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Integrated modelling and optimization of coupled electricity and heating networks

The coupling between the electricity and heating networks is increasing due to the integration of co- and poly-generation technologies at the distribution networks. This project aims at modelling, simulating and optimization of multi-energy systems (MES) in general, and coupled heating and electricity networks in particular, with the full consideration of networks' physical and operational parameters. The project lays down the ground for better management of smart electricity grids and smart thermal grids in an integrated way so that district/urban energy systems can be operated in a cost effective, secure and efficient way.

Funded by:

This research is performed within the framework of the Erasmus Mundus Joint Doctorate SELECT+ program ‘Environomical Pathways for Sustainable Energy Services’ and funded with support from the Education, Audiovisual, and Culture Executive Agency (EACEA) (FPA-2012-0034) of the European Commission.​

Time period:

Oct 2016 - Oct 2020

Project partners:

The research is conducted under the SELECT+ Joint Doctoral program framework between KTH Royal Institute of Technology (Sweden) and IMT Atlantique (France).


Energy systems at district/urban level are getting more complex and diversified from time to time. Coupling different energy carriers in the form of multi-energy systems (MES) is reported to have a better environmental and economic performance relative to the conventional (single-carrier) energy systems. One of such a promising MES is the combination of district heating and electricity networks. The coupling between these two networks is increasing due to the integration of co- and poly-generation technologies at the distribution networks. Electrification of district heating networks, especially using heat pumps, is also widely recommended in literature. Due to lack of suitable modelling tools, however, it is challenging to get the details of operational parameters of coupled electricity and heating networks at the same time. Recently, literatures tried to model load flow problems of lightly coupled networks for very specific network topologies.

In this project, a more general and flexible load flow model of MES is developed using an extended energy hub approach. All local generations and detailed network parameters of MES are taken into account. The model is developed using Matlab® and illustration is made by taking case studies of electricity and heating networks that are strongly coupled using combined heat and power (CHP) plants and heat pumps. Additional submodules are developed considering the interaction between electricity, heat and fuel in the energy hubs consisting of solar PV, heat pumps, CHPs and gas boilers. Hourly variations in the electrical and thermal loads, solar radiation, and scheduling of the energy technologies are considered to demonstrate the capacity of the proposed model in capturing the pseudo-dynamic operating parameters of the two networks. The influence of coupling technologies on both networks is illustrated and hourly variations of operating parameters are discussed.

Scenario-based comparative study shows that the location of heat pumps’ in the network influences the loss and operating cost of the overall system. A methodology based on nested particle swarm optimization is then proposed to find the optimal placement and size of heat pumps in a large district energy system. The results of an integrated optimization applied on the case study show that a better voltage profile, a reduction of up to 41.2% of the electric loss and reduction of 5% of the overall operating cost can be achieved when compared to the optimization that considers only the heating network.

It is also found that meshed district heating networks have a relatively higher loss than radial networks. Additional study is made on topology reduction of meshed networks using energy and exergy analysis. Thermo-economic optimization is then applied to determine the most economical supply temperature of the heat sources and return temperatures of the heat consumers.

The tool developed is very promising. Further study will be made on integration of thermal storage, thermo-economic optimization in time series and competitiveness analysis of heat pumps and gas fired CHPs for different price signals and different network topology. The tool is also flexible enough to consider optimization of district energy systems at planning phase.

Aim and objectives

The main objective is to develop a general framework that can be used to model multi-carrier energy networks and simulate multi-energy systems in an integrated way. Then detailed models and optimization algorithms will be developed for coupled electricity and heating networks consisting of various distributed energy technologies.


  • A general modelling framework is developed using An Extended Energy Hub Approach.
  • The model is applied on heating and electricity networks consisting of heat pumps, combined heat and power plants, wind turbines, solar PV and gas boilers.
  • Optimization algorithm is integrated into the model and applied for operating cost optimization and optimal placement of heat pumps.
  • Exergy analysis is combined with load flow study to identify lossy branches in an electrified district heating network.


G. T. Ayele, P. Haurant, B. Laumert, and B. Lacarrière, “An extended energy hub approach for load flow analysis of highly coupled district energy networks: Illustration with electricity and heating”, Appl. Energy, vol. 212, pp. 850–867, Feb. 2018.

G. T. Ayele, P. Haurant, B. Laumert, and B. Lacarrière, “Pseudo-dynamic simulation on a district energy system made of coupling technologies”, ECOS 2018, Guimaraes, Portugal: Jun 2018.

G. T. Ayele, M. T. Mabrouk, P. Haurant, B. Laumert, B. Lacarrière and M. Santarelli, “Exergy analysis and thermo-economic optimization of a district heating network with heat pumps”, ECOS 2019, Wroclaw, Poland, Jun 2019.

G. T. Ayele, M. T. Mabrouk, P. Haurant, B. Laumert, and B. Lacarrière, “Optimal placement and sizing of heat pumps in a coupled electricity and heating networks”, Energy, vol. 182, pp. 122–184, Sep. 2019

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