grid code frequency response working group system inertia 8 - inertia...some tidal, wave, biomass...
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Grid Code Frequency Response Working GroupSystem Inertia Antony Johnson, System Technical Performance
Overview
Background to System Inertia
Transmission System need
Future Generation Scenarios
Initial Study Work
International Experience and Manufacturer Capability
Transmission System Issues
Conclusions
Frequency Change
Under steady state the mechanical and electrical energy must be balanced
When the electrical load exceeds the mechanical energy supplied, the system frequency will fall.
The rate of change of frequency fall will be dependant upon the initial Power mismatch and System inertia
The speed change will continue until the mechanical power supplied to the transmission system is equal to the electrical demand.
Why is Inertia Important
Inertia is the stored rotating energy in the system
Following a System loss, the higher the System Inertia (assuming no frequency response) the longer it takes to reach a new steady state operating frequency.
Directly connected synchronous generators and Induction Generators will contribute directly to System Inertia.
Modern Generator technologies such as Wind Turbines or wave and tidal generators which decouple the prime mover from the electrical generator will not necessarily contribute directly to System Inertia
Under the NGET Gone Green Scenario, significant volumes of new generation are unlikely to contribute to System Inertia
What is inertia?
Loss of Generatoron the system
Frequency Falls as demand > generation
Stored energy delivered to grid as MW
The stored energy is proportional to the speed of rotation squared3 types of event cause a change in frequency
Loss of generation (generator, importing HVDC link etc)Loss of load Normal variations in load and generator output
The maths behind inertia
∂f/∂t = Rate of change of frequency∆P = MW of load or generation lost2H = Two times the system inertia in MWs / MVA
∂f∂t
∆P2H=
∂f/∂t = Rate of change of frequency∆P = MW of load or generation lost2H = Two times the system inertia in MWs / MVA
∂f∂t
∆P2H=
H = Inertia constant in MWs / MVAJ = Moment of inertia in kgm2 of the rotating massω = nominal speed of rotation in rad/sMVA = MVA rating of the machine
½Jω2
MVAH =H = Inertia constant in MWs / MVAJ = Moment of inertia in kgm2 of the rotating massω = nominal speed of rotation in rad/sMVA = MVA rating of the machine
½Jω2
MVAH =
Typical H for a synchronous generator can range from 2 to 9 seconds (MWs/MVA)
An NGET Future Scenario
Plant closures12GW Coal & oil LCPD7.5GW nuclearSome gas & additional coal
Significant new renewable29 GW wind (2/3 offshore)Some tidal, wave, biomass & solar PVRenewable share of generation grows from 5% to 36%
Significant new non renewable build3GW of new nuclear3GW of new supercritical coal (some with CCS)
11GW of new gas
Electricity demand remains flat (approx 60 GW)Reductions from energy efficiency measuresIncreases from heat pumps & cars
Strategic Reinforcements
Sizewell
Pembroke
Osbaldwick
RowdownBeddington
ChessingtonWest
Landulph
Abham
Exeter
Axminster
Chickerell
Mannington
Taunton
Alverdiscott
Hinkley Point
Bridgwater
Aberthaw
Cowbridge
PyleMargam
SwanseaNorth
CardiffEast
Tremorfa
Alpha SteelUskmouthUpper Boat
Cilfynydd
ImperialPark
Rassau
Whitson
Seabank
Iron Acton
Walham
Melksham
Minety DidcotCulham
Cowley
Bramley
Fleet
Nursling
Fawley Botley Wood
Lovedean
Bolney
NinfieldDungeness
Sellindge
Canterbury
E de F
Kemsley
Grain
Kingsnorth
Rayleigh Main
Littlebrook
Tilbury
Warley
Barking
W.HamCity Rd
BrimsdownWaltham
Ealing
Mill HillWillesden
Watford
St Johns
Wimbledon
New Hurst
Elstree
Rye House
N.Hyde
Sundon
Laleham
Iver
Amersham Main
WymondleyPelham
Braintree
BurwellMain
Bramford
EatonSocon
Grendon
EastClaydon
Enderby
Walpole
NorwichMain
Coventry
Berkswell
Rugeley
Cellarhead
IronbridgeBushbury
Penn
Willenhall
OckerHill
KitwellOldbury
Bustleholm
Nechells HamsHall
BishopsWood
Feckenham
Legacy
Trawsfynydd
Ffestiniog
Dinorwig
Pentir
Wylfa
Deeside
Capenhurst Frodsham
Fiddlers
Rainhill
KirkbyListerDrive
Birkenhead
WashwayFarm
Penwortham
Carrington
SouthManchester
Daines
Macclesfield
Bredbury
Stalybridge
Rochdale
WhitegateKearsley
Elland
Stocksbridge
WestMelton
Aldwarke
Thurcroft
BrinsworthJordanthorpe
Chesterfield
Sheffield CityNeepsend
Pitsmoor
Templeborough ThorpeMarsh
Keadby
WestBurton
Cottam
HighMarnham
Staythorpe
Stanah
Heysham
Padiham
Hutton
BradfordWest Kirkstall Skelton
Poppleton
Thornton
Quernmore
Monk
EggboroughFerrybridge
Killingholme
SouthHumberBank Grimsby
West
Drax
Lackenby
GreystonesGrangetown
Saltholme
Norton
Spennymoor
Tod PointHartlepool
Hart Moor
Hawthorne Pit
Offerton
West BoldonSouth ShieldsTynemouth
StellaWest
Harker
Eccles
Blyth
IndianQueens
Coryton
RatcliffeWillington
Drakelow
Shrewsbury
Cross
Weybridge
Cross
Wood
North
FrystonGrange
Ferry
Winco Bank
Norton Lees
Creyke BeckSaltend North
Saltend South
Hackney
BaglanBay
LeightonBuzzard
PatfordBridge
Northfleet EastSinglewell
Fourstones
Humber Refinery
SpaldingNorth
West Thurrock
ISSUE B 12-02-09 41/177619 C Collins Bartholomew Ltd 1999
Dingwall
Dounreay
Newarthill
Cumbernauld
Kincardine
WishawStrathaven
KilmarnockSouth
Ayr
Coylton
Inveraray
HelensburghDunoon
Inverkip
DevolMoor
Hunterston
Sloy
Fort William
Bonnybridge
Neilston
Ceannacroc
Conon
Fort AugustusFoyers
Inverness
Stornoway
Elvanfoot
Kaimes
Glenrothes
Westfield
Grangemouth
Longannet
Linmill
Bathgate
Errochty Power Station
TornessCockenzie
Keith
Thurso
FasnakyleBeauly
Deanie
Lairg
Shin
Nairn
Kintore
Blackhillock
Elgin
Keith
Peterhead
Persley
Fraserburgh
InvergarryQuoich
CulligranAigas Kilmorack
GrudieBridge
Mossford
OrrinLuichart
Alness
Brora
CassleyDunbeath
Mybster
St. Fergus
Strichen
Macduff
Boat ofGarten
Redmoss
Willowdale
Clayhills
Dyce
Craigiebuckler
Woodhill
Tarland
DalmallyKillin
Errochty
Tealing
GlenagnesDudhope
Milton of CraigieDudhope
Lyndhurst
CharlestonBurghmuir
Arbroath
Fiddes
Bridge of Dun
Lunanhead
St. Fillans
Finlarig
LochayCashlie
Rannoch
TummelBridge
Clunie
Taynuilt
Nant
Cruachan
PortAnn
Carradale
Auchencrosh
Lambhill
ClydesMill
Glenluce
NewtonStewart
Maybole
Dumfries Ecclefechan
Berwick
Hawick
Galashiels
Dunbar
Meadowhead
Saltcoats
HunterstonFarm
SP TRANSMISSION LTD.
Kilwinning
Currie
Cupar
Leven
Redhouse
Glenniston
SCOTTISH HYDRO-ELECTRICTRANSMISSION
Telford Rd.Gorgie
KilmarnockTown
Busby
Erskine
Strathleven
MossmorranDunfermline
Broxburn
Livingston
Whitehouse
ShrubhillPortobello
Devonside
StirlingWhistlefield
SpangoValley
Ardmore
Broadford
Dunvegan
NGC
Easterhouse
EastKilbrideSouth
Gretna
Chapelcross
THE SHETLAND ISLANDS
Tongland
GlenMorrison
Clachan
400kV Substations275kV Substations400kV CIRCUITS275kV CIRCUITS
Major Generating Sites Including Pumped Storage
Connected at 400kVConnected at 275kVHydro Generation
TRANSMISSION SYSTEM REINFORCEMENTS
Langage
BlacklawWhitelee
Iverkeithing
Marchwood
BickerFenn
Coalburn
REINFORCED NETWORK
Under Construction or ready to startConstruction subject to consents
Very strong need case
Series Capacitors
RedbridgeTottenham
Strong need case
Future requirement, but no strongneed case to commenceat present
‘Gone Green 2020’
Quantitative Analysis
The effect of System Inertia is being quantitatively analysed through two methods:-
Energy Balance spread sheet approach
Utilising simple predictive output models based on an energy balance
System Study using a Test Network
Utilising Dynamic System Models
Energy Balance Spread Sheet Approach
System Considered
16.5 GW of Wind, 6.9 GW Nuclear, 1.6 GW Carbon Capture
Load Response 2% per Hz
Assumed loss – 1800MW
System Balanced at t = 0 seconds
Inertia considered in isolation
General Conclusion
The higher the inertia the longer it takes for the steady state frequency to be reached.
See subsequent slides
Energy Balance Spread Sheet – ResultsWind Generation with and Without Inertia
Variation in Inertia - Low Resolution
46
46.5
47
47.5
48
48.5
49
49.5
50
50.5
0 10 20 30 40 50 60
Time (s)
Freq
uenc
y Hz
H=0 H=3
Energy Balance Spread Sheet – ResultsWind Generation with and Without Inertia
Variation in Inertia - High Resolution
48.2
48.4
48.6
48.8
49
49.2
49.4
49.6
49.8
50
50.2
0 1 2 3 4 5 6
Time (s)
Freq
uenc
y (H
z)
H=0 H=3
Test network
G~TEST MACH..
-0.0
00.
051.
42
General Load
1353
.29
0.00
trf_1
07_1
07G
-9815...-3189...26.53
1
trf_1
07_1
07G
9826
.2..
3634
.4..
26.5
3
1
trf_1
05_1
05G
-1494...-195.4..83.63
1
trf_1
05_1
05G
1499.5..404.7383.63
1
trf_1
06_1
06G
3
3998
.8..
810.
2084
.52
1
trf_1
06_1
06G
3
-3989...-182.4..84.52
1trf_106_106G1
3999
.0..
1244
.2..
85.6
0
1
trf_106_106G1
-3987...-678.6..85.60
1
trf_102_102G
-1993...-175.1..87.43
1
trf_102_102G
1999
.5..
458.
3587
.43
1
trf_1
03_1
03G
2826
.0..
-34.
9185
.40
1
trf_1
03_1
03G
-2816...440.5785.40
1
Shunt 1
0.0086.98
1
Shunt 4
-0.00-150.8..
1
Shunt 3
-0.00-187.6..
1
Shunt 2
-0.00-17.75
1
G~sy
m_1
03_G
3_B
565.
21-6
.98
80.1
1
G ~
sym
_102
_G2
1999
.5..
458.
3582
.06
trf_1
02_1
01_T
1
-1960...-35.6764.63
trf_1
02_1
01_T
1
1971.5..192.8864.63
G~sy
m_1
03_G
3_E
565.
21-6
.98
80.1
1
G~sy
m_1
03_G
3_D
565.
21-6
.98
80.1
1
G~sy
m_1
03_G
3_C
565.
21-6
.98
80.1
1
G~sy
m_1
03_G
3_A
565.
21-6
.98
80.1
1
lod_107_L7
19196...1947.8..
lod_106_L6
9.71-0.00
lod_105_L5
1051.6..286.80
lod_104_L4
9.58-0.00
lod_103_L3
958.39287.52
lod_102_L2
21.650.00
lod_101_L1
1319.9..180.89
lne_
106_
107_
C7
-9380...1241.6..92.66
lne_
106_
107_
C7
9380.7..-168.3..92.66
G~sy
m_1
07_G
7
9826
.2..
3634
.4..
52.3
8
G~sy
m_1
06_G
3
3998
.8..
810.
2090
.67
G~sy
m_1
06_G
1
3999
.0..
1244
.2..
93.0
7
trf_1
06_1
04_T
3
1275.3..-515.5..69.04
trf_1
06_1
04_T
3
-1275...572.7769.04
lne_
104_
101_
C6
-557.7..284.5264.29
lne_
104_
101_
C6
604.65-239.4..64.29
lne_
104_
101_
C5
-557.7..284.5264.29
lne_
104_
101_
C5
604.65-239.4..64.29
lne_105_104_C2
86.05-78.8811.72
lne_105_104_C2
-84.7048.7311.72
lne_105_104_C1
86.05-78.8811.72
lne_105_104_C1
-84.7048.7311.72
trf_1
06_1
05_T
2
1491.5..-361.7..77.03
trf_1
06_1
05_T
2
-1491...456.6477.03
G~
sym_105_G5
1499.5..404.7377.66
lne_
105_
103_
C4
643.43-165.8..66.87
lne_
105_
103_
C4
-610.1..214.0566.87
lne_
105_
103_
C3
643.43-165.8..66.87
lne_
105_
103_
C3
-610.1..214.0566.87
lne_103_101_C8
-568.3..246.6461.25
lne_103_101_C8
571.72-208.7..61.25
106 GEN3
21.6
70.
9912
.46
105 GEN 21.510.98
14.67
103 GEN
20.6
40.
9425
.69
107 GEN
21.7
20.
99-0
.59
106 GEN1
21.9
71.
0011
.25
102 GEN
21.9
51.
0026
.54
107 BUS007 408.481.02-2.88
106 BUS006 405.011.013.63
105 BUS005 273.961.007.02
104 BUS004 273.981.005.80
103 BUS003 273.260.99
17.51
102 BUS002 408.691.02
18.65
101 BUS001 278.181.01
14.11
DIg
SILE
NT
Basic GB system representation
Approx 23GW demand
10 generators
5 generators providing frequency response
1320 MW load switched in (equivalent to loss of a 1320 MW generator)
Base case large disturbance – normal system inertia
60.0048.0036.0024.0012.000.000 [s]
50.04
49.86
49.68
49.50
49.32
49.14
106 BUS006: Electrical Frequency in Hz
X = 10.400 s
49.183 Hz
60.0048.0036.0024.0012.000.000 [s]
2.28E+4
2.24E+4
2.21E+4
2.18E+4
2.14E+4
2.11E+4
NON FREQENCY RESPONSE: Generation, Active Power in MW
X = 10.400 s
21331.314 MW
22713 MW
60.0048.0036.0024.0012.000.000 [s]
3027.
2812.
2596.
2381.
2166.
1951.
FREQUENCY RESPONSE: Generation, Active Power in MW
DIg
SILE
NT
Decreasing system inertia – large disturbance(½ and ¾ base case inertia)
60.0048.0036.0024.0012.000.000 [s]
50.10
49.78
49.46
49.14
48.82
48.50
106 BUS006: Frequency (Hz) base case inertia106 BUS006: Frequency (Hz) 0.5 x base case inertia106 BUS006: Frequency (Hz) 0.25 x base case inertia
Y = 48.800 Hz
60.0048.0036.0024.0012.000.000 [s]
2.28E+4
2.24E+4
2.21E+4
2.18E+4
2.14E+4
2.11E+4
NON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - base case inertiaNON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - 0.5 x base case inertiaNON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - 0.25 x base case inertia
60.0048.0036.0024.0012.000.000 [s]
3095.
2865.
2636.
2407.
2177.
1948.
FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - base case inertiaFREQUENCY RESPONSE: Total active power from generators providing frequency reponse - 0.5 x base case inertiaFREQUENCY RESPONSE: Total active power from generators providing frequency reponse - 0.25 x base case inertia
DIg
SILE
NT
International Experience and Manufacturer Capability
Hydro Quebec requires Generating Units in a Power Plant to have an inertia constant which is compatible with the inertia constants of existing Power Plants in the same region. The minimum inertia for wind power must equate to 3.5s.
GE Wind advertise a Wind Inertia Control on their Website
Enercon have completed modelling and field tests on a wind turbine and published a paper on this subject
Other manufacturers are believed to be investigating an inertial capability
Transmission System Issues
Optimum Performance Capability requirements based on the minimum needs of the Transmission System.
Prevention of under and over frequency incidents
Control System Design and performance
Filtering requirements if any (Noise Generation?)
Overall Co-ordination
Inertial contribution – Delivered from all plant
Primary Response – FSM – Containment
Secondary Response – FSM - Correction
Conclusions
Machine inertia significantly affects the rate and rise and rate of fall of System Frequency
It is likely to be cheaper (although some form of quantitative analysis would be required) to require all generators to contribute to System Inertia rather than having no requirement and requiring larger volumes of fast acting frequency response?
Non Discrimination
The inertial delivery requirements needs to be quantified
Delivery / Capability
Control System Settings / Filtering