1. Power Technologies International30 September 20021 Load Flow Modelling Service Project results 30 September 2002 Mick Barlow Srdjan Curcic

2. Power Technologies International30 September 20022 Content Project objectives Modelling assumptions Some potential issues with the proposed approaches to allocation of losses Illustration of the key results

3. Power Technologies International30 September 20023 Project objectives Power Technologies Int. has been commissioned to assist the assessment procedure of modification proposals P75 and P82, specifically: –to perform calculations of TLFs & TLMs for a specified number of SPs for P75 & P82 –to present the results in a form suitable for the assessment procedure; and –to draw attention to potential issues with the fundamentals of the two marginal approaches proposed (P75 & P82) This presentation contains an appropriate selection of the project results

4. Power Technologies International30 September 20024 Modelling assumptions MW injections are calculated from the metered volumes assuming they are constant (average) Power factors published in NGC’s SYS are used to calculate reactive power injections It is assumed that “offtake” metered volumes/injections are accurate and then the “delivery” volumes/injections are calculated to balance “offtake” metered volumes/injections and calculated variable active power system losses, while maintaining relative “deliveries” among the generators ( DICTATED BY DATA QUALITY )

5. Power Technologies International30 September 20025 Modelling assumptions Load flow assumptions: –Generation P is calculated as described above –Generation Q is calculated automatically by setting voltage target to 1.03 p.u. –Load P is calculated from the metered volumes –Load Q is calculated from typical power factors given in the NGC’s SYS –Transformer tap changer are set according to information in the NGC’s SYS for each voltage level –Transformer target voltage is set to produce reasonable voltage profile (between 0.97 and 1.03 p.u.) –SVC’s target voltage is set to values recommended in the NGC’s SYS

6. Power Technologies International30 September 20026 Modelling assumptions AC load flow calculations are using the standard NGC’s slack at Cowley PTI’s PSS/E-OPF is used for calculating marginal TLFs Out of TLFs obtained for active power injections and reactive power injections, unique TLFs are calculated that relate only to active power injections, while providing for the total losses incurred from a node TLF ij = (TLF Pij  P ij + TLF Qij  Q ij ) / P ij

7. Power Technologies International30 September 20027 Modelling assumptions On the basis of information in the NGC’s SYS, the fixed losses are assumed to be 200MW (peak), 180MW (trough) and 190MW (other periods – Autumn) For the purpose of calculating TLMs, these fixed losses are smeared across generators, proportionally to their power output

8. Power Technologies International30 September 20028 Issues with proposed allocation of losses Slack node – An issue with the marginal TLFs approach: The choice of the slack node potentially matters more that initially expected :

9. Power Technologies International30 September 20029 Issues with proposed allocation of losses Network & metered volumes are for 22 January 2002 Comparison is between slack node at Cowley and at Thorpe Marsh Slack node Illustrative example: Assume a generation metered volume of 1000MWh and a TLM of 0.94. That would attribute 60MWh of losses to this generation. Due to the indicated change in slack node this 60MWh of losses would change for 9.23%, on average.

10. Power Technologies International30 September 200210 Issues with proposed allocation of losses The sensitivity analysis to introduction/variation of power factors has been done in an simple exercise: For 02 January 2002 network and metered volumes two cases were calculated: –P.F. = 1 for all demand nodes –P.F. by NGC’s SYS Power factor

11. Power Technologies International30 September 200211 Issues with proposed allocation of losses Power factor At the level of TLFs the effect was much more tangible. This indicates: a)that reactive powers should not be ignored; and b)a possible need for further consideration

12. Power Technologies International30 September 200212 Summary: Issues with proposed allocation of losses There are some issues arising from the modelling TLFMG, nevertheless, have confidence in the modelling results

13. Power Technologies International30 September 200213 Illustration of key results P75

14. Power Technologies International30 September 200214 P75 (T1) Base cases 02 Jan. 02 (SP36) - Peak 01 Aug. 01 (SP8) - Trough 10 Oct. 01 (SP25) – Week day daylight 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

15. Power Technologies International30 September 200215 GSPG and TNUoS (gen) zones

16. Power Technologies International30 September 200216 Change P75 introduces – an example (based on marginal, GSPG zone, ½ h TLFs) North South 02 January 2002

17. Power Technologies International30 September 200217 Demand TLMs for P75 (based on marginal, GSPG zone, ½ h TLFs) North South

18. Power Technologies International30 September 200218 Change P75 introduces – an example (based on marginal, TNUoS (gen) zone, ½ h TLFs) North South 02 January 2002

19. Power Technologies International30 September 200219 Generation TLMs for P75 (based on marginal, TNUoS (gen) zone, ½ h TLFs) North South

20. Power Technologies International30 September 200220 P75 (T1) - Summary Introduction of Modification Proposal P75 would result in variable TLMs: –over time; and –across country with an overall, indicative variation between 0.95 and 1.06 for demand and between 0.94 and 1.09 for generation

21. Power Technologies International30 September 200221 P75 (T2) Variation of TLMs over time 02 Jan. 02 (SP8 & SP36) – Peak day 01 Aug. 01 (SP8 & SP36) – Trough day 10 Oct. 01 (SP1 – SP48) – Week day 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

22. Power Technologies International30 September 200222 P75: GSPG zone TLMs over sample time period - demand North South

23. Power Technologies International30 September 200223 P75: TNUoS (gen) zone TLMs over sample time period - generation North South

24. Power Technologies International30 September 200224 P75: GSPG zone TLMs over a day - Demand 10 October 2001 North South

25. Power Technologies International30 September 200225 P75: TNUoS (gen) zone TLMs over a day - Generation 10 October 2001 North South

26. Power Technologies International30 September 200226 P75 (T2) - Summary Introduction of Modification Proposal P75 would result in daily variation in TLMs of up to approximately 0.03 for demand and 0.045 for generation (the exception is TNUoS zone 5 with reversible hydro plants where the variation is up to 0.065) on a typical autumn working day

27. Power Technologies International30 September 200227 P75 (T3) Sensitivity to network configuration Indicative/Intact/Representative networks for the following SPs: 02 Jan. 02 (SP36) - Peak 01 Aug. 01 (SP8) - Trough 10 Oct. 01 (SP25) – Week day daylight 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

28. Power Technologies International30 September 200228 P75: GSPG zone TLMs - Demand sensitivity to network configuration North South 02 January 2002 (peak)

29. Power Technologies International30 September 200229 P75: TNUoS (gen) zone TLMs - Generation sensitivity to network configuration North South 02 January 2002 (peak)

30. Power Technologies International30 September 200230 P75: GSPG zone TLMs - Demand sensitivity to network configuration North South 01 August 2002 (trough)

31. Power Technologies International30 September 200231 P75: TNUoS (gen) zone TLMs - Generation sensitivity to network configuration North South 01 August 2002 (trough)

32. Power Technologies International30 September 200232 P75: GSPG zone TLMs - Demand sensitivity to network configuration North South 10 October 2001 (weekday daylight)

33. Power Technologies International30 September 200233 P75: TNUoS (gen) zone TLMs - Generation sensitivity to network configuration North South 10 October 2001 (weekday daylight)

34. Power Technologies International30 September 200234 P75: GSPG zone TLMs - Demand sensitivity to network configuration North South 11 October 2001 (weekday night)

35. Power Technologies International30 September 200235 P75: TNUoS (gen) zone TLMs - Generation sensitivity to network configuration North South 11 October 2001 (weekday night)

36. Power Technologies International30 September 200236 P75: GSPG zone TLMs - Demand sensitivity to network configuration North South 13 October 2001 (weekend daylight)

37. Power Technologies International30 September 200237 P75: TNUoS (gen) zone TLMs - Generation sensitivity to network configuration North South 13 October 2001 (weekend daylight)

38. Power Technologies International30 September 200238 P75: GSPG zone TLMs - Demand sensitivity to network configuration North South 14 October 2001 (weekend night)

39. Power Technologies International30 September 200239 P75: TNUoS (gen) zone TLMs - Generation sensitivity to network configuration North South 14 October 2001 (weekend night)

40. Power Technologies International30 September 200240 P75 (T3) - Summary Network configuration can have an effect on TLMs: –while there is almost no difference between intact and representative networks, –there is a tangible difference between indicative and intact networks

41. Power Technologies International30 September 200241 P75 (T4) Sensitivities to constraints 02 January 2002 (base case) 02 January 2002 (constrained case) 5 double circuits restricted for 20% below the flow level in base case

42. Power Technologies International30 September 200242 P75: GSPG zone TLMs - Demand sensitivity to constraints North South Losses: 758.5MW (base case), 573 (constrained case)

43. Power Technologies International30 September 200243 P75: TNUoS zone TLMs - Generation sensitivity to constraints North South Losses: 758.5MW (base case), 573 (constrained case)

44. Power Technologies International30 September 200244 P75 (T4) - Summary Constraints may have an impact on TLMs

45. Power Technologies International30 September 200245 P75 (T5) Comparison of Generation TLFs/TLMs and Demand TLFs/TLMs at the same node

46. Power Technologies International30 September 200246 P75: Comparison of Generation/Demand Zonal TLFs/TLMs Node: Rye House GSPG zone:7 TNUoS zone:10 SP:02 January 2002, SP36

47. Power Technologies International30 September 200247 P75 (T5) - Summary Discrepancies between TLMs for generation and demand at a node are not greatly exacerbated if generation and demand zones are different from one another Only one node has been assessed and this may not be representative

48. Power Technologies International30 September 200248 P75 (T6) Comparison of Nodal TLFs/TLMs with Zonal TLFs/TLMs

49. Power Technologies International30 September 200249 P75: Comparison of Nodal/Zonal TLMs (Demand) 02 January 2002 Winter peak (SP36)

50. Power Technologies International30 September 200250 P75: Comparison of Nodal/Zonal TLMs (Generation) 02 January 2002 Winter peak (SP36)

51. Power Technologies International30 September 200251 P75: Comparison of Nodal/Zonal TLMs (Demand) 01 August 2001 Summer trough (SP8)

52. Power Technologies International30 September 200252 P75: Comparison of Nodal/Zonal TLMs (Generation) 01 August 2001 Summer trough (SP8)

53. Power Technologies International30 September 200253 P75 (T6) - Summary Introduction of Modification Proposal P75 and its zonal TLMs (GSPG zones for demand and TNUoS (gen) zones for generation) would result in nodal TLMs for some nodes being closer to neighbouring zonal TLMs

54. Power Technologies International30 September 200254 P75 (T7) Model performance characteristics

55. Power Technologies International30 September 200255 Data capture depends on the source systems Data capture will be greatly improved once NGC’s state estimator is fully operational Amount, duration and quality of data depends on the source systems and the TLF modification applied The quality and consistency of the data determine the time and effort required to establish acceptable loadflow conditions P75: Input data

56. Power Technologies International30 September 200256 Once a suitable loadflow data set has been obtained it should take less than 10 seconds to obtain TLFs for all considered generation/demand points for a SP The output would be suitably structured list of TLFs Further post processing could be established to automatically produce a higher level of the output data P75: Processing and output data

57. Power Technologies International30 September 200257 P75 (T8) Sensitivities to flows on French Inter-connector 31 October 2001 (importing) 07 November 2001 (exporting)

58. Power Technologies International30 September 200258 P75: GSPG zone TLMs - sensitivity to flows on French Inter-connector North South Losses: 377.1MW (importing), 533.3 (exporting)

59. Power Technologies International30 September 200259 P75: TNUoS zone TLMs - sensitivity to flows on French Inter-connector North South Losses: 377.1MW (importing), 533.3 (exporting)

60. Power Technologies International30 September 200260 P75 (T9&10) Examples of moving generation deliveries for the selected nodes Greystones Barking Power

61. Power Technologies International30 September 200261 P75: GSPG zone TLMs - sensitivity to plant outages / response to signals North South 02 January 2002

62. Power Technologies International30 September 200262 P75: TNUoS (gen) zone TLMs - sensitivity to plant outages / response to signals North South 02 January 2002

63. Power Technologies International30 September 200263 For the base case of 02 January 2002 500MW were moved from Dinorwig to 5 different places Indian Queens P75 (T11) : Sensitivity to intermittent generation Blyth Harker Grain Norwich Dinorwig

64. Power Technologies International30 September 200264 P75: GSPG zone TLMs - Demand sensitivity to intermittent generation North South 02 January 2002

65. Power Technologies International30 September 200265 P75: TNUoS zone TLMs - Generation sensitivity to intermittent generation North South 02 January 2002

66. Power Technologies International30 September 200266 P75 (T8 to T11) - Summary TLMs in Modification Proposal P75 are only locally sensitive to plant withdrawal or plant relocation or to intermittent generation Note that for Task 8 (sensitivity to flow on French inter-connector) the effect is complicated as we have two different dates and SPs with different generation and demand profiles

67. Power Technologies International30 September 200267 Illustration of key results P82

68. Power Technologies International30 September 200268 P82 (T1) Variation of scaled TLFs over time 02 Jan. 02 (SP8 & SP36) – Peak day 01 Aug. 01 (SP8 & SP36) – Trough day 10 Oct. 01 (SP1 – SP48) – Week day 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

69. Power Technologies International30 September 200269 P82: GSPG zone ½ h TLMs over sample time period - Demand North South

70. Power Technologies International30 September 200270 P82: GSPG zone ½ h TLMs over sample time period - Generation North South

71. Power Technologies International30 September 200271 P82: GSPG zone ½ h TLMs over a day - Demand 10 October 2001 North South

72. Power Technologies International30 September 200272 P82: GSPG zone ½ h TLMs over a day - Generation 10 October 2001 North South

73. Power Technologies International30 September 200273 P82 (T1) - Summary Before implementing the averaging of TLFs, the variation in TLMs for P82 would be up to approximately 0.016 for demand and 0.017 for generation on a typical autumn working day

74. Power Technologies International30 September 200274 P82 (T2) Base cases 02 Jan. 02 (SP36) - Peak 01 Aug. 01 (SP8) - Trough 10 Oct. 01 (SP25) – Week day daylight 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

75. Power Technologies International30 September 200275 GSPG and TNUoS (gen) zones

76. Power Technologies International30 September 200276 Change P82 introduces – an example (based on scaled, GSPG zone, averaged TLFs) North South 02 January 2002

77. Power Technologies International30 September 200277 Demand TLMs for P82 (based on scaled, GSPG zone, averaged TLFs) North South

78. Power Technologies International30 September 200278 Change P82 introduces – an example (based on scaled, GSPG zone, averaged TLFs) North South 02 January 2002

79. Power Technologies International30 September 200279 Generation TLMs for P82 (based on scaled, GSPG zone, averaged TLFs) North South

80. Power Technologies International30 September 200280 P82 (T2) - Summary Introduction of Modification Proposal P82 would result in variable TLMs: –over time; and –across country with an overall variation between 0.99 and 1.03 for demand and between 0.975 and 1.015 for generation, where spatial variations are larger than temporal variations

81. Power Technologies International30 September 200281 P82 (T3) Variation of TLMs over time (based on average scaled TLFs) 02 Jan. 02 (SP8 & SP36) – Peak day 01 Aug. 01 (SP8 & SP36) – Trough day 10 Oct. 01 (SP1 – SP48) – Week day 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

82. Power Technologies International30 September 200282 P82: GSPG zone TLMs over sample time period - Demand North South

83. Power Technologies International30 September 200283 P82: GSPG zone TLMs over sample time period - Generation North South

84. Power Technologies International30 September 200284 P82: GSPG zone TLMs over a day - Demand 10 October 2001 North South

85. Power Technologies International30 September 200285 P82: GSPG zone TLMs over a day - Generation 10 October 2001 North South

86. Power Technologies International30 September 200286 P82 (T3) - Summary Introduction of Modification Proposal P82 would result in almost non-existent daily variations in TLMs (up to approximately 0.004 for demand and 0.004 for generation) on a typical autumn working day

87. Power Technologies International30 September 200287 P82 (T4) Sensitivity of TLFs & TLMs to choice of historic data and weightings

88. Power Technologies International30 September 200288 This task has not been completed as the required input data have not been provided P82: Sensitivity of TLFs & TLMs to historic data and weighting coefficients

89. Power Technologies International30 September 200289 P82 (T5) Sensitivities to constraints 02 January 2002 (base case) 02 January 2002 (constrained case) 5 double circuits restricted for 20% below the flow level in base case

90. Power Technologies International30 September 200290 P82: GSPG zone TLMs - Demand sensitivity to constraints North South Losses: 758.5MW (base case), 573 (constrained case)

91. Power Technologies International30 September 200291 P82: TNUoS zone TLMs - Generation sensitivity to constraints North South Losses: 758.5MW (base case), 573 (constrained case)

92. Power Technologies International30 September 200292 P82 (T5) - Summary TLMs in Modification Proposal P82 are almost insensitive to constraints – because the effects of such events would be averaged in the following year

93. Power Technologies International30 September 200293 P82 (T6) Comparison of Nodal TLFs/TLMs with Zonal TLFs/TLMs

94. Power Technologies International30 September 200294 P82: Comparison of Nodal/Zonal TLMs – Generation 02 January 2002 Winter peak (SP36)

95. Power Technologies International30 September 200295 P82: Comparison of Nodal/Zonal TLMs - Demand 02 January 2002 Winter peak (SP36)

96. Power Technologies International30 September 200296 P82: Comparison of Nodal/Zonal TLMs – Generation 01 August 2001 Summer trough (SP8)

97. Power Technologies International30 September 200297 P82: Comparison of Nodal/Zonal TLMs - Demand 01 August 2001 Summer trough (SP8)

98. Power Technologies International30 September 200298 P82 (T6) - Summary Introduction of Modification Proposal P82 and its zonal TLMs (GSPG zones only for both demand and generation) would result in nodal TLMs for some nodes being closer to neighbouring zonal TLMs

99. Power Technologies International30 September 200299 P82 (T7) Sensitivities to flows on French Inter-connector 31 October 2001 (importing) 07 November 2001 (exporting)

100. Power Technologies International30 September 2002100 P82: GSPG zone TLMs - Demand sensitivity to flows on French Inter-connector North South Losses: 377.1MW (importing), 533.3 (exporting)

101. Power Technologies International30 September 2002101 P82: GSPG zone TLMs - Generation sensitivity to flows on French Inter-connector North South Losses: 377.1MW (importing), 533.3 (exporting)

102. Power Technologies International30 September 2002102 P82 (T7) - Summary TLMs in Modification Proposal P82 are almost insensitive to direction of flows on the French inter-connector – because the effects of such events would be averaged in the following year

103. Power Technologies International30 September 2002103 P82 (T8) Degree to which a scaling factor of 0.5 recovers heating losses 02 Jan. 02 (SP36) - Peak 01 Aug. 01 (SP8) - Trough 10 Oct. 01 (SP25) – Week day daylight 11 Oct. 01 (SP11) – Week day night 13 Oct. 01 (SP25) – Weekend daylight 14 Oct. 01 (SP11) – Weekend night

104. Power Technologies International30 September 2002104 P82: Comparison between flat 0.5 scaling factor and the actual reconciliation factors

105. Power Technologies International30 September 2002105 P82: Nodal TLFs – recovery of heating losses with scaling factor 0.5 and the actual reconciliation factors

106. Power Technologies International30 September 2002106 P82 (T8) - Summary Scaling factor of 0.5 does not precisely recover heating losses but appears to be a reasonable approximation

107. Power Technologies International30 September 2002107 P82 (T9&10) Examples of moving generation deliveries for the selected nodes Greystones Barking Power

108. Power Technologies International30 September 2002108 P82: GSPG zone TLMs - Demand sensitivity to plant outages / response to signals North South 02 January 2002

109. Power Technologies International30 September 2002109 P82: GSPG zone TLMs - Generation sensitivity to plant outages / response to signals North South 02 January 2002

110. Power Technologies International30 September 2002110 For the base case of 02 January 2002 500MW were moved from Dinorwig to 5 different places Indian Queens P82 (T11) : Sensitivity to intermittent generation Blyth Harker Grain Norwich Dinorwig

111. Power Technologies International30 September 2002111 P82: GSPG zone TLMs - Demand sensitivity to intermittent generation North South 02 January 2002

112. Power Technologies International30 September 2002112 P82: GSPG zone TLMs - Generation sensitivity to intermittent generation North South 02 January 2002

113. Power Technologies International30 September 2002113 P82 (T9 to T11) - Summary TLMs in Modification Proposal P82 are almost insensitive to plant withdrawal or move or to intermittent generation – because the effects of such events would be averaged in the following year

114. Power Technologies International30 September 2002114 END OF PRESENTATION