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Dissertation
Modulation strategies of integrated HVAC systems used in residential buildings for demand-side management at different scales : dissertation presented in partial fulfillment of the requirements for the degree of doctor in engineering sciences
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Year: 2017

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Dissertation
Investigation of a Flooded Expansion Organic Rankine Cycle system
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Year: 2012 Publisher: [S.l.] : [chez l'auteur],

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Dissertation
Integration of heat demand and demand response in power systems to cover the flexibility requirements linked to high shares of variable renewable energy
Authors: --- --- --- ---
Year: 2017 Publisher: Liège Université de Liège (ULiège)

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Increasing the share of renewable energy generation in the generation mix is one of European's objectives. Increasing renewable generation sources complicates the power grid management. In particular, the variability of such energy sources increases the complexity of maintaining the demand-supply balance. More flexibility is needed.
The goal of this master thesis is to assess the potential of residential heating demand management to meet the flexibility needs linked to high shares in renewable generation. To that end, a heat demand model is developed and coupled to an existing unit commitment and dispatch model of the power system. The residential heating demand considered consists in the space heating demand and the domestic hot water demand and is coupled to the power system through flexible electric heating devices (heat pumps and domestic hot water heaters).
Several simulations are performed for Belgium. The potential benefits in 2015 are assessed. Then a parametric analysis is performed assessing the influence of the flexible devices penetration, the renewable capacity and the flexibility of the capacity mix. 
Results show operational cost benefits up to 35M€ and curtailment reduction up to 1 TWh with 1 million flexible electric heating systems. These benefits are reduced significantly when non-flexible units are replaced by flexible units and are increased when more renewable capacity is added. Moreover, when the number of flexible heating systems are increased, a saturation effect of the flexibility is observed.

In conclusion, the heat demand is able to provide non-negligible flexibility to the power system through flexible electric heating devices. The benefits due to the additional flexibility are increased when the flexibility need of the system increases and especially when more renewable energy is available. Results show that non negligible curtailed energy can be captured by the thermal storage when high shares of renewable capacity exist.


Dissertation
Investigation of different strategies to improve the performance and the self-consumption potential of a GCHP system with buffer storage and PV panels
Authors: --- --- --- ---
Year: 2017 Publisher: Liège Université de Liège (ULiège)

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During the last years, the interest for ground coupled heat pump (GCHP) and for renewable technologies has grown in the field of single-housold buildings. This work consists above all in creating a realistic environment for a single-family house equipped with PV and GCHP and simulating it with the TRNSYS program during January and February. In addition, this work has two other objectives.
First, the effects of cycling on the heat pump only have been assessed. The results show that promoting longer running times could increase the performances of the heat pump. However, considering the entire system, it seems that extending the minimum running time of the heat pump has no positive effect on the overall performance except reducing the total number of cycles, whose benefits are not measurable.
The second part of this work consists in improving the self-consumption potential of the system by increasing the consumption of PV generated electricity as much as possible. It is done by storing thermal energy into the building and into the buffer storage tank during power generation. The economical perspective is not taken into account. Two simple methods are presented. They both consist in increasing the set point temperatures of the rooms and of the storage tank but differ on the timing. Results show that the two methods could increase the self-consumption (also called supply cover factor) up to 61 % and 70 % respetively while the estimated overall achievable self-consumption is about 95 % (during January and February).


Dissertation
Development of a Unit Commitment and Optimal Dispatch model used to evaluate the effect of variable Renewable Energy Sources on the power system
Authors: --- --- --- --- --- et al.
Year: 2016 Publisher: Liège Université de Liège (ULiège)

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Abstract. The growing problem of climate change has risen global concerns about the way of using natural resources and has brought several initiatives such as the EU 2030 targets towards the cleaner energy production and the emissions reduction. The high penetration of Renewable energy Sources (RES) is considered as a remedy to this issue. However the higher integration of RES to the system is a rather challenging task for it's different components. Therefore there is a growing need for the introduction of higher flexibility to the system as a countermeasure for the unpredictable and unstable RES generation. 

In this report the flexibility potential coming from a portfolio of smart Domestic Hot Water Tanks (DHWT) is investigated. Their ability to provide Active Demand Response (ADR) in order to contribute to the more cost efficient electric system's operation is studied. These systems could allow to modify their electrical load pattern without affecting the final, thermal energy service they deliver, thanks to the thermal inertia of the system. The creation of a general model able to simulate the operation of DHWT is developed. This model is intended to be used in a unit commitment and power dispatch model in order to evaluate the contribution of Demand Side Management (DSM) into the higher RES integration. To accomplish this task first two detailed modeling approaches were followed. The first was was a Rule-Based Control (RBC) strategy able to simulate several thousands individual DHWT. This model was computationally efficient and allowed the simulation of 20000 tanks for 5 days with a sub-hourly operating time scale. The second analytical approach was a linear program (LP) that performed the same computation but for a decreased amount of tanks due to the high computational burden. In both models the ability of a centrally controlled (by an aggregator) portfolio to provide capacity and activation reserves are explored. The two approaches are compared in order to identify benefits and limitations. These models were the main guide towards the modeling of a Virtual Storage Plant (VSP) model. This model is able to follow and simulate the behavior of an increased number of DHWT without much detail. The assumptions made in the VSP model formulation are further explained. The ability of this model to perform in standard conditions and to participate in Demand Response operation are validated through the detailed models. This process lead to the creation of a VSP model that is able to simulate the behavior of a fleet of DHWT. The flexibility that can be offered along with the rate of RES penetration can be investigated by the integration of this model to Dispa-SET, a unit commitment and power dispatch model able to simulate the electric system.

Finally a part of this thesis is related to the improvement of the Dispa-SET simulations and the overall computed system's cost. This was performed by collecting yearly generation data available at Entso-e's website from thousands of generation units in Europe. Afterwards several methods were developed in order to acquire important real-time values for the simulation parameters. These methods are tailor made and are explained in detail. To our knowledge this is the first attempt to collect and process real time generation data for European units.


Dissertation
Modeling self-consumption from PV and home battery systems in Spain: economic impact of the regulatory framework
Authors: --- --- --- --- --- et al.
Year: 2016 Publisher: Liège Université de Liège (ULiège)

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The latest developments of battery technologies for solar applications have created high expectations in the field. Certain press articles claim that this new advances could revolutionize the solar energy sector and lead to autonomous residential PV systems or micro grids. Nevertheless, this assumptions lack of a proper scientific evaluation and it is still unclear when and under which circumstances battery storage can be viable without government subsidies or policy support.
This thesis explores the economical profitability of a grid connected PV system with and without battery in a standard dwelling in Spain for two different crucial moments of the Spanish photovoltaic regulation: 2008 when the solar energy boom occurred and 2016 when the solar energy sector is facing one of its weakest periods.
Three different scenarios have been evaluated to find out under which economic conditions, domestic batteries are profitable, considering the different changes in the photovoltaic legislation. Results indicate that latest change in the legislation, which eliminate FITs and add new fees to self-consumed electricity hinder the development of self-consumption. Concluding that without policy support battery storage is not yet economically feasible in Spain.

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