Grid Code Frequency Response Working Group System Inertia Antony - - PDF document

SLIDE 1

Grid Code Frequency Response Working Group System Inertia

Antony Johnson, System Technical Performance

SLIDE 2

Overview

Background to System Inertia Transmission System need Future Generation Scenarios Initial Study Work International Experience and Manufacturer Capability Transmission System Issues Conclusions

SLIDE 3

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.

SLIDE 4

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

• perating 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

SLIDE 5

What is inertia?

Loss of Generator

• n the system

Frequency Falls as demand > generation Stored energy delivered to grid as MW

The stored energy is proportional to the speed of rotation squared 3 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

SLIDE 6

The maths behind inertia

∂f/∂t = Rate of change of frequency ∆P = MW of load or generation lost 2H = Two times the system inertia in MWs / MVA

∂f ∂t ∆P 2H =

∂f/∂t = Rate of change of frequency ∆P = MW of load or generation lost 2H = Two times the system inertia in MWs / MVA

∂f ∂t ∆P 2H =

H = Inertia constant in MWs / MVA J = Moment of inertia in kgm2 of the rotating mass ω = nominal speed of rotation in rad/s MVA = MVA rating of the machine

½Jω2 MVA H =

H = Inertia constant in MWs / MVA J = Moment of inertia in kgm2 of the rotating mass ω = nominal speed of rotation in rad/s MVA = MVA rating of the machine

½Jω2 MVA H =

Typical H for a synchronous generator can range from 2 to 9 seconds (MWs/MVA)

SLIDE 7

An NGET Future Scenario

Plant closures

• 12GW Coal & oil LCPD
• 7.5GW nuclear
• Some gas & additional coal

Significant new renewable

• 29 GW wind (2/3 offshore)
• Some tidal, wave, biomass & solar PV
• Renewable share of generation grows from 5% to 36%

Significant new non renewable build

• 3GW of new nuclear
• 3GW of new supercritical coal (some with CCS)
• 11GW of new gas

Electricity demand remains flat (approx 60 GW)

• Reductions from energy efficiency measures
• Increases from heat pumps & cars

Strategic Reinforcements

Sizewell Pembroke Osbaldwick Rowdown Beddington Chessington West Landulph Abham Exeter Axminster Chickerell Mannington Taunton Alverdiscott Hinkley Point Bridgwater Aberthaw Cowbridge Pyle Margam Swansea North Cardiff East Tremorfa Alpha Steel Uskmouth Upper Boat Cilfynydd Imperial Park Rassau Whitson Seabank Iron Acton Walham Melksham Minety Didcot Culham Cowley Bramley Fleet Nursling Fawley Botley Wood Lovedean Bolney Ninfield Dungeness Sellindge Canterbury E de F Kemsley Grain Kingsnorth Rayleigh Main Littlebrook Tilbury Warley Barking W.Ham City Rd Brimsdown Waltham Ealing Mill Hill Willesden Watford St Johns Wimbledon New Hurst Elstree Rye House N.Hyde Sundon Laleham Iver Amersham Main Wymondley Pelham Braintree Burwell Main Bramford Eaton Socon Grendon East Claydon Enderby Walpole Norwich Main Coventry Berkswell Rugeley Cellarhead Ironbridge Bushbury Penn Willenhall Ocker Hill Kitwell Oldbury Bustleholm Nechells Hams Hall Bishops Wood Feckenham Legacy Trawsfynydd Ffestiniog Dinorwig Pentir Wylfa Deeside Capenhurst Frodsham Fiddlers Rainhill Kirkby Lister Drive Birkenhead Washway Farm Penwortham Carrington South Manchester Daines Macclesfield Bredbury Stalybridge Rochdale Whitegate Kearsley Elland Stocksbridge West Melton Aldwarke Thurcroft Brinsworth Jordanthorpe Chesterfield Sheffield City Neepsend Pitsmoor Templeborough Thorpe Marsh Keadby West Burton Cottam High Marnham Staythorpe Stanah Heysham Padiham Hutton Bradford West Kirkstall Skelton Poppleton Thornton Quernmore Monk Eggborough Ferrybridge Killingholme South Humber Bank Grimsby West Drax Lackenby Greystones Grangetown Saltholme Norton Spennymoor Tod Point Hartlepool Hart Moor Hawthorne Pit Offerton West Boldon South Shields Tynemouth Stella West Harker Eccles Blyth Indian Queens Coryton Ratcliffe Willington Drakelow Shrewsbury Cross Weybridge Cross Wood North Fryston Grange Ferry Winco Bank Norton Lees Creyke Beck Saltend North Saltend South Hackney Baglan Bay Leighton Buzzard Patford Bridge Northfleet East Singlewell Fourstones Humber Refinery Spalding North West Thurrock ISSUE B 12-02-09 41/177619 C Collins Bartholomew Ltd 1999 Dingwall Dounreay Newarthill Cumbernauld Kincardine Wishaw Strathaven Kilmarnock South Ayr Coylton Inveraray Helensburgh Dunoon Inverkip Devol Moor Hunterston Sloy Fort William Bonnybridge Neilston Ceannacroc Conon Fort Augustus Foyers Inverness Stornoway Elvanfoot Kaimes Glenrothes Westfield Grangemouth Longannet Linmill Bathgate Errochty Power Station Torness Cockenzie Keith Thurso Fasnakyle Beauly Deanie Lairg Shin Nairn Kintore Blackhillock Elgin Keith Peterhead Persley Fraserburgh Invergarry Quoich Culligran Aigas Kilmorack Grudie Bridge Mossford Orrin Luichart Alness Brora Cassley Dunbeath Mybster

• St. Fergus

Strichen Macduff Boat of Garten Redmoss Willowdale Clayhills Dyce Craigiebuckler Woodhill Tarland Dalmally Killin Errochty Tealing GlenagnesDudhope Milton of Craigie Dudhope Lyndhurst Charleston Burghmuir Arbroath Fiddes Bridge of Dun Lunanhead

• St. Fillans

Finlarig Lochay Cashlie Rannoch Tummel Bridge Clunie Taynuilt Nant Cruachan Port Ann Carradale Auchencrosh Lambhill Clydes Mill Glenluce Newton Stewart Maybole Dumfries Ecclefechan Berwick Hawick Galashiels Dunbar Meadowhead Saltcoats Hunterston Farm SP TRANSMISSION LTD. Kilwinning Currie Cupar Leven Redhouse Glenniston SCOTTISH HYDRO-ELECTRIC TRANSMISSION Telford Rd. Gorgie Kilmarnock Town Busby Erskine Strathleven Mossmorran Dunfermline Broxburn Livingston Whitehouse Shrubhill Portobello Devonside Stirling Whistlefield Spango Valley Ardmore Broadford Dunvegan NGC Easterhouse East Kilbride South Gretna Chapelcross

THE SHETLAND ISLANDS

Tongland Glen Morrison Clachan

400kV Substations 275kV Substations 400kV CIRCUITS 275kV CIRCUITS Major Generating Sites Including Pumped Storage Connected at 400kV Connected at 275kV Hydro Generation

TRANSMISSION SYSTEM REINFORCEMENTS

Langage Blacklaw Whitelee Iverkeithing Marchwood Bicker Fenn Coalburn

REINFORCED NETWORK

Under Construction or ready to start Construction subject to consents Very strong need case Series Capacitors

Redbridge Tottenham

Strong need case Future requirement, but no strong need case to commence at present

‘Gone Green 2020’

SLIDE 8

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

SLIDE 9

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

SLIDE 10

Energy Balance Spread Sheet – Results Wind 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 10 20 30 40 50 60 Time (s) Frequency Hz H=0 H=3

SLIDE 11

Energy Balance Spread Sheet – Results Wind 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 1 2 3 4 5 6 Time (s) Frequency (Hz) H=0 H=3

SLIDE 12

Test network

G ~

TEST MACH..

• 0.00

0.05 1.42 General Load 1353.29 0.00

trf_107_107G

• 9815...
• 3189...

26.53

1 trf_107_107G

9826.2.. 3634.4.. 26.53

1 trf_105_105G

• 1494...
• 195.4..

83.63

1 trf_105_105G

1499.5.. 404.73 83.63

1 trf_106_106G3

3998.8.. 810.20 84.52

1 trf_106_106G3

• 3989...
• 182.4..

84.52

1 trf_106_106G1

3999.0.. 1244.2.. 85.60

1 trf_106_106G1

• 3987...
• 678.6..

85.60

1 trf_102_102G

• 1993...
• 175.1..

87.43

1 trf_102_102G

1999.5.. 458.35 87.43

1 trf_103_103G

2826.0..

• 34.91

85.40

1 trf_103_103G

• 2816...

440.57 85.40

1 Shunt 1

0.00 86.98

1

Shunt 4

• 0.00
• 150.8..

1

Shunt 3

• 0.00
• 187.6..

1

Shunt 2

• 0.00
• 17.75

1

G ~

sym_103_G3_B

565.21

• 6.98

80.11 G ~

sym_102_G2

1999.5.. 458.35 82.06

trf_102_101_T1

• 1960...
• 35.67

64.63

trf_102_101_T1

1971.5.. 192.88 64.63 G ~

sym_103_G3_E

565.21

• 6.98

80.11 G ~

sym_103_G3_D

565.21

• 6.98

80.11 G ~

sym_103_G3_C

565.21

• 6.98

80.11 G ~

sym_103_G3_A

565.21

• 6.98

80.11

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

958.39 287.52

lod_102_L2

21.65 0.00

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 ~

sym_107_G7

9826.2.. 3634.4.. 52.38 G ~

sym_106_G3

3998.8.. 810.20 90.67 G ~

sym_106_G1

3999.0.. 1244.2.. 93.07

trf_106_104_T3

1275.3..

• 515.5..

69.04

trf_106_104_T3

• 1275...

572.77 69.04

lne_104_101_C6

• 557.7..

284.52 64.29

lne_104_101_C6

604.65

• 239.4..

64.29

lne_104_101_C5

• 557.7..

284.52 64.29

lne_104_101_C5

604.65

• 239.4..

64.29

lne_105_104_C2

86.05

• 78.88

11.72

lne_105_104_C2

• 84.70

48.73 11.72

lne_105_104_C1

86.05

• 78.88

11.72

lne_105_104_C1

• 84.70

48.73 11.72

trf_106_105_T2

1491.5..

• 361.7..

77.03

trf_106_105_T2

• 1491...

456.64 77.03 G ~

sym_105_G5

1499.5.. 404.73 77.66

lne_105_103_C4

643.43

• 165.8..

66.87

lne_105_103_C4

• 610.1..

214.05 66.87

lne_105_103_C3

643.43

• 165.8..

66.87

lne_105_103_C3

• 610.1..

214.05 66.87

lne_103_101_C8

• 568.3..

246.64 61.25

lne_103_101_C8

571.72

• 208.7..

61.25

106 GEN3

21.67 0.99 12.46

105 GEN 21.51

0.98 14.67

103 GEN

20.64 0.94 25.69

107 GEN

21.72 0.99

• 0.59

106 GEN1

21.97 1.00 11.25

102 GEN

21.95 1.00 26.54

107 BUS007 408.48

1.02

• 2.88

106 BUS006 405.01

1.01 3.63

105 BUS005 273.96

1.00 7.02

104 BUS004 273.98

1.00 5.80

103 BUS003 273.26

0.99 17.51

102 BUS002 408.69

1.02 18.65

101 BUS001 278.18

1.01 14.11

DIgSILENT

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)

SLIDE 13

Base case large disturbance – normal system inertia

60.00 48.00 36.00 24.00 12.00 0.000 [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 60.00 48.00 36.00 24.00 12.00 0.000 [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 60.00 48.00 36.00 24.00 12.00 0.000 [s] 3027. 2812. 2596. 2381. 2166. 1951. FREQUENCY RESPONSE: Generation, Active Power in MW

DIgSILENT

SLIDE 14

Decreasing system inertia – large disturbance

(½ and ¾ base case inertia)

60.00 48.00 36.00 24.00 12.00 0.000 [s] 50.10 49.78 49.46 49.14 48.82 48.50 106 BUS006: Frequency (Hz) base case inertia 106 BUS006: Frequency (Hz) 0.5 x base case inertia 106 BUS006: Frequency (Hz) 0.25 x base case inertia Y = 48.800 Hz 60.00 48.00 36.00 24.00 12.00 0.000 [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 inertia NON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - 0.5 x base case inertia NON FREQENCY RESPONSE: Total active power from generators NOT providing frequency reponse - 0.25 x base case inertia 60.00 48.00 36.00 24.00 12.00 0.000 [s] 3095. 2865. 2636. 2407. 2177. 1948. FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - base case inertia FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - 0.5 x base case inertia FREQUENCY RESPONSE: Total active power from generators providing frequency reponse - 0.25 x base case inertia

DIgSILENT

SLIDE 15

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

SLIDE 16

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

SLIDE 17

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