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

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

Power Technologies International30 September 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

Power Technologies International30 September 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 )

Power Technologies International30 September 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

Power Technologies International30 September 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

Power Technologies International30 September 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

Power Technologies International30 September 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 :

Power Technologies International30 September 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 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.

Power Technologies International30 September 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

Power Technologies International30 September 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

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

Power Technologies International30 September Illustration of key results P75

Power Technologies International30 September 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

Power Technologies International30 September GSPG and TNUoS (gen) zones

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September 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

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

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

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

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

Power Technologies International30 September P75 (T2) - Summary Introduction of Modification Proposal P75 would result in daily variation in TLMs of up to approximately 0.03 for demand and 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

Power Technologies International30 September 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

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

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

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

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

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

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

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

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

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September 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

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

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

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

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

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

Power Technologies International30 September 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

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

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September P75 (T7) Model performance characteristics

Power Technologies International30 September 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

Power Technologies International30 September 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

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

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

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

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

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

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September Illustration of key results P82

Power Technologies International30 September 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

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

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September GSPG and TNUoS (gen) zones

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

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

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

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

Power Technologies International30 September 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 and for generation, where spatial variations are larger than temporal variations

Power Technologies International30 September 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

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

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

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September 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

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

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

Power Technologies International30 September 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

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

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

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

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

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

Power Technologies International30 September 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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September 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

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

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

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

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

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

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

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

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

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

Power Technologies International30 September 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

Power Technologies International30 September END OF PRESENTATION