Integrated modelling of electrical and gas transmission networks in multi-energy systems

  • Stephen Clegg

Student thesis: Phd


The scope of this thesis is an investigation into the interactions between the gas and electrical transmission networks in the context of a low-carbon energy system with explicit considerations of the role played by multi-energy vectors, including heating, in future scenarios.Many energy systems are in a state of transition due to the growing need to reduce their carbon impact while maintaining reliability and reducing costs. The generation capacity of gas-fuelled power stations, as a cleaner alternative to coal, has been continuing to grow in many power systems. Furthermore, their operational characteristics are evolving as they are increasingly used to meet demand when there is a shortfall in renewable generation and are playing a role in contributing to the reliability of the power system. Additionally, changes to the heating sector (e.g., the electrification of heat or the increased use of combined heat-and-power) and the introduction of power-to-gas (to convert excess renewable electricity into hydrogen for successive energy generation) all lead to tighter interactions between the heat, gas and power sectors which require a multi-energy framework to assess.In this work this is achieved, firstly, through the development of integrated gas and power network modelling techniques. The power system modelling incorporates a multi-temporal DC optimal power flow, while gas network models use steady-state and transient flow analysis to allow for an assessment of the pressures and flows around the network. Additionally, a novel heat model is presented for a regional assessment of the heating demands of the British energy system, so that the impacts of changes to heating technologies on the gas and electrical transmission networks can be quantified in whole-energy system case studies.Power-to-gas technologies where (excess renewable) electrical energy is converted to hydrogen and then potentially synthetic natural gas which is then injected into the gas network where it can be stored and transported have the potential to increase the integration of renewable resources and reduce the carbon impact of both electricity and heating sectors. Models are presented which assess the operation of power-to-gas and its impact on the gas and electrical transmission networks as well as the benefits to the energy system. This uses power system modelling to assess the excess renewable energy (from wind and solar resources) that can be used in the power-to-gas process, with the amounts of produced hydrogen and synthetic natural gas also being evaluated considering constraints imposed by the gas network. The resulting case studies evaluate the impact on the gas and electrical networks and the benefit to the energy system by displacing natural gas and reducing carbon emissions.To assess the extent to which gas power stations can change their output to follow changes in renewable generation output, an integrated gas and electrical network flexibility model has been developed. This uses the notion of zonal linepack flexibility and allows for limits to be applied to the ability of gas turbines to change their output over the forthcoming hours with consideration of the intermittent nature of renewable generation.The developed models and methodologies are incorporated into a number of case studies using the British gas and electrical networks and heating sector showing their applicability to assessing future energy system needs.
Date of Award1 Aug 2017
Original languageEnglish
Awarding Institution
  • The University of Manchester
SupervisorPierluigi Mancarella (Supervisor) & John Moriarty (Supervisor)

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