
•Oil (Нефтяные) Fired Power
stations
•Gas Turbine (Газовы турбины)
Stations
Nuclear Electric
• Hydro Stations (ГЭС)
•Nuclear Stations (Атомные)
•Transmission (Трансмиссия)
12 Regional Electricity Companies
National Grid Company
12 Regional Electricity
Companies
16
60
Typical UK Electricity
Demand in Winter
50
2003 and 2005
30
Sat
20
Sun
Mon
Tue s
We d
Thurs
Fri
4th - 10th January 2003
10
11th - 17th January 2003
12th - 18th February 2005
0
0
24
48
72
96
120
144
168
60
50
40
GW
GW
40
30
20
4th January 2003
10
11th January 2003
16th February 2005
0
0
3
6
9
12
15
18
21
24
Hours
17
Comparison of Demand Forecast and Outcome
GW
Predicted and Actual Demand 27th - 28th September
2008
45
40
35
30
25
20
15
10
5
0
predicted
actual
0
6
12
18
24
30
36
42
48
time (hours)
Data for 48 hour period covering 27th and 28th September 2008
Note: there was an alert on 28th from period 45 (i.e. 22:30)
meaning no actual data is available from this time.
18
Obtaining Information from BMREPORTS
• Total Demand for electricity on a half hour basis may be
accessed from: www.bmreports.com
INDO: Initial Demand Outturn
ITSDO: Initial Transmission
Demand Out-turn –
includes transmission
losses etc
What is today’s demand:
What are today’s wholesale prices?
19
The changing face of the Electricity Market in the UK
• A brief review of the UK Electricity Industry prior to 1990.
• The Electricity Markets in the 1990s after Privatisation
– the first system know as the “Pool”.
– Some Countries operate a derivative of the “Pool”
• Operation of the Pool – the bidding Process
• The New Electricity Trading Arrangements NETA (2001)
• The British Electricity Trading and Transmission Arrangements
(BETTA).
• The Supply of Electricity since 1990
• Conclusions
20
Scottish
Nuclear
Scottish Hydro
(Атомная) *
Consumers
Потребители
Scottish Power
Scotland
Шотландия
Electricité de France
PowerGen
IndependentsНезависимые
The
BNFL (Magnox)
England and Wales
Англия и Уэльс
Licensed
Consumers
Suppliers
Лицензирова
нные
поставщики
Потребители
IndustryПромышленность
Nuclear Electric *
Eastern **
Innogy
Pool
Пул
RECs
Second
Tier
Consumers
Вторичные
потребители
21
The Operation of The Electricity Pool: 1990 – 2001
• Only the Generators (>100 MW) bid into the POOL to
supply electricity e.g. National Power (now Innogy),
PowerGen etc
• The National Grid Company published projected
demands for the following day and invited bids
• The Generators supplied bids for each generating set in
each station for each half-hour period of the following
day
• The NGC sorted bids to determine which generating
sets would be used for each particular period, and
which ones would have capacity made available
22
1250 MW
1250 MW
1250 MW
1250 MW
1250 MW
10000 MW
Bid from company E £19.50 per MWh
Bid from company D £19.40 per MWh
Bid from company C £19.32 per MWh 32500 MW
Bid from company B £19.31 per MWh
Bid from company A £19.20 per MWh (0.96R / kWh)
Range of bids from companies
in range £18 - £19 per MWh
0.90 - 0.95 Roubles per kWh
10000 MW
Range of bids from companies
in range £15 - £18 per MWh
System
Marginal
Price
= £19.31
SMP
0.75 - 0.9 Roubles per kWh
10000 MW
Range of bids from companies
in range <£15 per MWh
0.75 Roubles per kWh
Companies
up to and
including B
successful
£1 ~ 50 Roubles
23
The Operation of The Electricity Pool
• All Companies who were successful were paid the SMP
for all units generated irrespective of what their bid was
• The bids were for the single half-hour period and fresh
bids were required for all half hour periods
• It was possible for companies to bid £0 and this would
guarantee that they generated and paid SMP
– However, if all Companies did the same they would
have to generate electricity for nothing
• In addition to the SMP, there was also a capacity charge
relating to the generating capacity which was requested to
be available
24
The Operation of The Electricity Pool
• Capacity Charge paid to all Generators who had
been requested to have capacity available.
-based on formula(по формуле):
LOLP * (VOLL - SMP)
Loss of Load Probability
Value of Lost Load
VOLL: was set by the Regulator at around £2400 per MWH
LOLP: normally a very low figure but could become significant if
there was a shortfall in generating
Capacity Charge: signal to ensure sufficient capacity was available.
Pool Input Price (PIP) = SMP + LOLP * (VOLL - SMP)
25
Электрический пул
System Constraints (Система давления):
•Some Power Stations constrained “ON” to ensure security of
supply even when their bid was more expensive
(Некоторые электростанции constrained “ON” обеспечить снабжение,
даже в случае более дорогих заявок)
•Some Power Stations constrained “OFF” even when their bid was
cheaper (-excess of capacity in one region)
(Некоторые электростанции constrained “OFF” обеспечить снабжение,
даже в случае более дешевых заявок)
•Constrained Stations paid their “Bid” Price
(уплачивали их «заявочную» цену)
•POOL Output Price: (POP) = Pool Input Price + Uplift
•Uplift represented the additional charges incurred to National Grid
Company because of System Constraints
•Suppliers purchased Electricity at Pool Output Price
(Поставщики закупают э/э на Пуле по цене производителя)
26
Электрический пул: A Review
 Need for strong Regulatory Body to ensure prices were not
fixed.
 Evidence suggested price manipulation took place in early
years.
 Regulator required major generators to dispose of some
stations.
 The lack of Demand Side Bidding was a weakness
 Charges for Transmission Losses were averaged over
whole Network.
•Customers in North subsidised those in South
•Generators in South subsidised those in North
• These issues have been partly resolved under BETTA
Separate discussions relating to Distribution Charges
are also under way
27
Changes in Regional Electricity Companies in the 1990s
1990
Scottish &
Southern
Scottish
Power
United
Utilities
Scottish
Power
• Take-over
Scottish Power takes over
MANWEB
• Vertical Integration
• nPower acquire Midlands
• PowerGen acquire East
Midlands
• United Utilities formed
– in NORWEB area
PowerGen
nPower
• Mergers
Scottish &
Southern
c. 1998
Scottish Hydro &
Southern become
Scottish & Southern
28
The changing face of the Electricity Market in the UK
• The New Electricity Trading Arrangements NETA (2001)
• The British Electricity Trading and Transmission Arrangements
(BETTA).
– BETTA essentially extended NETA to cover Scotland.
– There were few changes in England and Wales apart from Transmission
issues
– Operation of the Trading Market remained the same
•
•
•
– Although minor modification take place all the time
In BETTA
Both Generating and Demand Side Bidding Takes Place
Most Electricity is traded outside Balancing Mechanism
• Favours those who guarantee specific levels of generation/supply
in advance
• Favours those who can guarantee flexibility in output / demand
at short notice.
29
Operation of BETTA
The basic principles
•
•
•
Основные принципы
Generators and Suppliers are penalised if they deviate from
their agreed level of generation / supply.
System security is maintained via the Balancing Mechanism
Renewable Generators e.g. Wind and small CHP (~10 MW)
can be adversely affected.
•
•
Generation and Supply focuses on:
Balancing Mechanism (BM) Units
 Generating BM Units: Demand BM Units
 Trading between Generating and Demand BM Units
– Only the volume traded ( not price) has to be notified.
30
NETA/ BETTA The Balancing Mechanism: A Summary
•
Initial Physical Notification (IPN) – 24 hours in advance
 System Operator checks sufficient capacity is available.
• Final Physical Notification (FPN)
Gate Closure for Real Time Period of 30 mins
 Initially 3.5 hours before REAL Time
 later reduced to 1 hour.
Current Day
Day Before
Real
Time
IPN
FPN
3.51 hours
hour
Gate Closure
30
mins
Operation of Balancing
Mechanism
• Changes to contract position cannot be made after Gate Closure
• Balancing Mechanism provides System Security
31
NETA/ BETTA: Operation of the The Balancing Mechanism:
 Generators and suppliers are penalised if they deviate from their
contract position at the final physical notification (FPN).
 The System Operator negotiates with balancing Mechanism (BM)
units to increase/decrease the amount of electricity available to
maintain system security and ensure system remains stable.
•
•
Case 1:
Too little electricity on the system
– Generators can OFFER to INCREASE output
– Suppliers can OFFER to REDUCE consumption
Time
OFFER
FPN
OFFER
•
Time
FPN
If OFFER is agreed then Generators / Suppliers are PAID for any
electricity increased / reduced under the OFFER.
 Separate charges apply for these services.
32
The New Electricity Trading Arrangements
Новая система оптовой торговли НЕТА
The Balancing Mechanism
•
•
Балансирующий механизм
To allow system to remain stable
Too little electricity on the system
– Generators can OFFER to INCREASE output
– Suppliers can OFFER to REDUCE consumption
Time
OFFER
FPN
OFFER
FPN
Time
• If OFFER is agreed then Generators / Suppliers are PAID
for any electricity increased / reduced under the OFFER.
33
The New Electricity Trading Arrangements
Case 2: Too much electricity on the system
– Generators can BID to REDUCE output
– Suppliers can BID to INCREASE consumption
Time
OFFER
Bid
FPN
OFFER
Bid
FPN
Time
• If BID is agreed then Generators / Suppliers PAY for any
reduction in generation / increase in demand under the BID.
34
The Balancing Mechanism: Offers and Bids
Generators / Suppliers may submit OFFERs or BIDs which differ
for different levels of deviation from the Final Physical Notification
50 - 100 MW: £50 per MWh (2.5 Roubles per kWh)
25 - 50 MW: £30 per MWh (1.5 Roubles per kWh)
0 - 25 MW: £20 per MWh (1 Rouble per kWh)
FPN
окончательная физическая нотификация
Example of Differential Offers from a Generator
National Grid Company normally accepts OFFERS / BIDS which
are cheapest unless System Constraints prevent this.
35
The Balancing Mechanism: Undo Offers/Undo Bids
What happens if System Operator has got it wrong?
• OFFERs / BIDs cannot be cancelled
• UNDO BID removes an OFFER and is usually less than the OFFER
• UNDO OFFER removes a BID and is usually more than the BID
•
OFFERs / UNDO BIDs [ or BIDs / UNDO OFFERs]
are submitted in pairs
OFFER / UNDO BID:
Pair +2
OFFER / UNDO BID:
Pair +1
BID / UNDO OFFER:
Pair -1
BID / UNDO OFFER:
Pair -2
FPN
36
The Balancing Mechanism: Imbalance Charges
Charges for imbalance depend on whether BM unit is deviating in same direction
as overall system or not.
Example shows cases where imbalance is in same direction as system
Actual Metered Volume
FPN
Paid SSP
FPN
Pays SBP
Settled
bilaterally
between
contracting
parties
Установлено в
двустороннем
порядке
договаривающ
имися
сторонами
Установлено в
двустороннем
порядке между
сторонами
Settled
bilaterally
between
parties
Actual
Metered
Volume
37
Distributed
Distributed Network
Network Ownership
Ownership in
in 2005
2010/11
2004
Scottish & Southern
Iberdrola
Scottish Power
United Utilities
CE Electric UK
Regional
Supply
Ownership
ElectricitéNetworks
de France
UKPower
Western Power
PowerGen
Central Networks
Distributed
Network
Ownership
Владение
распределите
льной сети
Aquila
Scottish & Southern
Scottish Power
Iberdrola
nPower
E.ON (PowerGen)
Electricité de France
In 2007, Scottish Power
became part of Iberdrola
38
Changes when BETTA came into force – April 1st 2005
• Integrated Trading System operating England and Wales with
Scotland
• Before BETTA
– System and Transmission Network Operator in England and
Wales was National Grid Company (NGC).
– System and Transmission Network Operator in South of
Scotland was Scottish Power
– System and Transmission Network Operator in North of
Scotland was Scottish and Southern
• After BETTA
– National Grid Company become System Operator for whole of
England, Wales and Scotland.
– NGC now Transmission operator for England and Wales
– In Scotland the two companies now hold the respective
transmission Network Licences
– Issues of differences in Transmission Protocol had to be resolved –
including the use of the Inter connector
– Charges for Transmission Losses had to be addressed
39
P/kWh
Impact on System Sell and Buy Prices
50
45
40
35
30
25
20
15
10
5
0
Sell Price
Buy Price
0
3
6
9 12 15 18 21
Sunday 6th December 2010
0
3
6
9 12 15 18 21
Monday 7th December 2010
Example of System Sell Price (SSP) and System Buy Price (SBP)
corresponding with First Point of Triad 2010-2011.
40
Impact on Wholesale Charges
How well has it performed since starting on 27th March 2001?
Wholesale Electricity Prices
12
10
p/kWh
8
UK becomes net
importer of gas
Completion of
Langeled Gas Line
to Norway
6
4
41
2
0
2001
Oil reaches
$140 a barrel
2003
2005
2007
2009
2011
Wholesale prices rose rapidly in 2004/2005, fell sharply from mid
2006, rose rapidly since mid 2007 then fell but are less stable.
41
1
2
4
3
5
8
7
Generator Connection Charges under BETTA
Плата за подключение к генератору
энергоснабжения по BETTA
9
11
10 12
6
13
14
15
19
16
17
18
20
27
21
22
26
A
> £25 per kW
B
£20 to £25 per kW
C
£15 to £20 per kW
D
£10 to £15 per kW
E
£5 to £10 per kW
F
£0 to £5 per kW
G
- £5 to £0 per kW
H
- £10 to -£5 per kW
25
24
23
42
Generation Connection Charges from April 1st 2013
No. Zone Name
Tariff (£/kW)
1
North Scotland
25.418971
2
East Aberdeenshire
22.795139
3
Western Highlands
26.146895
4
Skye and Lochalsh
30.251919
5
Eastern Grampian and Tayside
21.546049
6
Central Grampian
19.750208
7
Argyll
18.515568
8
The Trossachs
16.491922
9
Stirlingshire and Fife
16.403825
10 South West Scotland
15.529814
11 Lothian and Borders
12.836108
12 Solway and Cheviot
11.072685
13 North East England
8.641032
14 North Lancashire and The Lakes
7.475188
Note: Updated Values on
those in handout and
current as of October 2013
These are general charges for each area in addition
there are additional charges reflecting the capabilities
of the local regions around each substation
43
Generation Connection Charges from April 1st 2013
No.
15
16
17
18
19
20
21
22
23
24
25
26
27
Zone Name
South Lancashire, Yorkshire and Humber
North Midlands and North Wales
South Lincolnshire and North Norfolk
Mid Wales and The Midlands
Anglesey and Snowdon
Pembrokeshire
South Wales
Cotswold
Central London
Essex and Kent
Oxfordshire, Surrey and Sussex
Somerset and Wessex
West Devon and Cornwall
Tariff (£/kW)
6.342092
5.184032
3.486470
2.442909
7.409039
5.566128
2.916588
0.038756
-4.442372
0.191397
-1.692437
-3.045193
-5.165609
In addition there is a local sub-station tariff which varies from as much as
£+5.805051 per kW at Edinbane on Skye in the SHETL area
to as little -£0.742416 per kW at Mark Hill in the SPTL area.
44
Demand Connection Charges 2012 - 2013
• Beware!!!!
• The TRIAD Approaches!!!
on 1st November!
What is the TRIAD?
A modified measure of peak
demand over winter period
45
Demand Connection Charges 2012 - 2013
The Triad occurs in the period 1st November –
28th/29th February
It is the mean of the following:
1) The maximum demand in any one half hour in
the above time period.
2) The second highest demand in any one half
hour provided it is separated from (1) by at
least 10 days.
3) The third highest demand in any one half hour
period provided that it is separated from (1)
and (2) by at least 10 days
46
Demand Connection Charges from April 1st 2013
Demand Zone Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Northern Scotland
Southern Scotland
Northern
North West
Yorkshire
N Wales & Mersey
East Midlands
Midlands
Eastern
South Wales
South East
London
Southern
South Western
TRIAD
Demand
(£/kW)
11.048877
16.789820
22.346537
25.184470
25.485035
25.631093
28.213308
29.201069
29.891866
27.541773
32.827362
34.083066
33.752057
33.551731
This table has updated figures for 1st October 2013
Energy
Consumed
(p/kWh)
1.515130
2.362577
3.079732
3.651462
3.508859
3.665429
3.956866
4.148986
4.153363
3.685374
4.564101
4.601445
4.741274
4.598152
47
Example how TRIAD charges can be mitigated
Peak demand occurs at time of TRIAD - form process working
Shift process by say 2 hours will reduce the TRIAD charge by over 25% or
£13628 - see handout
48
NBS-M017
2013
CLIMATE CHANGE GOVERNANCE AND
COMPLIANCE
8. Regulated Power Zones and
Smart Grids
Recipient of James Watt Gold Medal
N.K. Tovey (杜伟贤) M.A, PhD, CEng, MICE, CEnv
Н.К.Тови М.А., д-р технических наук
49
49
4949
REGULATED POWER ZONES
• Transmission and Distribution Networks are critical to electricity
security.
• Losses on line:
= I 2 R where I is the current and R is resistance
• the power transmitted P = V * I - V = voltage
– Typical UK domestic voltage - 240V
– European Voltage 220V
– North American Voltage
110V
• These are nominal voltages and system must control voltages within
a narrow band of this.
Losses are reduced by increasing
voltage
Voltage
%loss relative to 240 V
240
100.0%
11000
0.047603%
33000
0.005289%
132000
0.000331%
400000
0.000036%
50
REGULATED POWER ZONES
• The consequence of resistive losses is that the transmission
and distribution cables heat up and may typically be
running at 50o C+
• As they heat up they expand and the cables will sag more
at mid-span with a the possibility of a flashover.
• This means that there will be less sag when the cable
temperature is lower – i.e. in winter and also in times of
higher wind speeds when the cooling effect of the wind will
be greatest.
There is thus a maximum power load that any cable can take
and this limits the number of connections that can be made.
A further problem with AC transmission is
that current flows mostly through the skin
with much of the cross section not used
effectively.
Unlike DC
51
REGULATED POWER ZONES
Traditional way to allocate generation connections:
• Order of application according to potential maximum
connection capacity up to total capacity of
transmission/distribution line.
• A safe approach which ensures that transmission/ distribution
lines are not overloaded.
BUT
• May not make optimum use of transmission capacity.
Example:
• Suppose a line has 2000 MW capacity – a typical 400 kV
ciruit capcity
• Order of connection allocations:
– Generator 1: 1000 MW – say with 2 x 500 MW sets
– Generator 2:
500 MW
– Generator 3:
500 MW – with 2 x 250 MW sets.
52
REGULATED POWER ZONES
Generating Sets
Total installed
capacity
Generator 1
2 x 500 MW
1000 MW
Generator 2
1 x 500 MW
500 MW
Generator 3
2 x 250 MW
500 MW
• If all sets are generating – 2000MW i.e. capacity of line and no
more sets can connect without the expense of transmission line
upgrade.
• If generating sets are fossil fuel, then they may have a
relatively high load factor and traditionally that has not been
a problem.
• BUT if say one of Generator 1’s sets is not generating, only
1500 MW of the 2000 MW of the line capacity is used.
• BUT no new generators can connect as the inactive set may
come back on line.
Grandfathering Rights
53
REGULATED POWER ZONES
Problem is exacerbated with generating plant of low load factor e.g.
wind and was first identified in Orkney where significant renewable
generation threatened to seriously overload distribution system.
Orkney is connected to mainland by 1 x 30 MW and 1 x 20 MW
cable. A fossil fired power station on Flotta associated with the oil
terminal must run for safety reasons typically around 4.5 MW.
Burgar Hill had historic rights of around 7 MW with the European
Marine Energy Centre (EMEC) a further 7MW also in this category.
Thereafter there were several other wind developments which
threatened to exceed total capacity of cables to mainland as it was
assumed that one of the two cables might be out of action giving only
a maximum potential connection capacity of 20 MW.
54
REGULATED POWER ZONES
Total Historic Generating Capacity ~ 18.5 MW
Minimum Demand in Orkney
~
7 MW
Capacity of smaller cable to mainland ~ 20 MW
Maximum Generation on Orkney which would not overload
single mainland cable is
27 MW – i.e
8.5 MW new capacity could be connected.
But EMEC capacity is often 0 MW, and rarely is Burgar Hill
at its rated output.
If dynamic dispatch of generation capacity is used much more
generation could be connected.
55
REGULATED POWER ZONES
Evaluate total system capability at any one time
C = mainland connection capacity (i.e. 20 or 30 or 50 MW)
+ instantaneous demand on Orkney
Subtract from this those generating connection which have
grandfathering rights, but only up to the amount of
instantaneous generation (NOT maximum connection rights)
This gives maximum additional capacity which can be
connected at that time.
If this also is done on a first application first served basis, it
would be possible to connect much more renewable generation
than otherwise possible.
However, it may mean that wind turbines at the end of the
queue may not be able to generate when wind speed is
optimum and returns on investment are best
56
REGULATED POWER ZONES
Suppose C =
is 10 MW
60 MW – i.e. both cables operating and demand
If Flotta output is 7 MW and EMEC is 7MW and Burgar Hill
say 3.5 MW (i.e less than rated connection of 7MW as wind
speed is low – i.e. instantaneous load factor is 50%)
Available additional connection is 60 – 17.5 i.e 42.5 MW
If this were take by additional Wind at 50% load factor then 85
MW of additional capacity could connect.
BUT if wind speed increased to rated speed of wind turbines,
Burgar Hill would now be at 7 MW and available capacity
would be 39 MW.
If all of this were as wind turbines at rated output (i.e. 100%
load factor) only 39 MW could actually generate and 46 MW
would have to shut down at the time they were most
productive.
57
REGULATED POWER ZONES
Consequence of Dynamic Regulation of Power Zone
• More effective use of transmission/distribution cables is
made
• A greater proportion of renewable energy can be brought
on line at an earlier stage
BUT
• Those connecting last may find return on investment poor.
Lincolnshire RPZ operates only to transmit power from
offshore wind farm
• Does not primarily address demand, but cooling effect on
cables to minimise sag
• In winter – higher wind speeds – greater output capacity
from wind turbines
• BUT weather is cooler and cooling effect of wind on cables
is greater so cables can transmit more
58
SMART GRIDS – DYNAMIC REGULATION of DEMAND
ELECTRIC VEHICLES: Widespread deployment of electric vehicles
could adversely affect the generation of electricity – leading to less
effective use of generating capacity.
80000
Existing peak demand
occurs around 17:00
the time when most
people return home .
Electric Vehicles
Normal Demand
70000
Demand (MW)
60000
30000
Owners would
potentially would
start charging their
vehicles potentially
exacerbating the load
profile
20000
Electric Vehicle demand from
Dave Openshaw
50000
40000
0
2
4
6
8
10 12 14 16 18 20 22 24
Time (hrs)
http://81.29.73.156/~eeegrdev99/uploads/DOCS/778-20100726131949.pdf
59
SMART GRIDS – DYNAMIC REGULATION of DEMAND
Electric Vehicles with Smart Charging
80000
Strategy 2:
Encourage people not to
charge between 17:00 and
21:00 with a reduced tariff.
Assume 75% take this up
~ would remove light green
area.
70000
Demand (MW)
Strategy 1:
Unrestricted charging as
per previous slide
60000
50000
40000
30000
20000
0
2
4
6
8
10 12 14 16 18 20 22 24
Time (hrs)
Strategy 3:
Discharge remaining store
in car batteries to help
existing peak. i.e. move
green area to red – at
further reduced tariff –
example shows 25% of
people adopting this.
60
SMART GRIDS – DYNAMIC REGULATION of DEMAND
HEAT Pumps: Widespread deployment of Heat Pumps
would exacerbate electricity demand
100000
90000
Heat Pumps
Normal Demand
80000
Demand (MW)
70000
60000
50000
40000
30000
20000
10000
0
0
2
4
6
8
10
12
14
16
18
20
22
24
Time (hrs)
Heat Pump demand from Dave Openshaw
http://81.29.73.156/~eeegrdev99/uploads/DOCS/778-20100726131949.pdf
61
SMART GRIDS – DYNAMIC REGULATION of DEMAND
100000
90000
80000
Demand (MW)
70000
60000
50000
displaced demand
40000
trough
30000
Peak Lopped
20000
morning peak
regulated HP demand
10000
Normal Demand
0
0
2
4
6
8
10 12 14
Time (hrs)
16
18
20
22
24
There is a less “peaky” demand from heat pumps than electric vehicles
because of thermal store benefits from under floor heating,
Use of an additional thermal store could help further to fill mid-day peak
and lop peak morning and evening periods for charge overnight.
62