1 National Grid Network Modelling Software Review

1 National Grid Network Modelling Software Review

Network Modelling Software Review A presentation to Transmission Workstream Angus Paxton 5 th February 2009 National Grid Network Modelling Software Review

About Pöyry Energy Consulting • 42 energy consulting staff based in Oxford • 250 energy consulting staff throughout Europe • 15 European offices from Madrid to Moscow • Provide a wide range of advice to a wide range of clients • Gas, power, carbon, renewables and associated markets (oil, coal) • Due diligence, group strategies, market modelling and simulation, regulatory support, business process design, policy making, trading tactics, technical auditing, price projections, market training • Government departments, regulators, monopolies, producers, generators, retailers, consumers, associations • Pöyry plc group company adds many other dimensions, e. g. – oil and gas engineering – IGL Consultants (Aberdeen) – capital financing – Pöyry Capital (London) 3 National Grid Network Modelling Software Review

Network Model Software Review • Driven by the Network Model Obligation – Requires NGG to maintain and make available a Network Model – Requires independent proof to Regulator of fitness for purpose • What is the purpose? • Gas Act obligation – develop…economic and efficient • Licence obligations – – 1 in 20 Transmission Planning Code Network Model Obligation Information requests • Network code obligations • Safety Case – IGE/GL/2 4 National Grid Network Modelling Software Review

GL/2 and network analysis • GL/2 sets out requirements for network analysis • GL/2 implicitly acknowledges pressure and flow relationship is not linear – Empirically derived, thermodynamic formula – Requires consideration of Joule Thompson coefficient, i. e. considers that natural gas is not an ideal gas – formulae are very complicated • Mathematics: – In-flows must equal out-flows – Loops require algorithms & computation – Compressors and optimisation make computation more difficult • Overarching requirement to validate against actual measured network performance – network validation • Flows & pressures within 5% 5 National Grid Network Modelling Software Review

Falcon replacement • Thorough procurement process – Short-list – Shorter-list – Single product • New product (Simone) used by – E. On – HAI – BEB – Energienet. dk – VNG – AGGM – Gd. F Suez / GRTgaz – Transgas (Portugal) – Gaz-System • NGG considered that Ofgem/industry may require assurance, per Network Model Obligation & Transmission Planning Code 6 National Grid Network Modelling Software Review

Observation and validation • Series of tests independently created by Pöyry Energy Consulting – Based on the Transmission Planning Code – Incorporating consideration of other analytical requirements • Considered: – – – Basic functionality Supply and demand flows Capacity discovery Energy/volumetric conversion Gas component tracking – Compressors – Flow control valves & other plant – Error handling, analysis – Configurations, reinforcement – Management and other functionality • Pöyry Energy Consulting granted unfettered access to equivalent models in both Simone and Falcon • We ran through the series of tests • We also examined the validation work undertaken in both products 7 National Grid Network Modelling Software Review

Mathematical depths • Pöyry also briefly checked the underlying maths – Momentum term was neglected in Falcon – not requried to model transients – Momentum term included in Simone – underlying equations therefore different – Differences in compressor model specification – surfaces, not a set of coordinates – better compressor modelling – Differences in computation algorithm – more efficient and far more stable • Software documentaion references have been cross-referenced to independent, academic literature • Variables required/decribed are usual for fluid dynamics 8 National Grid Network Modelling Software Review

Findings • New product very stable • Fit for existing network analyses (offline, long-term) • Simulation of NTS as good as, if not better than, GF • One minor finding: – Compressor inlet temperature reset under a very particular situation • Short compressor loop - very unusual configuration • Unlikely set of conditions • Response from software vendor (within 2 weeks) is apparently: “ah. . . yes… now fixed for the next release!” • Additional functionality could be very useful – Subject to licensing, Ofgem or other third party could do some limited examination/audit of network analyses 9 National Grid Network Modelling Software Review

Report published • Available (now/shortly) through National Grid and Pöyry Energy Consulting (UK) websites www. nationalgrid. com www. ilexenergy. co. uk • Questions? 10 National Grid Network Modelling Software Review

Angus Paxton angus. paxton@poyry. com +44 1865 812263 Andy Morris andrew. morris@poyry. com +44 1865 812212 Pöyry Energy Consulting King Charles House Park End Street Oxford, UK OX 1 1 JD +44 (0)1865 722660 www. poyry. com www. ilexenergy. com Pöyry Energy (Oxford) Ltd. Registered in England No. 2573801. King Charles House, Park End Street, Oxford OX 1 1 JD. National Grid Network Modelling Software Review

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