A THREE-PHASE FOUR-WIRE STATE ESTIMATOR ALGORITHM FOR LOW VOLTAGE NETWORKS MANAGEMENT

International audienceThe low voltage networks management plays even more a key role for distribution system operators due to the fast development of the distributed energy resources. European low voltage networks have particularities (four-wire, unbalance, small network at electric grid extremities) which should be considered when a state estimator is created. This paper presents a three-phase four-wire state estimator algorithm. To analyse the performance of this algorithm, we consider a LV test network

Characterization and Modeling of LV Cables Considering External Parameters for Distribution Networks

In response to the climate emergency, new uses are plugged to low voltage (LV) electrical networks. The development of self-consumption complicates the LV grid operation, and force distribution system operators (DSOs) to better model and characterize their networks. DSOs mainly use a three-conductor model (3 CM) to compute power flows, and consider error margins of 2% for voltage profiles to reflect their model inaccuracy. The characteristics of the future LV grids call into question these margins, and the models used. In this paper, a four-conductor model (4 CM), and an additional model named 4 CMext, that considers external parameters (i.e., cable temperature, ground electrical resistivity, and value/number of the earthing resistances) are proposed. The best model for cable characterization and voltage profile calculation is chosen; the 4 CMext is more adapted for the characterization, and corresponds with the finite element model, with an error margin of 4%, experimental measurements of 15%, and French cable manufacturer data of 0.5%. For the voltage profile, the 4 CMext provides a more detailed view of the critical cases that could lead to a violation of the limits of the EN 50160 standard than 3 CM and 4 CM. Violations of high or low voltages are underestimated by two to six times by the 3 CM and 4 CM. Not considering external parameters can lead to a voltage profile error of above 3%. In this paper, we recommend that DSOs use the 4 CMext to represent LV networks, which would allow LV networks to be used closer to their physical limits, and avoid or postpone network reinforcements

Modélisation de l’impédance des câbles : Étude de sensibilité et impact sur le réseau BT

International audienceAvec le déploiement massif de nouveaux clients sur le réseau basse tension (BT), des écarts importants entre les calculs fournis par les modèles et les mesures du terrain sont observés par les gestionnaires de réseaux. Cette problématique est particulièrement vraie sur les réseaux BT dont les caractéristiques sont connues avec moins de précision. En particulier, les modèles de liaison restent à améliorer avec la spécificité du conducteur de neutre. Ce papier s’intéresse aux principales dépendances de la matrice d’impédance des câbles BT.Elles seront étudiées avec une approche éléments finis sous FiniteElement Method Magnetics(FEMM)et avec une approche analytique. L’impact de ces dépendances sera mis en avant dans l’étude des réseaux BT en utilisant le logicielPower Factory(PF)

Impact of environmental conditions on the voltage profile of LV networks

International audienceEuropean distribution system operators (DSOs) should meet EN 50160 standard requirements on the whole network. With the development of distributed energy resources (DER), DSOs need to have a better insight of their low voltage (LV) networks. In this paper, we study the joint impact of external conditions (cable temperature, the ground resistivity and the ground resistances) on the voltage profile of three LV networks in four cases. The results show that some voltage problems cannot be seen by using only usual values of those external conditions. By considering the values that are closer to the real conditions, the voltage analysis will be more accurate and in some cases, additional problems can be detected. To be sure that the EN 50160 standard is met, a global study of LV networks including the external conditions should be done

Estimation des paramètres d'un câble LVAC pour une utilisation dans un réseau LVDC

Despite the rise of LVDC grids, the type of cable to use is still debated. An interesting solution would be the reused AC cables. Through experimental measurements and comparison with an analytical model, this works provides values for steady state and transient analysis of a French distribution cable in DC grids.Malgré l'essor des réseaux LVDC, le type de câble à utiliser fait toujours l'objet d'un débat. Une solution intéressante consisterait à réutiliser des câbles à courant alternatif. Grâce à des mesures expérimentales et à une comparaison avec un modèle analytique, ce travail fournit des valeurs pour l'analyse en régime permanent et en régime transitoire d'un câble de distribution français dans les réseaux à courant continu