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European 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.

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International audienceIn this study, algorithms for directional relays using only current measurements are presented. Developed for radial distribution networks, these algorithms will determine fault direction based on ratios between variations of sequence currents during and before faults: ΔI 2/ΔI 0 ratio for line-to-ground faults and the ΔI 2/ΔI 1 ratio for line-to-line faults. The ratios are used as input of a support vector machine classifier, which was trained beforehand thanks to simulation tools. The classifier classifies ratios into two categories, according to the fault location: upstream or downstream towards the relay. Test results from simulations show good performances of the algorithms in most cases, with the presence of different distributed generation technologies. Moreover, impact of certain factors on algorithms, such as measurement errors, high-impedance faults or network reconfiguration, is studied. Finally, the implementation of algorithms is also discussed

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