Prévision à court terme de la demande électrique des maisons intelligentes et des réseaux de distribution

This thesis is devoted to the short-term forecasting of electricity demand of smart homes and distribution grids. The household demand data provided by smart meters is analyzed to characterize the electricity demand at the local scale and compared to this at the regional scale, so as to examine the aggregation effect. This thorough analysis enables the designing of models that forecast the future demand. The models make use of advanced statistical tools and machine-learning techniques. The inputs are selected with special care for their relevancy to the household demand. To be deployed in an operational environment, the models must be replicable: low to no maintenance, adaptability to various situations, and robustness to the lack of data. Several demand forecasting products are developed and compared to actual datasets: probabilistic forecasts at different temporal and spatial resolutions, and daily demand scenarios. Finally, the habits related to a domestic appliance, namely the charging of an electric vehicle battery, are modeled in order to generate forecasting scenarios of the appliance demand.Cette thèse s’intéresse à la prévision à court terme de la demande électrique d’une maison intelligente et des réseaux de distribution. Les données mesurées par les compteurs intelligents permettent de caractériser la demande électrique à l’échelle d’une maison et de la comparer à la demande régionale, pour étudier notamment l’effet de foisonnement. Cette analyse permet de développer des modèles de prévision de cette demande. Ces modèles sont de nature statistique et font usage de méthodes d’apprentissage automatique. Un soin particulier est porté à la sélection de variables d’entrée pertinentes. Afin d’être déployés dans un environnement opérationnel, les modèles doivent faire preuve de réplicabilité : fonctionnement autonome, aptitude à s’adapter à de multiple situations, et robustesse face aux données erronées. Plusieurs produits de prévision sont développés et évalués avec plusieurs jeux de données : des prévisions probabilistes à différentes résolutions, et des scénarios journaliers de la demande. Enfin, les habitudes relatives à un usage électrique particulier, à savoir le chargement d’une batterie de véhicule électrique, sont modélisées pour produire des scénarios prédictifs de la demande de cet usage spécifique

Modeling Electric Vehicle Consumption Profiles for Short-Term Forecasting and Long-Term Simulation

International audienceThe growing number of electric vehicles (EV) is challenging the traditional distribution grid with a new set of consumption curves. We employ information from individual meters at charging stations that record the power drawn by an EV at high temporal resolution (i.e. every minute) to analyze and model charging habits. We identify 5 types of battery that determine the power an EV draws from the grid and its maximal capacity. In parallel, we identify 4 main clusters of charging habits. Charging habits models are then used for two applications: short-term forecasting and long-term simulation. We start by forecasting day-ahead consumption scenarios for a single EV. By summing scenarios for a fleet of EVs, we obtain probabilistic forecasts of the aggregated load, and observe that our bottom-up approach performs similarly to a machine-learning technique that directly forecasts the aggregated load. Secondly, we assess the expected impact of the additional EVs on the grid by 2030, assuming that future charging habits follow curren behavior. Although the overall load logically increases, the shape of the load is marginally modified, showing that the current network seems fairly well-suited to this evolution

Modeling and Forecasting Electric Vehicle Consumption Profiles

International audienceThe growing number of electric vehicles (EV) is challenging the traditional distribution grid with a new set of consumption curves. We employ information from individual meters at charging stations that record the power drawn by an EV at high temporal resolution (i.e., every minute) to analyze and model charging habits. We identify five types of batteries that determine the power an EV draws from the grid and its maximal capacity. In parallel, we identify four main clusters of charging habits. Charging habit models are then used for forecasting at short and long horizons. We start by forecasting day-ahead consumption scenarios for a single EV. By summing scenarios for a fleet of EVs, we obtain probabilistic forecasts of the aggregated load, and observe that our bottom-up approach performs similarly to a machine-learning technique that directly forecasts the aggregated load. Secondly, we assess the expected impact of the additional EVs on the grid by 2030, assuming that future charging habits follow current behavior. Although the overall load logically increases, the shape of the load is marginally modified, showing that the current network seems fairly well-suited to this evolution

Robust Day-Ahead Forecasting of Household Electricity Demand and Operational Challenges

In the recent years, several short-term forecasting models of household electricity demand have been proposed in the literature. This is partly due to emerging smart-grid applications, which require these kinds of forecasts to manage systems such as smart homes, prosumer aggregations, etc., and partly thanks to the availability of data from smart meters, which enable the development of such models. Since most models are academically developed, they often do not address challenges related to their implementation in a real-world environment. In the latter case, several issues arise, related to data quality and availability, which affect the operational performance and robustness of a forecasting system. In this paper, we design a hierarchical forecasting framework based on a total of 5 probabilistic models of varying complexity, after analyzing the respective performance and advantages of the models with an offline dataset. This multi-layered framework is necessary to address the various problematic situations occurring in practice and abide by the requirements for a real-world deployment. The forecasting system is deployed in a real-world case and evaluated here on data from 20 households. Field data, comprising forecasts and measurements, are analyzed for each household. A detailed comparison is drawn between the online and offline performances. Since a notable degradation is observed in the operational environment, we discuss at length the reasons for such an effect. We determine that the exact settings of the training and test periods are marginally responsible, but that the main cause is the intrinsic evolution of the demand time series, which hinders the forecasting performance. This evolution is due to unknown household characteristics that need to be monitored to provide more adaptable models

A novel method for decomposing electricity feeder load into elementary profiles from customer information

International audienceTo plan a distribution grid involves making a long-term forecast of sub-hourly demand, which requires modeling the demand and its dynamics with aggregated measurement data. Distribution system operators (DSOs) have been recording electricity sub-hourly demand delivered by their medium-voltage feeders (around 1000—10,000 customers) for several years. Demand profiles differ widely among the various considered feeders. This is partly due to the varying mix of customer categories from one feeder to another. To overcome this issue, elementary demand profiles are often associated with customer categories and then combined according to a mix description. This paper presents a novel method to estimate elementary profiles that only requires several feeder demand curves and a description of customers. The method relies on a statistical blind source model and a new estimation procedure based on the augmented Lagrangian method. The use of feeders to estimate elementary profiles means that measurements are fully representative and continuously updated. We illustrate the proposed method through a case study comprising around 1000 feeder demand curves operated by the main French DSO Enedis. We propose an application o that uses the obtained profiles to evaluate the contribution of any set of new customers to a feeder peak load. We show that profiles enable a simulation of new unmeasured areas with errors of around 20%. We also show how our method can be used to evaluate the relevancy of different customer categorizations

Probabilistic Day-Ahead Forecasting of Household Electricity Demand

International audienceForecasting electricity demand at the local level of a building up to a feeder is increasingly necessary in several applications in the smart-grids context. Actors like aggregators and retailers, and tools like home energy management systems, require such forecasts as input. In this paper, a probabilistic day-ahead forecasting model is proposed to predict hourly electrical demand from individual households. This stochastic model uses smart-meter data and temperature predictions to make quantile forecasts. Performance is evaluated using data from a real-life smart grid demonstration site developed in Évora, Portugal as part of the European project SENSIBLE. The proposed model consistently outperforms a persistence model and provides reliable probabilistic forecasts

Stochastic operation of home energy management systems including battery cycling

International audienceThe present work proposes a stochastic approach for Day-Ahead operation of Home Energy Management Systems when batteries, solar photovoltaic resources and Electric Water Heaters are considered. The optimization problem minimizes the operation costs formed by energy procurement in the wholesale market and the equivalent cycling aging cost of the batteries, and also includes the uncertainty of the PV production and the load. The complete two-stage stochastic formulation results in a Mixed-Integer Nonlinear Programming problem that is decomposed using a Competitive Swarm Optimizer to handle the calculation of the battery cycling aging cost. A Storage Disaggregation Algorithm based on Lagrangian relaxation is used to reduce the problem size and to allocate individual State of Charge for the batteries. In addition, the advantages of considering a stochastic approach are shown by means of the Value of the Stochastic Solution. This methodology has been developed in the context of the Horizon 2020 project SENSIBLE as part of the tasks related to a use case that considers an aggregator that participates in the electricity market with a portfolio of prosumers with active demand capability

Optimal Scheduling of Storage Devices in Smart Buildings Including Battery Cycling

International audienceThis paper presents an optimization model for energy management in smart buildings, when electrochemical and thermal storage are considered as flexibilities to achieve minimum operation costs. The optimization problem takes into account the battery’s cycling cost and the possibility of storing energy in the electric water heater. To deal with the cycling aging process, the problem is decomposed into two subproblems that are iteratively solved, in which a Particle Swarm Optimization decides the battery’s State of Charge and then a day-ahead dispatch takes place to determine the total operation cost. This approach allows us to deal with the non-linearities of battery aging in a simple an effective way. The results show that the potential presence of both storage technologies has a positive impact on the operation costs; they also show the impact on the device settings when battery’s cycling aging cost is considered. This methodology has been developed in the context of the Horizon 2020 project SENSIBLE as part of the tasks related to the use case, Flexibility and Demand Side Management in Market Participation

Day-Ahead Management of Smart Homes Considering Uncertainty and Grid Flexibilities

International audienceThis paper presents an optimization model for Home Energy Management Systems from an aggregator's standpoint. The aggregator manages a set of resources such as PV, elec-trochemical batteries and Thermal Energy Storage by means of Electric Water Heaters. The resources are managed in order to participate in the day-ahead energy market, considering also local flexibility needs. The resulting model is a mixed-integer linear programming problem in which the aim is to minimize day-ahead operation costs for the aggregator while complying with DSO flexibility constraints in the form of maximum allowed net power exchange and ramping limits. Three sources of uncertainty are considered: day-ahead energy prices, PV production and load. Kernel Density Estimator and a backward reduction algorithm are used to create price scenarios and Robust Optimization is used to model PV and load uncertainties. The obtained results show the changes in the operation of the aggregator when grid flexibilities are considered and the impacts on the operation costs. In addition, a proposal for bidding in local flexibility markets is shown

Residential Electrical and Thermal Storage Optimisation in a Market Environment

International audienceThis paper presents a method for the energy management of a set of smart homes, in which batteries, thermal storage and demand response are considered as flexibilities in order to achieve minimum operation costs. To cope with the uncertainty of load forecast, a two-stage stochastic optimization process is proposed, in which the first stage decision is the committed energy to be purchased, and the second stage returns the devices’ set-points. This methodology has been developed in the context of the Horizon 2020 project SENSIBLE as part of the tasks related to the use case, Flexibility and Demand Side Management in Market Participation