Exploiting the Synergies from Coupled Electricity and Heat Distribution Networks : Modelling, simulation and optimization based on an extended energy hub approach

Abstract: Recent literature shows that there is a significant potential of decarbonisation and efficiency improvement that can be achieved through the synergy from multi-energy systems (MESs). Coupling technologies, such as co-generation plants, heat pumps and thermal storages are widely recommended as means of unlocking additional flexibility and increasing the penetration of renewables in the heating and electricity sectors. In view of that, the size and number of coupling technologies, such as combined heat and power plants and heat pumps (HPs), being installed in the heat distribution networks are increasing. As these technologies are exclusively managed by the district heating network operators, their operation sometimes becomes suboptimal from the electricity network point of view, and they (in particular large HPs) may cause overloading of the low voltage electricity distribution networks.Integrated simulation and optimisation models are required to exploit the synergies effectively without compromising the constituent distribution networks of MES. Such models are not yet well developed. The conventional single-energy-carrier simulation tools are not capable of capturing key operating parameters of the multi-carrier distribution networks either.A novel methodology for simulation and optimisation of MES is developed in this thesis based on an Extended Energy Hub (EEH) approach. The general framework is first developed in modular form so that it can be easily adapted for any type of multi-carrier energy networks. The framework is then used to develop the details of an integrated load flow model governing coupled heating and electricity distribution networks. Various load flow case studies with radial and meshed topologies are considered for demonstration and numerical validation of the proposed model.The load flow model is further combined with a particle swarm optimisation algorithm in order to conduct integrated optimal power flow studies. Its contribution to the state of art is demonstrated by studying the optimal placement of coupling technologies, such as HPs and boilers in coupled heating and electricity distribution networks. The capacity of the model is further illustrated by exploiting the synergies using HPs together with thermal storage in the presence of intermittent renewables and variable electricity price signal.It is shown that the EEH-based simulation and optimisation methodologies proposed in this thesis are very effective, flexible and easily scalable in capturing the key operating parameters of integrated electricity and district heating networks. The models can be used as a platform for further studies on integration of smart grids and smart thermal networks.

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